Chapter 28: Carboxylic Acids and Their Derivatives PDF

60 1306 Carboxylic acids and Their derivatives Chapter E3 28 Carboxylic acids and Their derivatives [O} ID Carboxylic acids are the compounds containing D YG (1) Carboxylic acids are classified as monocarboxylic acids, dicarboxylic acids, tricarboxylic acids etc. depending on the number of – COOH gr...

60 1306 Carboxylic acids and Their derivatives Chapter E3 28 Carboxylic acids and Their derivatives [O} ID Carboxylic acids are the compounds containing D YG (1) Carboxylic acids are classified as monocarboxylic acids, dicarboxylic acids, tricarboxylic acids etc. depending on the number of – COOH groups present in the molecule. CH 3 COOH C H 2 COOH C H 2 COOH CH 2 COOH C HCOOH | | | U CH 2 COOH Monocarbox y lic acid Dicarboxy lic acid K 2 Cr2 O7 Carboxylic acid K 2 Cr2O7 [O ] RCHO   Aldehy de The carboxyl group is made up of carbonyl (>C=O) and hydroxyl (–OH) group. Classification alcohol RCOOH monocarbox y lic acid  Aldehyde can be oxidized to carboxylic acid with mild oxidising agents such as ammonical silver U     the carboxyl functional group  – C – OH   ||   O  [O ] RCH 2 OH  RCHO   RCOOH Carboxylic Acids nitrate solution [ Ag 2 O or Ag (NH 3 )2 OH  ]  Methanoic acid can not be prepared oxidation method.  Ketones can be oxidized under drastic conditions using strong oxidising agent like K 2 Cr2 O7.  Methyl ketones can also be converted to carboxylic acid through the haloform reaction.  R – C  CH 3  3 I 2  3 NaOH  || H 2O O R  C  OH  CHI 3  3 NaI  3 H 2 O || Tricarboxylic acid ST (2) Monocarboxylic acids of aliphatic series are commonly known as fatty acids such as palmitic acid (C15 H 31 COOH ) and stearic acid C17 H 35 COOH . (3) The general formula for monocarboxylic acids is Cn H 2n 1COOH or Cn H 2n O2. Where n = number of carbon atoms. (4) The carboxylic acids may be aliphatic or aromatic depending upon whether – COOH group is attached to aliphatic alkyl chain or aryl group respectively. Methods of preparation of monocarboxylic acid (1) By oxidation of alcohols, aldehydes and ketones by O (2) By Hydrolysis of nitriles, ester, anhydrides and acid chloride (i) Hydrolysis of nitriles  HCl R  C  N  HOH  R  C or NaOH  R C OH  Rearrangem ent    NH  O H O 2  RCOOH  NH 4 Cl NH 2 HCl (ii) Hydrolysis of Esters HCl RCOOR ' HOH  RCOOH  R ' OH Ester OH  Acid (iii) Hydrolysis of Anhydrides Alcohol Carboxylic acids and Their derivatives 1307 (vi) From acid amides O || CH 3  C CH 3  C  H / OH  Acid RCONH 2  H 2 O  RCOOH  NH 3 O  HOH  2CH 3 COOH Ethanoic acid || or Alkali Amide Acid RCONH 2  HNO 2 RCOOH  N 2  H 2 O O Ethanoic anhydride Amide (iv) Hydrolysis of acid chloride and nitro alkane Nitrous acid Physical properties of monocarboxylic acids H  / OH  R  C  Cl  HOH  RCOOH  HCl (1) Physical state : The first three members (upto 3 carbon atoms) are colourless, pungent smelling liquids. The next six members are oily liquids having unpleasant smell. The higher members are colourless and odourless waxy solids. || O 85 % H SO 60 2 4 R  CH 2  NO 2    RCOOH R C X   X  3 NaOH  R  C  X OH    H 2O OH    OH  O  3 NaX OH R C    O Dry ether || O  C  O  RMgX   R  C  OMgX Carbon dioxide Grignard reagent H / H O 2   RCOOH  Mg(OH )X H PO 4 CH 2  CH 2  CO  H 2 O 3 CH 3 CH 2 COOH D YG 500 1000 atm &350 C (5) Special methods (i) Carboxylation of sodium alkoxide HCl RONa  CO RCOONa  RCOOH Sod. salt Acid (ii) Action of heat on dicarboxylic acid R  CH  The solubility of lower members of carboxylic acids is due to the formation of hydrogen bonds between the – COOH group and water molecules.  Acetic acid exists in the solution in dimer form due to intermolecular hydrogen bonding. The observed molecular mass of acetic acid is 120 instead of 60. U (4) From Alkene or Hydro-carboxy-addition (koch reaction) Sod. alkoxide acids are soluble in alcohol, ether and benzene etc. ID (3) From Grignard Reagent (2) Solubility : The lower members of the aliphatic carboxylic acid family (upto C4) are highly soluble in water. The solubility decreases with the increase in the size of the alkyl group. All carboxylic E3 (v) Hydrolysis of Trihalogen : COOH  CO 2   R  CH 2 COOH COOH heat Monocarbox ylic acid U Substituted malonic acid (3) Melting point (i) The melting points of carboxylic acids donot vary smoothly from one member to another. (ii) The melting point of the acids having even number of carbon atoms are higher than those containing an odd number immediately above and below them. (iii) The acids with even number of carbon atoms have the – COOH group and the terminal – CH3 group on the opposite side of the carbon chain. (iv) In the case of odd numbers, the two groups (iii) From acetoacetic ester ST CH 3 COOH CH 3 CO CHRCO O C 2 H 5 Hydrolysis   RCH 2 COOH  C 2 H 5 OH OH H OH H (iv) Oxidation of alkene and alkyne [O ] RCH  CH R    RCOOH  R COOH Alkene Hot alkaline KMnO 4 (i)O 3 R  C  C  R   R  COOH  R COOH Alkyne (ii)H 2 O (v) The Arndt-Eistert synthesis H O R  C  Cl  CH 2 N 2 R  C  CHN 2 2 || || O O Ag 2O R  CH 2  COOH lie on the same side of the chain. CH2 CH3 CH2 COOH CH2 the two terminal groups lie on the opposite sides of the chain CH3 CH2 CH2 COOH the two terminal groups lie on the same side of the chain When the terminal groups lie on the opposite sides the molecules fit into each other more closely. More effective packing of the molecule in the lattice. Therefore, results into higher melting point. (4) Boiling point : Boiling point of carboxylic acids increase regularly with increase of molecular 1308 Carboxylic acids and Their derivatives mass. Boiling points of carboxylic acids are higher than those of alcohols of same molecular mass. This is due to intermolecular hydrogen bonding between two acid molecules. similarly : CCl 3 COOH  CHCl 2COOH  CH 2ClCOOH  CH 3 COOH H–O CH3 – C (iii) Inductive effect is stronger at -position than position similarly at -position it is more stronger than at  - C – CH3 O O–H position Hydrogen bonding Acetic acid dimer Example: CH 3  CH 2  C H  COOH  CH 3  C H  CH 2  COOH Acidic nature of monocarboxylic acids |  C H 2  CH 2  CH 2  COOH (i) A molecule of carboxylic acid can be represented as a resonance hybrid of the following structures... O: ..  O H  R .. (iv) Relative acid strength in different compounds RCOOH  HOH  ROH  HC  CH  NH 3  RH   Greater the value of Ka or lesser the value of pK a C  O H.. stronger is the acid, i.e. pK a = – log K a (II)  Acidic nature ( K a )  1/molecular weight U (I) | | Cl ID O: D YG (ii) Due to electron deficiency on oxygen atom of the hydroxyl group (Structure II), their is a displacement of electron pair of O–H bond toward the oxygen atom. This facilitate the release of hydrogen as proton (H+). R C  O  O  H   R  C  O  R C O O  R  C O O O Resonance hy brid  1.27 A  1.27 A   U (iii) The resulting carboxylate ion also stabilized by resonance (As negative charge is dispersed on both the oxygen atom). This enhance the stability of carboxylate anion and make it weaker base or strong acid. ST (i) An electron withdrawing substituent (– I effect) stabilizes the anion by dispersing the negative charge and therefore increases the acidity. O  O (I)  GC  The formic acid is strongest of all fatty acids.  Acetic acid is less weak acid than sulphuric acid due to less degree of ionisation. Chemical properties of monocarboxylic acids (1) Reaction involving removal of proton from – OH group (i) Action with blue litmus : All carboxylic acids turn blue litmus red. (ii) Reaction with metals 2CH 3 COOH  2 Na 2CH 3 COONa  H 2 O  O 2CH 3 COOH  Zn (CH 3 COO )2 Zn  H 2 Zinc acetate (iii) Action with alkalies CH 3 COOH  NaOH CH 3 COONa  H 2 O Acetic acid  (II) (ii) An electron releasing substituent (+ I effect) stabilizes negative charge on the anion resulting in the decrease of stability and thus decreased the acidity of acid. K a Value HCOOH  CH 3 COOH  C 2 H 5 COOH 17. 7  10  5 1.75  10  5 1.3  10  5 Sodium acetate (2) Effect of substituent on acidic nature GC | Cl E3 Cl (1) Cause of acidic nature.. 60 O R C Thus, the acidic strength decreases in the order : FCH 2COOH  ClCH 2COOH  BrCH 2COOH  ICH 2COOH Hydrogen bonding || Electron with drawing nature of halogen : F > Cl > Br > I Sodium acetate (iv) Action with carbonates and bicarbonates 2CH 3 COOH  Na 2 CO 3 2CH 3 COONa  CO 2  H 2 O Sod. acetate CH 3 COOH  NaHCO 3 CH 3 COONa  CO 2  H 2 O Sod. acetate  Reaction of carboxylic acid with aqueous sodium carbonates solution produces bricks effervescence. However most phenols do not produce Carboxylic acids and Their derivatives effervescence. Therefore, this reaction may be used to distinguish between carboxylic acids and phenols. (2) Reaction involving replacement of –OH group (i) Formation of acid chloride CH 3 COOH  PCl 5 3 CH 3 COCl  POCl 3  HCl 3 CH 3 COOH  PCl 3 3 CH 3 COCl  H 3 PO 3 (ii) Heating of calcium salts Acetyl chloride heat Sodium salt Conc.H2SO  Ethyl alcohol 4 OC 2 H 5 Ethyl acetate (Fruity smelling) (a) The reaction is shifted to the right by using excess of alcohol or removal of water by distillation. reactivity of Ketone (iii) Electrolysis : (Kolbe's synthesis) CH 3 COOC 2 H 5  H 2 O alcohol towards RCOONa ⇌ RCOO   Na  At anode 2 RCOO  R  R  2CO 2  2e  2 At cathode 2 Na   2e  2 Na   2 NaOH  H 2 2H O Electrolysis 2CH 3 COOK  2 H 2 O  Potassium acetate ID (b) The esterification. 60 (RCOO )2 Ca  RCOR  CaCO 3 (ii) Formation of esters (Esterification) Acetic acid tert-alcohol < sec-alcohol < pri-alcohol < methyl alcohol (c) The acidic strength of carboxylic acid plays only a minor role. D YG When methanol is taken in place of ethanol. then reaction is called trans esterification. (iv) Formation of amides  heat CH 3 COOH  NH 3  CH 3 COONH 4  Amm. acetate CH 3 CONH 2  H 2 O Acetamide (v) Formation of acid anhydrides CH 3 COO H CH 3 CO Heat   O  H 2O CH 3 CO OH P2 O 5 CH 3 CO Acetic acid Acetic anhydride U (vi) Reaction with organo-metallic reagents ether ST R' CH 2 MgBr  RCOOH  R ' CH 3  RCOOMgBr Alkane (3) Reaction involving carbonyl (>C = O) group: LiAlH 4 Reduction : R  C  OH  R  CH 2  OH || O (4) Reaction involving attack of carboxylic group (– COOH) O || (CO ) 2 (i) Decarboxylation : R  C  OH  R  H Ethane heat CH 3 COOAg  Br2  Silver acetate CCl 4 CH 3 Br  Methyl bromide AgBr  CO 2  In Hunsdiecker reaction, one carbon atom less alkyl halide is formed from acid salt. (v) Formation of amines (Schmidt reaction) H SO (conc.) 4 RCOOH  N 3 H 2  RNH 2  CO 2  N 2 Acid Hydrazoic acid Primary amine In Schmidt reaction, one carbon less product is formed. (vi) Complete reduction P CH 3 COOH  6 HI  CH 3 CH 3  2 H 2 O  3 I2 Acetic acid Ethane In the above reaction, the – COOH group is reduced to a CH 3 group. (5) Reaction involving hydrogen of -carbon Halogenation (i) In presence of U.V. light H Cl | Carboxylic acid are difficult to reduce either by catalytic hydrogenation or Na C2 H5 OH CH 3  CH 3  2CO 2  2 KOH  H 2 (iv) Formation of Alkyl halide (Hunsdiecker's reaction) U R3CCOOH  R2CHCOOH  RCH 2COOH  CH 3COOH  HCOOH Acetic acid Alkane heat CaO CH 3 COOH  SOCl 2 CH 3 COCl  SO 2  HCl CH 3 CO OH  H Sodium salt HCOONa  NaOH  H 2  Na2CO3 Acetyl chloride Acetic acid CaO RCOONa  NaOH  R  H  Na 2 CO 3  When sodium formate is heated with sodalime H2 is evolved. (Exception) Acetyl chloride Acetic acid When anhydrous alkali salt of fatty acid is heated with sodalime then : E3 Acetic acid 1309 U.V. |  C  COOH  Cl 2     C  COOH  HCl | |  -chloro acid (ii) In presence of Red P and diffused light [Hell Volhard-zelinsky reaction] Carboxylic acid having an -hydrogen react with Cl2 or Br2 in the presence of a small amount of red phosphorus to give chloro acetic acid. The reaction is known as Hell Volhard-zelinsky reaction. 1310 Carboxylic acids and Their derivatives Cl , red P (ii) It melts at 8.4°C and boils at 100.5°C. Cl , red P 4 4 CH 3 COOH 2 ClCH 2 COOH 2  HCl Acetic acid  HCl Chloro acetic acid Cl 2 CHCOOH Dichloro acetic acid Cl 2 , red P4  Cl 3 CCOOH  HCl (iii) It is miscible with water, alcohol and ether. It forms azeotropic mixture with water. Trichloro acetic acid (iv) It is strongly corrosive and cause blisters on Individual members of monocarboxylic acids skin. Formic Acid or Methanoic acid (HCOOH) Formic acid is the first member of monocarboxylic acids series. It occurs in the sting of bees, wasps, red ants, stinging nettles. and fruits. In traces it is present in perspiration, urine, blood and in caterpillar's. (1) Methods of preparation (i) Oxidation of methyl alcohol or formaldehyde (v) It exists in aqueous solution as a dimer involving hydrogen bonding. HCl HCN  2 H 2O  HCOOH  NH 3 ; | H O CH 2OH | CHOH | |  HCOOH  CHOH Formic acid CH 2OH Glycerol monoformat e | CH 2OH Glycerol The following procedure is applied obtaining anhydrous formic acid. for 2 HCOOH  PbCO 3 (HCOO )2 Pb  CO 2  H 2O ; U Lead formate (HCOO )2 Pb  H 2 S PbS  2 HCOOH ppt. (x) As a reducing agent. Acetic Acid (Ethanoic Acid) (CH3COOH) CH 2OH (COOH )2 2 H 2 O plastics, water (xi) In the manufacture of oxalic acid. D YG CH 2OOCH CO 110 C | CH 2OH Glycerol monoxalate Glycerol of U 100 120 C | 2   CHOH o (vii) In the manufacture proofing compounds. (ix) In the preparation of nickel formate which is used as a catalyst in the hydrogenation of oils. CH 2OOC COO H 2   (vi) As an antiseptic and in the treatment of gout. ID (iii) Laboratory preparation Oxalic acid (v) As coagulating agent for rubber latex. (viii) In electroplating to give proper deposit of metals. NaOH HCN  H 2O   HCOONa  NH 3 | (iii) In textile dyeing and finishing. E3 (ii) Hydrolysis of hydrocyanic acid : Formic acid is formed by the hydrolysis of HCN with acids or alkalies. CHOH (ii) In the preservation of fruits. (iv) In leather tanning. Formic acid CH 2OH  HO OC COOH (i) In the laboratory for preparation of carbon monoxide. 60 Pt CH 3 OH  O2  HCOOH  H 2 O (3) Uses : Formic acid is used. Formic acid ST (iv) Industrial preparation : Formic acid is prepared on industrial scale by heating sodium hydroxide with carbon monoxide at 210°C under a pressure of about 10 atmospheres. Acetic acid is the oldest known fatty acid. It is the chief constituent of vinegar and hence its name (Latin acetum = vinegar) (1) Preparation (i) By oxidation of acetaldehyde (Laboratorypreparation) 7 CH 3 CHO 22  CH 3 COOH Na Cr O H 2 SO 4 (O ) (ii) By hydrolysis of methyl cyanide with acid HCl CH 3CN  2 H 2O  CH 3COOH  NH 3 (iii) By Grignard reagent O ||  H 2O H CH 3 MgBr  CO 2 CH 3  C  OMgBr     O   ||    CH 3  C  OH      CO  NaOH   HCOONa 210 o C, 10 atm Sodium formate Sodium formate thus formed is distilled with sodium hydrogen sulphate, when anhydrous formic acid distils over. HCOONa  NaHSO 4 HCOOH  Na2SO 4 (2) Physical properties (i) It is a colourless pungent smelling liquid. (iv) By hydrolysis of acetyl chloride, acetic anhydride or acetamide and ester H SO (conc.) 4   (a) CH 3 COOC 2 H 5  H 2 O 2 Ester CH 3COOH  C2 H5 OH Carboxylic acids and Their derivatives (c) By the action of CO on methyl alcohol : Methyl alcohol and carbon monoxide react together under a pressure of 30 atmospheres and 200°C in presence of a catalyst cobalt octacarbonyl, Co2(CO)8 to form acetic acid. acetylchloride (c) CH 3 CO 2 O  H 2O  2CH 3 COOH dil.HCl (v) Manufacture of acetic acid (a) From ethyl alcohol (Quick vinegar process) : Vinegar is 6-10% aqueous solution of acetic acid. It is obtained by fermentation of liquors containing 12 to 15% ethyl alcohol. Fermentation is done by Bacterium Mycoderma aceti in presence of air at 30-35°C. The process is termed acetous fermentation. Mycoderma aceti CH 3 CH 2 OH  O2  CH 3 COOH  H 2 O Methyl alcohol 30 atm 200 C Acetic acid (2) Physical properties (i) At ordinary temperature, acetic acid is a colourless, corrosive liquid with a sharp pungent odour of vinegar. It has a sour taste. (ii) Below 16.5°C, it solidifies as an icy mass, hence it is named glacial acetic acid. Acetic acid It is a slow process and takes about 8 to 10 days for completion. In this process, the following precautions are necessary: (iv) It is miscible with water, alcohol and ether in all proportions. ID  The concentration of the ethyl alcohol should not be more than 15%, otherwise the bacteria becomes inactive. (iii) It boils at 118°C. The high boiling point of acetic acid in comparison to alkanes, alkyl halides or alcohols of nearly same molecular masses is due to more stronger hydrogen bonding between acid molecules. This also explains dimer formation of acetic acid in vapour state. E3 Bacter ia Co (CO ) 2 8 CH 3 OH  CO   CH 3 COOH 60 dil.HCl (b) CH 3 COCl  H 2 O  CH 3 COOH  HCl Ethyl alcohol 1311  The supply of air should be regulated. With less air the oxidation takes place only upto acetaldehyde stage while with excess of air, the acid is oxidised to CO2 and water. (3) Uses : It is used, U  The flow of alcohol is so regulated that temperature does not exceed 35°C, which is the optimum temperature for bacterial growth. (v) It is good solvent for phosphorus, sulphur, iodine and many organic compounds. D YG Acetic acid can be obtained from vinegar with the help of lime. The calcium acetate crystallised from the solution is distilled with concentrated sulphuric acid when pure acetic acid distils over. (b) From acetylene : Acetylene is first converted into acetaldehyde by passing through 40% sulphuric acid at 60°C in presence of 1% HgSO4 (catalyst). H SO (dil.) 4 CH  CH  H 2O 2   CH 3 CHO Acetylene HgSO 4 Acetaldehyde U The acetaldehyde is oxidised to acetic acid by passing a mixture of acetaldehyde vapour and air over manganous acetate at 70°C. Manganous acetate ST 2CH 3 CHO  O2   2CH 3 COOH 70 C  Acetylene required for this purpose is obtained by action of water on calcium carbide. CaC 2  2 H 2 O Ca(OH )2  C2 H 2 The yield is very good and the strength of acid prepared is 97%. The method is also quite cheap. (i) As a solvent and a laboratory reagent. (ii) As vinegar manufacturing pickles. for table purpose Formic acid (iv) For making various organic compounds such as acetone, acetic anhydride, acetyl chloride, acetamide and esters. (v) For making various useful metallic acetates, such as: (a) Basic copper acetate which is used for making green paints. (b) Al, Fe and Cr acetates which are used as mordants in dyeing. (c) Lead tetra-acetate which is a good oxidising agent. (d) Basic lead acetate which is used in the manufacture of white lead. (e) Aluminium acetate which is used in the manufacture of water-proof fabrics. (f) Alkali acetates which are used as diuretics. Acetic acid 1. Acidic nature, (i) With electropositive metals Forms salts, Hydrogen is evolved. for (iii) In coagulation of rubber latex. Table : 28.1 Comparison of Formic Acid and Acetic Acid Property and Forms salts. Hydrogen is evolved. 1312 Carboxylic acids and Their derivatives HCOOH  Na HCOONa  (ii) With bases (iii) With carbonates and bicarbonates 1 H2 2 CH 3 COOH  Na CH 3 COONa  1 H2 2 Forms salts. Forms salts. HCOOH  NaOH HCOONa  H 2O CH 3COOH  NaOH CH 3COONa  H2O Forms salts. Carbon dioxide is evolved. Forms salts. Carbon dioxide is evolved. HCOOH  NaHCO 3 HCOONa  H 2O  CO2 CH 3COOH  NaHCO 3 CH 3COONa  H 2O  CO2 Forms esters when treated with alcohols. HCOOH  C2 H5OH HCOOC 2 H5  H 2O Forms esters when treated with alcohols. 60 2. Ester formation H SO (conc.) 4 CH 3 COOH  C2 H 5 OH 2  CH 3COOC 2 H5  H 2O Forms formyl chloride which decomposes into CO and HCl. Forms acetyl chloride which is a stable compound. HCOOH  PCl5 HCOCl (HCl  CO)  POCl 3  HCl CH 3COOH  PCl5 E3 3. Reaction with PCl5 CH 3COCl  POCl 3  HCl 4. Heating of ammonium salt Forms formamide. Forms acetamide. 5. Heating alone it decomposes into CO2 and H2 HCOOH CO2  H 2 Decomposed into CO and H2O Conc. Unaffected Unaffected HCOOH   CO  H 2O H 2 SO 4 Unaffected D YG 7. Reaction with Cl2 in presence of red P U 6. Heating with conc. H2SO4 CH 3COONH 4 CH 3CONH 2  H 2O ID HCOONH 4 HCONH 2  H 2O Forms mono, di or trichloro acetic acids. 8. Action of heat on salts, (i) Calcium salt Forms formaldehyde. (HCOO )2 Ca HCHO  CaCO 3 Forms acetone. (CH 3COO)2 Ca CH 3COCH 3  CaCO 3 (ii) Sodium salt Forms sodium oxalate. Unaffected. heat 2 HCOONa | COONa COONa (iii) Sodium salt with Forms sodium carbonate and H2. ST 9. Electrolysis of sodium or potassium CaO Forms sodium carbonate and methane. CaO HCOONa  NaOH  Na2CO3  H 2 CH 3COONa  NaOH  CH 4  Na2CO3 It evolves hydrogen. It forms ethane. Unaffected Forms acetic anhydride. U soda-lime  H2 salt 10. On heating with P2O5 PO 5 2CH 3 COOH 2   (CH 3 CO )2 O  H 2O 11. Reducing nature, (i) Tollen's reagent Gives silver mirror or black precipitate. Unaffected. HCOOH  Ag 2O 2 Ag  CO2  H 2O (ii) Fehling's solution Gives red precipitate Unaffected. HCOOH  2CuO Cu 2O  CO2  H 2O (iii) Mercuric Forms a white ppt. which changes to Unaffected. Carboxylic acids and Their derivatives chloride 1313 greyish black. HgCl2 Hg2Cl2 2 Hg (iv) Acidified KMnO4 Decolourises Unaffected. 12. Acid (neutral solution) + NaHSO3 + Sodium nitroprusside. Greenish blue colour. Unaffected. 13. Acid (neutral solution) + neutral Red colour which changes to brown ppt. on Wine red colour. heating. (2) Descent of series : Conversion of acetic acid Interconversions into formic acid. (1) Ascent of series : Conversion of formic acid into acetic acid. E3 N3H NaNO 2 HCl   CH 3 NH 2   CH 3 OH H 2 SO 4 (i) Ca (OH ) hea t 2 HCOOH   ( HCOO )2 Ca  Formic acid Calcium formate Formaldehy de r Formic acid Additio n product H Methy l amine Br2 / KOH Acetic acid Ni HI 2 CH 3 OH   CH 3 I Methyl alcohol Amm.aceta te Acetamide Methyl iodide KCN(Alc.) H 2O CH 3 COOH   CH 3 CN  Cl 2 NaOH Sodalime    CH 3 COONa   CH 4   CH 3 Cl D YG H Acitic acid heat U HCHO CH 3 NH 2 CH 3 COOH  CH 3 COONH 4  CH 3 CONH 2 Acetic acid Formaldehy de [O] Formaldehy de NH 3 [O ]   CH 3 COOH (ii) Methy l alcohol ID H Ethy l alcohol Methy l amine [O ] HCOOH   HCHO HCHO CH3MgB H 2O [O ] CH 3 CHO    CH 3 CH 2 OH   CH 3 CH 2 OMgBr Acetaldehyde 60 ferric chloride Methyl cy anide heat Sodium acetate Arndt-Eistert homologation : This is a convenient method of converting an acid, RCOOH to RCH2COOH. Methy l chloride AgOH [O ] [O ] HCOOH   HCHO   CH 3 OH Formic acid Formaldehy de Na 2 Cr 2 O7 Methy l alcohol H 2 SO 4 SOCl 2 CH 2 N 2 RCOOH    RCOCl   RCOCHN 2 Ag2O EtOH hv Methane Hy droly sis RCH 2 COOH    RCH 2 COOC 2 H 5 U Conversion of Acetic acid into other organic compound (CH3CO)2O CH3 – CH3 Electrolys is CH3 COCl ST Ethane Sodali Sodium acetate me CH3COONa Cl2 hv CH3 – CH2Cl CH3CH2NH2 NH3 Ethyl amine CH3CH2CH2NH2 n-Propyl amine AgOH Ethyl chloride [H] LiAlH CH3CH2CN CH3 – COOH Acetic acid H2 O CH3CH2COOH H+ Propionic acid 4 CH4 Methane Cl2 hv CH3 Cl AgOH CH3OH [O] Methyl alcohol Methyl chloride NaOH 2 [O] Acetaldehyde HCHO (CH3COO)2Ca Calcium acetate hea t CH3COCH3 Acetone H2 / Ni Iodofor m A Formic H2SO4 COONa Oxalic acid Sodium oxalate CH3CHOHCH3 Isopropyl alcohol heat | COONa Conc. H2SO4 acetylene HCOONa Sodium formate CH3CH= CH2 Propene 500° C HC ≡ CH NaO H HCOOH acid COOH I2 + NaOH CHI3 [O] Formaldehyde | Ca(OH) CH3 – CHO Ethyl alcohol COOH CH3COOH [O] CH3 – CH2OH KCN Acetic anhydride Cl2 ClCH2CH= CH2 Allyl chloride E3 60 1314 Carboxylic acids and Their derivatives U The acids containing two carboxylic groups are called dicarboxylic acids. The saturated dicarboxylic acid are represented by the general formula Cn H 2n (COOH )2 where n = 0, 1, 2, 3 etc. HO  C  (CH 2 )n  C  OH or HOOC(CH 2 )n COOH || O D YG || O According to IUPAC system, the suffix-dioic acid is added to the name of parent alkane, i.e. Alkane dioxic acid. Table : 28.2 Formula HOOCCOOH It is found in the form of calcium oxalate in stony deposits in kidneys and bladdar in human body. Oxalic acid present in tomatoes. (1) Methods of Preparation (i) By oxidation of ethylene glycol with acidified potassium dichromate CH 2 OH COOH K Cr O7 |  4[O] 2 2  |  2 H 2O H 2 SO 4 CH 2 OH COOH ID Dicarboxylic acids Common name IUPAC name Glycol (ii) By hydrolysis of cyanogen with conc. CN COOH 2( HCl ) hydrochloric acid : |  4 H 2 O    |  2 NH 4 Cl CN COOH (iii) By heating sodium or potassium in a current of carbon dioxide at 360°C Oxalic acid Ethanedioic acid Malonic acid 1-3 Propanedioic acid HOOCCH2CH2 COOH Succinic acid 1,4-Butanedioic acid HOOC(CH2)3COOH Glutaric acid 1,5-Pentanedioic acid COOH HNO 3 C12 H 22 O11  18 [O]    6 |  5H 2O V2 O5 Sucrose COOH 1,6-Hexanedioic acid (v) Industrial method ST U HOOCCH2COOH HOOC(CH2)4 COOH Adipic acid Oxalic Acid or Ethanedioic Acid COOH or (COOH)2 or (C2H2O4) | COOH Oxalic acid is first member of dicarboxylic series. It occurs as potassium hydrogen oxalate in the wood sorel, rhubarb and other plants of oxalis group and as calcium oxalate in plants of rumex family. COONa heat 2 Na  2CO 2   | COONa Sodium oxalate (iv) Laboratory preparation Oxalic acid COONa 360 C 2 HCOONa    |  H2 Sod. formate COONa Sod. oxalate Sodium formate is obtained by passing carbon monoxide over fine powdered of sodium hydroxide. 200 C CO  NaOH    HCOONa 8 10 atm The sodium oxalate thus formed is dissolved in water and calcium hydroxide is added. The precipitate of calcium oxalate is formed which is separated by Carboxylic acids and Their derivatives filtration. It is decomposed with calculated quantity of dilute sulphuric acid. COONa |  Ca(OH )2 COONa COO | COO COOH COCl |  2 PCl 5 |  2 POCl 3  2 HCl COOH COCl Oxalyl chloride Ca  2 NaOH (v) Reaction with ammonia Calcium oxalate COO | COO COOH Ca  H 2 SO 4 (dil.) |  CaSO 4 COOH Calcium sulphate Oxalic acid (soluble) COONH 4 COONH 4 COOH NH 3 |  NH 3 |  | COOH COOH COONH 4 (insoluble ) Acid ammonium oxalate (2) Physical Properties (i) Action of heat : It becomes anhydrous. 100 105 C (COOH )2 2 H 2 O  (COOH )2  2 H 2 O Anhydrous oxalic acid HCOOH CO 2  H 2 2KMnO 4  3 H 2 SO 4 K 2 SO 4  2MnSO 4  3 H 2 O  5[O] COOH   [O] 2 CO 2  H 2 O   5 | COOH  COOH 2 KMnO 4  3 H 2 SO 4  5 | K 2 SO 4  2 MnSO 4  10 CO 2  8 H 2 O COOH Pot. permangan ate  Oxalic KMnO 4 solution. U On further heating, formic acid also decomposes. D YG OH COOH H SO 4 | 2   CO  CO 2  H 2 O (conc.) COOH O=C (ii) Acidic nature O=C Salt formation COOK | COOK COOK KOH   | COOK Acid pot. oxalate U Oxalic acid Oxalic acid acid Colourless decolourises the acidic (vii) Reaction with ethylene glycol (b) Heating with conc. H2SO4 COOH |  KOH COOH Oxamide (vi) Oxidation : When oxalic acid is warmed with acidified KMnO 4. (Purple) (a) At 200°C, (COOH )2  HCOOH  CO 2 Formic acid Oxamic acid ID (3) Chemical Properties CONH 2 | CONH 2 E3 (iv) It is poisonous in nature. It affects the central nervous system. heat 60 CONH 2 | COOH (ii) The hydrated form has the melting point 101.5°C while the anhydrous form melts at 190°C. (iii) It is soluble in water and alcohol but insoluble in ether. Amm. oxalate – 2H2O – H2O heat (i) It is a colourless crystalline solid. It consists of two molecules of water as water of crystallisation. Hy drated oxalic acid 1315 Pot. oxalate ST COOH COONa |  2 NaHCO 3 |  2 CO 2  2 H 2 O COOH COONa Sod. oxalate COOH COONa |  Na 2 CO 3 |  H 2 O  CO 2 COOH COONa | + heat –H2O CH2 OH Oxalic acid O=C CH2 | | O=C CH2 HO O Ethylene glycol Ethylene oxalate CH 2OH COOH Zn (viii) Reduction : |  4 H   |  H 2O H 2 SO 4 COOH COOH Glycolicacid CH 2OH COOH Electrolytic reduction COOH 2|  |  | 6[ H ] COOH COOH CHO  2H 2O Glyoxalic acid (ix) Reaction with Glycerol : At 100° – 110°C, formic acid is formed. At 260°, allyl alcohol is formed. COOC 2 H 5 COOH C H OH COOC 2 H 5 C H OH | 2 5  | 2 5  | COOH COOH COOC 2 H 5 (iv) Reaction with PCl5 : CH2 | Glycolicacid (iii) Esterification Ethyl hydrogen oxalate O HO Ethyl oxalate (4) Uses : Oxalic acid (Polyprotic acid) is used, (i) In the manufacture of carbon monoxide, formic acid and allyl alcohol. (ii) As a laboratory reagent and as a standard substance in volumetric analysis. (iii) In the form of antimony salt as a mordant in dyeing and calico printing. 1316 Carboxylic acids and Their derivatives RCH  CHCOOH  H 2 O  CO 2 (iv) In the manufacture of inks. (vi) In the form of ferrous potassium oxalate as developer in photography. (5) Analytical test (i) The aqueous solution turns blue litmus red. (ii) The aqueous solution evolves effervescences with NaHCO 3. (iii) The neutral solution gives a white precipitate with calcium chloride solution. It is insoluble in acetic acid. H 2 C 2 O 4  ( NH 4 )2 C 2 O 4   CaC 2 O 4 CaCl 2 Oxalic acid Amm.oxalate Calcium oxalate (4) Uses : Its diethyl ester (malonic ester) is a valuable synthetic reagent for preparation of a variety of carboxylic acids. Succinic Acid or Butane-1,4-Dioic Acid : CH 2 COOH | CH 2 COOH or (CH 2 )2 (COOH) 2 or (C 4 H 6 O 4 ) It was first obtained by the distillation of yellow fossil, resin, amber and hence its name (Latin, Succinum = amber). It is also formed in small amount during the fermentation of sugar. (1) Methods of Preparation (iv) Oxalic acid decolourises hot potassium permanganate solution having dilute sulphuric acid. (v) With hot conc. H 2 SO 4 , it evolves carbon monoxide which burns with blue flame. (i) From ethylene CH 2 CH 2 Br CH 2 CN Br2 H O HCl NaCN ||   |   | 2  CH 2 COOH CH 2 CH 2 Br CH 2 CN | Ethy lene Ethy lene Ethy lene CH 2 COOH bromide cy anide Succinic acid ID Malonic Acid or Propane-1,3-Dioic Acid COOH or CH 2 (COOH) 2 or (C 3 H 4 O 4 ) CH 2 COOH E3 NH 4 OH  -  unsaturate d acid 60 (v) For removing ink stains and rust stains and for bleaching straw, wood and leather. acid (hydroxy succinic acid) by oxidation. (1) Methods of Preparation : From acetic acid Cl KCN ( Aq.) D YG 2 CH 3 COOH  CH 2 ClCOOH   P Acetic acid CH 2COOH CHCOOH Ni ||  H 2   | heat CH COOH CHCOOH 2  This is an industrial method. U The acid occurs as calcium salt in sugar beet. It was so named because it was first obtained from malic (ii) From maleic acid [catalytic reduction] Chloroacet ic acid H 2O H  CH 2 CNCOOH   CH 2 Cyano acetic acid COOH COOH Malonic acid (2) Physical Properties (i) It is a white crystalline solid. (ii) It's melting point is 135°C. U (iii) It is soluble in water and alcohol but sparingly soluble in ether. (iii) Reduction of tartaric acid or malic acid CH 2 COOH CHOHCOOH CHOHCOOH HI HI |   |   | P P CHOHCOOH CH 2 COOH CH 2 COOH Tartaric acid Succinic acid (2) Physical properties (i) It is a white crystalline solid. It melts at 188 o C (ii) It is less soluble in water. It is comparatively more soluble in alcohol. (3) Chemical Properties : Succinic acid gives the usual reactions of dicarboxylic acid, some important reactions are : (3) Chemical Properties (i) Action of heat : At 300°C (i) Action of heat CH 2 COOH CH 2 CO 300 C |    | CH 2 COOH (– H 2 O ) CH 2 CO ST (a) Heating at 150°C : CH 2 (COOH )2 CH 3COOH  CO2 H OH | O  C  C C | | P2 O 5  O   O  C  C  C  O  2 H 2 O heat Carbon suboxide OH H (ii) Reaction with aldehyde : With aldehydes, - unsaturated acids are formed. RCH  O  H 2 C Aldehyde Succinic acid O Succinic anhy dride (ii) With ammonia (b) Heating with P2O5 : | Malic acid COOH Pyridine  COOH heat CH 2COOH CH 2COONH 4 NH 3 heat |  |   H 2O CH 2COOH CH 2COONH 4 Ammonium succinate CH 2CONH 2 CH 2CO heat |  | CH 2CONH 2  NH 3 CH 2CO Succinamid e (iii) Reaction with Br2 Succinimid e NH Carboxylic acids and Their derivatives CH 2  CO | CH 2  CO CH 2  CO NaOH NH  Br2  | 0 C CH 2  CO Succinimid e N  Br  HBr N - bromosucci nimide (N.B.S) (3) Chemical Properties It shows all the general reaction of dicarboxylic acids. (i) Action of heat (iv) Reaction with ethylene glycol HOOC  (CH 2 )2  CO OH  H OCH 2  CH 2 O H  HO OC  (CH 2 )2  CO OH ....... – H2O HOOC(CH2)4 COOH hea t 300° C Adipic acid E3 nH 2 N (CH 2 )6 NH 2  nHO  C  (CH 2 )4  C  OH hexamethyl ene diamine (i) From benzene (In industries) H2 Benze ne O HNO3 || || ID nylon-66 (4) Uses : It is used in the manufacture of several polymers. Unsaturated Acids : When the double bond presents in the carbon chain of an acid is called unsaturated acid. || Acrylicacid H C COOH Maleic acid Acrylic Acid or Prop-2-Enoic Acid CH 2  CH  COOH or (C 3 H 4 O 2 ) Cyclohexan ol HOOC – (CH2)4 – COOH Adipic acid U Cyclohexano ne O |  ( N  (CH 2 )6  N  C  (CH 2 )4  C )n  SeO3 H3BO3, heat Cyclohexa ne H O | HNO3 O2 Catalyst H Example: CH 2  CH  COOH  H  C  COOH D YG OH || O adipic acid U (1) Methods of Preparation || O – nH2O or (C 6 H10 O 4 ) It was first obtained by the oxidation of fats (Latin, adeps = fat.) C = O + CO2 + H2O (ii) Formation of Nylon-66 [Reaction with hexa methylene diamine] Adipic Acid or Hexane-1,6 –Dioic Acid 2 | H2C Cyclopentan one (4) Uses : It finds use in volumetric analysis, medicine and in the manufacture of dyes, perfumes and polyester resins. CH 2 CH 2 COOH | or (CH 2 )4 (COOH) CH 2 CH 2 COOH C H2C 60 (CH 2 )2  CO ]n  OH  H 2 O When sodium or potassium salt in aqueous solution is electrolysed, ethylene is obtained at anode. H2 C H2 HOOC  (CH 2 )2  CO  [OCH 2  CH 2 O  OC Polyester 1317  It is an industrial method. ST (ii) From tetrahydrofuran (THF) CH 2 CH 2 | |  2CO  HOH HOOC  (CH 2 )4  COOH Adipicacid CH 2 CH 2 O (1) Methods of Preparation (i) From allyl alcohol CH 2 CH 2 Br || Br2  C HBr CH | | CH 2OH CH 2OH | CH 2 Zn ||  C HBr   C H | [O ] | hea t COOH COOH AgNO 3 CH 2  CHCHO  [O]  CH 2  CHCOOH NH 4 OH (iii) From propionic acid Br2 P CH 3 CH 2COOH   Propionic acid HVZ reaction Alc. KOH CH 3 CHBrCOOH   CH 2  CHCOOH  - Bromopropi onic acid (2) Physical Properties (iv) By heating -hydroxy propionic acid ZnCl 2 C H 2  CH 2  COOH   CH 2  CH  COOH | (ii) It is fairly soluble in alcohol and ether but less soluble in water. CH 2 Br HNO 3 (ii) By oxidation of acrolein THF (i) It is a white crystalline solid. Its melting point is 150°C. | OH  -hydroxy propionic acid heat,  H 2 O : 1318 Carboxylic acids and Their derivatives (v) From vinyl cyanide HCl 2 2 HC  CH  HCN   CH 2  CH  CN 90 C Acetylene Acryl chloride Vinyl cyanide H H O 2   CH 2  CH  COOH (4) Uses : Its ester are used for making plastics such as Lucite and plexiglass. Unsaturated dicarboxylic acids (vi) From ethylene cyanohydrin  HCN Conc. H SO 4 CH 2  CH 2  C H 2  CH 2  CN 2  heat  H 2 O | OH O Ethylene cyanohydri n Ethylene oxide H H O 2 CH 2  CH  CN     CH 2  CHCOOH The molecular formula of the simplest unsaturated dicarboxylic acid is HOOC.CH  CH.COOH This formula, however represents two chemical compounds, maleic acid and fumaric acid, which are geometrical isomers. || H C COOH Industrial method : This is a new method of its manufacture. Trans- form (Fumaric acid) E3 (1) Methods of Preparation of Maleic Acid CH  CH  CO  H 2 O   CH 2  CHCOOH (i) By catalytic oxidation of 2-butene or benzene CH CH 3 CHCOOH V O5 ||  30 2 2  | |  2H 2O 400 C CHCOOH CH CH 3 (2) Physical Properties  It is colourless pungent smelling liquid. Its boiling point is 141°C. Maleic acid 2 Butene ID  It shows properties of an alkene as well as of an acid. (3) Chemical Properties || H C COOH Cis- form (Maleic acid) Ni(CO )4  It is miscible with water, alcohol and ether. HOOC  C  H H  C  COOH Vinyl cyanide (acrylonitrile) C6 H 6  Benzene CH CO 9 V O5 O 2 2  | | o 2 400 C CH CO CHCOOH H O H O 2 | | CHCOOH Maleic anhydride U (ii) From malic acid : (i) With nascent hydrogen (Na and C2H5OH) Ni CH (OH )COOH | CH 2  CHCOOH  2[H ]   CH 3 CH 2 COOH acids CH 2 COOH : D YG (ii) With halogens and halogen Markownikoff's rule is not followed. Malic acid (Hydroxy succinic acid)  ,  -Dibromopro pionic acid CH 2  CHCOOH  HBr BrCH 2  CH 2 COOH  -Bromopropi onic acid (iii) Oxidation : In presence of dilute alkaline KMnO4. CH 2  CHCOOH  [O]  H 2 O CH 2 OHCHOHCOOH U (iv) Salt formation CH 2  CHCOOH  KOH CH 2  CHCO O K   H 2 O 2CH 2  CHCOOH  Na2CO3 2CH 2  CHCO O Na   H 2 O  CO 2 Sodium acrylate (v) Ester formation Conc. H SO 4 CH 2  CHCOOH  HOC 2 H 5 2   H 2O CH 2  CH  COOC 2 H 5 Ethyl acrylate Maleic acid (intermedi ate) Sodium salt O Maleic anhydride Maleic acid (2) Methods of Preparation of Fumaric Acid (i) From H C COOH HCl ||  boil H C COOH maleic acid HOOC C  H || H C COOH : Maleic acid Glyceric acid  On vigorous oxidation, oxalic acid is formed. CHCOOH CH CO heat heat | | | |  H 2O H 2O CHCOOH CH CO CH COONa CH COOH H  H 2O NaOH | |  | | boil CH COONa CH COOH CCl 4 CH 2  CHCOOH  Br2   CH 2 Br  CHBrCOOH ST PCl5 60 Cu Cl (vi) With CH 2  CHCOOH  PCl 5 CH 2  CH  COCl (ii) chlorate By oxidation of furfural with sodium CH HOOC C  H NaClO3 ||  4[O]  ||  CO 2 C CHO H C COOH HC || HC O (iii) By heating malic acid at about 150°C for long time CH (OH )COOH HOOC  C  H heat |  || 150 C ,  H 2 O CH 2 COOH H  C  COOH Malic acid (iv) By heating bromosuccinic acid with alcoholic potash : By heating bromosuccinic acid with alcoholic potash. Carboxylic acids and Their derivatives 1319 Palmitic and stearic acids are waxy colourless (3) Physical Properties (i) Both are colourless crystalline solids. Both are soluble in water. (ii) The melting point of maleic acid (130.5°C) is lower than the melting point of fumaric acid (287°C). (4) Chemical Properties (i)O Maleic acid O  H 2O Maleic anhydride COOH | | H  C  OH H  C  COOH Br water H  C  Br Alk.KMnO 4 |   || 2  | H  C  OH (Syn - addition) H  C  COOH (anti - addition) Br  C  H Maleic acid (Cis) | | COOH D YG Tartaric acid (Meso) (Racemic mixture) COOH | H  C  OH | HO  C  H COOH | H  C  COOH H  C  Br Br water   || 2  | (Syn - addition) HOOC  C  H (anti - addition) H  C  Br Alk.KMnO 4 | Fumaric acid (Trans) COOH Tarta ric acid (Racemic mixture) | COOH ((Meso) Higher fatty acids ST U Palmitic, stearic and oleic acids are found in natural fats and oils as glyceryl esters. They have derived their names from the natural source from which they are prepared by hydrolysis with alkali. Table : 28.3 Name acids of Source Molecular formula Palmitic acid Palm oil CH 3 (CH 2 )14 COOH Stearic acid Stear (meaning tallow) CH 3 (CH 2 )16 COOH Olive oil. CH 3 (CH 2 )7 CH  CH (CH 2 )7 COOH Oleic acid CH 3 (CH 2 )7 CHO  HOOC(CH 2 )7 CHO It is used for making soaps, lubricants and detergents. (1) Difference between oils and fats : Oils and fats belong to the same chemical group, yet they are different in their physical state. (i) Oils are liquids at ordinary temperature (below 20°C) while fats are semi solids or solids (their melting points are more than 20°C). A substance may be classed as fat in one season and oil in another season or the same glyceride may be solid at a hill station and liquid in plains. Thus, this distinction is not U COOH COOH (ii)Zn  H 2 O ID Both form succinic acid on reduction with sodium amalgam. They undergo addition reactions with bromine, hydrobromic acid, water, etc. and form salts, esters and acid chlorides as usual. With alkaline KMnO4 solution, they get oxidised to tartaric acid. 3 CH 3 (CH 2 )7 CH  CH (CH 2 )7 COOH  E3 Chemically, both the acids give the reactions of alkenes and dibasic acids except that the maleic acid on heating forms an anhydride while fumaric acid does not give anhydride. CHCOOH CHCO hea t ||  | | CHCOOH CHCO solids with melting points 64°C and 72°C, respectively. They are insoluble in water but soluble in ethanol and ether. They find use in the manufacture of soaps and candles. Soaps contain sodium or potassium salts of these higher fatty acids. Oleic acid has low melting point, i.e., 16°C. It is insoluble in water but soluble in alcohol and ether. Besides the reactions of acids, it also gives reactions of alkenes. Two aldehydes are formed on ozonolysis. 60 CH 2COOH HOOC  C  H Alc. KOH |  ||  KBr  H 2 O CH.( Br )COOH H  C  COOH well founded as the physical state depends on climate and weather. (ii) The difference in oils and fats is actually dependent on the nature of monocarboxylic acid present in the glyceride. Oils contain large proportion of the glycerides of lower carboxylic acids, (e.g., butyric acid, caprylic acid and caproic acid) and unsaturated fatty acids, (e.g., oleic, linoleic and linolenic acids) while fats contain a large proportion of glycerides of higher saturated carboxylic acids, (e.g., palmitic, stearic acids). Lard (fat of hogs) is a solid fat and its composition in terms of fatty acids produced on hydrolysis is approximately 32% palmitic acid, 18% stearic acid, 45% oleic acid and 5% linolenic acid. Olive oil on the other hand, contains 84% oleic acid, 4% linoleic acid, 9% palmitic acid and 3% stearic acid. (2) Physical Properties of oils and Fats (i) Fats are solids, whereas oils are liquids. (ii) They are insoluble in water but soluble in ether, chloroform and benzene. (iii) They have less specific gravity than water and consequently float on the surface when mixed with it. 1320 Carboxylic acids and Their derivatives substances. (v) They have specific melting points, specific gravity and refractive index hence they can be identified by these oil constants. (vi) Animal fats contain cholesterol, an unsaturated alcohol, whereas vegetable fats contains phytosterol. (3) Chemical Properties : They give reactions of carbon-carbon double bonds and ester groups. CH 2 O COC 17 H 35 | CH 2 OH 3H O | C HO COC 17 H 35  2 C HOH  3 C17 H 35 COOH | | CH 2 O COC 17 H 35 CH 2 OH Tristearin Glycerol Stearic acid (b) Base hydrolysis [Saponification] CH 2 OCOR CH 2 OH | | C HOCOR  3 NaOH C HOH  3 RCOONa | | CH 2 OCOR CH 2 OH Sa lt fatty acid (Soap) 60 (iv) Pure fats and oils are colourless, odourless and tasteless but natural fats and oils possess a characteristic odour due to presence of other Fat or oil Glycerol (c) Enzyme hydrolysis : Enzyme like lipase, when added to an emulsion of fat in water, hydrolyses it into (a) By superheated steam (ii) Hydrogenation : In the presence of finally E3 acid and glycerol in about two or three days. (i) Hydrolysis (i) Acid value : It indicates the amount of free divided nickel, at low pressure the hydrogenation process acid present in the oil or fat. It is defined as the is called hardening of oils. number of milligrams of KOH required to neutralize O || CH 2 O C C17 H 35 O || CHO C (CH 2 )7 CH CH (CH 2 )7 CH 3 O determined by dissolving a weighed amount of oil or || CH 2 O C (CH 2 )7 CH  CH (CH 2 )7 CH 3 O 3 H || 2  CHO C C17 H 35 O || CH 2O C C17 H 35 Gly cery l rioleate t or triolein (Liquid oil) Tristearin (A solid fat) || D YG (iii) Hydrogenolysis [Reduction to alcohol] O || CH 2OH | CH  O  C  C17 H 35  CHOH  3 C17 H 35 CH 2 OH | 200 atm Octadecy l alcohol O CH 2OH || CH 2  O  C  C17 H 35 6 H2 Tristearin (iv) Drying : Certain oils, containing glycerides U of unsaturated fatty acids having two or three double bonds have the tendency of slowly absorbing oxygen from atmosphere and undergoing polymerisation to ST form hard transparent coating. This process is known as drying and such oils are called drying oils. Unsaturated oils such as linseed oil are, therefore, used as medium of paints and varnishes. (v) Rancidification : On long storage in contact with air unpleasant and moisture, smell. The solution of indicator. KOH using phenolphthalein as an || CH 2O C (CH 2 )7 CH CH (CH 2 )7 CH 3 CH 2  O  C  C17 H 35 O fat in alcohol and titrating it against a standard U Ni, Heat ID the free acid present in one gram of the oil or fat. It is O oils and process fats is develop known as rancidification. It is believed that rancidification occurs due to hydrolysis-oxidation. (4) Analysis of oils and fats (ii) Saponification value : It is a measure of fatty acids present as esters in oils and fats. It is defined as the number of milligrams of KOH required to saponify one gram of the oil or fat or number of milligrams of KOH required to neutralize the free acids resulting from the hydrolysis of one gram of an oil or fat. It is determined by refluxing a Saponification number of fat or oil = 168 ,000 , M Where M = molecular mass (iii) Iodine value : Iodine value of a fat or oil is a measure of its degree of unsaturation. It is defined as the number of grams of iodine taken up by 100 grams of fat or oil for saturation. For a saturated acid glyceride, the iodine value is zero. Thus, the iodine value for a fat is low whereas for oil, it is high. As iodine does not react readily, in actual practice, iodine monochloride is used. Iodine monochloride is known as Wij's reagent. (iv) Reichert-Meissl value, (R/M value) : It indicates the amount of steam volatile fatty acids present in the oil or fat. It is defined as the number of millilitres of 0.1 N KOH solution required to neutralize the distillate of 5 grams of hydrolysed fat. It is determined by hydrolysing a known weighed amount (5 grams) of the fat with alkali solution and the Carboxylic acids and Their derivatives 1321 (iii) Oils like linseed oil, tung oil, etc., are used mixture is acidified with dilute sulphuric acid and steam distilled. The distillate is cooled, filtered and titrated against 0.1 N KOH. for the manufacture of paints, varnish, etc. (iv) Castor oil is used as purgative and codliver (5) Uses oil as a source of vitamins A and D. Almond oil is used in pharmacy. Olive oil is also used as medicine. (i) Many oils and fats are used as food material. (v) Oils are (ii) Oils and fats are used for the manufacture of glycerol, fatty acids, soaps, candles, vegetable ghee, margarine, hair oils, etc. also used as lubricants and illuminants. Property 60 Table : 28.4 Difference between vegetable oils and Mineral oils Vegetable oils Minerals oils These are triesters of glycerol with higher fatty acids. These are hydrocarbons (saturated). Kerosene oil–Alkanes from C12 to C16. 2. Source Seeds root and fruits of plants. 3. Hydrolysis Undergo hydrolysis with alkali. Form soap and glycerol. No hydrolysis occurs. 4. On adding NaOH and phenolphthalein Decolourisation of pink colour occurs. No effect. 5. Burning Burns slowly 6. Hydrogenation Hydrogenation occurs in presence of catalyst. Solid glycerides (fats) are formed. E3 1. Composition ID These occur inside earth in the form of petroleum. Burn very readily. No hydrogenation occurs. U nickel D YG (6) Soaps : Soaps are the metallic salts of higher fatty acids such as palmitic, stearic, oleic, etc. The sodium and potassium salts are the common soaps which are soluble in water and used for cleansing purposes. Soaps of other metals such as calcium, magnesium, zinc, chromium, lead, etc., are insoluble in water. These are not used for cleansing purposes but for other purposes (lubricants, driers, adhesives, etc.) Ordinary soaps (sodium and potassium) are the products of hydrolysis of oils and fats with sodium ST U hydroxide or potassium hydroxide. The oils and fats are mixed glycerides and thus soaps are mixtures of salts of saturated and unsaturated long chain carboxylic acids containing 12 to 18 carbon atoms. This process always yields glycerol as a byproduct. CH 2OCOR1 | CH 2OH | R1COONa  C HOCOR 2  3 NaOH C HOH  R 2 COONa | |  CH 2OCOR 3 CH 2OH R3 COONa Triglyceride Glycerol Soap There are three methods for manufacture of soaps : (iii) Modern process (7) Synthetic Detergents : The synthetic detergents or Syndets are substitutes of soaps. They have cleansing power as good or better than ordinary soaps. Like soap, they contain both hydrophilic (water soluble) and hydrophobic (oil-soluble) parts in the molecule. C12 H 25 OSO 3 Na Hy drophobi c Hy drophilic part part Sodium laury l sulphate (Detergent) C15 H 31 COONa Hy drophobi c Hy drophilic p art par t Sodium palmitate (Soap) Some of the detergents used these days are given below: (i) Sodium alkyl sulphates : These are sodium salts of sulphuric acid esters of long chain aliphatic alcohols containing usually 10 to 15 carbon atoms. The alcohols are obtained from oils or fats by hydrogenolysis. CH 3 (CH 2 )10 CH 2 OH  HO SO 3 H Lauryl alcohol Sulphuric acid NaOH CH 3 (CH 2 )10 CH 2 OSO 2 OH  Lauryl hydrogen sulphate (i) The cold process (ii) The hot process CH 3 (CH 2 )10 CH 2 OSO 2 ONa Sodium lauryl sulphate (Detergent ) 1322 Carboxylic acids and Their derivatives The other examples are sodium cetyl sulphate, and sodium stearyl sulphate, C16 H 33 OSO 2ONa cetyl alcohol (C16 H 33OH ) , ceryl alcohol (C26 H53OH ) , CH 3 (CH 2 )16 CH 2OSO 3 Na. Unlike ordinary soaps, they do Waxes are insoluble in water but are readily soluble in benzene, petroleum, carbon disulphide etc. Waxes on hydrolysis with water yields higher fatty acids and higher monohydric alcohols. not produce OH ions on hydrolysis and thus can be safely used for woollen garments. (ii) Sodium alkyl benzene sulphonates : Sodium p-dodecyl benzene sulphonate (S.D.S.) acts as a good detergent. It is most widely used since 1975. CH 3 | AlCl 3 CH 3 (CH 2 )9 CH  CH 2  C6 H 6    CH 3 (CH 2 )9 C H  C6 H 5 2 - Dodecy l benzene (S.D.S.) sulphonate When hydrolysis is carried with caustic alkalies, soap and higher monohydric alcohols are formed. C15 H 31 COOC 16 H 33  NaOH C16 H 33 OH  C15 H 31 COONa (i) Bees wax, Br C18 H 37 Myricyl palmitate, C15 H31COOC 30 H61 (ii) Spermaceti wax, Cetyl palmitate, C15 H31COOC16 H33 (iii) Carnauba wax, ID (iii) Quaternary ammonium salts : Quaternary ammonium salts with long chain alkyl group have been used as detergents, e.g., trimethyl stearyl ammonium bromide. (CH 3 )3 N Cetyl alcohol The common waxes are: | (i) H 2 SO 4    CH 3  (CH 2 )9  C H  C6 H 4  SO 3 Na These long chain alkyl benzene (L.A.S.) are most widely used syndets. Palmitic acid Sodium palmitate (Soap) CH 3 (ii) NaOH Cetyl palm itate E3 1- Dodecene C15 H 31COOC 16 H 33  H 2 O C15 H 31COOH  C16 H 33 OH 60 – myricyl alcohol (C30 H61OH ) , etc. Myricyl cerotate, C25 H51COOC 30 H61 Waxes are used in the manufacture of candles, polishes, inks, water proof coating and cosmetic preparations. U (iv) Sulphonates with triethanol ammonium ion in place of sodium serve as highly soluble materials for liquid detergents.     O  SO 2  N H (CH 2  CH 2 OH )3    D YG R (v) Partially esterified polyhydroxy compounds also acts as detergents. CH 2 OH | C17 H 35 COOCH 2  C  CH 2 O H | CH 2 OH Pentaeryth ritol monosteara te U Detergents are superior cleansing agents due to following properties. ST (i) These can be used both in soft and hard waters as the calcium and magnesium ions present in hard water form soluble salts with detergents. Ordinary soap cannot be used in hard water. (ii) The aqueous solution of detergents are neutral. Hence these can be used for washing all types of fabrics without any damage. The solution or ordinary soap is alkaline and thus cannot be used to wash delicate fabrics. (8) Waxes : Waxes are the esters of higher fatty acids with higher monohydric alcohols. The acids and alcohols commonly found in waxes are palmitic, cerotic acid (C25 H51COOH ) , melissic acid (C30 H61COOH ) and Waxes obtained from plants and animals are different than paraffin wax which is a petroleum product and a mixture of higher hydrocarbons (20 to 30 carbon atoms). So paraffin wax is not an ester. Candles are prepared by mixing paraffin wax (90%) with higher fatty acids like stearic and palmitic. The fatty acids are added to paraffin wax as to give strength to candles. The mixture is melted and poured into metal tubes containing streched threads. On cooling candles are obtained. Substituted carboxylic acids The compounds formed by the replacement of one or more hydrogen atoms of the hydrocarbon chain part of the carboxylic acids by atoms or groups such as X (halogen), OH or NH2, are referred to as substituted acids. For example, CH 2 ClCOOH ; CH 2 OHCOOH ; Chloroacet ic acid Hydroxyace tic acid CH 2 NH 2 COOH Aminoaceti c acid The position of the substituents on the carbon chain are indicated by Greek letters or numbers. 6 5 4 3 2      1 C  C  C  C  C  C OOH For example, Carboxylic acids and Their derivatives CH 3 CHOHCH 2 COOH  - Hydroxybut yric acid 2 - Hydroxypro panoic acid 3 - Hydroxybut anoic acid Lactic Acid or -hydroxy propionic acid or 2hydroxy propanoic acid It is the main constituent of sour milk. It is manufactured by fermentation of molasses by the micro-organism (Bacterium acidi lactici-sour milk) in presence of CaCO 3. CH (OH )COOK CH (OH )COOK CH (OH )COO 2|  Ca(OH ) 2 |  | CH (OH )COOH CH (OH )COOK CH (OH )COO (1) Method of Preparation From acetaldehyde : Pot.hydrog en tartrate CaCl2 HCN CH 3 CH (OH )CN  -2KCl Cyanohydri n CH 3 CHOHCOOH Lactic acid (2) Physical Properties CH 3 CHOHCOONa D YG  CH 3 CHO Acetald eh yd e CH 3 CHOCOCH 3 | COOH Acetyl lactic acid Sod. Lactate Heat Conc. H2SO4 Form ic acid Dil. H2SO4 Heat 130°C NaOH CH3COCl CH 3 CHOHCOOH HI CH 3 CH 2 COOH  Propionicacid Lactic Acid CH 3CHO or CH 3COOH arc Br Acetylene Pd BaSO 4 Ethylene CH 2 CN CH 2 CO 2 H H O H 2 KCN (CH 2 Br )2   | 2  | Ethy lene bromide CH 2 CN CH 2 CO 2 H Red P   | Br2 Succinic acid CHBrCOOH AgOH | CHBrCOOH CHOHCOOH CHOHCOOH  , '-Dibromo succinic Tartaric acid acid (iii) From glyoxal cyanohydrin : CH (OH )CN CHO HCN |    | CHO CH (OH )CN Glyoxal CH (OH )COOH H O H 2 | CH (OH )COOH Glyoxal cyanohydri n Tartaric acid (2) Physical Properties : It is a colourless crystalline compound. It is soluble in water and alcohol CH 3 COCOOH forms). Natural tartaric acid is the dextro variety. It CH 3 CHClCOCl Pyruvic acid ST Lactylchloride (4) Uses : It is used in medicine as calcium and iron lactates, as mordant in dyeing, as acidulant in beverages and candies, as a solvent (ethyl and butyl lactates) for cellulose nitrate. Tartaric Acid. Or ,'-Dihydroxy succinic acid or 2,3-Dihydroxy-Butane-1,4-Dioic acid HO  C H  COOH | HO CH COOH It is found as free or potassium salt in grapes, tamarind, and berries. (1) Methods of Preparation H Electric Fenton's reagent [O] Fe2+/H2O2 or Ag2O U PCl5 KMnO4 H2SO4 Tartaric acid 2 2  CH 2  CH 2  C  H 2  CH  CH  U (3) Chemical Properties : It gives reactions of secondary alcoholic group and a carboxylic group. HCOOH CH (OH )COOH Ca  H 2 SO 4 CaSO 4  | CH (OH )COOH ID It is hygroscopic and very soluble in water. It is optically active and exists in three distinct forms. CO+H2O CH (OH )COO | CH (OH )COO (ii) Synthetic method It is a colourless syrupy liquid having a sour taste and smell. Lactide Ca Pot.tartra te (Filtrate) Calcium tartrate (ppt.) H 2O H  E3 CH 3 CHO  Acetaldehyde (i) Argol which separates as a crust during fermentation of grape juice is impure potassium hydrogen tartrate. Argol is boiled with limewater. Calcium tartrate is precipitated which is filtered. The solution contains potassium tartrate which is also precipitated by addition of CaCl2. The calcium salt is then decomposed with calculated quantity of dilute H2SO4. The precipitate (CaSO4) is filtered and the filtrate on concentration gives the crystals of tartaric acid. 60 CH 3 CHOHCOOH ;  - Hydroxypro pionic acid 1323 but insoluble in ether. It contains two asymmetric carbon atoms and thus shows optical isomerism (four contains two secondary alcoholic groups and two carboxylic groups. Optical Isomerism in tartaric acid COOH COOH | H  C  OH | HO  C  H | COOH d+ Dextrorotatory Tartaric acid | HO  C  H | H  C O H | COOH l-(Leavorotatory acid) Optical active COOH | H C  OH | H C  OH | COOH Meso-Tartaric acid (Optical inactive) 1324 Carboxylic acids and Their derivatives (iii) Meso tartaric acid-optically inactive due to internal compensation. (i) d + Tartaric acid-Dextro-rotatory (ii) l –Tartaric acid-Leavorotatory Optical active (3) Chemical Properties Potassium tartrate Pot.acid tartrate CHOHCOOK CHOHCOOK and | | CHOHCOOH CHOHCOOK It forms two series of CH 3 COCOOH salts Pyruvic acid [O] Fe 2  /H 2 O2 Heat Fenton's reagent HI Heat CH 2 COOH CHOHCOOH HI  | | Heat CH 2COOH CH 2COOH Malic acid Sucinic acid 60 Tartronic acid + Sliver mirror (Test of tartaric acid) CH (OH )COOH [O ] |    K 2 Cr2 O7 /H 2 SO 4 COOH AgNO3 NH4OH E3 CHOHCOOH | CHOHCOOH T artaricacid HBr Fehling's solution CHBrCOOH | CHBrCOOH  , 'Dibromo succinic acid C(OH )COOH || C(OH )COOH Dihydroxy meleic acid COOH | COOH Oxalic acid CH (OH )COOH COOH [O ] |   | COOH COOH T artronicacid Oxalic acid ID Complex NaOOCCH  OformationO  HC  COONa Cu | | NaOOCCH O O  HC  COONa (1) Methods of Preparation D YG U (4) Uses : It is used in carbonated beverages and effervescent tablets, in making baking powder (cream of tartar) and mordant in dyeing (potassium hydrogen tartrate), in preparing Fehling's solution (sodium potassium tartrate–Rochelle salt), in medicine as emetic, dyeing and calico-printing (tartar emeticpotassium antimonyl tartrate) and silver mirroring. (5) Tests (i) When heated strongly, tartaric acid chars readily giving a smell of burnt sugar to produce free carbon and pyruvic acid. U (ii) With AgNO3 : A neutral solution of tartaric acid gives a white ppt. which is soluble in ammonia. A silver mirror is obtained on warming the ammonical (i) By Fermentation : Citric acid is obtained by carrying fermentation of dilute solution of molasses with micro-organism, Aspergillus nigar, at 26-28°C for 7 to 10 days. The resulting solution is neutralised with Ca(OH )2 to form insoluble precipitate, calcium citrate. It is decomposed by dilute H 2 SO 4. The CaSO 4 is filtered off and the solution is concentrated under vacuum to get crystals of citric acid. (ii) By Lemon juice : It is also obtained from lemon juice. The juice is boiled to coagulate proteins. From clear solution, citric acid is obtained as calcium salt with Ca(OH )2. ST silver nitrate solution (Tollen's reagent). (iii) With Fenton's reagent : (H2O2 containing a little of ferrous salt) and caustic soda, It gives a violet colour. (iv) With Resorcinol and conc. H2SO4 : It gives blue colour. Citric Acid Or 2-Hydroxypropane Or 1,2,3-Tri Carboxylic Acid Or -Hydroxy Tricarballylic Acid It occurs in the juice of citrus fruits such as lemon, galgal, orange, lime, etc. Lemon juice contains 6-10% of citric acid. (iii) By synthetic method CH 2 OH | CH 2 Cl | CH 2 Cl | C HOH   CHOH   CO HCl ( g ) | CH 2 OH | heat (in acetic acid) CH dil. HNO 3 [O ] 2 Cl | CH 2 Cl Gly cerol HCN CH 2 COOH CH 2 CN CH 2 Cl | | OH OH KCN C(OH )COOH   C  C CN CN | | | CH 2 COOH CH 2 CN CH 2 Cl | H 2O / H  Carboxylic acids and Their derivatives (2) Physical Properties : It is a colourless crystalline compound. It possesses one water molecule as water of crystallisation. It is soluble in water and alcohol but less soluble in ether. It is not optically active compound. It is nontoxic in nature. It behaves as an alcohol and tribasic acid. 1325 Aromatic acid containing-COOH group in the side chain, they are considered as aryl substituted aliphatic acid. Examples CH2COOH CH = CHCOOH (3) Chemical properties With alkalies and alcohols, it forms three series of salts and esters, respectively | CH 2 COOH Aconitic acid Cinnamic acid Phenyl acetic acid 60 CHCOOH || CCOOH Benzoic Acid (1) Methods of Preparation CH 2 COOH CH 2 COOH | | C(OH )COOH CH3COCl C(OCOCH 3 )COOH HCl | | CH 2 COOH CH 2 COOH M ono acelyderiv ative Citric acid Hl reductio n OH CH3 (iii) From Grignard reagent O || Mg C– O I OMgI || Phenyl mag. iodide COOH Addition product H  orOH  C6 H 5 COOCH 3  H 2 O  C6 H 5 COOH  CH 3 OH Methyl ben zoate Benzoic acid Methanol (v) From trihalogen derivatives of hydrocarbons COOH CCl3 C(OH) 3 + 3KOH + H2O – 3 KCl Benzotrichlor ide (vi) From benzene COCl2 COOH NO2 I Benzoic acid COOH H2 O/NaOH (vii) From Toluene COOH H3C [O],  KMnO4/OH or alkaline K2Cr2O7 Benzoic acid Unstabl e COCl m-Nitro benzoic acid OH + Mg (iv) By hydrolysis of esters COOH NH2 COOH H + , H2 O +C=O COOH Phthalic acid Anthranilic acid Benzoic acid Benzoic acid AlCl3 Salicylic acid O + 2NH3 U D YG ST U Aromatic acid contain one or more carboxyl group (COOH) attached directly to aromatic nucleus. Examples COOH COOH COOH H+ or OH– Benzonitril e Aromatic Carboxylic Acids O-toluic acid alcohol COOH Benzaldehyde Benzyl alcohol + 2H2O (4) Uses : It finds use in making lemonades, as acidulant in food and soft drinks and makes the lemon sour, as mordant in dyeing and calico printing. Ferric ammonium citrate, magnesium citrate (as an antacid and laxative), sodium or potassium citrate are used in medicine. Ferric ammonium citrate finds use in making blue prints. Benzoic acid Benzyl (ii) From hydrolysis of nitriles or cyanides CN COOH CH 2 COOH | CHCOOH | CH 2 COOH Tricarball ytic acid CH 2 COOH | CO | CH 2 COOH Acetone dicarboxyl ic acid O ID Fuming H2SO4 heat (i) From oxidation of [Laboratory method] CHO CH2OH E3 Heat, 150°C [Friedel-craft reaction] 1326 Carboxylic acids and Their derivatives  Chromic trioxide in glacial acetic acid or Co-Mn acetate can also be taken in place of alkaline KMnO 4. (viii) From o-xylene [Industrial method] CH3 CH3 CO [O] V2O5 COOH HO H O CO COOH COOH p- positions. Thus if resonance producing group is present in the m-position it will not exert its effect. In case resonance and inductive effects both operate in the molecule, resonance effect stronger overpowers the inductive effect. Thus on the above basis, the following order of acidity can be explained. OH Cl NO2 COOH (2) Physical Properties COOH Soda lime (i) It is a white crystalline solid. p-Nitrobenzoic p-Chlorobenzoic acid acid – NO2 group – Cl group exerts exerts – I effects, + R – R and – I effects Similarly : COOH (iv) It has a faint aromatic odour and readily sublimes and is volatile in steam.  C6 H5 COOH ⇌ C6 H 5 CO O  H  D YG  stabilised to a greater extent than the carboxylic acid (ArCOOH). || O |  Ar  C  OH  Ar  C  O H O || | Resonance in carboxylat e anion Equivalent structure and hence    more stable  U Non - equivalent structure and    hence less stable  O Ar  C  O   Ar  C  O Resonance in carboxylic acid COOH COOH Acidity is only due to electron withdrawing inductive effect of the – NO2 group (resonance does not affect the m-position) while in the p-isomer acidity is due to electron withdrawing inductive as well as resonance effect. Since the carboxylate anion ( ArCO O) is resonance O COOH NO2 U (3) Acidity of Aromatic Carboxylic Acid : Aromatic acid dissociates to give a carboxylate anion and proton. p-Hydroxybenzoic acid – OH group exerts + R and – I effects 2 ID (iii) It is sparingly soluble in cold water but fairly soluble in hot water, alcohol and ether. COOH Benzoic acid No other group NO NO2 (ii) It has m.p. 394 K. COOH COOH COOH E3 COOH [O] V2O5 60 Soda lime (ix) From naphthalene [Industrial method] being Effect of Substituents on Acidity : The overall influence of a substituent on acidity of substituted ST benzoic acids is due to two factors. (i) Inductive effect : If the substituent exerts–I effect, it increases the acidity of carboxylic acids, while if it exerts + I effect it decreases the acidity. Inductive effect affects all positions, i.e., o–, m– and p–. (ii) Resonance effect : Like inductive effect, if the resonance producing group exerts minus effect i.e., if it withdraws electrons, it increases the strength of the benzoic acid. Similarly, if the group causes +R effect it decreases the acidity of benzoic acid. However, remember that resonance effect affects only o- and The acidity of the three isomers of hydroxybenzoic acids follows the following order. COOH OH OH OH COOH COOH – I effect +M effect COOH Resonance effect cannot operate and hence only the acid-strengthening –I effect takes part with the result m-hydroxybenzoic acid is stronger acid than benzoic acid. Like other substituted benzoic acid. Acidic character among benzoic acids having different electron releasing group. COOH COOH COOH COOH > OCH3 > > CH3COOH > OH NH2 (4) Chemical Properties : (i) Reactions of carboxylic group (ii) Reactions of aromatic ring (i) Reactions of Carboxylic Group (a) Reaction with metals CH3 Carboxylic acids and Their derivatives COOH +2 Na COONa + H2 (b) Reaction with Alkalies Or NaHCO3 Or Na2CO3 : COOH + NaOH (h) Reduction COONa + H2O COOH + LiAlH4 or NaHCO3 or Na2CO3 (c) Formation of Esters : CH2OH + H2O Benzyl alcohol (i) Decarboxylation In presence of ortho substituent the rate of esterification is greatly decreased due to steric effect. C6 H 5 COOAg The 2Methylbenzoic acid substituted 2, 6-Dimethyl benzoic acid phenylacetic 2,6-Dimethyl phenylacetic acid acid is + HCOOH (j) Hunsdiecker reaction : C2H5Br This is due to the fact that in such cases the attack of the alkyl group of the alkyl halides is on the oxygen atom of the COOH group but not on the sterically hindered carbon atom. U (d) Formation of acid chloride COOH COCl + POCl3 + HCl ST + PCl5 or SOCl2 Benzoyl Chloride (e) Reaction with N3H [Schmidt reaction] COOH NH2 H2SO4 + N3H 50° C + CO2 + N2 Anilin (f) Reaction with sodalime e + CO2 Benzen e (g) Reaction with anhydride COOH + (CH3CO)2 O  heat Phenyl halide (ii) Reactions of Aromatic Ring (a) Nitration COOH COOH + HNO3 H2SO4 NO (b) Sulphonation m-nitrobenzoic 2 acid COOH COOH + Fuming SO3H H2SO4 m-sulpho benzoic acid (c) Chlorination COOH COOH + Cl2 Fecl3 Cl (d) Reduction m-chloro benzoic acid COOH COOH Na/amyl Boil, 3H2 alcohol Cyclo hexanoic acid (5) Uses : Benzoic acid is used, (i) in medicine in the form of its salts especially as urinary antiseptic. (ii) As sodium benzoate for preservation of food such as fruit juices, tomato ketchup, pickles etc. COOH NaOH + CaO 4  C6 H 5  X  CO 2   AgX Silver ben zoate ( Br2 or Cl 2 ) U D YG AgNO3 in CCl  X2 easily esterified because – COOH group is separated from benzene ring by – CH2 – part. The ortho-substituted benzoic acids can be easily esterified by treating the silver salt of the acid with COOH i.e., COOAg alkyl halides, COOC2H5 H3C H3C H3C CH3 CH3 CH3 CHO +CO2 + H2O MnO  E3 ; COOH ID The esterification of the various benzoic acids : CH2COOH COOH COOH COOH HC CH3 CH3 H3C CH3 3 60 Aromatic acid (benzoic acid) having no group in its ortho positions can be readily esterified with alcohol in presence of a mineral acid. COOH COOC2H5 + + C2H5OH H + H2O Benzoic acid 1327 (iii) In the preparation of aniline blue. (iv) In treatment of skin diseases like eczema. O O || || C–O– C Benzoic anhydride (6) General Tests 1328 Carboxylic acids and Their derivatives (i) Benzoic acid dissolves in hot water but separates out in the form of white shining flakes on cooling. (ii) It evolves CO2 with sodium bicarbonate, i.e., it gives effervescence with sodium carbonate. (iii) Neutral ferric chloride gives a buff coloured precipitate. 60 (iv) When warmed with ethyl alcohol and a little conc. H2SO4, a fragrant odour of ethyl benzoate is obtained. (v) When heated strongly with soda lime, benzene vapours are evolved which are inflammable. E3 Cinnamic Acid [-Phenyl acrylic acid] CH = CH – COOH OH COOH Salicylic acid [O-Hydroxy benzoic acid]; (1) Methods of Preparation (i) By Perkin's reaction ID Salicylic acid is present in many essential oils in the form of esters. Oil of winter green is a methyl ester CH COONa 3 C6 H 5 CHO  (CH 3 CO )2 O   of salicylic acid. 180 C C6 H5 CH  CHCOOH  CH 3 COOH (ii) By Claisen condensation (1) Methods of preparation U (i) Kolbe Schmidt reaction C H ONa ' C6 H 5 CHO  CH 3 COOC 2 H 5 2 5  H O ONa OCOONa C6 H 5 CH  CHCOOC 2 H 5 2 CO2 Ester 125°C, Pressure D YG H C6 H 5 CH  CHCOOH  C2 H 5 OH (iii) By knoevenagel reaction Sodium phenoxide OH COONa Rearrangeme nt Sodium Sodium phenyl carbonate salicylate dil. HCl NH 3 C6 H 5 CHO  CH 2 (COOH )2  heat OH C6 H5 CH  CHCOOH  CO2  H 2O COOH (iv) Industrial method 200 C C 6 H 5 CHCl 2  H 2 CHCOONa    C 6 H 5 CH  CHCOOH  NaCl  HCl Benzal chloride Salicylic acid Sodium acetate ST U (2) Physical Properties (i) It is a white crystalline solid and its melting point 133°C. (ii) It is sparingly soluble in water. (iii) It exhibits geometrical isomerism. C6 H 5  C  H C6 H 5  C  H || || H  C  COOH HOOC C  H Trans - form (Cinnamic acid) Cis- form (Allocinnamic acid) Cinnamic acid (stable form) occurs in nature both free and as esters in balsams and resins. (3) Chemical properties Oxidation CrO3 Reduction Na(Hg)/H2O Reduction LiAlH4 – 10°C C6H5CHO distilled and separated by steam distillation. (ii) Reimer-Tiemann reaction OH +CCl4+ KOH OH Heat (a) Cl COOH C6H5CH2CH2CH2OH 3-Phenyl propyl alcohol C6H5CH = CHCH2OH C6H5CH = CH2 Styrene OH Fuse with NaOH COOH o-Chlorobenzoic acid SO3K -Phenyl propionic acid COOH (iii) From benzene derivatives Benzaldehyde Benzoic acid C6H5CH2CH2COOH OH Dil. HCl COOK + C6H5COOH Cinnamyl alcohol Soda lime It is a commercial method. The reaction yields both o- and p- isomers. Salicylic acid is more volatile (b) Fuse with KOH COOH o-Sulphobenzoic acid OH CH2OH Salicyl alcohol + [O] Chromi c acid OH COOH OH COOH Carboxylic acids and Their derivatives 1329 (c) OH CH3 +[O] OH PbO/NaOH COOH oCresol (iii) Decarboxylation NH2 (e) COOH Anthranilic acid COOH N2Cl NaNO2/HC l 0°C Salicylic acid H2 O OH COOH Salicylic acid chloroform. (v) Reaction with ferric chloride solution OH COOH (iv) It is steam volatile. Violet colouration (vi) Reaction with PCl5 U D YG (3) Chemical properties (i) Reaction with Na2CO3, NaHCO3 or NaOH O C – OH COO– Na+ OH Aq. Na2CO3 Mono sodium salicylate Aq. NaOH U COONa OH Cl PCl5 COOH COCl Salicylic acid o-Chlorobenzoyl chloride (vii) Bromination OH OH Br2 water Br COOH Br 2,4,6,-Tribromophenol (viii) Nitration ONa Disodium salicylate COOH ST Methyl salicylate Salicylic acid Methyl salicylate is an oily liquid (oil of winter green) with pleasant material. It is also used in medicine in the treatment of rheumatic pain and as a remedy for aches, sprains and bruises. It is used in perfumery and as a flavouring. It is used for making of iodex. POCl3 B r Salicylic acid OH OH (ii) Reaction with alcohols or phenols OH OH +H2O + CH3OH HCl(gas ) COOH COOCH3 Salicylic acid FeCl3 Solution Salicylic acid (v) It is poisonous in nature. However, its derivative used in medicine internally and externally as antipyretic and antiseptic. + C6H5OH Aspirin (Acetyl salicylic acid)  Aspirin is a white solid, melting point 135°C. It ID (iii) It is sparingly soluble in cold water but readily soluble in hot water, alcohol, ether and COOH COOH Acetyl chloride is used as antipyretic and pain killer (analgesic action). (ii) Its m.p. is 156°C. OH OCOCH3 Pyridine E3 (i) It is a colourless needle shaped crystalline compound. OH + ClCOCH3 COOH (2) Physical properties Salicylic acid Phenol (iv) Acetylation t OH || + CO2 OH OH COOH hea  60 (d) Salol is a white solid m.pt. 43°C. It is a good internal antiseptic. It is used in making of toothpastes. Salol absorbs ultraviolet light and its main use now is sun-screening agent and stabiliser of plastics. O2 N Fuming HNO3 Salicylic acid NO 2 NO2 2,4,6,-Trinitrophenol Phthalic acid [1,2,-Benzene dicarboxylic acid] COOH COOH There are three isomer (ortho, meta, para) of benzene dicarboxylic acid. COOH COOH COOH COOH OH COOH COOH COOC6H5 Phenyl salicylate (salol) Benzene-1,2dicarboxylic acid (Phthalic acid) Benzene-1,3dicarboxylic acid (Isophthalic acid) Benzene-1,4dicarboxylic acid (Terphthalic acid) 1330 Carboxylic acids and Their derivatives (1) Methods of preparation (i) By the oxidation of o-xylene : CH3 CH3 CH3 [O] KMnO4 COOH [O] COOH COOH o-Xylene Phthalic acid o-Toluic acid 60 (ii) From naphthalene (Industrial method) : It is known as aerial oxidation. CO CO Fuming H2SO4 O COONa COONa NaOH Phthalic anhydride COOH COOH (i) It is colourless crystalline compound. (ii) Its melting point is not sharp (195–213°C). ID (2) Physical properties E3 Naphthalene HgSO4,300° C U (iii) It is sparingly soluble in cold water but soluble in hot water, alcohol, ether, benzene etc. (3) Chemical properties COONa D YG NaOH COOH Acid salt NaOH COONa Acid derivatives COONa The compounds which are obtained by replacing the OH of the carboxylic group by other atoms or groups Disodium phthalate COOC2H5 U C2H5OH ST O  R  C  group is common to all the derivatives and || COOC2H5 COOC2H5 Ethyl phthalate COOH O is known as acyl group and these derivatives are termed as acyl compound.  The important derivatives are given below : COCl Group replacing – OH COCl Phthaloyl chloride (X  F, Cl, Br, I) CO Heat O – H2 O CO  NH 2 Phthalic anhydride heat Benzen e COO COO Name Acyl halide Amide Structure O || R  C X O || R  C  NH 2 Soda lime Hg (CH3COO)2 || acid derivatives. C2H5OH PCl5 Phthalic acid such as X  ,  NH 2 , – OR and O  C  R are known as COOH Ethyl hydrogen phathalate COOH (4) Uses : It is used in the manufacture of plastics, dyes and other compounds such as phthalic anhydride, phthalimide, anthraquinone and fluorescein etc. Hg Carboxylic acids and Their derivatives ester (iii) Inductive effect : Higher the –I effect, more O || R  C  OR  ( R  m ay be R ) OOCR anhydride O O || || R  C O  C  R Reactivity Acyl derivatives are characterised by nucleophilic substitution reactions. L O Cl where R may be alkyl or aryl group. (1) Methods of Preparation : 60 L Nu.. |  C O.. : R  C  O : L R C  O :  : Nu .. Acyl Halides R  C (i) From carboxylic acid RCOOH  PCl 5 RCOCl  POCl 3  HCl Nu R reactive is the acyl compound. Inductive effect of oxygen in ester is greater than nitrogen in amide, hence ester is more reactive than an amide. 3 RCOOH  PCl 3 3 RCOCl  H 3 PO 3 (ii) Industrial method : By distilling anhydrous sodium acetate Intermediate O E3 OR  1331 heat || 3CH 3 COONa  PCl 3  3CH 3 COCl  Na 3 PO3 (L  X , NH 2 , O  C  R or OR ) heat O O || || C  O  R  C O  C R  R  C R X O OR O  R C NH 2 Sodium acetate Acetyl chloride heat (CH 3 COO )2 Ca  SO 2 Cl 2  2CH 3 COCl  CaSO 4 Calcium acetate Sulphuryl chloride Acetyl chloride (iii) With thionyl chloride : RCOOH  SOCl 2 RCOCl  SO 2  HCl This is the best method because SO 2 and HCl are U Out of acid halides, the acid chlorides are more important ones. 2CH 3 COONa  POCl 3  2CH 3 COCl  NaPO 3  NaCl ID The relative reactivities of various acyl compounds have been found to be in the following order: D YG The overall order of reactivity can be accounted for in terms of the following three factors: (i) Basicity of the leaving group (ii) Resonance effects and (iii) Inductive effects. (i) Basicity of the leaving group : Weaker bases are good leaving groups. Hence, the acyl derivatives with weaker bases as leaving groups are more reactive. Chloride ion is the weakest base while – NH 2 is the strongest base. Thus, acyl chlorides are most reactive and amides are least reactive. ST U (ii) Resonance effect : The leaving group in each case has an atom with lone pair of electrons adjacent to the carbonyl group. The compound exists, therefore, as a resonance hybrid. O O || RC |.. L  R  C  gases and easily escape leaving behind acyl chloride. (2) Physical properties : The lower acyl chloride are mobile, colourless liquid while the higher members are coloured solids. Acyl chloride have very pungent, irritating order and are strong lachrymators (tears gases) They fume in air due to hydrochloric acid by hydrolysis. the formation of They are readily soluble in most of the organic solvent. Acyl chloride don't form intermolecular hydrogen bonding. Therefore, their boiling points are lower than those of their parent acids. (3) Chemical properties  O O O | || || R  C  Cl  : Nu  R  C  Cl R  C  Cl  | | Nu Nu Cl   H  HCl L This makes the molecule more stable. The greater the stabilization, the smaller is the reactivity of the acyl compound. (i) Hydrolysis : CH 3 COCl  HOH CH 3 COOH  HCl However, acyl chlorides are least affected by resonance. Due to lower stabilization, the acid chlorides are more reactive as the loss of Cl is easier. Greater stabilization is achieved by resonance in esters and amides and thus, they are less reactive. Benzoic acid Acetyl chloride C 6 H 5 COCl  Benzoyl chloride Acetic acid H 2 O C 6 H 5 COOH  H 2 O (ii) Reaction with alcohols (alcoholysis) CH 3 COCl  CH 3 CH 2 OH CH 3 COOCH 2 CH 3  HCl Ethyl acetate 1332 Carboxylic acids and Their derivatives aq NaOH or C 6 H 5 COCl  C 2 H 5 OH   C 6 H 5 COOC 2 H 5  Pyridine Benzoyl chloride Ethyl alcohol Ethyl benzoate reaction is called Schotten || H 2O  CH 3 CH 2 C  OH ( N 2 ) Baumann (ix) Reaction with water reaction. (iii) Reaction with salts of carboxylic acid   Pyridine O O || || AgNO / H O 3 CH 3 COCl  2 CH 3 COOH  AgCl  HNO 3 (x) Reaction with chlorine CH 3 COCl  CH 3 COO Na   CH 3 C  O  C  CH 3 Red P CH 3 COCl  Cl 2   Cl  CH 2  CO  Cl  HCl Acetic anhydride (iv) Reaction with benzene (acylation) : This reaction is called friedel craft reaction. COCH3 Anhyd. AlCl3  CH 3 COCl  (xi) Reaction with Grignard reagent CH 3 CO Cl  IMg CH 3 CH 3 COCH 3  Mg  HCl Methyl magnesium iodide Acetone E3 COC6H5 H O CH 3 COCl  KCN CH 3 COCN 2 CH 3 COCOOH Acetyl cyanide Anhy d. AlCl 3  C6 H 5 COCl     HCl ID OH  ClOCCH 3 COOH (v) Reaction with ammonia or amines : CH 3 COCl  Acetyl chloride 2 NH 3 CH 3 CONH 2  NH 4 Cl Acetamide Salicylic acid C6 H 5 COCl  2 NH 3 C6 H 5 CONH 2  NH 4 Cl Pyruvic acid (xiii) Reaction with Salicylic acid Benzopheno ne Benzoy l chloride I Cl (xii) Reaction with KCN Acetopheno ne Acetyl chloride Mono - - chloroacet yl chloride 60 This O HCl OOCCH 3 + HCl COOH Acetyl salicylicacid (Aspirin) (xiv) Reaction with ether U Benzamide However, acyl chlorides react with amines to form substituted amides. D YG O ZnCl 2 CH 3 COCl  C 2 H 5 OC 2 H 5   anhy. Diethyl ether CH 3 COOC 2 H 5  C 2 H 5 Cl || CH 3 COCl  H 2 NC 2 H 5 CH 3 C  NH  C2 H 5 Ethyl acetate Ethyl chloride N -Ethyl acetamide CH 3 COCl  (C 2 H 5 )2 NH CH 3 CON (C 2 H 5 )2  HCl N, N - Diethyl acetamide (vi) Reduction LiAlH or 4 CH 3 COCl   NaBH 4 : CH 3 CH 2 OH Ethanol (Primary alcohol) Pd / BaSO U 4 CH 3 COCl  H 2   CH 3 CHO  HCl This reaction is called Rosenmund reaction. ST (vii) Reaction with organocadmium compounds (formation of ketones) (xv) Reaction with sodium peroxide (Peroxide formation) O  || Acetyl chloride Acetopheno ne  (xvi) hydrazine Reaction with hydroxylamine and CH 3 COCl  H 2 NOH CH 3 CONHOH  HCl Hydroxyl amine Acetyl hydroxylam ine (hydroxami c acid) CH 3 COCl  H 2 NNH 2 CH 3 CONHNH 2  HCl Acetyl hydrazine O || (i) As an acetylating agent. (ii) In the estimation and determination of number of hydroxyl and amino groups.   CH 3  C  Cl  2C H 2  N  N CH 3  C  CH  N  N Diazometha ne O || (4) Uses (viii) Reaction with diazomethane O O || Acetyl peroxide Hydrazine Acetone 2C6 H 5 COCl  (CH 3 )2 Cd 2C6 H 5 COCH 3  CdCl 2 ||  2CH 3  C  Cl  N a O  O N a CH 3 C  O  O  C  CH 3  2 NaCl 2CH 3 COCl  (CH 3 )2 Cd 2CH 3 COCH 3  CdCl 2 Dimethyl Cadmium  Diazoaceto ne (iii) In the preparation of acetaldehyde, acetic anhydride, acetamide, acetanilide, aspirin, acetophenone etc. Carboxylic acids and Their derivatives Far more rapidly CH 3 CONH 2  NaOH   CH 3 COONa  NH 3 O NH 2 Acid Amides R  C 1333 (ii) Amphoteric nature (Salt formation) where, R  CH 3 ,  CH 2CH 3 ,  C6 H5 It shows feebly acidic as well as basic nature. (1) Methods of preparation CH 3 CONH 2  HCl (conc. ) CH 3 CONH 2.HCl Acetamide hy drochloride (only stable in aqueous solution) (i) Ammonolysis of acid derivatives 2CH 3 CONH 2  HgO (CH 3 CONH )2 Hg  H 2 O CH 3 COCl  2 NH 3 CH 3 CONH 2  NH 4 Cl Acetamide Acetamide (CH 3 CO )2 O  2 NH 3 CH 3 CONH 2  CH 3 COONH 4 Ether CH 3 CONH 2  Na   CH 3 CONHNa  Amm. acetate Sodium acetamide NH 3 C 6 H 5 CONH 2  HCl (iii) Benzamide (ii) From ammonium salts of carboxylic acids (Laboratory Method) Reduction Acetamide Ethy lamine Na / C 2 H 5 OH C6 H 5 CONH 2  4[H ]    C6 H 5 CH 2 NH 2  H 2O Benzamide Heat CH 3 COONH 4  CH 3 CONH 2  H 2 O (iii) By partial hydrolysis of alkyl cyanide : Dehydration CH 3 CONH 2  CH 3 C  N  H 2O P2 O5 Acetamide heat Methy l cy anide P2 O 5 C6 H 5 CONH 2   C6 H 5 C  N  H 2 O heat ID  Ammonium acetate is always heated in presence of glacial acetic acid to avoid the side product ( CH 3 COOH ). Benzamide Pheny l cy anide C6 H 5 CONH 2   C6 H 5 C  N SOCl 2 Conc. HCl CH 3 C  N  CH 3 CONH 2 Pheny l cy anide (v) Reaction with nitrous acid Acetamide U NaNO 2 / HCl CH 3 CONH 2  HONO    CH 3 COOH  N 2 (iv) By heating carboxylic acid and urea heat Benzy lamine (iv) Acetamide H 2 O / OH  1 H2 2 LiAlH 4 CH 3 CONH 2  4[H ]   CH 3 CH 2 NH 2  H 2 O E3 C 6 H 5 COCl  Benzoyl chloride Mercuric acetamide 60 Acetamide Mercuric Oxide Acetic acid H 2 N  C  NH 2  R  C  OH  R  C  NH 2  CO 2  NH 3 || O O || O D YG || Amide  H 2O C6 H 5 CONH 2  HONO 2  C6 H 5 COOH NaNO / HCl Benzoic acid (2) Physical properties (i) Physical state : Formamide is a liquid while all other amides are solids. (ii) Boiling points : Amides have high boiling points than the corresponding acids. Boiling points 494 K Acetic Acid Boiling points 391 K U Acetamide Benzamide Boiling points 563 K Benzoic acid Boiling points 522 K ST The higher boiling points of amides is because of intermolecular hydrogen bonding H R H R H R | | | | | |.......... H  N  C  O......... H  N  C  O......... H  N  C  O (iii) Solubility : The lower members of amide family are soluble in water due to the formation of hydrogen bonds with water. (3) Chemical properties (i) Hydrolysis Slowly CH 3 CONH 2  H 2O  CH 3 COOH  NH 3 Rapidly CH 3 CONH 2  H 2 O  HCl   CH 3 COOH  NH 4 Cl  N 2  H 2O (vi) Hofmann bromamide reaction or Hofmann degradation : This is an important reaction for reducing a carbon atom from a compound, i.e., CONH 2 is changed to  NH 2 group. CH 3 CONH 2 Acetamide Br2  CH 3 NH 2 NaOH or KOH Methyl amine (p-) This reaction occurs is three steps: O || CH 3  C  NH 2  Br2  KOH CH 3 CONHBr  KBr  H 2 O Acetobromamide O || CH 3  C  NHBr  KOH CH 3 NCO  KBr  H 2 O Methy l isocy anate CH 3 NCO  2 KOH CH 3 NH 2  K 2CO 3 Methy l amine CH 3 CONH 2  Br2  4 KOH CH 3 NH 2  2 KBr  K2CO 3  2 H 2O  In this reaction a number of intermediates have been isolated; N-bromamides, RCONHBr ; salts of these bromamides [RCONBr  ] K  ; Isocyanates, RNCO.  Nitrene rearranges to form isocyanate. 1334 Carboxylic acids and Their derivatives C2 H 5 Br  CH 3 COOAg Ethy l bromide Silver acetate (vii) Action with alcohol : HCl CH 3 CONH 2  CH 3 OH  CH 3 COOCH 3  NH 4 Cl 70 C (iv) From ether : methyl acetate BF 3 CH 3  O  CH 3  CO  CH 3 COOCH 3 (viii) Reaction with grignard reagent (v) CH3MgBr   OMgBr OH   | | H 2O / H  CH  C  NH     CH 3  C  NH  MgBr 3 2   Hy droly sis | |   CH 3 CH 3   Unstable - NH3 Esters, R  C  OR || These are the most important class of acid derivatives and are widely distributed in nature in plants, fruits and flowers. (1) Methods of preparation [Esterification] : O R  C  OH  H OR  H+ || R  C  OR  H 2 O U Ester CH 3 COOH  CH 2 N 2 Acetic acid Ether   CH 3 COOCH 3  N 2 Diazometha ne ST C6 H 5 COOH  CH 2 N 2 Benzoic acid Methyl acetate Ether  C6 H 5 COOCH 3  N 2 Diazometha ne Methyl ben zoate  With diazomethane is the best method. (ii) From acid chloride or acid anhydrides CH 3 CO Cl  H OC 2 H 5 CH 3 COOC 2 H 5  HCl Acetyl chloride CH 3 CO CH 3 CO Ethyl alcohol || Flavour Ester Flavour Banana Raspberry Jasmine Isobutyl formate Ethyl butyrate Apricot Octyl acetate Orange E3 D YG O acid | Pineapple (ii) Solubility : They are sparingly soluble in water but readily soluble in organic solvents such as alcohol, ether etc. (iii) Boiling points : Their boiling points are lower than the corresponding acids because of the absence of hydrogen bonding. i.e., ethyl acetate = 77.5oC. (3) Chemical properties (i) Hydrolysis : dil. acid CH 3 COOC 2 H 5  H 2 O CH 3 COOH  C 2 H 5 OH U Amides such as dimethyl formamide (DMF), dimethyl acetamide (DMA) are used as solvents for organic and inorganic compounds. O || H O O (2) Physical properties (i) Physical state and smell : Esters are colourless liquids (or solids) with characteristic fruity smell. Flavours of some of the esters are listed below : ID (i) In organic synthesis. The compounds like methyl cyanide, Methylamine and ethylamine can be prepared. || Al (OC 2 H 5 )3 CH 3  C  H  O  C  CH 3    CH 3  C  OC2 H 5 Amyl acetate Benzyl acetate Amyl butyrate (4) Uses (iii) As a wetting agent and as soldering flux. Methyl acetate From Tischenko reaction : Ester O   ||   CH 3  C  CH 3  Acetone     (ii) In leather tanning and paper industry. 350 K Methoxy methane CH 3  Mg  Br  CH 3  CONH 2 CH 4  CH 3  CONH  MgBr (i) From carboxylic Laboratory method. Ethy l acetate 60 o CH 3 COOC 2 H 5  AgBr Ethyl acetate Acetic acid Ethyl alcohol CH 3 COOC 2 H 5  NaOH  CH 3 COONa  C 2 H 5 OH Ethyl acetate Sod. acetate Ethyl alcohol Hydrolysis of ester by alkalies (NaOH) is known as saponification and leads to the formation of soaps  This reaction (saponification) is irreversible because a resonance stabilized carboxylate (acetate) ion is formed.  The acid hydrolysis of esters is reversible. (ii) Reaction with ammonia (ammonolysis) : CH 3 CO OC 2 H 5  H NH 2 CH 3 CONH 2  C 2 H 5 OH Ethyl acetate Acetamide (iii) Reduction LiAlH 4 2C 2 H 5 OH CH 3 COOC 2 H 5  4[H ]  or Na / C 2 H 5 OH COOC 2 H 5 CH 2 OH LiAlH 4  4 H  Ethyl acetate  C 2 H 5 OH or Na / C 2 H 5 OH O  CH 3 CH 2OH CH 3 COOCH 2CH 3  CH 3 COOH Acetic anhydride C 6 H 5 CO Cl Benzoyl chloride Ethyl acetate Ethyl alcohol  H OC 2 H 5 C 6 H 5 COOC 2 H 5  HCl Ethyl alcohol (iii) From alkyl halide : Ethyl benzoate Ethyl benz oate Benzyl alcohol  Reduction in presence of Na / C2 H 5 OH is known as Bouveault Blanc reduction. Carboxylic acids and Their derivatives  The catalytic hydrogenation of ester is not easy and requires high temperature and pressure. The catalyst most commonly used is a mixture of oxides known as copper chromate (CuO.CuCr2O4 ). CH 3 COOC 2 H 5  H 2 NNH 2 CH 3 CONHNH 2  C2 H 5 OH Hy drazine Acid hy drazide (x) Halogenation Red P CH 3 COOC 2 H 5  Br2   CH 2 BrCOOC 2 H 5  HBr  Bromoethyl acetate O || (xi) Reaction with HI CuO.CuCr 2 O 4 R  C  O R   2 H 2    RCH 2 OH  R OH CH 3 COOC 2 H 5  HI CH 3 COOH  C 2 H 5 OH 525 K , 200  300 atm Acetic acid (iv) Reaction with PCl5 or SOCl2 C6 H 5 COOC 2 H 5  PCl 5 C6 H 5 COCl  POCl 3  C 2 H 5 Cl (v) Benzoyl chloride Reaction with alcohols : On refluxing ester undergoes exchange of alcohols residues. R C H+ CH 3 COOC 2 H 5  CH 3 OH CH 3 COOCH 3  C 2 H 5 OH Ethyl acetate Methyl acetate  This reaction is known as alcoholysis or trans esterification. D YG OMgBr O | || CH 3 MgBr CH 3  C  CH 3    CH 3  C  CH 3 | CH 3 H+ artificial flavours and (iii) In the preparation of ethyl acetoacetate. (5) General Tests (i) It has sweet smell It is neutral towards litmus (iii) A pink colour is developed when one or two drops of phenolphthalein are added to dilute sodium hydroxide solution. The pink colour is discharged when shaken or warmed with ethyl acetate. (iv) Ethyl acetate on hydrolysis with caustic soda solution forms two compounds, sodium acetate and ethyl alcohol. U OMgBr   |   CH 3  C  OC 2 H 5  CH 3 MgBr CH 3  C  OC 2 H 5  |   Ethyl acetate CH 3   O || making CH 3 COOC 2 H5  NaOH CH 3 COONa  C2 H 5 OH C2H5OMgBr (vi) Reaction with Grignard reagents In (ii) O  ROH OR R C (ii) essences. ID O  ROH OR (Excess) As a solvent for oils, fats, cellulose, 60 Ethyl chloride (i) resins etc. E3 CH 3 COOC 2 H 5  SOCl 2 CH 3 COCl  C 2 H 5 Cl  SO 2 Ethyl benzoate Ethy l alcohol (4) Uses CH 3COOC 2 H5  PCl5 CH 3COCl  C2 H5Cl  POCl 3 Acetyl chloride 1335 H2 O Acid Anhydride CH 3 CO CH 3 CO O or (CH 3 CO)2 O (1) Method of preparation (i) From carboxylic acid O O || || Quartz tube O O || || R  C  OH  H O  C  R   R  C  O  C  R  H 2 O Acid anhydride Porcelain chips 1073 K OH | U CH 3  C  CH 3 | P O 10 C6 H 5 CO OH  H OOCC 6 H 5 4   heat CH 3 3 o alcohol ST (vii) Claisen condensation O Benzoic anhydride C 2 H 5 O  Na  CH 3  C  OC 2 H 5  H  CH 2 COOC 2 H 5   Ethy l acetate (2 molecules) O || CH 3  C  CH 2 COOC 2 H 5  C 2 H 5 OH (ii) From carboxylic acid salt and acyl chloride [Laboratory method] Py CH 3 COONa  CH 3 COCl   CH 3 COOCOCH 3  NaCl Acetic anhydride Ethy l acetoaceta te (  - ketoester) (viii) Reaction with hydroxyl amine O O || || Ethy l acetate HNOH Py C6 H 5 COONa  C6 H 5 COCl   C6 H 5 COOCOC 6 H 5 Benzoic anhydride  NaCl base   CH 3  C  NHOH  C 2 H 5 OH Hy droxy lamine (ix) Reaction with hydrazine O || C6 H 5  C  O  C  C6 H 5  H 2 O || CH 3  C  OC 2 H 5  H O || Hy droxamic acid (iii) From acetylene 1336 Carboxylic acids and Their derivatives CH 3 HgSO 4 Distill  2CH 3 COOH  |   heat CH CH (OOCCH 3 )2 CH (CH 3 CO)2 O  HCl CH 3 COCl  CH 3 COOH ||| CH 3 CHO  CH 3 CO CH 3 CO O (v) Reaction with chlorine (CH 3 CO )2 O  Cl 2 CH 3 COCl  CH 2 ClCOOH Acety lchloride Monochloro acetic acid Acetic anhy dride (vi) Reaction with PCl5 (iv) From acetaldehyde : (CH 3 CO)2 O  PCl 5 2CH 3 COCl  POCl 3 Cobalt CH 3 CHO  O 2    2CH 3  C  O  O  H acetate || (CH 3 CO)2 O  H 2 O 60 (vii) Friedel craft's reaction O AlCl 3 (CH 3 CO )2 O  C6 H 6   C6 H 5 COCH 3  CH 3 COOH Benzene (2) Physical properties (CH 3 CO )2 O  CH 3 CHO CH 3 CH (OOCCH 3 )2 Acetaldehyde LiAlH 4 (CH 3 CO )2 O  CH 3 CH 2 OH || D YG Hydrolysis : O (x) Action with ether : CH 3 CO O.COCH 3  C 2 H 5  O  C 2 H 5 2CH 3 COOC 2 H 5 CH 3 COOCOCH 3 Acetic acid Action with ammonia (CH 3 CO )2 O  2 NH 3 CH 3 CONH 2  CH 3 COONH 4 Acetamide Amm.acetate U (iii) Acetylation : Acetic anhydride react with compound having active hydrogen. (CH 3 CO )2 O  C 2 H 5 OH CH 3 COOC 2 H 5  CH 3 COOH Ethy l alcohol || (4) Uses : Acetic anhydride is used (i) as an acetylating agent. (ii) For the detection and estimation of hydroxyl and amino group. (iii) in the manufacture of cellulose acetate, aspirin, phenacetin, acetamide, acetophenone, etc. Ethy l acetate Urea or Carbamide O  C ST N  Ethy l acetamide (CH 3 CO )2 O  HN (C 2 H 5 )2 CH 3 CON (C 2 H 5 )2  CH 3 COOH Diethy lamine N , N  Diethy l acetamide (CH 3 CO )2 O  H 2 NC 6 H 5 CH 3 CONHC 6 H 5  CH 3 COOH Aniline OH Acetanilide Salicylic acid OOCCH 3  CH 3 COOH COOH Acetyl salicylic acid (Aspiriin) (iv) Action of dry HCl NH 2 NH 2 Urea may be considered as diamide of an unstable and dibasic carbonic acid from which both the hydroxyl groups have been replaced by  NH 2 groups. OC OH COOH O O O (CH 3 CO )2 O  H 2 NC 2 H 5 CH 3 CONHC 2 H 5  CH 3 COOH Ethy l amine Ethy l acetate  N 2 O 5 CH 3  C  O  N || Acetic anhy dride (CH 3 CO )2 O  Diethy l ether O CH 3  C  O  C  CH 3  H 2 O 2CH 3 COOH (ii) Ethyl alcohol (xi) Action with N2O5 (3) Chemical Properties (i) Ether U (iii) Boiling points : The boiling points of acid anhydrides are higher than those of carboxylic acids because of the greater molecular size. Ethylidene acetate (ix) Reduction ID (ii) Solubility : They are generally insoluble in water but are soluble in the organic solvents such as ether, acetone, alcohol, etc. (viii) Reaction with acetaldehyde E3 (i) Physical state : Lower aliphatic anhydrides are colourless liquids with sharp irritating smell. The higher members of the family as well as the aromatic acid anhydrides are solids in nature. Acetopheno ne  OH NH 2   O  C OH Carbonic acid  NH 2  OH NH 2   O  C OH Carbamic acid, (Monoamide )  NH 2 NH 2 Urea, diamide of carbonic acid or carbamide  First time isolated from urine in 1773 by Roulle and hence the name urea was given. Carboxylic acids and Their derivatives  It was the first organic compound synthesised in the laboratory from inorganic material (by heating a mixture of ammonium sulphate and potassium cyanate) or o 40 C CaCN 2  H 2 O  H 2 SO 4    NH 2 CONH 2  CaSO 4 by Wohler in 1828. (b) From carbon dioxide and ammonia  This preparation gave a death blow to Vital force theory. o 150  200 C CO 2  2 NH 3   NH 2 COONH 4 Ammonium carbamate  It is the final decomposition product of protein's metabolism in man and mammals and is excreted along with urine. (i) nitric acid From urine : Urine is treated with conc. where crystals of urea nitrate CO(NH 2 )2.HNO 3 are obtained. 2CO(NH 2 )2.HNO 3  BaCO 3 2CO(NH 2 )2  Ba(NO3 )2  H 2O  CO 2 Urea nitrate H 2O (2) Physical properties : Urea is a colourless, odourless crystalline solid. It melts at 132 o C. It is very soluble in water, less soluble in alcohol but insoluble in ether, chloroform and benzene. Crystal structure: In solid urea, both nitrogen atoms are identical.  H2N NH 2 1.37 Å C Urea Urea 60 (1) Method of preparation o heat (140 C)   NH 2 CONH 2 E3  Adults excrete about 30 grams of urea per day in the urine. H2 N NH 2  2 KCNO Potassium cy anate  ( NH 4 )2 SO 4 2 NH 4 CNO  K 2 SO 4 Ammonium sulphate Ammonium cy anate NH 4 CNO  NH 2 CONH 2 On heating Ammonium cyanate Urea This indicates that C  N bond in urea has some double bond character. D YG (i)  The solid residue is extracted with alcohol and the extract evaporated when the crystals of urea are Carbony l chloride (Phosgene) OC 2 H 5  2 NH 3 O  C OC 2 H 5 U OC Urea Ethy l carbonate (urethane) NH 2  2C 2 H 5 OH NH 2 Urea ST By partial calcium 14 ). It Oxalic acid Urea oxalate Urea is a stronger base than ordinary amide. It is due to the resonance stabilization of cation, the negatively charged oxygen coordination with one proton. atom is capable  NH 2   NH 2 H2N  C NH2 C || | | OH OH OH  An aqueous solution of urea is neutral. Calcium Carbide Calcium cyanamide NH 2  H OH The cyanamide is treated with dilute sulphuric o acid at 40 C where partial hydrolysis occurs with the formation of urea. H SO H O CaSO 4 (H 2 O 2 ) 4 CaCN 2 2 H 2 NCN 2 H 2 NCONH 2 Cyanamide (ii) Hydrolysis (Urea) OH Aq. alkali or OC      O  C NH 2  H OH Urea of  H2 N heat CaC 2  N 2  CaCN 2  C It 2 NH 2 CONH 2  H 2 C2 O4 (NH 2CONH 2 )2 H 2 C2O4 H2N of formation): Urea nitrate C hydrolysis (Salt NH 2 CONH 2  HNO 3 (conc. ) NH 2 CONH 2.HNO 3 (iii) Industrial method (a) cyanide nature forms solt with strong acid. (b) From phosgene or alkyl carbonate NH 2  2 HCl NH 2 Basic behaves as a weak monoacid base (K b  1.5  10 obtained. It can be recrystalised