Chemistry Notes for NEET Chapter 28: Carboxylic Acids and Their Derivatives PDF

60 Chapter E3 28 Carboxylic acids and Their derivatives Carboxylic acids are the compounds containing the carboxyl     functional group  – C – OH  | |    O  C H 2 COOH C H 2 COOH CH 2 COOH C HCOOH | | | CH 2 COOH Monocarbox ylic acid [ Ag 2 O or Ag(NH 3 )2 OH  ]  Ketones can be oxidized...

60 Chapter E3 28 Carboxylic acids and Their derivatives Carboxylic acids are the compounds containing the carboxyl     functional group  – C – OH  | |    O  C H 2 COOH C H 2 COOH CH 2 COOH C HCOOH | | | CH 2 COOH Monocarbox ylic acid [ Ag 2 O or Ag(NH 3 )2 OH  ]  Ketones can be oxidized under drastic conditions using strong oxidising agent like K 2 Cr2 O7. U 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 agents  Methanoic acid can not be prepared by oxidation method. The carboxyl group is made up of carbonyl (>C=O) and hydroxyl (– OH) group. Classification  Aldehyde can be oxidized to carboxylic acid with mild oxidising such as ammonical silver nitrate solution ID Carboxylic Acids Tricarboxylic acid Dicarboxylic acid U (2) Monocarboxylic acids of aliphatic series are commonly known as fatty acids such as palmitic acid (C15 H 31COOH ) and stearic acid  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 || O (2) By Hydrolysis of nitriles, ester, anhydrides and acid chloride (i) Hydrolysis of nitriles  HCl R  C  N  HOH  R  C or NaOH  C17 H 35 COOH . The general formula for monocarboxylic acids is Cn H 2n 1COOH or Cn H 2n O2. Where n = number of carbon atoms. ST (3) (4) The carboxylic acids may be aliphatic or aromatic depending upon whether – COOH group is attached to aliphatic alkyl chain or aryl group respectively. [O} [O] RCH 2 OH  RCHO   RCOOH alcohol [O ] RCHO   Aldehyde RCOOH monocarbox ylicacid HCl HCl RCOOR ' HOH  RCOOH  R' OH OH  Ester Acid Alcohol (iii) Hydrolysis of Anhydrides O || CH 3  C CH 3  C H  / OH  O  HOH  2CH 3 COOH Ethanoic acid || K 2Cr2O7 Carboxylic acid K 2Cr2O7 H O 2  RCOOH  NH 4 Cl NH 2 (ii) Hydrolysis of Esters Methods of preparation of monocarboxylic acid (1) By oxidation of alcohols, aldehydes and ketones O R C OH  Rearrangem ent    NH  O Ethanoic anhydride (iv) Hydrolysis of acid chloride and nitro alkane H  / OH  R  C  Cl  HOH  RCOOH  HCl || O the increase in the size of the alkyl group. All carboxylic acids are soluble in alcohol, ether and benzene etc. 85% H SO 2 4 R  CH 2  NO 2    RCOOH (v) Hydrolysis of Trihalogen : R C  The solubility of lower members of carboxylic acids is due to the formation of hydrogen bonds between the – COOH group and water molecules. OH    H 2O OH    OH  O  3 NaX OH R C (3) From Grignard Reagent Dry ether || O  C  O  RMgX   R  C  OMgX Carbon dioxide Grignard reagent H  / H 2O   RCOOH  Mg(OH )X (4) From Alkene or Hydro-carboxy-addition (koch reaction) E3 CH 2  CH 2  CO  H 2 O  CH 3 CH 2 COOH 3 5001000atm & 350C (iv) In the case of odd numbers, the two groups lie on the same side of the chain. (5) Special methods (i) Carboxylation of sodium alkoxide CH HCl Acid CH (ii) Action of heat on dicarboxylic acid COOH  CO 2   R  CH 2 COOH COOH heat Monocarboxylic acid Substituted malonic acid (iii) From acetoacetic ester CH CH 3 2 2 COOH 2 the two terminal groups lie on the same side of the chain the two terminal groups lie on the opposite sides of the chain D YG 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 CH 3 CH 2 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. U R  CH CH COOH 2 ID RONa  CO RCOONa  RCOOH Sod. salt (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 – CH group on the opposite side of the carbon chain. H 3 PO 4 Sod. alkoxide (3) Melting point (i) The melting points of carboxylic acids donot vary smoothly from one member to another. O     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. 60 X   X  3 NaOH  R  C  X (4) Boiling point : Boiling point of carboxylic acids increase regularly with increase of molecular 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. Hot alkaline KMnO 4 Hydrogen bonding (i)O 3 R  C  C  R   R  COOH  R COOH Alkyne O (ii)H 2 O H–O CH – C C – CH 3 (v) The Arndt-Eistert synthesis O O–H 3 H O U R  C  Cl  CH 2 N 2 R  C  CHN 2 2 || O O ST || R  CH 2  COOH (vi) From acid amides Acid RCONH 2  H 2 O  RCOOH  NH 3 Amide or Alkali Acid RCONH 2  HNO 2 RCOOH  N 2  H 2 O Amide Hydrogen bonding Acetic acid dimer Ag 2O Nitrous acid Acidic nature of monocarboxylic acids (1) Cause of acidic nature (i) A molecule of carboxylic acid can be represented as a resonance hybrid of the following structures... O: ||.... O: |  R  C  O H  R  C  O H Physical properties of monocarboxylic acids (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...  (I).. (II) (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 ). + (2) Solubility : The lower members of the aliphatic carboxylic acid family (upto C ) are highly soluble in water. The solubility decreases with 4 O  R C O O  R  C O O O Resonance hybrid  1.27 A  1.27 A   (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. (i) An electron withdrawing substituent (– I effect) stabilizes the anion by dispersing the negative charge and therefore increases the acidity. O  O CH 3 COOH  NaOH CH 3 COONa  H 2 O Acetic acid 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 2O Sod. acetate (2) Effect of substituent on acidic nature GC (iii) Action with alkalies  O  O GC (I)   Reaction of carboxylic acid with aqueous sodium carbonates solution produces bricks effervescence. However most phenols do not produce effervescence. Therefore, this reaction may be used to distinguish between carboxylic acids and phenols. (i) (2) Reaction involving replacement of –OH group Formation of acid chloride 60  O  O  H   R  C  CH 3 COOH  PCl5 3CH 3 COCl  POCl3  HCl (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. Acetic acid Acetyl chloride 3CH 3 COOH  PCl3 3CH 3 COCl  H 3 PO3 E3 R C Acetic acid Acetyl chloride CH 3 COOH  SOCl 2 CH 3 COCl  SO 2  HCl Electron with drawing nature of halogen : F > Cl > Br > I Acetic acid Thus, the acidic strength decreases in the order : (ii) Formation of esters (Esterification) CH 3 CO OH  H Acetic acid similarly : Conc.H SO OC2 H 5 ID FCH2COOH  ClCH 2COOH  BrCH2COOH  ICH 2COOH Acetyl chloride 2 CH 3 COOC 2 H 5  H 2 O CCl 3 COOH  CHCl 2COOH  CH 2ClCOOH  CH 3 COOH Example: CH 3  CH 2  C H  COOH  CH 3  C H  CH 2  COOH | Cl D YG | Cl Ethyl acetate (Fruity smelling) (a) The reaction is shifted to the right by using excess of alcohol or removal of water by distillation. (b) The reactivity of alcohol towards esterification. tert-alcohol < sec-alcohol < pri-alcohol < methyl alcohol (c) The acidic strength of carboxylic acid plays only a minor role. U (iii) Inductive effect is stronger at -position than -position similarly at position it is more stronger than at  -position 4  Ethyl alcohol  C H 2  CH 2  CH 2  COOH | Cl (iv) Relative acid strength in different compounds RCOOH  HOH  ROH  HC  CH  NH 3  RH R3CCOOH  R2CHCOOH  RCH 2COOH  CH 3COOH  HCOOH 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  Acetic acid Amm. acetate CH 3 CONH 2  H 2 O  Greater the value of K or lesser the value of pK a stronger is a U the acid, i.e. pK a = – log K a  Acidic nature ( K a )  1/molecular weight ST K a Value HCOOH  CH 3 COOH  C 2 H 5 COOH 17.7  10  5 1.75  10  5 1.3  10  5 Acetamide (v) Formation of acid anhydrides CH 3 COO H CH 3 CO Heat   CH 3 CO OH P2 O 5 CH 3 CO O  H 2O Acetic anhydride Acetic acid  The formic acid is strongest of all fatty acids.  Acetic acid is less weak acid than sulphuric acid due to less degree of ionisation. (vi) Reaction with organo-metallic reagents Chemical properties of monocarboxylic acids (3) Reaction involving carbonyl (>C = O) group: (1) Reaction involving removal of proton from –OH group (i) Action with blue litmus : All carboxylic acids turn blue litmus ether R' CH 2 MgBr  RCOOH  R' CH 3  RCOOMgBr Alkane LiAlH 4 R  CH 2  OH Reduction : R  C  OH  || O red. (ii) Reaction with metals 2CH 3 COOH  2 Na 2CH 3 COONa  H 2 Sodium acetate 2CH 3 COOH  Zn (CH 3 COO )2 Zn  H 2 Zinc acetate Carboxylic acid are difficult to reduce either by catalytic hydrogenation or Na C2 H 5 OH (4) Reaction involving attack of carboxylic group (– COOH) O Cl , red P || 4 Cl 2 CHCOOH 2 Cl 3 CCOOH (CO ) 2 (i) Decarboxylation : R  C  OH  R  H When anhydrous alkali salt of fatty acid is heated with sodalime then : CaO RCOONa  NaOH  R  H  Na 2 CO 3 Sodium salt Alkane heat  HCl Dichloro acetic acid  When sodium formate is heated with sodalime H is evolved. (Exception) 2 Trichloro acetic acid Individual members of monocarboxylic acids 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 CaO HCOONa  NaOH  H 2  Na 2 CO 3 Pt CH 3 OH  O2  HCOOH  H 2O 60 Formic acid (ii) Heating of calcium salts (ii) Hydrolysis of hydrocyanic acid : Formic acid is formed by the hydrolysis of HCN with acids or alkalies. heat (RCOO )2 Ca  RCOR  CaCO 3 HCl HCN  2 H 2O  HCOOH  NH 3 ; Ketone (iii) Electrolysis : (Kolbe's synthesis) NaOH HCN  H 2O   HCOONa  NH 3 RCOONa ⇌ RCOO   Na  (iii) Laboratory preparation CH 2OH  HO OC COOH At anode 2 RCOO  R  R  2CO 2  2e   |  | 2H 2O CH 2OH | CCl 4 Silver acetate  AgBr  CO 2 Methyl bromide D YG H SO (conc.) 4 RCOOH  N 3 H 2  RNH 2  CO 2  N 2 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 Ethane U In the above reaction, the – COOH group is reduced to a CH 3 ST (5) Reaction involving hydrogen of -carbon Halogenation (i) In presence of U.V. light H Cl U.V. Glycerol monoformat e Glycerol The following procedure is applied for obtaining anhydrous formic acid. 2 HCOOH  PbCO3 (HCOO)2 Pb CO 2  H 2O ; Lead formate (HCOO)2 Pb  H 2 S PbS  2 HCOOH ppt. Formic acid (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.  CO  NaOH   HCOONa 210o C, 10 atm Sodium formate Sodium formate thus formed is distilled with sodium hydrogen sulphate, when anhydrous formic acid distils over. (ii) It melts at 8.4°C and boils at 100.5°C. (iii) It is miscible with water, alcohol and ether. It forms azeotropic mixture with water. |  -chloro acid (ii) In presence of Red P and diffused light [Hell Volhard-zelinsky Carboxylic acid having an -hydrogen react with Cl or Br in the presence of a small amount of red phosphorus to give chloro acetic acid. The reaction is known as Hell Volhard-zelinsky reaction. 2 Cl , red P 2 4 4 CH 3 COOH 2 ClCH 2 COOH 2 Chloro acetic acid | CH 2OH (i) It is a colourless pungent smelling liquid. reaction]  HCl Formic acid (2) Physical properties | Cl , red P |  HCOOH  CHOH HCOONa  NaHSO 4 HCOOH  Na2SO 4  C  COOH  Cl 2    C  COOH  HCl | CH 2OH (COOH )2 2 H 2 O CH 2OH  In Hunsdiecker reaction, one carbon atom less alkyl halide is formed from acid salt. (v) Formation of amines (Schmidt reaction) | CHOH 110C | CH 2OH Glycerol monoxalate | CH 3 Br Hydrazoic acid | CO 2   CHOH U heat CH 3 COOAg  Br2  Acetic acid 100 120 C o CH 2OOCH (iv) Formation of Alkyl halide (Hunsdiecker's reaction) group.   ID  2 H 2 O  Ethane Acetic acid CH 2OOC COO H  H 2O Glycerol Electrolysis CH 3  CH 3  2CO 2  2 KOH  H 2 Acid Oxalic acid CHOH At cathode 2 Na  2e 2 Na   2 NaOH  H 2 2CH 3 COOK Potassium acetate E3 Sodium salt  HCl (iv) It is strongly corrosive and cause blisters on skin. (v) It exists in aqueous solution as a dimer involving hydrogen bonding. (3) Uses : Formic acid is used. (i) In the laboratory for preparation of carbon monoxide. (ii) In the preservation of fruits. (iii) In textile dyeing and finishing. (iv) In leather tanning. (v) As coagulating agent for rubber latex. (vi) As an antiseptic and in the treatment of gout. (vii) In the manufacture of plastics, water proofing compounds. (viii) In electroplating to give proper deposit of metals. (ix) In the preparation of nickel formate which is used as a catalyst in the hydrogenation of oils. (x) As a reducing agent.  The flow of alcohol is so regulated that temperature does not exceed 35°C, which is the optimum temperature for bacterial growth. 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% HgSO (catalyst). 4 H SO (dil.) 4 CH  CH  H 2O 2   CH 3 CHO Acetylene Acetic Acid (Ethanoic Acid) (CH3COOH) Acetic acid is the oldest known fatty acid. It is the chief constituent of vinegar and hence its name (Latin acetum = vinegar) (1) Preparation HgSO 4 Acetaldehy de The acetaldehyde is oxidised to acetic acid by passing a mixture of acetaldehyde vapour and air over manganous acetate at 70°C. 60 (xi) In the manufacture of oxalic acid. Manganous acetate 2CH 3 CHO  O2   2CH 3 COOH 70C  Acetylene required for this purpose is obtained by action of water on calcium carbide. (i) By oxidation of acetaldehyde (Laboratory-preparation) E3 CaC2  2 H 2 O Ca(OH)2  C2 H 2 7 CH 3 CHO 22  CH 3 COOH Na Cr O H 2 SO 4 (O ) The yield is very good and the strength of acid prepared is 97%. The method is also quite cheap. (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, Co (CO) to form acetic acid. (ii) By hydrolysis of methyl cyanide with acid HCl CH 3 CN  2 H 2O  CH 3COOH  NH 3 O || H O H CH 3 MgBr  CO 2 CH 3  C  OMgBr 2  ID (iii) By Grignard reagent D YG H SO (conc.) 4 (a) CH 3 COOC 2 H 5  H 2 O 2  Ester CH 3 COOH  C2 H 5 OH dil. HCl (b) CH 3 COCl  H 2O  CH 3 COOH  HCl acetylchloride (c) CH 3 CO 2 O  H 2O  2CH 3 COOH dil. HCl ST U (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 2OH  O2  CH 3 COOH  H 2O Ethyl alcohol Bacter ia Acetic acid It is a slow process and takes about 8 to 10 days for completion. In this process, the following precautions are necessary:  The concentration of the ethyl alcohol should not be more than 15%, otherwise the bacteria becomes inactive. 8 Co (CO ) 2 8   CH 3 COOH 30 atm200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. (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. (iv) It is miscible with water, alcohol and ether in all proportions. (v) It is good solvent for phosphorus, sulphur, iodine and many organic compounds. (3) Uses : It is used, (i) As a solvent and a laboratory reagent. (ii) As vinegar for table purpose and for manufacturing pickles. (iii) In coagulation of rubber latex. (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 waterproof fabrics. (f) Alkali acetates which are used as diuretics. U O   ||    CH 3  C  OH      (iv) By hydrolysis of acetyl chloride, acetic anhydride or acetamide and ester CH 3 OH  CO Methyl alcohol 2  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 CO and water. Table : 28.1 Comparison of Formic Acid and Acetic Acid Property Formic acid 1. Acidic nature, 2 Acetic acid (i) With electro-positive metals Forms salts, Hydrogen is evolved. Forms salts. Hydrogen is evolved. 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  H 2O Forms salts. Carbon dioxide is evolved. Forms salts. Carbon dioxide is evolved. HCOOH  NaHCO3 HCOONa  H 2O  CO 2 CH 3COOH  NaHCO3 CH 3COONa  H 2O  CO 2 Forms esters when treated with alcohols. Forms esters when treated with alcohols. 60 2. Ester formation HCOOH  C2 H5 OH HCOOC2 H5  H 2O H SO (conc.) 4 CH 3 COOH  C2 H 5 OH 2  CH 3COOC2 H5  H 2O 5 Forms acetyl chloride which is a stable compound. HCOOH  PCl5 HCOCl (HCl  CO )  POCl3  HCl 4. Heating of ammonium salt Forms formamide. 2 Unaffected 2 HCOOH CO 2  H 2 2 Decomposed into CO and H O 4 Unaffected 2 Conc. 7. Reaction with Cl presence of red P 8. Action of heat on salts, (i) Calcium salt in Unaffected D YG 2 U HCOOH   CO  H 2O H 2 SO 4 (ii) Sodium salt Forms acetone. (CH 3COO)2 Ca CH 3COCH 3  CaCO3 Forms sodium oxalate. Unaffected. heat COONa COONa Forms sodium carbonate and H.  H2 2 CaO 5 ST 2 11. Reducing nature, (i) Tollen's reagent (ii) Fehling's solution (iii) Mercuric chloride Forms sodium carbonate and methane. CaO HCOONa  NaOH  Na 2CO 3  H 2 CH 3 COONa  NaOH  CH 4  Na 2CO 3 It evolves hydrogen. It forms ethane. U 9. Electrolysis of sodium or potassium salt 10. On heating with P O Forms mono, di or trichloro acetic acids. Forms formaldehyde. (HCOO)2 Ca HCHO  CaCO3 2 HCOONa | (iii) Sodium salt with sodalime CH 3COONH 4 CH 3CONH 2  H 2O ID it decomposes into CO and H 6. Heating with conc. H SO CH 3COCl  POCl3  HCl Forms acetamide. HCOONH 4 HCONH 2  H 2O 5. Heating alone CH 3COOH  PCl5 E3 Forms formyl chloride which decomposes into CO and HCl. 3. Reaction with PCl Unaffected Gives silver mirror or black precipitate. Forms acetic anhydride. PO 5 2CH 3 COOH 2   (CH 3 CO )2 O  H 2O Unaffected. HCOOH  Ag2O 2 Ag  CO 2  H 2O Gives red precipitate Unaffected. HCOOH  2CuO Cu 2O  CO 2  H 2O Forms a white ppt. which changes to greyish black. Unaffected. HgCl2 Hg2Cl2 2 Hg (iv) Acidified KMnO 12. Acid (neutral solution) + NaHSO + Sodium nitroprusside. 4 3 Decolourises Greenish blue colour. Unaffected. Unaffected. Red colour which changes to brown ppt. on heating. 13. Acid (neutral solution) + neutral ferric chloride Wine red colour. Interconversions (2) Descent of series : Conversion of acetic acid into formic acid. (1) Ascent of series : Conversion of formic acid into acetic acid. 3 CH 3 NH 2 2 CH 3 OH Ca(OH ) N H hea t 2 (i) HCOOH   ( HCOO)2 Ca  HCHO Formic acid NaNO H 2 SO 4 Methyl alcohol [ O] Formaldehy de Calcium formate HCl Methyl amine [O ] HCOOH   HCHO CH3MgBr Formic acid Formaldehy de [O ] 2  CH 3 CH 2 OH   CH 3 CH 2OMgBr CH 3 CHO  CH 3 NH 2 Acetaldehyde Methyl amine H O H Addition product 60 Ethyl alcohol Br2 / KOH   CH 3 COOH [O ] CH 3 COOH  CH 3 COONH 4  CH 3 CONH 2 NH 3 Aceticacid HCHO Formaldehy de Aceticacid HI  CH 3 OH   CH 3 I Methyl alcohol Methyl iodide KCN(Alc.) CH 3 COOH   CH 3 CN  H 2O H Aciticacid Amm. acetate Methyl cyanide Cl 2 NaOH Sodalime    CH 3 COONa   CH 4   CH 3 Cl heat Sodium acetate Arndt-Eistert homologation : This is a convenient method of converting an acid, RCOOH to RCH COOH. ID 2 CH 2 N 2 RCOOH   RCOCl   RCOCHN 2 SOCl 2 EtOH Acetamide E3 (ii) H 2 Ni heat hv Methane Methyl chloride AgOH [O ] [O ] HCOOH   HCHO   CH 3 OH Ag2O Formic acid Hydrolysis RCH 2 COOH    RCH 2 COOC 2 H 5 Formaldehy de Na 2 Cr2 O7 Methyl alcohol H 2 SO 4 U Conversion of Acetic acid into other organic compound (CH CO) O 2 Cl hv CH – CH 3 CH – CH Cl 2 3 3 CH CH NH 3 2 Electrolysis 3 CH COCl CH CH CH NH 2 2 n-Propyl amine Sodalime CH COONa 3 2 CH Sodium acetate CH CH CN 3 CH CH COOH Propionic acid 2 (CH COO) Ca 2 3 3 heat CH COCH 2 3 HCHO 3 H SO | H /Ni 2 COONa Oxalic acid Sodium oxalate 3 Conc. H SO 2 HCOONa Sodium formate CH CH= CH 4 3 3 Isopropyl alcohol Acetone Propene 500°C Cl 2 2 CHI Iodoform 2 3 2 Methyl amine 5 NH PO CH CN heat Methyl cyanide 2 5 3 C2H5OH CH COOC H 3 3 Acetyl chloride [H] LiAlH 3 2 CH CH NH 3 2 2 Ethyl amine 4 5 Ethyl acetate CH CHO 3 Acetaldehyde HCN OH CH CH Cyanohydrin HO H 2 3 + CN 2 Allyl chloride CH NH Br /KOH 2 Acetamide 2 2 acetylene A CH CONH g PCl or SOCl ClCH CH= CH HC ≡ CH 3 3 Rosenmund's reduction heat | 4 COOH CH CHOHCH 2 3 Formic acid COONa COOH CH CHOHCOOH 3 Lactic acid NaOH HCOOH [O] Formaldehyde Methyl alcohol I + NaOH CH COCl 3 Acetic acid 2 [O] CH OH Methyl chloride Calcium acetate 3 + U ST Ca(OH) 3 CH – COOH [O] 3 Acetaldehyde H NaOH CH COOH CH – CHO [O] 2 HO 2 AgOH CH Cl 2 hv 4 [H] LiAlH 4 Cl Methane 3 Ethyl alcohol NH3 2 Ethyl amine 3 CH – CH OH AgOH 2 Ethyl chloride D YG Ethane KCN 3 Acetic anhydride 2 Dicarboxylic acids 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 COONa |  Ca(OH )2 COONa O 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 Common name Oxalic acid Malonic acid Succinic acid Glutaric acid Adipic acid 2 Oxalic acid (soluble) (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. (iv) It is poisonous in nature. It affects the central nervous system. 4 (3) Chemical 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 Hydrated oxalic acid U 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. D YG 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 Glycol U (ii) By hydrolysis of cyanogen with conc. hydrochloric acid : CN COOH 2( HCl ) |  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 COONa heat 2 Na  2CO 2   | COONa ST (insoluble) (i) It is a colourless crystalline solid. It consists of two molecules of water as water of crystallisation. Ethanedioic acid 1-3 Propanedioic acid 1,4-Butanedioic acid 1,5-Pentanedioic acid 1,6-Hexanedioic acid ID 2 2 COOH Ca  H 2 SO 4 (dil.) |  CaSO 4 COOH Calcium sulphate (2) Physical Properties IUPAC name Oxalic Acid or Ethanedioic Acid COOH | or (COOH) or (C H O ) COOH COO | COO E3 HOOCCOOH HOOCCH2COOH HOOCCH2CH2 COOH HOOC(CH2)3COOH HOOC(CH2)4 COOH Ca  2 NaOH Calcium oxalate || Formula COO | COO 60 || 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 filtration. It is decomposed with calculated quantity of dilute sulphuric acid. (a) At 200°C, (COOH )2  HCOOH  CO 2 Formic acid On further heating, formic acid also decomposes. HCOOH CO 2  H 2 (b) Heating with conc. H SO 2 4 COOH H SO 4 | 2   CO  CO 2  H 2 O COOH (conc.) (ii) Acidic nature Salt formation COOH |  KOH COOH Oxalic acid COOK | COOK Acid pot. oxalate COOK KOH   | COOK Pot. oxalate COOH COONa |  2 NaHCO 3 |  2CO 2  2 H 2 O COOH COONa Sod. oxalate Sodium oxalate (iv) Laboratory preparation COOH HNO 3 C12 H 22 O11  18[O]    6 |  5H 2O V2 O5 Sucrose COOH COOH COONa  Na 2 CO 3 |  H 2 O  CO 2 | COOH COONa (iii) Esterification Oxalic acid (v) Industrial method COONa 360 C 2 HCOONa    |  H2 Sod. formate COONa COOC 2 H 5 COOC 2 H 5 COOH C H OH C H OH | 2 5  | 2 5  | COOH COOH COOC 2 H 5 Ethyl hydrogen oxalate Sod. oxalate Sodium formate is obtained by passing carbon monoxide over fine powdered of sodium hydroxide. 200 C CO  NaOH    HCOONa 8 10 atm (iv) Reaction with PCl : 5 Ethyl oxalate (5) Analytical test (i) The aqueous solution turns blue litmus red. COOH COCl |  2 PCl5 |  2 POCl3  2 HCl COOH COCl (ii) The aqueous solution evolves effervescences with NaHCO 3. Oxalyl chloride (iii) The neutral solution gives a white precipitate with calcium chloride solution. It is insoluble in acetic acid. (v) Reaction with ammonia Oxalic acid Amm. oxalate – 2H O heat 2 CONH 2 | CONH 2 Oxamic acid Malonic Acid or Propane-1,3-Dioic Acid or CH 2 (COOH) Oxamide (vi) Oxidation : When oxalic acid is warmed with acidified KMnO4. 2 KMnO4  3 H 2 SO 4 K 2 SO 4  2 MnSO 4  3 H 2 O  5[O] Colourless (vii) Reaction with ethylene glycol O HO CH | + O=C OH Oxalic acid O=C D YG O=C 2 | CH –H O 2 CH | heat 2 | O=C CH 2 HO 2 O Ethylene glycol Cl Glycolic acid U CH 2OH COOH Electrolytic reduction COOH 2|  |  |  2H 2O 6[ H ] COOH COOH CHO Glycolic acid KCN ( Aq.) 2 CH 3 COOH   CH 2 ClCOOH  P Acetic acid Chloroacet ic acid H O H CH 2 CNCOOH 2  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. (iii) It is soluble in water and alcohol but sparingly soluble in ether. (3) Chemical Properties (i) Action of heat (a) Heating at 150°C : CH 2 (COOH )2 CH 3 COOH  CO 2 (b) Heating with P O : 2 Ethylene oxalate CH 2OH COOH Zn  4 H   |  H 2O (viii) Reduction : | H 2 SO 4 COOH COOH Glyoxalic acid (ix) Reaction with Glycerol : At 100° – 110°C, formic acid is formed. At 260°, allyl alcohol is formed. (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. (iv) In the manufacture of inks. (v) For removing ink stains and rust stains and for bleaching straw, wood and leather. (vi) In the form of ferrous potassium oxalate as developer in photography. ST The acid occurs as calcium salt in sugar beet. It was so named because it was first obtained from malic acid (hydroxy succinic acid) by oxidation. U  Oxalic acid decolourises the acidic KMnO4 solution. OH or (C 3 H 4 O 4 ) ID Oxalic acid 2 COOH COOH CH 2 (1) Methods of Preparation : From acetic acid COOH   [O] 2CO 2  H 2 O   5 | COOH   COOH | 2 KMnO4  3 H 2 SO 4  5 K 2 SO 4  2 MnSO 4  10 CO 2  8 H 2 O COOH Pot. permangan ate (Purple) Calcium oxalate (v) With hot conc. H 2 SO 4 , it evolves carbon monoxide which burns with blue flame. 2 – H O heat CONH 2 | COOH Amm.oxalate (iv) Oxalic acid decolourises hot potassium permanganate solution having dilute sulphuric acid. 60 Acid ammonium oxalate NH 4 OH CaCl 2 H 2 C 2 O4   (NH 4 )2 C 2 O4    CaC2 O4 COONH 4  | COONH 4 NH 3 E3 COONH 4 COOH |  NH 3 | COOH COOH 5 H OH | | O  C  C C | | P O 5  O 2   O  C  C  C  O 2H 2O heat Carbon suboxide OH H (ii) Reaction with aldehyde : With aldehydes, - unsaturated acids are formed. RCH  O  H 2 C Aldehyde COOH Pyridine  COOH heat RCH  CHCOOH  H 2 O  CO 2  -  unsaturate d acid (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 (i) From ethylene CH 2 CH 2 Br CH 2 CN Br2 H 2 O HCl NaCN ||   |   |    CH 2 COOH CH 2 CH 2 Br CH 2 CN | Ethylene Ethylene Ethylene CH 2 COOH cyanide bromide It was first obtained by the oxidation of fats (Latin, adeps = fat.) (1) Methods of Preparation (i) From benzene (In industries) OH Succinic acid (ii) From maleic acid [catalytic reduction] H CH 2COOH CHCOOH Ni ||  H 2   | heat CH COOH CHCOOH 2 Benzene 3 Cyclohexanol HNO 3 60 Succinic acid HOOC – (CH ) – COOH 2 Malic acid Cyclohexanone (ii) From tetrahydrofuran (THF) O (2) Physical Properties (i) It is a white crystalline solid. Its melting point is 150°C. Succinic anhydride U (ii) It is fairly soluble in alcohol and ether but less soluble in water. CH 2COOH CH 2COONH 4 heat NH 3 |  |   H 2O CH 2COOH CH 2COONH 4 (3) Chemical Properties It shows all the general reaction of dicarboxylic acids. D YG Ammonium succinate CH 2CONH 2 CH 2CO heat |  | CH 2CONH 2  NH 3 CH 2CO Succinamid e Succinimid e O THF (ii) With ammonia CH 2  CO | CH 2  CO CH 2 CH 2 | |  2CO  HOH HOOC  (CH 2 )4  COOH Adipic acid CH 2 CH 2 ID (3) Chemical Properties : Succinic acid gives the usual reactions of dicarboxylic acid, some important reactions are : (i) Action of heat : At 300°C E3 (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. 4 Adipic acid  It is an industrial method. (iii) Reaction with Br 3 3 (2) Physical properties Succinic acid SeO O CHOHCOOH CHOHCOOH HI CH 2 COOH HI |   |   | P P CHOHCOOH CH 2 COOH CH 2 COOH CH 2 COOH CH 2 CO 300 C |    | CH 2 COOH (– H 2 O ) CH 2 CO 3 2 H BO , heat Cyclohexane  This is an industrial method. (iii) Reduction of tartaric acid or malic acid Tartaric acid HNO O 2 Catalyst (i) Action of heat H NH Succinimide HOOC(CH ) COOH 2 4 Adipic acid HC 2 heat 300°C 2 C | C = O + CO + H O HC 2 2 2 2 CH 2  CO NH  Br2  | 0 C CH 2  CO NaOH C H N  Br  HBr N - bromosuccinimide (N.B.S) U (iv) Reaction with ethylene glycol 2 Cyclopentanone (ii) Formation of Nylon-66 [Reaction with hexa methylene diamine] nH 2 N (CH 2 )6 NH 2  nHO  C  (CH 2 )4  C  OH hexamethyl ene diamine HOOC  (CH 2 )2  CO OH  H OCH 2  CH 2 O H  HO OC  (CH 2 )2  CO OH ....... ST – H2 O || O adipic acid – nH O 2 H H O O | | || ||  ( N  (CH 2 )6  N  C  (CH 2 )4  C )n  HOOC  (CH 2 )2  CO  [OCH 2  CH 2 O  OC nylon-66 (CH 2 )2  CO ]n  OH  H 2 O Polyester When sodium or potassium salt in aqueous solution is electrolysed, ethylene is obtained at anode. (4) Uses : It finds use in volumetric analysis, medicine and in the manufacture of dyes, perfumes and polyester resins. Adipic Acid or Hexane-1,6 –Dioic Acid CH 2 CH 2 COOH | or (CH 2 )4 (COOH) CH 2 CH 2 COOH || O (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. Example: CH 2  CH  COOH  H  C  COOH || Acrylic acid H C COOH Maleic acid Acrylic Acid or Prop-2-Enoic Acid 2 or (C 6 H 10 O 4 ) CH 2  CH  COOH (1) Methods of Preparation or (C 3 H 4 O 2 ) (i) From allyl alcohol CH 2 2CH 2  CHCOOH  Na 2CO3 CH 2 Br || CH 2 Br | Br2 | HNO 3  C HBr CH CH 2 Zn 2CH 2  CHCO O Na   H 2O  CO 2 ||  C HBr   C H | | CH 2OH CH 2OH | [O ] COOH Sodium acrylate | hea t (v) Ester formation COOH Conc.H SO 4 CH 2  CHCOOH  HOC2 H 5 2  (ii) By oxidation of acrolein  H 2O AgNO 3 CH 2  CHCHO  [O]  CH 2  CHCOOH CH 2  CH  COOC 2 H 5 NH 4 OH Ethyl acrylate (vi) With CH 2  CHCOOH  PCl5 CH 2  CH  COCl Br2 P  (iii) From propionic acid : CH 3 CH 2COOH  HVZ reaction  -Bromopropionic acid (iv) By heating -hydroxy propionic acid (4) Uses : Its ester are used for making plastics such as Lucite and plexiglass. Unsaturated dicarboxylic acids ZnCl2 C H 2  CH 2  COOH   CH 2  CH  COOH E3 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. heat,  H 2 O OH  -hydroxy propionic acid (v) From vinyl cyanide H  C  COOH Cu Cl HCl 2 2 HC  CH  HCN   CH 2  CH  CN Vinylcyanide H  H 2O H C COOH  HCN Conc.H SO (1) Methods of Preparation of Maleic Acid (i) By catalytic oxidation of 2-butene or benzene CH CH 3 CHCOOH V O5 ||  30 2 2  | |  2H 2 O 400C CHCOOH CH CH 3 4 CH 2  CH 2  C H 2  CH 2  CN 2  U heat  H 2 O | OH O D YG H  H 2O CH 2  CH  CN   CH 2  CHCOOH C6 H 6  Benzene Ni(CO) (2) Physical Properties U  It is colourless pungent smelling liquid. Its boiling point is 141°C.  It is miscible with water, alcohol and ether.  It shows properties of an alkene as well as of an acid. (3) Chemical Properties (i) With nascent hydrogen (Na and C H OH) 5 Ni ST CH 2  CHCOOH  2[H ]   CH 3 CH 2 COOH (ii) With halogens and halogen acids : Markownikoff's rule is not followed. CH (OH )COOH | CH 2 COOH Malic acid (Hydroxy succinic acid)  ,  -Dibromopro pionic acid CH 2  CHCOOH  HBr BrCH 2  CH 2 COOH  -Bromopropionic acid CHCOOH CH CO heat heat | | | |  H 2O  H 2O CHCOOH CH CO Maleic acid (intermedi ate) Maleic anhydride Sodium salt Maleic acid (2) Methods of Preparation of Fumaric Acid (i) From maleic acid H C COOH HCl HOOCC  H ||  || boil H C COOH H C COOH Maleic acid (ii) By oxidation of furfural with sodium chlorate CH HOOC C  H NaClO3 ||  4[O]  ||  CO 2 C CHO H C COOH HC || HC (iii) Oxidation : In presence of dilute alkaline KMnO. 4 CH 2  CHCOOH  [O]  H 2 O CH 2 OHCHOHCOOH Glyceric acid  On vigorous oxidation, oxalic acid is formed. (iv) Salt formation CH 2  CHCOOH  KOH CH 2  CHCO O K   H 2 O O CH COONa CH COOH H  H 2O NaOH | |  | | boil CH COONa CH COOH CCl 4 CH 2  CHCOOH  Br2   CH 2 Br  CHBrCOOH CHCOOH H O H O 2 | | CHCOOH (ii) From malic acid : Industrial method : This is a new method of its manufacture. 4 CH  CH  CO  H 2 O   CH 2  CHCOOH CH CO 9 V O5 O 2 2  | | o 2 400 C CH CO Maleic anhydride Vinylcyanide (acrylonitrile) 2 Maleic acid 2 Butene Ethylene cyanohydrin Ethylene oxide || H C COOH Trans- form (Fumaric acid) Cis- form (Maleic acid)   CH 2  CH  COOH (vi) From ethylene cyanohydrin HOOC  C  H || ID 90C Acetylene 5 Acryl chloride Alc. KOH CH 3 CHBrCOOH   CH 2  CHCOOH | PCl 60 Propionic acid O (iii) By heating malic acid at about 150°C for long time CH (OH )COOH heat |  150C ,  H 2 O CH 2 COOH Malic acid HOOC  C  H || H  C  COOH : (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 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 hea t CHCO ||  | | CHCOOH CHCO Maleic acid O  H 2O Maleic anhydride 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 KMnO solution, they get oxidised to tartaric acid. COOH COOH | | H  C  OH H  C  COOH Br water H  C  Br Alk.KMnO4 |   || 2  | (Syn addition) (anti addition) H  C  COOH H  C  OH Br  C  H Maleic acid (Cis) | COOH | COOH Tartaric acid (Meso) COOH COOH | COOH Tarta ric acid (Racemic mixture) | Alk.KMnO  4  H  C  COOH H  C  Br Br water || 2  | (anti - addition) H  C  Br HOOC  C  H D YG H  C  OH | HO  C  H (Syn - addition) | Fumaric acid (Trans) COOH ((Meso) Higher fatty acids 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 of acids Palmitic acid Source Palm oil Stear (meaning tallow) Olive oil. ST Stearic acid Oleic 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. U (Racemic mixture) | 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. ID 4 (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). 60 CH 2COOH HOOC  C  H Alc. KOH |  ||  KBr  H 2 O CH.( Br)COOH H  C  COOH 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 well founded as the physical state depends on climate and weather. E3 (iv) By heating bromosuccinic acid with alcoholic potash : By heating bromosuccinic acid with alcoholic potash. Molecular formula (iv) Pure fats and oils are colourless, odourless and tasteless but natural fats and oils possess a characteristic odour due to presence of other 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. (i) Hydrolysis (a) By superheated steam CH 2 O COC17 H 35 | CH 3 (CH 2 )14 COOH CH 3 (CH 2 )16 COOH CH 2 OH | 3H 2O C HO COC17 H 35  C HOH  3 C17 H 35 COOH | | CH 2 O COC17 H 35 CH 2 OH Tristearin Glycerol Stearic acid (b) Base hydrolysis [Saponification] CH 3 (CH 2 )7 CH  CH (CH 2 )7 COOH CH 2 OCOR | Palmitic and stearic acids are waxy colourless 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. (i)O 3 CH 3 (CH 2 )7 CH  CH (CH 2 )7 COOH  (ii)Zn  H 2 O CH 2 OH | C HOCOR  3 NaOH C HOH  3 RCOONa | | CH 2 OCOR CH 2 OH Fat or oil Glycerol Salt fatty acid (Soap) (c) Enzyme hydrolysis : Enzyme like lipase, when added to an emulsion of fat in water, hydrolyses it into acid and glycerol in about two or three days. (ii) Hydrogenation : In the presence of finally divided nickel, at low pressure the hydrogenation process is called hardening of oils. O (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 O || || CH 2 O C (CH 2 )7 CH  CH (CH 2 )7 CH 3 O CH 2 O C C17 H 35 O || CHO C (CH 2 )7 CH CH (CH 2 )7 CH 3 O 3 H 2  Ni , Heat || CHO C C17 H 35 O || CH 2O C (CH 2 )7 CH CH (CH 2 )7 CH 3 CH 2O C C17 H 35 Glyceryl trioleate or triolein (Liquid oil) Tristearin(A solid fat) = (iii) Hydrogenolysis [Reduction to alcohol] 60 || || CH 2OH | CH  O  C  C17 H 35  CHOH  3 C17 H 35 CH 2 OH | 200 atm Octadecyl alcohol O CH 2OH || CH 2  O  C  C17 H 35 6 H2 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 O CH 2  O  C  C17 H 35 O 168,000 , M Tristearin 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 mixture is acidified with dilute sulphuric acid and steam distilled. The distillate is cooled, filtered and titrated against 0.1 N KOH. (5) Uses (i) Many oils and fats are used as food material. (ii) Oils and fats are used for the manufacture of glycerol, fatty acids, soaps, candles, vegetable ghee, margarine, hair oils, etc. (iii) Oils like linseed oil, tung oil, etc., are used for the manufacture of paints, varnish, etc. (iv) Castor oil is used as purgative and codliver oil as a source of vitamins A and D. Almond oil is used in pharmacy. Olive oil is also used as medicine. (v) Oils are also used as lubricants and illuminants. ID (iv) Drying : Certain oils, containing glycerides of unsaturated fatty acids having two or three double bonds have the tendency of slowly absorbing oxygen from atmosphere and undergoing polymerisation to 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. E3 || titrating it against a standard solution of KOH using phenolphthalein as an indicator. D YG U (v) Rancidification : On long storage in contact with air and moisture, oils and fats develop unpleasant smell. The process is known as rancidification. It is believed that rancidification occurs due to hydrolysisoxidation. (4) Analysis of oils and fats (i) Acid value : It indicates the amount of free acid present in the oil or fat. It is defined as the number of milligrams of KOH required to neutralize the free acid present in one gram of the oil or fat. It is determined by dissolving a weighed amount of oil or fat in alcohol and Table : 28.4 Difference between vegetable oils and Mineral oils 2. Source Vegetable oils These are triesters of glycerol with higher fatty acids. Minerals oils These are hydrocarbons (saturated). Kerosene oil–Alkanes from C to C. These occur inside earth in the form of petroleum. No hydrolysis occurs. No effect. 12 U Property 1. Composition ST 3. Hydrolysis 4. On adding NaOH and phenolphthalein 5. Burning 6. Hydrogenation Seeds root and fruits of plants. Undergo hydrolysis with alkali. Form soap and glycerol. Decolourisation of pink colour occurs. Burns slowly Hydrogenation occurs in presence of nickel catalyst. Solid glycerides (fats) are formed. (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.) Burn very readily. No hydrogenation occurs. 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 | Ordinary soaps (sodium and potassium) are the products of hydrolysis of oils and fats with sodium hydroxide or potassium hydroxide. 16 |  CH 2OCOR 3 CH 2OH R3 COONa Triglyceride Glycerol Soap There are three methods for manufacture of soaps : CH 2 OH | (i) The cold process C17 H 35 COOCH 2  C  CH 2 O H | (ii) The hot process CH 2 OH (iii) Modern process Pentaeryth ritol monosteara te C15 H 31 COONa Hydrophobi c Hydrophili c part part 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. and cetyl alcohol (C16 H 33OH ) , ceryl alcohol (C26 H 53OH ) , myricyl alcohol (C30 H 61OH ) , etc. CH 3 (CH 2 )10 CH 2 OH  HO SO 3 H Lauryl alcohol 60 C12 H 25 OSO 3 Na Hydrophobi c Hydrophili c part part Sodium lauryl sulphate (Detergent ) Detergents are superior cleansing agents due to following properties. (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 H 51COOH ) , melissic acid (C30 H 61COOH ) E3 (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. Sulphuric acid NaOH Lauryl hydrogen sulphate C15 H 31COOC16 H 33  H 2O C15 H 31COOH  C16 H 33OH ID CH 3 (CH 2 )10 CH 2OSO 2OH  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. Cetyl palmitate CH 3 (CH 2 )10 CH 2OSO 2ONa Sodium lauryl sulphate (Detergent ) examples and are sodium cetyl sodium stearyl sulphate, sulphate, Cetyl alcohol When hydrolysis is carried with caustic alkalies, soap and higher monohydric alcohols are formed. C15 H 31COOC16 H 33  NaOH C16 H 33OH  C15 H 31COONa U The other C16 H 33 OSO 2 ONa Palmitic acid Sodium palmitate (Soap) CH 3 (CH 2 )16 CH 2 OSO 3 Na. Unlike ordinary soaps, they do not The common waxes are: produce OH ions on hydrolysis and thus can be safely used for woollen garments. (i) Bees wax, Myricyl palmitate, C15 H 31COOC30 H 61 D YG – (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 | AlCl3 CH 3 (CH 2 )9 CH  CH 2  C6 H 6    CH 3 (CH 2 )9 C H  C6 H 5 1- Dodecene 2 - Dodecyl be nzene CH 3 |   CH 3  (CH 2 )9  C H  C 6 H 4  SO 3 Na (i)H 2 SO 4 U (ii) NaOH (S.D.S.) ST These long chain alkyl benzene sulphonate (L.A.S.) are most widely used syndets. (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 Br C18 H 37 (iv) Sulphonates with triethanol ammonium ion in place of sodium serve as highly soluble materials for liquid detergents. R     O  SO 2  N H (CH 2  CH 2 OH )3    (v) Partially esterified polyhydroxy compounds also acts as detergents. (ii) Spermaceti wax, Cetyl palmitate, C15 H 31COOC16 H 33 (iii) Carnauba wax, Myricyl cerotate, C25 H 51COOC30 H 61 Waxes are used in the manufacture of candles, polishes, inks, water proof coating and cosmetic preparations. 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 NH , are referred to as substituted acids. For example, 2 CH 2 ClCOOH ; CH 2 OHCOOH ; Chloroacet ic acid Hydroxyacetic 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 potassium tartrate which is also precipitated by addition of CaCl. The calcium salt is then decomposed with calculated quantity of dilute H SO. The precipitate (CaSO ) is filtered and the filtrate on concentration gives the crystals of tartaric acid. For example, 2 2 CH 3 CHOHCH 2 COOH  - Hydroxybutyric acid 3 - Hydroxybutanoic acid  - Hydroxypropionic acid 2 - Hydroxypropanoic acid CH (OH )COOK CH (OH )COOK CH (OH )COO 2|  Ca(OH ) 2 |  | CH (OH )COOH CH (OH )COOK CH (OH )COO Lactic Acid or -hydroxy propionic acid or 2-hydroxy propanoic acid It is the main constituent of sour milk. It is manufactured by fermentation of molasses by the micro-organism (Bacterium acidi lacticisour milk) in presence of CaCO 3. Pot.hydrogen tartrate Pot.tartra te (Filtrate) CH (OH )COO | CH (OH )COO From acetaldehyde : Tartaric acid H O H (ii) Synthetic method  HCN CH 3 CH (OH )CN 2  H Electric Acetylene Pd BaSO 4 E3 (2) Physical Properties It is a colourless syrupy liquid having a sour taste and smell. It is hygroscopic and very soluble in water. It is optically active and exists in three distinct forms. Red P   | Br2  CH 3 CHO Acetaldehy de ID HI CH 3 CH 2 COOH  Lactic Acid PCl5 KMnO4 H2SO4 CH (OH )CN CHO HCN |   | CHO CH (OH )CN Glyoxal Tartaric acid CH (OH )COOH H O H 2 | CH (OH )COOH Glyoxal cyanohydrin Tartaric acid Propionic acid (2) Physical Properties : It is a colourless crystalline compound. It is soluble in water and alcohol but insoluble in ether. It contains two asymmetric carbon atoms and thus shows optical isomerism (four forms). Natural tartaric acid is the dextro variety. It contains two secondary alcoholic groups and two carboxylic groups. Fenton's reagent [O] Fe2+/H2O2 or Ag2O Optical Isomerism in tartaric acid CH 3 COCOOH CH 3 CHO or CH 3 COOH CH 3 CHClCOCl (4) Uses : It is used in medicine as calcium and Py iron lactates, ruvic acid as Lacty lchloride mordant in dyeing, as acidulant in beverages and candies, as a solvent (ethyl and butyl lactates) for cellulose nitrate. | U H  C  OH | HO  C  H d+ Dextrorotatory Tartaric acid | COOH | | HO  C  H | H  C O H H C  OH | H C  OH | | | COOH HO  C H  COOH HO CH COOH It is found as free or potassium salt in grapes, tamarind, and berries. (1) Methods of Preparation (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 COOH COOH Tartaric Acid. Or ,'-Dihydroxy succinic acid or 2,3-DihydroxyButane-1,4-Dioic acid ST CHOHCOOH CH3COCl CH 3 CHOHCOOH Dil. H2SO4 Heat 130°C CHOHCOOH (iii) From glyoxal cyanohydrin : D YG Formic acid CHBrCOOH U NaOH Conc. H2SO4 AgOH | Succinic acid acid CH 3 CHOCOCH 3 | COOH Acetyllactic acid Sod. Lactate Heat CHBrCOOH  , '-Dibromo succinic (3) Chemical Properties : It gives reactions of secondary alcoholic group and a carboxylic group. Lactide Ethylene CH 2 CN CH 2 CO 2 H H 2O H  2 KCN (CH 2 Br)2   |   | Ethylene bromide CH 2 CN CH 2 CO 2 H Lactic acid CH 3 CHOHCOONa Br 2 2  CH 2  CH 2  C  H 2  CH  CH  Cyanohydrin CH 3 CHOHCOOH HCOOH Calcium tartrate (ppt.) CH (OH )COOH Ca  H 2 SO 4 CaSO 4  | CH (OH )COOH arc CO+H2O Ca CaCl2 -2KCl (1) Method of Preparation CH 3 CHO  Acetaldehy de 4 4 60 CH 3 CHOHCOOH ; COOH COOH Meso-Tartaric acid (Optical inactive) l-(Leavorotatory acid) Optical active (i) d + Tartaric acid-Dextro-rotatory Optical active (ii) l –Tartaric acid-Leavorotatory (iii) Meso tartaric acid-optically inactive due to internal compensation. (3) Chemical Properties CH 3 COCOOH Pot. acid tartrate Potassium tartrate CHOHCOOK CHOHCOOK and | | CHOHCOOH CHOHCOOK It forms two series of salts Py ruvic acid C(OH )COOH || C(OH )COOH Dihy droxy meleic acid [O] Fe 2  /H 2 O 2 Heat Fenton' s reagent CHOHCOOH | CHOHCOOH Tartaric acid HBr HI Heat olution CHBrCOOH | CHBrCOOH  , 'Dibromo succinic acid AgNO3 Tartronic acid + Sliver mirror (Test of tartaric acid) NH4OH CH (OH )COOH [O ] |    K 2 Cr2 O7 /H 2 SO 4 COOH COOH | COOH Oxalic acid (5) Tests (i) When heated strongly, tartaric acid chars readily giving a smell of burnt sugar to produce free carbon and pyruvic acid. (ii) With AgNO : A neutral solution of tartaric acid gives a white ppt. which is soluble in ammonia. A silver mirror is obtained on warming the ammonical silver nitrate solution (Tollen's reagent). 60 | CH 2 COOH Aconiticacid Heat, 150°C (iii) With Fenton's reagent : (H O containing a little of ferrous salt) and caustic soda, It gives a violet colour. 2 2 (iv) With Resorcinol and conc. H SO : It gives blue colour. 2 With alkalies and alcohols, it forms three series of salts and esters, respectively CHCOOH || CCOOH ID 3 (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. (3) Chemical properties E3 (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 calicoprinting (tartar emetic-potassium antimonyl tartrate) and silver mirroring. U 4 CH 2 COOH | C(OH )COOH | CH 2 COOH Citric acid Citric Acid Or 2-Hydroxypropane Or 1,2,3-Tri Carboxylic Acid Or Hydroxy Tricarballylic Acid D YG It occurs in the juice of citrus fruits such as lemon, galgal, orange, lime, etc. Lemon juice contains 6-10% of citric acid. Fuming H2SO4 heat CH3COCl HCl CH 2 COOH | C(OCOCH 3 )COOH | CH 2 COOH Mono acelyderivative Hl reduction (1) Methods of Preparation (i) By Fermentation : Citric acid is obtained by carrying fermentation of dilute solution of molasses with micro-organism, Aspergillus nigar, at 2628°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 U under vacuum to get crystals of citric acid. ST (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. (iii) By synthetic method CH 2 OH CH 2 Cl | | CH 2 COOH CH 2 COOH | | CHCOOH CO | | CH 2 COOH CH(4) 2 COOH Uses : It finds use in making lemonades, as acidulant in food and Tricarballytic acid Acetone soft drinks dicarboxyl and makesicthe lemon sour, as mordant in dyeing and calico acid 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. Aromatic Carboxylic Acids Aromatic acid contain one or more carboxyl group (COOH) attached directly to aromatic nucleus. Examples COOH CH 2 Cl COOH | HCl ( g ) 3 C HOH    CHOH   CO | CH 2 OH | heat (in acetic acid) CH 2 Cl dil. HNO [O ] CH COOH 3 | CH 2 Cl COOH Glycerol HCN Benzoic acid O-toluic acid Phthalic acid COOH CH 2 COOH CH 2 CN CH 2 Cl | | | H 2O / H  OH OH KCN C(OH )COOH   C  C CN CN | | | CH 2 COOH CH 2 CN CH 2 Cl COOH OH Salicylic acid COOH NH Anthranilic acid NO 2 2 m-Nitro benzoic acid Aromatic acid containing-COOH group in the side chain, they are considered as aryl substituted aliphatic acid. Examples (ix) From naphthalene [Industrial method] COOH CH = CHCOOH CH COOH 2 [O] VO 2 COOH Soda lime COOH 5 (2) Physical Properties (i) It is a white crystalline solid. Cinnamic acid Benzoic AcidPhenyl acetic acid (ii) It has m.p. 394 K. (iii) It is sparingly soluble in cold water but fairly soluble in hot water, alcohol and ether. 60 (1) Methods of Preparation (i) From oxidation of Benzyl alcohol [Laboratory method] CHO CH OH 2 (iv) It has a faint aromatic odour and readily sublimes and is volatile in steam. COOH O (3) Acidity of Aromatic Carboxylic Acid : Aromatic acid dissociates to give a carboxylate anion and proton. O CN C6 H 5 COOH ⇌ C6 H 5 CO O  H  Benzoic acid COOH H or OH + + 2H O  Since the carboxylate anion ( ArCO O) is resonance stabilised to a greater extent than the carboxylic acid (ArCOOH). – + 2NH 2 3 O | C – OMgI || Ar  C  OH  Ar  C  O H Resonance in carboxylic acid Non - equivalent structure and    hence less stable  COOH | H , HO +C=O + OH + Mg 2 I Phenyl mag. Addition product (iv) By hydrolysis of esters iodide D YG Benzoic acid H  orOH  C6 H 5 COOCH 3  H 2 O  C6 H 5 COOH  CH 3 OH Methyl benzoate Benzoic acid Methanol (v) From trihalogen derivatives of hydrocarbons CCl 3 + HO + 3KOH Benzotrichloride 2 – 3 KCl Benzoic acid Unstable U (vi) From benzene COCl COOH ST O O || | Ar  C  O   Ar  C  O Resonance in carboxylate anion Equivalent structure and hence    more stable  Effect of Substituents on Acidity : The overall influence of a substituent on acidity of substituted 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 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 being stronger overpowers the inductive effect. Thus on the above basis, the following order of acidity can be explained. [Friedel-craft reaction] H O/NaOH 2 2 AlCl COOH C(OH) 3 | U O  ID Benzoic acid (iii) From Grignard reagent COCl O O Benzonitrile MgI E3  Benzaldehyde (ii) From or cyanides Benzylhydrolysis alcohol of nitriles OH NO Cl COOH COOH 2 3 (vii) From Toluene HC COOH 3 p-Nitrobenzoic acid – NO group exerts – R and – I effects [O],  2 KMnO /OH or alkaline K Cr O 4  Chromic trioxide in glacial acetic acid or Co-Mn acetate can also be taken in place of alkaline KMnO 4. 2 2 7 CH 3 [O] VO 2 3 5 CO O COOH Benzoic acid No other group p-Hydroxybenzoic acid – OH group exerts + R and – I effects Similarly : NO NO 2 2 COOH NO 2 COOH (viii) From o-xylene [Industrial method] CH p-Chlorobenzoic acid – Cl group exerts – I effects, + R COOH HOH CO COOH COOH COOH Soda lime COOH COOH Acidity is only due to electron withdrawing inductive effect of the – COOH NO 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. The acidity of the three isomers of hydroxybenzoic acids follows the following order. OH COOH OH COOH COCl + POCl + HCl + PCl or SOCl 2 5 3 2 Benzoyl Chloride (e) Reaction with N H [Schmidt reaction] 3 COOH + NH OH NH + CO + N H SO 2 2 4 50° C 3 2 (f) Reaction with sodalime COOH Resonance effect cannot operate and hence only the acidstrengthening –I effect takes part with the result m-hydroxybenzoic acid is stronger acid than benzoic acid. Like other substituted benzoic acid. Benzene COOH 3 OCH (4) ChemicalOH Properties : NH 3 CH 2 2 Benzoic anhydride COOH + LiAlH 3 ID COOH 2 3 2  2 2 (j) Hunsdiecker reaction : U COONa +H CHO +CO + H O MnO + HCOOH in CCl4  X 2  C6 H 5  X  CO 2 heat Silver benzoate (Br2 or Cl2 ) Phenyl halide 2 C6 H 5 COOAg (b) Reaction with Alkalies Or NaHCO Or Na CO : 3 COOH + NaOH D YG COONa + HO 2 or NaHCO or Na CO (c) Formation of Esters : Aromatic acid (benzoic acid) having no group in its ortho positions can be readily esterified with alcohol in presence of a mineral acid. 3 COOH COOC H H + C H OH + HO In presence of ortho substituent the rate of esterification is greatly 2 5 + 2 2 (i) Decarboxylation COOH +2 Na 2 CH OH + HO 4 Benzyl alcohol (i) Reactions of carboxylic group (ii) Reactions of aromatic ring (i) Reactions of Carboxylic Group (a) Reaction with metals 3 | E3 > O |  + (CH CO) O (h) Reduction > > CH COOH > O C–O–C 3 COOH COOH 2 (g) Reaction with anhydride Acidic character among benzoic acids having different electron releasing group. COOH + CO NaOH + CaO 60 + M effect COOH Aniline COOH COOH – I effect 2   AgX (ii) Reactions of Aromatic Ring (a) Nitration COOH COOH H SO + HNO 2 4 3 NO 2 (b) Sulphonation m-nitrobenzoic acid COOH COOH 5 2 U decreased due to steric effect. + Fuming H SO 2 The esterification of the various benzoic acids : COOH CH HC 3 3 ST COOH Benzoic acid 2-Methylbenzoic acid COOH CH HC 3 3 CH COOH CH SO H 3 2 3 COOH ; 2, 6-Dimethyl benzoic acid 2,6-Dimethyl phenylacetic acid HC 3 HC 3 3 AgNO 3 COOH + Cl HC 3 3 C H Br 2 COOC H CH 2 Fecl 3 2 Cl 2 COOAg CH m-sulpho benzoic acid (c) Chlorination The substituted phenylacetic acid is easily esterified because – COOH group is separated from benzene ring by – CH – part. The ortho-substituted benzoic acids can be easily esterified by treating the silver salt of the acid with alkyl halides, i.e., COOH CH 4 (d) Reduction m-chloro benzoic acid COOH COOH 5 Na/amyl alcohol 3 5 Boil, 3H 2 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. (d) Formation of acid chloride 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. (iii) In the preparation of aniline blue. (iv) In treatment of skin diseases like eczema. (6) General Tests (i) Benzoic acid dissolves in hot water but separates out in the form of white shining flakes on cooling. (ii) It evolves CO with sodium bicarbonate, i.e., it gives effervescence with sodium carbonate. 2 60 (iii) Neutral ferric chloride gives a buff coloured precipitate. OH (iv) When warmed with ethyl alcohol and a little conc. H SO , a fragrant odour of ethyl benzoate is obtained. 2 4 COOH Salicylic acid [O-Hydroxy benzoic acid]; Salicylic acid is present in many essential oils in the form of esters. Oil of winter green is a methyl ester of salicylic acid. E3 (v) When heated strongly with soda lime, benzene vapours are evolved which are inflammable. Cinnamic Acid [-Phenyl acrylic acid] (1) Methods of preparation CH = CH – COOH (i) Kolbe Schmidt reaction ONa (1) Methods of Preparation (i) By Perkin's reaction OCOONa CO OH COONa Rearrangement 2 ID 125°C, Pressure CH COONa 3 C6 H 5 CHO  (CH 3 CO )2 O   180C C6 H 5 CH  CHCOOH  CH 3 COOH (ii) By Claisen condensation C H ONa ' Sodium salicylate Sodium phenyl carbonate dil. HCl OH U C6 H 5 CHO  CH 3 COOC 2 H 5 2 5  Sodium phenoxide COOH H 2O C6 H 5 CH  CHCOOC 2 H 5  H Ester D YG C6 H 5 CH  CHCOOH  C 2 H 5 OH (iii) By knoevenagel reaction NH 3 C6 H 5 CHO  CH 2 (COOH )2  heat C6 H 5 CH  CHCOOH  CO 2  H 2O (iv) Industrial method 200 C C6 H 5 CHCl 2  H 2 CHCOONa   C6 H 5 CH  CHCOOH  NaCl  HCl Benzal chloride U || || HOOC C  H Trans - form (Cinnamic acid) Cis- form (Allo cinnamic acid) ST H  C  COOH Oxidation C H CHO + C H COOH CrO Benzaldehyde Benzoic acid 3 Reduction Na(Hg)/H O 6 Reduction LiAlH – 10°C 6 5 5 2 5 2 2 2 C H CH = CHCH OH 6 5 2 Cinnamyl alcohol C H CH = CH 6 distilled 2 Cinnamic acid 5 2 Styrene Br 2 Cl C H CHBrCHBrCOOH 6 5 Dibromocinnamic acid OH Fuse with NaOH COOH COOH o-Chlorobenzoic acid (b) SO K OH Fuse with 3 KOH COOH o-Sulphobenzoic acid (c) OH OH Chromic + [O] acid CH OH COOH 2 Salicyl alcohol (d) OH OH PbO/NaOH +[O] COOH 3 o-Cresol 2 3-Phenyl propyl alcohol 4 Soda lime (a) -Phenyl propionic acid 6 COOH COOK 5 C H CH CH CH OH OH Dil. HCl (iii) From benzene derivatives CH 6 OH Heat 4 C H CH CH COOH 2 5 OH +CCl + KOH COOH Cinnamic acid (stable form) occurs in nature both free and as esters in balsams and resins. (3) Chemical properties 6 (ii) Reimer-Tiemann reaction Sodium acetate (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 C H (CH) COOH o- and pIt is a commercial method. The reaction yields bothacid Salicylic isomers. Salicylic acid is more volatile and separated by steam distillation. NH N Cl 2 (e) NaNO /HCl 2 2 COOH Anthranilic acid Anthranilic acid 0°C COOH heat HO 2 OH COOH OH Cl PCl (2) Physical properties 5 COOH (i) It is a colourless needle shaped crystalline compound. COCl Salicylic acid o-Chlorobenzoyl chloride (vii) Bromination (ii) Its m.p. is 156°C. OH (iii) It is sparingly soluble in cold water but readily soluble in hot water, alcohol, ether and chloroform. OH Br Br Br water 2 COOH (iv) It is steam volatile. Salicylic acid (v) It is poisonous in nature. However, its derivative used in medicine internally and externally as antipyretic and antiseptic. Br 2,4,6,-Tribromophenol (viii) Nitration OH 60 (3) Chemical properties OH (i) Reaction with Na CO , NaHCO or NaOH 2 3 Fuming HNO 3 O COOH | C – OH COO Na – Aq. Na CO Salicylic acid + 2 2,4,6,-Trinitrophenol Phthalic acid [1,2,-Benzene dicarboxylic acid] OH OH COOH Mono sodium salicylate Aq. NaOH COOH COONa There are three isomer (ortho, meta, para) of benzene dicarboxylic COOH OH HCl(gas) +H O 2 3 COOCH 3 U Methyl salicylate Salicylic acid D YG 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. POCl + C H OH COOH Salicylic acid 6 (i) By the oxidation of o-xylene : CH 5 Phenyl salicylate (salol) U  Salicylic acid COOH COOH 4 o-Toluic acid Phthalic acid (ii) From naphthalene (Industrial method) : It is known as aerial oxidation. Fuming H SO 2 CO CO 4 HgSO ,300°C 4 COONa COONa NaOH O Phthalic anhydride Naphthalene 2 COOH Phenol ST + ClCOCH COOH (2) Physical properties OH OCOCH 3 (i) It is colourless crystalline compound. Pyridine 3 COOH COOH Acetyl chloride Aspirin (Acetyl salicylic acid)  Aspirin is a white solid, melting point 135°C. It is used as antipyretic and pain killer (analgesic action). (ii) Its melting point is not sharp (195–213°C). (iii) It is sparingly soluble in cold water but soluble in hot water, alcohol, ether, benzene etc. (3) Chemical properties (v) Reaction with ferric chloride solution COONa NaOH OH FeCl COOH COOH [O] 3 + CO OH (iv) Acetylation Salicylic acid KMnO 3 o-Xylene (iii) Decarboxylation OH CH [O] 3 CH 3 6 COOH Benzene-1,4-dicarboxylic acid (Terphthalic acid) (1) Methods of preparation 5 COOC H COOH Benzene-1,3-dicarboxylic acid (Isophthalic acid) Benzene-1,2-dicarboxylic acid (Phthalic acid) OH 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. COOH COOH COOH COOH (ii) Reaction with alcohols or phenolsDisodium salicylate OH ID acid. ONa OH 2 NO 3 Salicylic acid + CH OH COOH NO 2 3 E3 2 ON 3 Solution COOH Violet colouration Acid salt Salicylic acid NaOH (vi) Reaction with PCl 5 COONa COONa Disodium phthalate C H OH 2 COOC H 2 5 COOH 5  The important derivatives are given below : Group replacing – OH Name (X  F, Cl, Br, I) Structure Acyl halide O || R  C X  NH 2 Amide O || R  C  NH 2 OR  ester O || R  C  OR  60 ( R  may be R ) OOCR anhydride O || O || R  C O  C  R E3 Reactivity Acyl derivatives are characterised by nucleophilic substitution reactions. Nu R C  O :  : Nu .. L ID L Nu.. |  C O.. : R  C  O : L R Intermediate O || (L  X , NH 2 , O  C  R or OR) U The relative reactivities of various acyl compounds have been found to be in the following order: U D YG R ST (4) Uses : It is used in the manufacture of plastics, dyes and other compounds such as phthalic anhydride, phthalimide, anthraquinone and fluorescein etc. O O || || C  O  R  C O  C R  R  C X  carboxylic group by other atoms or groups such as X ,  NH 2 , – OR and O  C  R are known as acid derivatives. || O  R  C  group is common to all the derivatives and is known as || O acyl group and these derivatives are termed as acyl compound. O NH 2 Out of acid halides, the acid chlorides are more important ones. 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. (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 || The compounds which are obtained by replacing the OH of the  R C OR O Acid derivatives O RC |.. L  R  C  L This makes the molecule more stable. The greater the stabilization, the smaller is the reactivity of the acyl compound. 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. (iii) Inductive effect : Higher the –I effect, more 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. (iv) Reaction with benzene (acylation) : This reaction is called friedel craft reaction. COCH O Cl Acyl Halides R  C Anhyd. AlCl 3  CH 3 COCl  where R may be alkyl or aryl group. 5 Anhyd. AlCl3  C6 H 5 COCl     HCl Benzophenone 60 Benzoyl chloride (ii) Industrial method : By distilling anhydrous sodium acetate (v) Reaction with ammonia or amines : CH 3 COCl  2 NH 3 Acetyl chloride heat 3CH 3 COONa  PCl3  3CH 3 COCl  Na 3 PO3 heat 2CH 3 COONa  POCl3  2CH 3 COCl  NaPO3  NaCl CH 3 CONH 2  NH 4 Cl Acetamide C6 H 5 COCl  2 NH 3 C6 H 5 CONH 2  NH 4 Cl Acetyl chloride E3 Benzamide However, acyl chlorides react with amines to form substituted heat (CH 3 COO )2 Ca  SO 2 Cl 2  2CH 3 COCl  CaSO 4 Sulphuryl chloride COC H 6 : 3 RCOOH  PCl3 3 RCOCl  H 3 PO3 Calcium acetate  HCl Acetopheno ne Acetyl chloride (1) Methods of Preparation (i) From carboxylic acid RCOOH  PCl5 RCOCl  POCl3  HCl Sodium acetate 3 amides. Acetyl chloride O || (iii) With thionyl chloride : CH 3 COCl  H 2 NC 2 H 5 CH 3 C  NH  C2 H 5 RCOOH  SOCl 2 RCOCl  SO 2  HCl ID N - Ethyl acetamide CH 3 COCl  (C2 H 5 )2 NH CH 3 CON (C2 H 5 )2  HCl D YG | Nu | Nu  HCl U Cl  H  (i) Hydrolysis : CH 3 COCl  HOH CH 3 COOH  HCl Acetyl chloride Acetic acid N, N -Diethyl acetamide Reduction (vi) LiAlH or 4 CH 3 COCl   NaBH 4 U This is the best method because SO 2 and HCl are 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 the formation of hydrochloric acid by hydrolysis. 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  : CH 3 CH 2 OH Ethanol (Primary alcohol) Pd / BaSO 4 CH 3 COCl  H 2   CH 3 CHO  HCl This reaction is called Rosenmund reaction. (vii) Reaction with organocadmium compounds (formation of ketones) 2CH 3 COCl  (CH 3 )2 Cd 2CH 3 COCH 3  CdCl 2 Dimethyl Cadmium Acetone 2C6 H 5 COCl  (CH 3 )2 Cd 2C6 H 5 COCH 3  CdCl 2 Acetopheno ne (viii) Reaction with diazomethane O O  || ||   CH 3  C  Cl  2C H 2  N  N CH 3  C  CH  N  N Diazometha ne Diazoaceto ne ST C6 H 5 COCl  H 2 O C6 H 5 COOH  H 2 O Benzoyl chloride O Benzoic acid H 2O  CH 3 CH 2 C  OH (ii) Reaction with alcohols (alcoholysis) CH 3 COCl  CH 3 CH 2 OH CH 3 COOCH 2 CH 3  HCl Ethyl acetate aq NaOH or C 6 H 5 COCl  C 2 H 5 OH   C 6 H 5 COOC 2 H 5  HCl Benzoyl chloride Ethyl alcohol Pyridine Ethyl benzoate ( N 2 ) (ix) Reaction with water AgNO / H O 3 CH 3 COCl  2 CH 3 COOH  AgCl  HNO3 (x) Reaction with chlorine This reaction is called Schotten Baumann reaction. (iii) Reaction with salts of carboxylic acid Red P CH 3 COCl  Cl 2   Cl  CH 2  CO  Cl  HCl Mono- -chloroacet yl chloride O O || || CH 3 COCl  CH 3 COO  Na    CH 3 C  O  C  CH 3 Pyridine || Acetic anhydride (xi) Reaction with Grignard reagent CH 3 CO Cl  IMg CH 3 CH 3 COCH 3  Mg Methyl magnesium iodide Acetone (iii) By partial hydrolysis of alkyl cyanide : I Cl Conc. HCl CH 3 C  N  CH 3 CONH 2 H 2 O / OH  (xii) Reaction with KCN (iv) By heating carboxylic acid and urea H O CH 3 COCl  KCN CH 3 COCN 2 CH 3 COCOOH Acetyl cyanide Pyruvic acid Acetamide heat H 2 N  C  NH 2  R  C  OH  R  C  NH 2  CO 2  NH 3 (xiii) Reaction with Salicylic acid || || O O || O Amide (2) Physical properties OOCCH 3 + HCl COOH Acetyl salicylicacid (Aspirin) (xiv) Reaction with ether 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 Ethyl acetate Ethyl chloride O ||    O O || || 2CH 3  C  Cl  N a O  O N a CH 3 C  O  O  C  CH 3  2 NaCl Acetyl chloride Acetyl peroxide (xvi) Reaction with hydroxylamine and hydrazine Hydroxyl amine Acetyl hydroxylamine (hydroxami c acid) CH 3 COCl  H 2 NNH 2 CH 3 CONHNH 2  HCl (4) Uses Acetyl hydrazine D YG Hydrazine (i) As an acetylating agent. (ii) In the estimation and determination of number of hydroxyl and amino groups. (iii) In the preparation of acetaldehyde, acetic anhydride, acetamide, acetanilide, aspirin, acetophenone etc. Acid Amides R  C The higher boiling points of amides is because of intermolecular hydrogen bonding H R H R H R | | | | | O NH 2 U where, R  CH 3 ,  CH 2CH 3 ,  C6 H 5 (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 2 O  CH 3 COOH  NH 3 Rapidly CH 3 CONH 2  H 2O  HCl    CH 3 COOH  NH 4 Cl Far more rapidly CH 3 CONH 2  NaOH   CH 3 COONa  NH 3 (ii) Amphoteric nature (Salt formation) It shows feebly acidic as well as basic nature. CH 3 CONH 2  HCl(conc.) CH 3 CONH 2.HCl Acetamide hydrochlor ide (only stable in aqueous solution) 2CH 3 CONH 2  HgO (CH 3 CONH )2 Hg  H 2 O Acetamide Mercuric Oxide Mercuric acetamide Ether CH 3 CONH 2  Na   CH 3 CONHNa  Sodium acetamide 1 H2 2 Reduction (iii) (i) Ammonolysis of acid derivatives CH 3 CONH 2  4[H ]  CH 3 CH 2 NH 2  H 2O ST (1) Methods of preparation LiAlH4 CH 3 COCl  2 NH 3 CH 3 CONH 2  NH 4 Cl Acetamide (CH 3 CO )2 O  2 NH 3 CH 3 CONH 2  CH 3 COONH 4 Acetamide Amm. acetate C6 H 5 COCl  NH 3 C6 H 5 CONH 2  HCl Benzoyl chloride |.......... H  N  C  O......... H  N  C  O......... H  N  C  O U CH 3 COCl  H 2 NOH CH 3 CONHOH  HCl (ii) Boiling points : Amides have high boiling points than the corresponding acids. Acetamide Boiling points 494 K Acetic Acid Boiling points 391 K Benzamide Boiling points 563 K Benzoic acid Boiling points 522 K ID (xv) Reaction with sodium peroxide (Peroxide formation) 60 Salicylic acid (i) Physical state : Formamide is a liquid while all other amides are solids. E3 OH  ClOCCH 3 COOH Acetamide Ethylamine Na / C 2 H 5 OH C6 H 5 CONH 2  4[H ]    C6 H 5 CH 2 NH 2  H 2O Benzamide Benzylamine Dehydration (iv) CH 3 CONH 2  CH 3 C  N  H 2O P2 O5 Acetamide heat Methyl cyanide Benzamide 2 5 C6 H 5 CONH 2   C6 H 5 C  N  H 2O P O (ii) From ammonium salts of carboxylic acids (Laboratory Method) Heat CH 3 COONH 4  CH 3 CONH 2  H 2 O Acetamide  Ammonium acetate is always heated in presence of glacial acetic acid to avoid the side product ( CH 3 COOH ). Benzamide heat Phenyl cyanide C6 H 5 CONH 2   C6 H 5 C  N SOCl 2 Phenyl cyanide (v) Reaction with nitrous acid (i) From carboxylic acid [Esterification] : Laboratory method. NaNO 2 / HCl CH 3 CONH 2  HONO    CH 3 COOH  N 2 O Aceticacid O ||  H 2O || H + R  C  OH  H OR  R  C  O R  H 2 O Ester C6 H 5 CONH 2  HONO   C6 H 5 COOH NaNO 2 / HCl Benzoic acid  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. Acetamide CH 3 COOH  CH 2 N 2 Acetic acid Methyl acetate Ether C6 H 5 COOH  CH 2 N 2 Benzoic acid  C6 H 5 COOCH 3  N 2 Diazometha ne Methyl benzoate  With diazomethane is the best method. (ii) From acid chloride or acid anhydrides Br2  CH 3 NH 2 NaOH or KOH Methyl amine (p-) CH 3 CO Cl  H OC 2 H 5 CH 3 COOC 2 H 5  HCl Acetyl chloride This reaction occurs is three steps: CH 3 CO CH 3 CO O || CH 3  C  NH 2  Br2  KOH CH 3 CONHBr  KBr  H 2 O Ethyl alcohol Ethyl acetate O  CH 3 CH 2 OH CH 3 COOCH 2CH 3  CH 3 COOH Ethyl acetate Acetic anhydride Ethyl alcohol E3 Acetobroma mide C6 H 5 CO Cl Benzoyl chloride O || CH 3  C  NHBr  KOH CH 3 NCO  KBr  H 2 O  H OC2 H 5 C6 H 5 COOC 2 H 5  HCl Ethyl alcohol Ethyl benzoate (iii) From alkyl halide : C2 H 5 Br  CH 3 COOAg CH 3 COOC 2 H 5  AgBr Methyl isocyanate CH 3 NCO  2 KOH CH 3 NH 2  K2CO 3 Ethyl bromide Methyl amine Silver acetate Ethyl acetate ID (iv) From ether : CH 3 CONH 2  Br2  4 KOH CH 3 NH 2  2 KBr  K 2 CO 3  2 H 2 O  ; HCl D YG CH 3 CONH 2  CH 3 OH  CH 3 COOCH 3  NH 4 Cl methyl acetate (viii) Reaction with grignard reagent CH 3  Mg  Br  CH 3  CONH 2 CH 4  CH 3  CONH  MgBr CH MgBr 3   OMgBr OH   | | H 2O / H  CH  C  NH     CH 3  C  NH  MgBr 3 2   Hydrolysis | |   CH 3 CH 3   Unstable U - NH 3 ST O   ||   CH 3  C  CH 3  Acetone     (4) Uses (i) In organic synthesis. The compounds like methyl cyanide, Methylamine and ethylamine can be prepared. (ii) In leather tanning and paper industry. (iii) As a wetting agent and as soldering flux. Amides such as dimethyl formamide (DMF), dimethyl acetamide (DMA) are used as solvents for organic and inorganic compounds. Esters, R  C  OR || O These are the most important class of acid derivatives and are widely distributed in nature in plants, fruits and flowers. (1) Methods of preparation 350 K Methoxy methane Methyl acetate (v) From Tischenko reaction : 3 CH 3  C  H  O  C  CH 3 25  CH 3  C  OC2 H 5 || U bromamides, RCONHBr; salts of these bromamides [RCONBr ] K Isocyanates, RNCO.  Nitrene rearranges to form isocyanate. (vii) Action with alcohol :  BF 3 CH 3  O  CH 3  CO  CH 3 COOCH 3  In this reaction a number of intermediates have been isolated; N- 70 o C  CH 3 COOCH 3  N 2 Diazometha ne 60 CH 3 CONH 2 Ether Al(OC H ) | || 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 : Ester Amyl acetate Benzyl acetate Amyl butyrate Flavour Banana Jasmine Apricot Ester Isobutyl formate Ethyl butyrate Octyl acetate Flavour Raspberry Pineapple Orange (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 = 77.5 C. (3) Chemical properties (i) Hydrolysis : dil. acid CH 3 COOC 2 H 5  H 2 O CH 3 COOH  C 2 H 5 OH o 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 OC2 H 5  H NH 2 CH 3 CONH 2  C2 H 5 OH Ethyl acetate Acetamide (iii) Reduction LiAlH 4 CH 3 COOC 2 H 5  4[H ]  2C2 H 5 OH or Na / C 2 H 5 OH COOC 2 H 5 O CH 2 OH LiAlH 4  4 H   C 2 H 5 OH or Na / C 2 H 5 OH Ethyl benzoate O || CH 3  C  OC2 H 5  H Ethyl acetate ||  CH 3  C  NHOH  C 2 H 5 OH base HNOH Hydroxamic acid Hydroxyl amine (ix) Reaction with hydrazine CH 3 COOC 2 H 5  H 2 NNH 2 CH 3 CONHNH 2  C2 H 5 OH Benzyl alcohol Hydrazine Red P CH 3 COOC 2 H 5  Br2   CH 2 BrCOOC2 H 5  HBr   Bromoethyl acetate (xi) Reaction with HI CH 3 COOC 2 H 5  HI CH 3 COOH  C 2 H 5 OH 60  Reduction in presence of Na / C2 H 5 OH is known as Bouveault Blanc reduction.  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.CuCr2 O4 ). Acid hydrazide (x) Halogenation Aceticacid || CuO.CuCr 2 O 4 R  C  OR  2 H 2   RCH 2 OH  ROH 525 K , 200  300 atm (iv) Reaction with PCl or SOCl 5 2 CH 3COOC2 H5  PCl5 CH 3COCl  C2 H5 Cl  POCl3 CH 3 COOC 2 H 5  SOCl 2 CH 3 COCl  C2 H 5 Cl  SO 2 Acetyl chloride Ethyl chloride C6 H 5 COOC 2 H 5  PCl5 C6 H 5 COCl  POCl3  C2 H 5 Cl Benzoyl chloride ID Ethyl benzoate R C + O  ROH OR R C CH 3 COOC 2 H 5  NaOH CH 3 COONa  C2 H 5 OH U (v) Reaction with alcohols : On refluxing ester undergoes exchange of alcohols residues. O H  ROH OR (Excess) Acid Anhydride CH 3 COOC 2 H 5  CH 3 OH CH 3 COOCH 3  C 2 H 5 OH Ethyl acetate Methyl acetate D YG  This reaction is known as alcoholysis or trans esterification. OMgBr   |   CH 3  C  OC 2 H 5  CH 3 MgBr CH 3  C  OC 2 H 5  |   Ethyl acetate CH 3   O OMgBr | O C2H5OMgBr (vi) Reaction with Grignard reagents || CH3 CO CH3 CO O or | (i) From carboxylic acid O O || || Quartz tube P O 10 C6 H 5 CO OH  H OOCC 6 H 5 4   heat || U O O || || C6 H 5  C  O  C  C6 H 5  H 2 O Benzoic anhydride 2 (ii) From carboxylic acid salt and acyl chloride [Laboratory method] OH ST | Py CH 3 COONa  CH 3 COCl   CH 3 COOCOCH 3  NaCl CH 3  C  CH 3 | o O || Acid anhydride Porcelain chips 1073 K HO + O || R  C  OH  H O  C  R  R  C  O  C  R  H 2O CH 3 H (CH3 CO)2 O (1) Method of preparation CH 3  C  CH 3   CH 3  C  CH 3 CH 3 MgBr Ethyl alcohol (4) Uses (i) As a solvent for oils, fats, cellulose, resins etc. (ii) In making artificial flavours and essences. (iii) In the preparation of ethyl acetoacetate. (5) General Tests (i) It has sweet smell (ii) 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. E3 O Aceticanhydride CH 3 C6 H 5 COONa  C6 H 5 COCl   C6 H 5 COOCOC 6 H 5 Py 3 alcohol (vii) Claisen condensation O Benzoic anhydride ||  NaCl C H O  Na  5 CH 3  C  OC2 H 5  H  CH 2 COOC 2 H 5 2    Ethyl acetate (2 molecules) O || CH 3  C  CH 2 COOC 2 H 5  C 2 H 5 OH Ethyl acetoacetate (  - ketoester) (viii) Reaction with hydroxyl amine (iii) From acetylene CH 3 HgSO 4 Distill  2CH 3 COOH  |   heat CH CH (OOCCH 3 )2 CH ||| CH 3 CHO  CH 3 CO CH 3 CO O AlCl 3 (CH 3 CO )2 O  C6 H 6   C6 H 5 COCH 3  CH 3 COOH Benzene Acetopheno ne Aceticanhydride (iv) From acetaldehyde : (viii) Reaction with acetaldehyde CH 3 CHO  O 2   2CH 3  C  O  O  H Cobalt acetate (CH 3 CO )2 O  CH 3 CHO CH 3 CH (OOCCH 3 )2 || Acetaldehy de Ethylidene acetate O (CH 3 CO )2 O  H 2 O (ix) Reduction LiAlH 4 (CH 3 CO )2 O  CH 3 CH 2 OH (2) Physical properties Ether Ethyl alcohol 60 (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. (x) Action with ether : CH 3 CO O.COCH 3  C 2 H 5  O  C2 H 5 2CH 3 COOC 2 H 5 Diethyl ether Ethyl acetate (ii) Solubility : They are generally insoluble in water but are soluble in the organic solvents such as ether, acetone, alcohol, etc. (xi) Action with N O (iii) Boiling points : The boiling points of acid anhydrides are higher than those of carboxylic acids because of the greater molecular size. CH 3 COOCOCH 3  N 2 O5 CH 3  C  O  N 5 E3 2 || O O O (3) Chemical Properties (4) Uses : Acetic anhydride is used (i) Hydrolysis : O || || ID (i) as an acetylating agent. O (ii) For the detection and estimation of hydroxyl and amino group. CH 3  C  O  C  CH 3  H 2 O 2CH 3 COOH Aceticanhydride (iii) in the manufacture of cellulose acetate, aspirin, phenacetin, acetamide, acetophenone, etc. Aceticacid U (ii) Action with ammonia (CH 3 CO )2 O  2 NH 3 CH 3 CONH 2  CH 3 COONH 4 Acetamide Amm. acetate D YG (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 Ethyl alcohol Ethyl amine 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. Ethyl acetate (CH 3 CO )2 O  H 2 NC 2 H 5 CH 3 CONHC 2 H 5  CH 3 COOH N  Ethyl acetamide OH OC OH Carbonic acid OH COOH OOCCH 3  CH 3 COOH COOH Acetyl salicylic acid (Aspiriin) ST Salicylic acid (iv) Action of dry HCl (CH 3 CO)2 O  HCl CH 3 COCl  CH 3 COOH (v) Reaction with chlorine  NH 2 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. Acetyl chloride  It was the first organic compound synthesised in the laboratory from inorganic material (by heating a mixture of ammonium sulphate and potassium cyanate) by Wohler in 1828.  This preparation gave a death blow to Vital force theory.  It is the final decomposition product of protein's metabolism in man and mammals and is excreted along with urine.  Adults excrete about 30 grams of urea per day in the urine. (1) Method of preparation (CH 3 CO )2 O  Cl 2 CH 3 COCl  CH 2 ClCOOH Monochloro acetic acid (vi) Reaction with PCl 5 (i) From urine : Urine is treated with conc. nitric acid where crystals of urea nitrate CO(NH 2 )2.HNO 3 are obtained. 2CO (NH 2 )2.HNO 3  BaCO3 2CO (NH 2 )2  Ba(NO 3 )2  H 2O  CO 2 Urea nitrate (CH 3 CO )2 O  PCl5 2CH 3 COCl  POCl3 (vii) Friedel craft's reaction NH 2 Acetanilide U Aniline  OH  O  C N , N  Diethyl acetamide (CH 3 CO )2 O  H 2 NC 6 H 5 CH 3 CONHC 6 H 5  CH 3 COOH (CH 3 CO )2 O  NH 2  OH  O  C (CH 3 CO )2 O  HN (C 2 H 5 )2 CH 3 CON (C 2 H 5 )2  CH 3 COOH Diethylamine NH 2 NH 2 Urea or Carbamide O  C (ii) Laboratory preparation Urea NH 2 CONH 2  HNO 3 (conc.) NH 2 CONH 2.HNO 3 (a) Wohler synthesis 2 KCNO Potassium cyanate Urea nitrate  (NH 4 )2 SO 4 2 NH 4 CNO  K 2 SO 4 Ammonium sulphate 2 NH 2 CONH 2  H 2 C2 O4 (NH 2 CONH 2 )2 H 2 C2 O4 Ammonium cyanate Oxalic acid  NH 2 CONH 2 On heating Ammonium cyanate Urea  The solid residue is extracted with alcohol and the extract evaporated when the crystals of urea are obtained. It can be recrystalised from water. Urea is a stronger base than ordinary amide. It is due to the resonance stabilization of cation, the negatively charged oxygen atom is capable of coordination with one proton.  H2N NH 2 Carbonyl chloride (Phosgene) NH 2 OC 2 H 5  2 NH 3 O  C OC 2 H 5 Ethyl carbonate (urethane)  C | | OH OH OH NH 2  2C 2 H 5 OH NH 2 NH 2  H OH (iii) Industrial method   O  C acid heat CaC 2  N 2  CaCN 2  C NH 2 CONH 2  2 NaOH 2 NH 3  Na 2 CO 3 Calcium cyanamide o H O 4 CaCN 2 2 H 2 NCN 2 H 2 NCONH 2 o (b) From carbon dioxide and ammonia o 150  200 C CO 2  2 NH 3   NH 2 COONH 4 Ammonium carbamate heat (140 C)   NH 2 CONH 2  H 2O Urea (Two moleculesof urea) heat NH 2CONH 2   NH 3  HOCN (H  N  C  O) Cyanic acid Polymerisa tion 3 HOCN  (HOCN )3 or (H 3 N 3 C3 O3 ) H U solid. It melts at 132 C. It is very soluble in water, less soluble in alcohol but insoluble in ether, chloroform and benzene. ST Crystal structure: In solid urea, both nitrogen atoms are identical.  1.37 Å C  H2 N  || O NH 2 C NH2 H2N  | O C | O This indicates that C  N bond in urea has some double bond character. (3) Chemical Properties (i) Basic nature (Salt formation): It behaves as a weak monoacid base (Kb  1.5  10 14 ). It forms solt with strong acid. Biuret when heated rapidly at 170 o C , polymerisation takes place: o NH 2 2 NH 3  CO 2  H 2 O Urea is identified by the test known as biuret test. The biuret residue is dissolved in water and made alkaline with a few drops of NaOH. When a drop of copper sulphate solution is added to the alkaline solution of biuret, a violet colouration is produced. (2) Physical properties : Urea is a colourless, odourless crystalline H2N (NH 4 )2 CO 3 Ammonium carbonate heat NH 2CO NH 2  H HNCONH 2   NH 2CONHCONH 2  NH 3 40 C   NH 2 CONH 2  CaSO 4 CaCN 2  H 2 O  H 2 SO 4  o NH 2 CONH 2  2 H 2 O (iii) Action of heat (Urea) D YG or An enzyme, urease, present in soyabean and soil also brings hydrolysis. U The cyanamide is treated with dilute sulphuric acid at 40 C where partial hydrolysis occurs with the formation of urea. (H 2 O 2 ) Ammonia  CO 2  H 2O ID Calcium Carbide  2 NH 3 OH Carbonic acid Urea (a) By partial hydrolysis of calcium cyanide OH Aq. alkali or OC NH 2  H OH Cyanamide C || (ii) Hydrolysis Urea H SO NH2  An aqueous solution of urea is neutral. Urea  CaSO4 H2N E3 OC  NH 2  2 HCl NH 2 Cl  2 NH O  C 3 Cl  C (b) From phosgene or alkyl carbonate  H2 N 60 NH 4 CNO OC Urea oxalate Isomeric change C O=C C=O or H N–H N C O Cyanuric acid (iv) Reaction with nitrous acid O N OH NaNO2 HCl H 2 N  CO  N H 2  2 HNO 2   HO N O H 2 CO 3  Carbonic acid 2 N 2  2H 2 O OC  H 2O CO 2 NH  C  O NH  C  O  2C 2 H 5 OH Parabanic acid (Oxalyl urea) (v) Reaction with alkaline hypohalides NH  H NaOH  Br2