Chemistry Notes on Phenol PDF

Chemistry Notes for Entrance Exams in Help For Entrance app/website. PHENOL Phenols are the organic compounds in which hydroxyl group (-OH) is directly linked to aromatic ring system....

Chemistry Notes for Entrance Exams in Help For Entrance app/website. PHENOL Phenols are the organic compounds in which hydroxyl group (-OH) is directly linked to aromatic ring system. OH or C6H5OH Preparation: 1. By fusing the sodium salt of benzene sulphonic acid with NaOH SO3H SO3Na OH NaOH  NaOH  + Na2SO3 Sodium benzene sulphonate 2. By hydrolysis of benzenediazonium chloride + N  NCl– OH Dil.H SO + H2O 2  4 + N2 + HCl [IOM 2007]  3. By heating chlorobenzene with caustic soda under pressure (Dow’s process) (commercial method) Cl ONa OH NaOH  NaOH   (Chlorobenzene) Sodium phenoxide phenol 4. From Cumene (Commercial method)  Chemistry Notes for Entrance Exams in Help For Entrance app/website. 5. By decarboxylation of salicylic acid with soda – lime OH OH COOH + NaOH CaO  + Na2CO3 6. From Grignard reagent MgBr OMgBr OH  + O2 Dry   ether  H CH 3 CH3 H O2 Benzene Benz Commercially, phenol (carbolic acid) is also obtained from middle oil fraction of Coal – tar distillation. ene 7. Rasching’s process: By heating chlorobenzene with steam at 4250 C in presence of CuCl2 at catalyst Cl CuCl 2 2 + 2HCl + O2  + 2H2O Cl OH CH3 CH3 CH3 Benz + H2O + HCl ene Benz Benz ene ene 8. From benzene OH V2O5 O2 300°C Chemical properties  Phenol shows electrophilic substitution reactions. [MOE 1997]  Phenols are acidic in nature  Electron – with drawing groups increase the acidity while electron donating groups decrease the acidity of phenol i.e. OH OH OH OH NO2OH NO2 NO2 < < < < NO2 NO2 NO2 NO2 (P - cresol) (phenol) (p – nitro phenol) (2, 4-dinitro phenol) (2, 4, 6-trinitro phenol) 1. Action of neutral ferric chloride Phenol gives violet colour with FeCl3. It is the RXn used for distinguishing phenol from carboxylic acid.  Chemistry Notes for Entrance Exams in Help For Entrance app/website. 2. Reduction with Zinc dust C6H5OH + Zn ditilltion   C6H6 + ZnO (Phenol) (Benzene) 3. Alkylation: C6H5OH + NaOH C6H5ONa + H2O Δ i. C6H5ONa + CH3I  C6H5OCH3 + NaI (Anisole) ii. C6H5ONa + CH3COCl C6H5OC2H5 + NaI (Phenetole) This RXn is called William son’s synthesis 4. Acylation i. C6H5OH + CH3COCl Pyridine   C6H5OCOCH3 + HCl ii. C6H5OH + (CH3CO)2H Pyridine   C6H5OCOCH3 + CH3COOH or CH 3COONa or few drops of conc. H 2SO 4 5. Benzoylation / schotten – Baumann RXn O OH COCl O–C + NaOH  + HCl Phenol Benzoyl chloride (Phenyl benzoate) 6. RXn with phosphorus pentachloride OH Cl + PCl5 + POCl3 + H2O (Chlorobenzene poor yield) OH + PCl5 (C6H5O)3P = 0 excess  Chemistry Notes for Entrance Exams in Help For Entrance app/website. 7. RXn with Ammonia OH NH2 2nCl + NH3  2 + H2O (Phenol) (Aniline) 8. Halogenation OH OH Br Br H 2O + 3Br2   Phenol Br 2, 4, 6 – Tribromophenol (white ppt) OH OH OH CS2 Br + Br2  0 + 0 C Br (p-bromophenol) (O – Bromophenol) major minor 9. Sulphonation OH OH SO3H H SO 2  4 150 – 250C (o-phenol sulphonic acid) OH OH H SO  0 2  0 4 15 – 25 C SO3H (P – Phenol Sulphonic acid) 10. Nitration OH OH OH NO2H dil.HNO3  + o-nitrophenol NO2 (p-nitrophenol)  Chemistry Notes for Entrance Exams in Help For Entrance app/website. OH NO2 OH NO2 Conc. HNO3  NO2 2, 4, 6 – Trinitrophenol (Picric acid) 11. Friedel Craft Reaction a. Alkylation OH OH OH R RX  + AlX3 b. Acylation R OH OH OH COR + 3H2 RCOX   + AlCl3 COR 12. Hydrogenation + 3H2  Ni 150 - 2000C (Phenol) (Cyclohexanol) 13. Kolbe Reaction OH ONa + NaOH + H2O ONa OH COONa 0 + CO2 125  C 6 – 7 atm (Sod. Phenoxide) (Sod. Salicylate) OH OH COONa COOH  H (Salicylic acid)  Chemistry Notes for Entrance Exams in Help For Entrance app/website. Use of Salicylic acid OCOCH3 COONa (CH3CO)2O OH [MOE 2062,2056] CH3COCl Acetyl Salicylic acid (aspirin) COOH OH COOC6H5 C6H5OH Conc. H2SO4 POCl3 CH3OH (Salol) Phenyl Salicylate OH COOCH3 (Methyl Salicylate) (Oil of winter green) 14. Reimer – Tiemann Reaction OH ONa OH CHO CHO H + CHCl3 + NaOH  [MOE 2000] (Salicyladehyde) OH OH OH COONa COOH H + CCl4 + NaOH  (Salicylic acid)  Chemistry Notes for Entrance Exams in Help For Entrance app/website. 15. Oxidation OH O O  2 CrO2Cl2 O Hydroquinone (phenoquinone) OH OH OH OH K 2S2 O8  + (potassium per sulphate) O (Quinol) (catechol) 16. Condensation reaction:   HO + Cl N  N   HO N = N + HCl Benzenediazonium P-hydroxyazobenzene chloride 17. Laderer – Mannose reaction: (Phenol – formaldehyde resin) Phenol & formaldehyde in presence of NaOH polymerise to give a 3D cross linked polymer known as bakelite. 18. Liberman's nitroso reaction: conc. H SO  NaNO Phenol  2  4  3 Red brown colour NaOH  Indophenol  (deep blue colour) 19. Reactions due to acidic nature Na 1 C6H5OH C6H5ONa + 2 H2 NaOH C6H5ONa + H2O Uses:  Making bakelite  As starting material for manufacturing drugs like salol, aspirin, phenolpthalein, picric acid etc.  Used as antiseptics and disinfectant. Note: Ethylene glycol is a dihydroxy alcohol. [MOE 2003] Glycerol is a trihydroxy alcohol. [IOM 2009] Alcohol poisoning occurs due to presence of methyl alcohol. [IOM 2005, IOM 2010]  Chemistry Notes for Entrance Exams in Help For Entrance app/website. Rectified alcohol is converted into absolute alcohol by addition of benzene. [IOM 1999]  Rectified alcohol is converted into absolute alcohol by addition of benzene. [IOM 1999]  Methylalcohol is known as wood spirit since it is obtained by destructive distillation of wood.  Ethylalcohol is also known as grain alcohol.  Proof spirit = Alcohol + water in which 51% alcohol by volume and 49.3% alcohol by weight. If % of alcohol  = over proof spirit If % of alcohol  = underproof spirit  Denatured spirit: contains 5 to 10% CH 3OH. Also known as methylated spirit.  Absolute alcohol: 100% C2H5OH  Rectified spirit = 96.56% ethyl alcohol + 4.44% water OR 96.87% ethylalcohol + 4.13% water (in some books)  Tincture of iodine = 2 – 3% alc. soln of iodine.  Beer (from barley) = contains 3 – 5% ethanol  Cidar (from apple juice) = contains 3 – 6% ethanol.  Grape wines like port & sherry = 15 – 20 % ethanol.  Whisky, Brandy, Rum & Gin = 40 – 50% ethanol  Aqueous solution of phenol is known as carbolic acid  Salol is used as intestinal antiseptics.