Preparation of Carboxylic Acids

From Primary Alcohols and Aldehydes

• Easily oxidized to carboxylic acid by using KMnO4 in neutral, alkaline or acidic medium

• Or K2Cr2O7 and CrO3 in acidic medium (Jones’ Reagent)

• Aldehydes can be oxidized by using a mild oxidizing agent like Tollen’s reagent

From Nitriles and Amides

• Nitriles are hydrolyzed to amides in the presence of catalysts like OH- and H+

• Mild reaction conditions help stop the reaction at amide stage

From Alkylbenzenes

• Alkylbenzenes vigorously oxidize with chromic acids or acidic/alkaline KMnO4

• During oxidation, the chain gets oxidized with -COOH group but the aromatic nucleus remains intact

• Only 1* and 2* alkyl chains are oxidized due to presence of benzylic hydrogen

From Grignard’s Reagent

• Grignard Reagent reacts with dry ice (CO2) in ethereal solution to produce salts of carboxylic acids, which on acidification with mineral acids give corresponding carboxylic acids

From Acyl Halides and Anhydrides

• Acyl halides, on being hydrolyzed with water give corresponding carboxylic acid

• When hydrolyzed with an aqueous base, give us carboxylate ion that on acidification gives corresponding acid

• Anhydrides when hydrolyzed with water give corresponding carboxylic acid

From Esters

• Acidic hydrolysis : Directly gives us carboxylic acids

• Basic hydrolysis : Gives carboxylates that on acidification get converted to carboxylic acids