33. Carboxylic acids and derivatives

• Recall preparation of benzoic acid: (a) reaction of an alkylbenzene with hot alkaline KMnO₄ and then dil. acid, exemplified by methylbenzene

• Describe the reaction of carboxylic acids with PC l ₃ and heat, PCl ₅ or SOCl ₂ to form acyl chlorides

• Recognise that some carboxylic acids can be further oxidised: - (a) the oxidation of methanoic acid, HCOOH, with Fehling’s reagent or Tollens’ reagent or acidified KMnO₄ or acidified K₂Cr₂O₇ to form carbon dioxide and water - (b) the oxidation of ethanedioic acid, HOOCCOOH, with warm acidified KMnO₄ to form carbon dioxide

• Describe/explain: the relative acidities of carboxylic acids, phenols and alcohols

• Describe/explain: the relative acidities of chlorine-substituted carboxylic acids

33.2.1

• Recall preparation of esters: (a) reaction of alcohols with acyl chlorides using the formation of ethyl ethanoate and phenyl benzoate; as examples

• Recall preparation of acyl chlorides: (a) reaction of carboxylic acids with PCl ₃ and heat, PCl ₅ or SOCl ₂

• Describe reactions of acyl chlorides: - (a) hydrolysis on addition of water at room temp. to produce the carboxylic acid and HCl - (b) reaction with an alcohol at room temp. to produce an ester and HCl - (c) reaction with phenol at room temp. to produce an ester and HCl - (d) reaction with ammonia at room temp. to produce an amide and HCl - (e) reaction with a primary or secondary amine at room temp. to produce an amide and HC l

• Describe the addition–elimination mechanism of acyl chlorides in reactions in 33.3.2(a)–(e)

• Explain the relative ease of hydrolysis of acyl chlorides, alkyl chlorides and halogenoarenes (aryl chlorides)