Carboxylic acids and derivatives (A Level) flashcards

Topic 27: Carboxylic acids and derivatives

Name the ester CH₃CH₂CH₂COOCH₃

Methyl butanoate (from butanoic acid and methanol). The alcohol part is named first.

Esterification: reagents and conditions

Carboxylic acid + alcohol, warm, with a concentrated H₂SO₄ catalyst. Reversible: CH₃COOH + CH₃OH ⇌ CH₃COOCH₃ + H₂O

Acid vs alkaline hydrolysis of an ester

Acid (dilute acid, reflux): reversible, gives the carboxylic acid. Alkaline (NaOH(aq), reflux): goes to completion, gives the carboxylate salt.

Soap and biodiesel from fats and oils

Soap: fat + 3NaOH → 3 sodium salts of long-chain acids + glycerol. Biodiesel: oil + 3CH₃OH (catalyst) → 3 methyl esters + glycerol.

Four uses of esters

Solvents, plasticisers, perfumes and food flavourings.

Products of ethanoyl chloride with water, ethanol, ammonia and methylamine

Water: ethanoic acid. Ethanol: ethyl ethanoate. Ammonia: ethanamide. Methylamine: N-methylethanamide. HCl is the by-product (as a salt with excess NH₃ or amine).

Name the mechanism for acyl chlorides with nucleophiles

Nucleophilic addition–elimination.

Why is ethanoic anhydride used rather than ethanoyl chloride to make aspirin?

Its by-product is ethanoic acid, not corrosive HCl gas; it reacts less vigorously so it is easier to control; it is hydrolysed less readily, and is cheaper.

Required practical 10: how do you recrystallise an impure organic solid?

Dissolve in the minimum volume of hot solvent, hot-filter if needed, cool to crystallise, filter under reduced pressure, wash with a little cold solvent and dry.

Fats and oils

Esters of glycerol with three long-chain carboxylic acids.