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*Revision Materials* 1 Atomic Structure 2 Atoms, molecules and stoichiometry 3 Chemical Bonding 4 States of matter 5 Chemical energetics 6 Electrochemistry 7 Equilibria 8 Reaction kinetics 9 The Periodic Table, chemical periodicity 10 Group 2 11 Group 17 12 Nitrogen and sulfur 13 Organic 14 Hydrocarbons 15 Halogen compounds 16 Hydroxy compounds 17 Carbonyl compounds 18 Carboxylic acids and derivatives 19 Nitrogen compounds 20 Polymerisation 21 Organic synthesis 22 Analytical techniques 23 Chemical energetics 24 Electrochemistry 25 Equilibria 26 Reaction kinetics 27 Group 2 28 Chemistry of transition elements 29 Organic 30 Hydrocarbons 31 Halogen compounds 32 Hydroxy compounds 33 Carboxylic acids and derivatives 34 Nitrogen compounds 35 Polymerisation 36 Organic synthesis 37 Analytical techniques

33 Carboxylic acids and derivatives

33.1 Carboxylic acids 33.2 Esters 33.3 Acyl chlorides

Esters

Specification Reference Organic Chemistry, Carboxylic Acids and Derivatives 33.2

Quick Notes

  • Esters can be formed by reacting an alcohol with an acyl chloride.
  • This is a condensation reaction that produces an ester and hydrogen chloride (HCl).
  • Examples:
    • Ethanol + Ethanoyl chloride → Ethyl ethanoate + HCl
    • Phenol + Benzoyl chloride → Phenyl benzoate + HCl

Full Notes

Formation of Esters from Alcohols and Acyl Chlorides

Esters can be made via nucleophilic addition–elimination reactions between alcohols and acyl chlorides.

Phenol is also able to react with acyl chlorides to form an ester, however it is less reactive than alcohols due to resonance in the aromatic ring (see Phenol for more detail).

General Reaction:

CIE A-Level Chemistry ester formation reaction between alcohols and acyl chlorides.

R–OH (alcohol) + R'–COCl (acyl chloride) → R'–COOR (ester) + HCl

This is a type of condensation reaction because a small molecule (HCl) is eliminated during the reaction.

Examples

Example Formation of Ethyl Ethanoate

CIE A-Level Chemistry ester formation example showing reaction between ethanonyl chloride and ethanol to form ethylethanoate.

Example Formation of Phenyl Benzoate

CIE A-Level Chemistry ester formation example showing reaction between phenol and benzoyl chloride to form phenyl benzoate.

Why Use Acyl Chlorides?

The reaction between acyl chlorides and alcohols is fast and does not require a catalyst meaning it is generally more efficient than esterification using carboxylic acids and sulfuric acid.

However, it produces HCl gas, which is corrosive and must be handled carefully.

Summary