CIE A Level Chemistry (9701) 2019-2021

Revision Notes

7.4.1 Alcohols

Reaction of Alcohols With Acyl Chlorides

  • Acyl chlorides are reactive organic compounds with a -COCl functional group
  • The carbonyl carbon is electron-deficient and has a partial positive charge
  • It is therefore susceptible to nucleophilic attack
  • The carbon-chlorine bond breaks and white fumes of hydrogen chloride, HCl are formed

Reaction with alcohols and phenols

  • Acyl chlorides react with alcohols and phenols to form esters in a nucleophilic substitution reaction
  • The -OH group acts as a nucleophile and attacks the carbonyl carbon to substitute the chlorine atom
  • Forming esters using acyl chlorides is more effective compared to using carboxylic acids as:
    • Acyl chlorides are more reactive (so the ester is produced faster)
    • Acyl chloride reactions go to completion (so more of the ester is produced)

Reaction with alcohols

  • The reaction of acyl chlorides with alcohols is vigorous and white fumes of HCl gas are formed

 

Hydroxy Compounds - Reaction with Alcohols, downloadable AS & A Level Chemistry revision notes

Acyl chlorides react vigorously with alcohols to form esters

Reaction with phenols

  • For the reaction of acyl chlorides with phenols to occur, heat and a base are required
    • The base is needed to deprotonate the phenol and form a phenoxide ion
    • The phenoxide ion is a better nucleophile than the original phenol molecule and will be able to attack the carbonyl carbon

 

Hydroxy Compounds - Reaction with Phenols, downloadable AS & A Level Chemistry revision notes

Acyl chlorides react with phenols when heated and in the presence of a base to form esters

Hydroxy Compounds - Formation of Phenoxide, downloadable AS & A Level Chemistry revision notes

A base is needed to form a phenoxide ion which is a better nucleophile than phenol; now, nucleophilic attack on the carbonyl carbon can more readily occur

Author: Francesca

Fran has taught A level Chemistry in the UK for over 10 years. As head of science, she used her passion for education to drive improvement for staff and students, supporting them to achieve their full potential. Fran has also co-written science textbooks and worked as an examiner for UK exam boards.
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