Alcohols & Acyl Chlorides (CIE A Level Chemistry)

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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 from acyl chlorides rather than carboxylic acids is more effective because::
    • Acyl chlorides are more reactive (so they produce the ester 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

Esterification of an aliphatic alcohol using an acyl chloride 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

Esterification of phenol using an acyl chloride

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

formation-of-the-phenoxide-ion

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

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Richard

Author: Richard

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Richard has taught Chemistry for over 15 years as well as working as a science tutor, examiner, content creator and author. He wasn’t the greatest at exams and only discovered how to revise in his final year at university. That knowledge made him want to help students learn how to revise, challenge them to think about what they actually know and hopefully succeed; so here he is, happily, at SME.