CIE AS/A Level Chemistry 33.2 Esters Study Notes- 2025-2027 Syllabus
CIE AS/A Level Chemistry 33.2 Esters Study Notes – New Syllabus
CIE AS/A Level Chemistry 33.2 Esters Study Notes at IITian Academy focus on specific topic and type of questions asked in actual exam. Study Notes focus on AS/A Level Chemistry latest syllabus with Candidates should be able to:
recall the reaction by which esters can be produced:
(a) reaction of alcohols with acyl chlorides using the formation of ethyl ethanoate and phenyl benzoate as examples
Preparation of Esters from Acyl Chlorides
Esters can be produced by the reaction of alcohols or phenols with acyl chlorides. You must be able to recall the reagents, conditions and products of this reaction, as exemplified by the formation of ethyl ethanoate and phenyl benzoate.
General Reaction
An acyl chloride reacts with an alcohol or phenol to form an ester and hydrogen chloride.
\( \mathrm{RCOCl + R’OH \rightarrow RCOOR’ + HCl} \)
The reaction is rapid, occurs at room temperature and does not require a catalyst.
Example 1: Formation of Ethyl Ethanoate
Ethyl ethanoate is formed when ethanol reacts with ethanoyl chloride.
\( \mathrm{CH_3COCl + CH_3CH_2OH \rightarrow CH_3COOCH_2CH_3 + HCl} \)
The acyl chloride provides the ethanoate part of the ester name, and the alcohol provides the ethyl part.
Example 2: Formation of Phenyl Benzoate
Phenyl benzoate is formed when phenol reacts with benzoyl chloride.
\( \mathrm{C_6H_5COCl + C_6H_5OH \rightarrow C_6H_5COOC_6H_5 + HCl} \)
This reaction shows that phenols, like alcohols, can form esters with acyl chlorides.
Key Features of the Reaction
- reaction is fast and usually vigorous
- steamy white fumes of HCl may be observed
- reaction is irreversible
Mechanism (for Recall)
The reaction proceeds via an addition–elimination mechanism, in which:
- the alcohol or phenol acts as a nucleophile
- chloride ions are eliminated as a leaving group
Acyl chlorides react with alcohols and phenols at room temperature to form esters and hydrogen chloride.
Example
Name the ester formed when ethanol reacts with ethanoyl chloride.
▶️ Answer / Explanation
Ethyl ethanoate.
Example
Describe the reagents and products when phenyl benzoate is prepared from an acyl chloride.
▶️ Answer / Explanation
Benzoyl chloride reacts with phenol at room temperature.
The products are phenyl benzoate and hydrogen chloride.