A Levels Chemistry (9701)•9701/13/M/J/22
Explanation
Esterification Identifies Alcohol and Carboxylic Acid
Steps:
- Analyze the ester's structure: the -OR group comes from the alcohol (R-OH), and the R'COO- from the carboxylic acid (R'COOH).
- Identify the alkyl chain: straight propyl (CH3CH2CH2-) matches propan-1-ol.
- Identify the acyl chain: 2-methylpropanoyl ((CH3)2CHCO-) matches 2-methylpropanoic acid.
- Verify reaction: acid + alcohol → ester + water, confirming B's components form the given ester.
Why B is correct:
- Propan-1-ol (CH3CH2CH2OH) and 2-methylpropanoic acid ((CH3)2CHCOOH) yield CH3CH2CH2OC(O)CH(CH3)2 via Fischer esterification.
Why the others are wrong:
- A: Forms (CH3)2CHCH2OC(O)CH2CH3, with branched alcohol chain.
- C: Forms (CH3)3COC(O)CH3, with tertiary alcohol and shorter acid.
- D: Forms (CH3)2CHOC(O)CH3, with branched secondary alcohol.
Final answer: B
Topic: Carboxylic acids and derivatives
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