An organic compound (A) (molecular formula C₈H₁₆O₂) was hydrolysed with dilute sulphuric acid to give a carboxylic acid (B) and an alcohol (C). Oxidation of (C) with chromic acid produced (B). (C) on dehydration gives but-1-ene. Write equations for the reactions involved.
Identification of Compounds:
Since compound (A) (C₈H₁₆O₂) hydrolyses to give a carboxylic acid (B) and an alcohol (C), (A) must be an ester.
(C) on dehydration gives but-1-ene. Dehydration of alcohols removes water to form alkenes. Therefore, (C) must be butan-1-ol.
Oxidation of (C) with chromic acid produces (B). Since (C) is butan-1-ol, its oxidation gives butanoic acid (B).
Thus, (A) is butyl butanoate formed from butanoic acid and butan-1-ol.
Reaction Equations:
1. Hydrolysis of ester (A): CH₃CH₂CH₂COOCH₂CH₂CH₂CH₃ + H₂O → CH₃CH₂CH₂COOH + CH₃CH₂CH₂CH₂OH (Butyl butanoate) (Butanoic acid) (Butan-1-ol)
2. Oxidation of alcohol (C): CH₃CH₂CH₂CH₂OH →[CrO₃-H₂SO₄] CH₃CH₂CH₂COOH (Butan-1-ol) (Butanoic acid)
3. Dehydration of alcohol (C): CH₃CH₂CH₂CH₂OH →[H₂SO₄, heat] CH₃CH₂CH=CH₂ + H₂O (Butan-1-ol) (But-1-ene)
Explanation
The question tests understanding of ester hydrolysis, alcohol oxidation, and dehydration reactions. The key deduction is that since oxidation of alcohol (C) gives the same carboxylic acid (B) obtained from hydrolysis, both (B) and (C) must have the same number of carbon atoms. Since (C) dehydrates to but-1-ene, it must be butan-1-ol. Therefore, (B) is butanoic acid and (A) is butyl butanoate. The context provides the oxidation reaction of butan-1-ol to butanoic acid using CrO₃-H₂SO₄ as reference.
Solution Steps
Step 1: Identify (A) as ester since hydrolysis gives carboxylic acid and alcohol
Step 2: Deduce (C) is butan-1-ol since dehydration gives but-1-ene
Step 3: Deduce (B) is butanoic acid since oxidation of butan-1-ol gives butanoic acid
Step 4: Identify (A) as butyl butanoate (ester of butanoic acid and butan-1-ol)
Step 5: Write balanced equations for all three reactions