Question

Compound A with molecular formula (C₂H₆O) on oxidation by PCC gives compound B, which on treatment with dilute alkali forms compound C (a β-hydroxy aldehyde). B on oxidation by potassium permanganate forms C.
Identify A, B, C and D and write all the chemical equations involved.

Hint:

- PCC is a mild oxidizing agent used for converting alcohols to aldehydes.
- Aldehydes without $\alpha$-substitution undergo aldol condensation in basic medium.
- KMnO\textsubscript{4} strongly oxidizes aldehydes to carboxylic acids.

Answer 1

Step 1: Compound A has formula C₂H₆O → Likely an alcohol.
A = Ethanol (CH₃CH₂OH)
Step 2: Oxidation by PCC (mild oxidizing agent) converts ethanol to aldehyde.
CH₃CH₂OH + [O] (PCC) → CH₃CHO (Acetaldehyde)
So, B = Acetaldehyde
Step 3: B reacts with dilute alkali to give $\alpha$-hydroxy aldehyde → Aldol reaction:
2 CH₃CHO + dil. NaOH → CH₃CH(OH)CH₂CHO
So, C = 3-Hydroxybutanal
Step 4: B on oxidation with KMnO₄ gives carboxylic acid:
CH₃CHO + [O] → CH₃COOH
So, D = Acetic acid Summary:
A = Ethanol
B = Acetaldehyde
C = 3-Hydroxybutanal
D = Acetic acid