Question

A $ \beta $ - hydroxy carbonyl compound is obtained by the action of $ NaOH $ on

• A. $ R_{3}CCHO $
• B. $ C_{6}H_{5}CHO $
• C. $ CH_{3}CHO $
• D. $ HCHO $

Answer 1

Answer: (C)

$\beta$-hydroxy carbonyl compound is obtained by the action of $NaOH$ on $CH_{3}CHO$ as follows:
$\underset{\text{Acetaldehyde}}{{CH_{3}CHO}}+CH_{3}CHO \xrightarrow{Dil. NaOH }$

Mechanism
Step-I Formation of enolate ion

Step-II Attack of enolate ion on carbonyl group of second molecule of acetaldehyde

Step-III Anion (I) abstracts a hydrogen from water to form $\beta$-hydroxy, carbonyl compound