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. $C{H}_{3}CHO$
• D. $HCHO$

Answer 1

Answer: (C)

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

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