Question

Which of the following on reaction with Grignard's reagent followed by hydrolysis forms tertiary alcohol ?

• A. \(\text{HCHO}\)
• B. \(\text{CH}_3\text{CHO}\)
• C. \(\text{CH}_3\text{-CH}_2\text{-CHO}\)
• D. \(\text{CH}_3-\text{CO}-\text{CH}_3\)

Hint:

Only a ketone gives a tertiary alcohol; HCHO gives primary and other aldehydes give secondary.

Answer 1

The Correct Option is D

Step 1: Count the groups on the carbinol carbon:
The new alcohol carbon is the old carbonyl carbon plus the R group from the Grignard reagent.

Step 2: Apply:
HCHO has two H on carbonyl C, so the product has 1 carbon neighbour: primary. An aldehyde RCHO has one H and one R, so the product has 2 carbon neighbours: secondary. A ketone has two R groups, so the product has 3 carbon neighbours: tertiary.

Step 3: Pick:
Among the choices only $\text{CH}_3\text{COCH}_3$ is a ketone.

Final Answer:
Option (D) acetone is the answer. \[ \boxed{\text{CH}_3\text{COCH}_3 \text{ (D)}} \]