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: Understanding the Concept:
A Grignard reagent adds to the carbonyl carbon. After hydrolysis, the type of alcohol depends on the carbonyl compound used.

Step 2: Key Rules:
Formaldehyde (HCHO) gives a primary alcohol. Any other aldehyde gives a secondary alcohol. A ketone gives a tertiary alcohol.

Step 3: Detailed Explanation:
Acetone, \(\text{CH}_3\text{COCH}_3\), reacts with, for instance, \(\text{CH}_3\text{MgBr}\):
\[ \text{CH}_3\text{COCH}_3 + \text{CH}_3\text{MgBr} \rightarrow (\text{CH}_3)_3\text{C-OMgBr} \xrightarrow{\text{H}_2\text{O}} (\text{CH}_3)_3\text{C-OH} \]
The product is tert-butyl alcohol, a tertiary alcohol, because the carbinol carbon has three alkyl groups.

Step 4: Why the other options are wrong.
HCHO (A) gives a primary alcohol. \(\text{CH}_3\text{CHO}\) (B) and \(\text{CH}_3\text{CH}_2\text{CHO}\) (C) are aldehydes and give secondary alcohols.

Final Answer:
Acetone gives a tertiary alcohol, option (D). \[ \boxed{\text{CH}_3\text{COCH}_3 \text{ (D)}} \]