Question

Which from following is a primary benzylic alcohol?

• A. \(\text{C}_6\text{H}_5\text{CH}_2\text{OH}\)
• B. \(\text{C}_6\text{H}_5-\text{CH}\langle _{\text{OH}}^{\text{CH}_3}\)
• C. \(\text{H}_2\text{C} = \text{CH}-\text{CH}\langle _{\text{OH}}^{\text{CH}_3}\)
• D. \(\text{H}_2\text{C} = \text{CH}-\text{CH}_2\text{OH}\)

Hint:

A benzylic alcohol has OH on a carbon attached to a benzene ring; primary means that carbon has only one other carbon.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
In a benzylic alcohol the \(-\text{OH}\) is on an \(sp^3\) carbon directly attached to an aromatic ring. It is primary if that carbon is bonded to only one other carbon (the ring).

Step 2: Check (A):
\(\text{C}_6\text{H}_5\text{CH}_2\text{OH}\) is benzyl alcohol. The carbinol carbon is attached to the ring, two H and OH, so it is primary and benzylic.

Step 3: Check (B):
\(\text{C}_6\text{H}_5\text{CH}(\text{OH})\text{CH}_3\) is benzylic but the carbinol carbon bonds to two carbons, so it is secondary.

Step 4: Check (C) and (D):
(C) is a secondary allylic alcohol. (D) is allyl alcohol, a primary allylic alcohol. Neither has a benzene ring, so they are not benzylic.

Final Answer:
Benzyl alcohol is the primary benzylic alcohol, option (A). \[ \boxed{\text{(A) } \text{C}_6\text{H}_5\text{CH}_2\text{OH}} \]