Answer
Which Will Form a Secondary Alcohol?
Excess Grignard reagent + ester → acidic workup
This reaction generally produces a tertiary alcohol.
Mechanism:
- Grignard reagent adds to the ester to form a ketone intermediate.
- Excess Grignard attacks again, forming a tertiary alcohol after acidic workup.
❌ Does NOT yield a secondary alcohol.
Organolithium reagent + ketone → acidic workup
Organolithium reagents are highly reactive and add to ketones forming a tertiary alcohol.
❌ Produces a tertiary alcohol, not secondary.
Ethyl Grignard reagent + aldehyde → acidic workup
This forms a secondary alcohol.
Mechanism:
- Ethyl Grignard attacks the electrophilic carbon of the aldehyde.
- After protonation in acidic workup, a secondary alcohol forms.
✅ This is a correct method for forming a secondary alcohol.
Ketone + sodium borohydride (NaBH₄)
This also yields a secondary alcohol.
Mechanism:
- NaBH₄ reduces ketones to secondary alcohols by hydride transfer.
✅ This is also correct for forming a secondary alcohol.
Correct Answer: Two of these
✔ The correct options that form a secondary alcohol are:
- Ethyl Grignard reagent + aldehyde → secondary alcohol
- Ketone + NaBH₄ → secondary alcohol
✅ Final Answer: Two of these