[Rus450]

There is a question in my textbook asking for the reaction conditions required to convert methyl propanoate to 4-ethyl-4-heptanol. The answer key states that using propylmagnesium bromide in ethoxide with acid workup will yield the desired product. However, this does not make sense to me. Where is the extra carbon coming from on the carbonyl side of the molecule and why is there an ethyl group where the carbonyl was and not a propyl?

[Aldebaran]

This looks to me like a fairly standard Grignard reaction with an ester. You finish up with A tertiary alcohol R and R2 and R2 attached to the original carbonyl carbon atom along with the hydroxyl group. In this case R is the ethyl R2 being the propyl groups and R1 would be the methyl group which leaves. I think you should be able to find the mechanism if you search on Grignard with esters.

[hollytara]

Remember the ester can react with 2 equivalents of Grignard.