Question

Draw the mechanism for the addition of methylmagnesium bromide to propanoyl chloride (CH3CH2COCl) to give 2-methyl-2-butanol.

Answer 1

Reaction mechanism has been shown below

Step-by-step explanation:

It is an example of nucleophilic acyl substituion reaction followed by nucleophilic addition reaction by methylmagnesium bromide.

This reaction is possible in presence of excess methyl magnesium bromide.

Here methyl group from methyl magnesium bromide first replaces Cl by nucleophilic acyl substitution through addition-ellimination mechanism. Then methyl group of methyl magnesium bromide adds onto carbonyl group through nucleophlic addition. Lastly, work up of product mixture yields 2-methyl-2-butanol.

Full mechanism has been shown below.