4. (a) A nitrile is a useful functional group that can be turned into a variety of carbonyls.

One common reaction is the hydrolysis of nitriles to carboxylic acids. We all learned this

reaction in our previous courses. Provide an arrow-pushing mechanism for this

transformation.

-CN

H₂O+

OH

(b) Using your mechanism from above as a guide, extrapolate the mechanism to explain

the transformation below. Provide a mechanism that converts a nitrile into a lactone.

S

CN

H₂O*

A

OH

(c) Using a similar mechanism, a nitrile can react with an alkene under acidic conditions

to form an amide. Provide an arrow pushing mechanism for this transformation. Hint: the

alkene reacts with acid first.

CH₂CN, H₂O*