Question

Draw the products of each reaction.

a.

b.

Short answer

a.

b.

Step-by-step solution

Acetal Hydrolysis

Acetal is hydrolyzed via two-step mechanism, the acetal is converted to a hemiacetal and later into a carbonyl compound.

Consider the hydrolysis of the given acetals

a. The open acetal is converted to a hemiacetal by the nucleophilic addition of a water molecule and removal of one molecule of methanol. Later another molecule of methanol is removed forming the C-O bond. Deprotonation of the resonance stabilized carbocation would give the required carbonyl compound.

Formation of products in reaction a

b. The cyclic acetal undergoes nucleophilic attack by the water molecule in the acidic medium to form the corresponding gem-1,2-diol and carbonyl compound.

Formation of Products in reaction b