Question

Draw the products of each reaction.

a.

b.

Short answer

a.

b.

Step-by-step solution

Formation of cyclic hemiacetals 

An acid, as well as a base, catalyzes the formation of a cyclic hemiacetal. Hydroxy aldehydes get subjected to intramolecular cyclization leading to the creation of cyclic hemiacetal.

Conversion of hemiacetal to acetal

The conversion of cyclic hemiacetals to acetals happens on the reaction of the particular hemiacetal with alcohol in the presence of an acid. The OH group is converted to the OR group in this particular reaction.

Predicting the products formed in each reaction

a. The given cyclic hemiacetal can be converted to acetal by reacting it with alcohol in the presence of an acid. The hydroxyl group of the hemiacetal gets converted to the alkoxy group. The reaction can be given as:

Products formed in reaction a

b. The conversion of cyclic hemiacetal to acetal can take place with the help of alcohol in the presence of an acid. The acetal formed in the reaction has an alkoxy group in place of the hydroxyl group that was present in the reactant. The reaction can be given as:

Products formed in reaction b