Which of the following are

a. hemiacetals?

b. acetals?

c. hydrates?

Hemiacetals and acetals are formed by reacting a carbonyl compound with alcohol.

Aldehydes and ketones react with alcohol in the presence of an acid. The acid catalyst activates the carbonyl.

The oxygen of the carbonyl group forms a bond with proton making the carbonyl carbon more electrophilic. The oxygen atom of the alcohol reacts with the electrophilic centre forming hemiacetal. Hemiacetals contain an –OH group (hydroxyl group) and an –OR group (alkoxy group) attached to the same carbon atom.

Hemiacetals react with another alcohol molecule to form acetals in the same mechanism. Acetals contain two –OR groups attached to the same carbon.

Compounds formed by the reaction of carbonyl compounds with water are called hydrates, and the reaction is called hydrolysis.

Acids or bases catalyze it. The catalyst is used to activate the carbonyl compound.

Hydrates contain two –OH groups attached to the same carbon atoms. Therefore, hydrates are germinal diols.

Compound 1-

It contains a hydroxyl group and a methoxy group attached to the same carbon atom. Therefore, it is a hemiacetal.

Compound 2-

It contains two ethoxy groups attached to the same carbon atom. Therefore, it is an acetal.

Compound 3-

The compound contains two methoxy groups attached to the same carbon atom. Therefore, it is an acetal.

Compound 4-

It contains two hydroxyl groups attached to the same carbon atom. Therefore, it is a hydrate.

Compound 5-

The compound contains two methoxy groups attached to the same carbon atom. Therefore, it is an acetal.

Compound 6-

It contains two hydroxyl groups attached to the same carbon atom. Therefore, it is a hydrate.

Compound 7-

It contains a hydroxyl group and a methoxy group attached to the same carbon atom. Therefore, it is a hemiacetal.

Compound 8-

It contains a hydroxyl group and a methoxy group attached to the same carbon atom. Therefore, it is a hemiacetal.

Therefore, the acetals, hemiacetals and hydrates of the given compound can be given as follows:

a. Hemiacetals- Compounds 1, 7, 8

b. Acetals- Compounds 2, 3, 5

c. Hydrates- Compounds 4, 6