Question

What is a cyclic acetal?

Answer 1

A cyclic acetal is an acetal in which the acetal carbon and one or both oxygen atoms are members of a ring.

Explanation:

An acetal is a compound that contains two ether groups on the same carbon atom.

If the two OH groups are part of a 1,2- or a 1,3-diol, the product is a cyclic acetal.

The video below describes how a cyclic acetal is formed from a diol.

The purple `color(purple)("O")` atom in the hemiacetal intermediate is held close to the hemiacetal carbon, so the intramolecular ring-closing reaction is fast.

Hence, cyclic acetals are more stable and easier to prepare than acyclic acetals.