Illustrated Glossary of Organic Chemistry

Acetal: A functional group in which carbon is attached by single bonds to two ether oxygen and two carbons (or hydrogens). A thioacetal has two sulfur atoms in place of an acetal's two oxygen atoms.

This disaccharide contains both an acetal moiety (C-O-C-O-C) and a hemiacetal moiety (C-O-C-O-H).

Molecular structure of 1,4-dithiaspiro[4.5]decane, a typical thioacetal.