1. An organic compound formed by the addition of an alcohol to an aldehyde, containing both a hydroxyl group and an ether linkage on the same carbon atom.
Usage: chemistry; organic chemistry term

Examples

• Glucose exists in solution as an equilibrium mixture of its open-chain aldehyde form and its cyclic hemiacetal form.
• The hemiacetal intermediate is a key step in the formation of acetals from aldehydes and alcohols.
• In carbohydrate chemistry, hemiacetals are crucial structures found in monosaccharides.
• The hemiacetal carbon is typically more reactive than a simple ether carbon.
• Formation of a hemiacetal requires both an aldehyde group and an alcohol functional group.