1. Organic compounds formed by the addition of an alcohol to an aldehyde or ketone, containing both a hydroxyl group and an ether linkage on the same carbon atom.
Usage: chemistry; plural form of hemiacetal; intermediate compounds in organic synthesis

Examples

• Hemiacetals are unstable intermediates that can easily convert to acetals under acidic conditions.
• The formation of hemiacetals is a key step in carbohydrate chemistry.
• Glucose exists in equilibrium between its open-chain aldehyde form and cyclic hemiacetals.
• Hemiacetals contain both a hydroxyl group and an ether functional group on the same carbon.
• In the laboratory, hemiacetals are often used as intermediates in the synthesis of more complex organic molecules.