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Any of a class of organic compounds that contain a carbonyl group (CO; seefunctional group) in which the carbon atom is bonded to at least one hydrogen atom. Many have characteristic odours. Oxidation (seeoxidation-reduction) of aldehydes yields acids; reduction produces alcohols. They participate in many chemical reactions and readily undergo polymerization into chains containing tens of thousands of the monomer molecule. The combination of aldehydes (e.g., formaldehyde) with other molecules results in several familiar plastics. Many aldehydes are large-scale industrial materials, useful as solvents, monomers, perfume ingredients, and intermediates. Many sugars are aldehydes, as are several natural and synthetic hormones and compounds such as retinal (a derivative of vitamin A, important in vision) and pyridoxal phosphate (a form of vitamin B).
This entry comes from Encyclopædia Britannica Concise. For the full entry on aldehyde, visit Britannica.com.