An aldehyde is a functional group characterized by an oxygen atom double bonded to a carbon atom at the end of a carbon chain, this carbon being bonded to just one other carbon atom:

(Where -R represents the carbon chain.)

Aldehyde names are formed by adding the suffix -al to the parent alkane, for example an aldehyde with 5 carbons is pentanal. Aldehydes can be produced by oxidation of primary alcohols. In the laboratory this may be achieved by heating the alcohol in an acidified solution of potassium dichromate, which is reduced to green Cr3+ during the reaction, or by the so called "Swern oxidation" ((CO)2Cl2 + (Me)2SO).

Examples of simple aldehydes:

Other aldehydes used in industry or everyday life: See also: Ketone