An aldehyde is an organic compound containing a terminal carbonyl group.This functional group, which consists of a carbon atom bonded to ahydrogen atom and double-bonded to an oxygen atom (chemical formulaO=CH-), is called the aldehyde group . The aldehyde group is also calledthe formyl or methanoyl group.
The word aldehyde seems to have arisen from al cohol dehyd rogenated .In the past, aldehydes were sometimes named after the correspondingalcohols, for example, vinous aldehyde for acetaldehyde. ( Vinous is fromLatin vinum = wine, the traditional source of ethanol; compare vinyl.)
The aldehyde group is polar. Oxygen, more electronegative than carbon,pulls the electrons in the carbon-oxygen bond towards itself, creating anelectron deficiency at the carbon atom.
Owing to resonance stabilization of the conjugate base, an Î±-hydrogen in analdehyde is more acidic than a hydrogen atom in an alkane, with a typicalpKa of 17.