An
alkyl is a
univalent radical consisting of
carbon and
hydrogen atoms, arranged in a chain. The alkyls form a
homologous series with the general formula C
nH
2n+1. They include
methyl, CH
3· (named after
methane),
ethyl (C
2H
5·),
propyl (C
3H
7·),
butyl (C
4H
9·),
pentyl (C
5H
11·), and so on. They are usually constituents of larger molecules, but when occurring independently, they are known as "
free radicals" and are very reactive.
The structure of an alkyl is like that of its alkane counterpart, but with one less hydrogen atom. For example, this is the structure of methyl, the smallest alkyl
A secondary alkyl group is branched with the central carbon atom linked to two carbon residues. Likewise, in tertiary alkyl groups, there are three carbon-linked substituents. In neopentane, the central carbon atom is quaternary.
Unbonded alkyls are free radicals, therefore they are formed only as instantaneous intermediates in reactions usually involving other free radicals. When a free radical is formed it very quickly reacts with something else to lose the unpaired electron.
