Butanediol, also called butylene glycol, may refer to any one of four stable structural isomers:
There are also two geminal diols (gem-diols), which are less stable:
Isobutylene glycol may be considered a kind of butylene glycol, similarly to butane historically including n-butane and i-butane (isobutane). The modern name for the closely related type of compounds is methylpropanediol. There are two stable structural isomers:
and one unstable geminal diol:
These three methylpropanediols are structural isomers of butanediols. They are not chiral.
2-Methylpropane-1,3-diol derivatives: