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: