Butanediol, also called butylene glycol, may refer to any one of four stable structural isomers:

• 1,2-Butanediol
• 1,3-Butanediol
• 1,4-Butanediol
• 2,3-Butanediol

Geminal diols

There are also two geminal diols (gem-diols), which are less stable:

• 1,1-Butanediol,^[1] hydrate of butanal
• 2,2-Butanediol,^[2] hydrate of butanone

Isobutylene glycol and methylpropanediol

Isobutylene glycol may be considered a kind of butylene glycol, similarly to butane historically including n-butane and isobutane. The modern name for the closely related type of compounds is methylpropanediol. There are two stable structural isomers:

• 2-methylpropane-1,2-diol
• 2-methylpropane-1,3-diol

and one unstable geminal diol:

• 2-methylpropane-1,1-diol (not a glycol)

These three methylpropanediols are structural isomers of butanediols. They are not chiral.

Examples

2-Methylpropane-1,3-diol derivatives:

• Crisnatol, an experimental medication
• 2-Methyl-2-propyl-1,3-propanediol, medication precursor and active metabolite