Geminal diol

The generic geminal diol. The 'R's represent any groups other than OH.

A geminal diol (or gem-diol for short) is any organic compound having two hydroxyl functional groups (-OH) bound to the same carbon atom. Geminal diols are a subclass of the diols, which in turn are a special class of alcohols. Most of the geminal diols are considered unstable.

The simplest geminal diol is methanediol CH
4
O
2
or H
2
C(OH)
2
. Other examples are: