Di-alcohol (divalent alcohol) are named glycol, which is a derivate from ethylene-glycol. These glycol are used for anti-freezing or frost-protection agents reducing the freezing temperature of other substances (e.g. water) considerably.
Well-known is the application as addition for cooling or windscreen washer systems. A famous brand name under the frost protection agents is Glysantine, an existing trademark of BASF since 1929.