Diols where the hydroxyl groups are separated by several carbon centers are generally prepared by hydrogenation of diesters of the corresponding dicarboxylic acids:
: (CH)(COR)  +  4 H   →   (CH)(CHOH)  +  2 HO  +  2 ROH
1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,10-decanediol are important precursors to polyurethanes.