1-Pentanol, (or n-pentanol, pentan-1-ol), is an alcohol with five carbon atoms and the molecular formula C5H11OH. 1-Pentanol is a colorless liquid with an unpleasant aroma. It is the straight-chain form of amyl alcohol, one of 8 isomers with that formula. The hydroxyl group (OH) is the active site of many reactions. The ester formed from 1-pentanol and butyric acid is pentyl butyrate, which smells like apricot. The ester formed from 1-pentanol and acetic acid is amyl acetate (also called pentyl acetate), which smells like banana.