Butanol
Butanol (also called butyl alcohol) is a four-carbon alcohol with a formula of C4H9OH, which occurs in five isomeric structures (four structural isomers), from a straight-chain primary alcohol to a branched-chain tertiary alcohol; all are a butyl or isobutyl group linked to a hydroxyl group (sometimes represented as BuOH, sec-BuOH, i-BuOH, and t-BuOH). These are 1-butanol, two stereoisomers of sec-butyl alcohol, isobutanol and tert-butyl alcohol.