1,3-Butanediol is an organic compound with the formula CH3CH(OH)CH2CH2OH, not to be confused with 1,4 Butanediol. With two alcohol functional groups, the molecule is classified as a diol. The compound without the R (or D) designation is racemic, which is what has been used in most studies before 2023. The compound is a colorless, bittersweet, water-soluble liquid. It is one of four common structural isomers of butanediol. It is used in grape flavoring, and as a precursor to some antibiotics.