rac-Hy-droxy-isovaleric acid.

The title compound (systematic name: rac-2-hydroxy-3-methylbutanoic acid), C5H10O3, is the constitutional isomer of α-hy-droxy-butanoic acid. In the crystal, hydrogen bonds involving the alcoholic hydroxyl group give rise to centrosymmetric dimers that are extended to sheets perpendicular to the crystallographic c axis.