Crystal and molecular structures of DL-methylsuccinic acid. I. A modification obtained by sublimation at 70°C in vacuo

The structure of the modification of DL-methylsuccinic acid [HOOC—CH₂—CH(CH₃)—COOH], obtained by sublimation at 70°C, has been determined from three-dimensional X-ray data. The crystals are monoclinic with a = 22.119, b = 5.230, c = 11.239 Å, β = 103.73%, Z = 8, space group C2/c. The structure was solved by direct methods and refined by block-diagonal least-squares methods to R = 0.060. The succinic acid skeleton of the molecule is bent. The molecules are linked into chains by centrosymmetric pairs of carboxyl groups.