The crystal structure of galactaric acid (mucic acid) at −147°: An unusually dense, hydrogen-bonded structure

Abstract

Galactaric acid, C 6H 10O 8, (CAS Reg. No. 526-99-8), is triclinic, P 1 , with cell dimensions at −147° [and 20°], a = 4.900(1) [4.918(1)], b = 5.728(1) [5.816(1)], c = 6.784(1) [6.849(1)] Å, α = 92.32(2) [92.31(2)], β = 93.74(2) [94.16(2)], γ = 93.08(2) [93.49(2)]°, V = 189.5 Å 3, Z = 1, D x = 1.831 [1.800], D m = [1.790] g.cm −3, molecular symmetry I . The structure was solved by the direct method, MULTAN, and refined to R = 0.034, R w = 0.039 for 787 reflections with F Obs > 3σ(F obs). The crystal structure has a system of strong, intermolecular hydrogen-bonds, which accounts for the high crystal density and low solubility in water.