STRUCTURE OF BETA,BETA-TREHALOSE

The structure of beta,beta-trehalose (beta-D-glucopyranosyl beta-D-glucopyranoside) tetrahydrate, C12H22O11.4H2O, is described. The molecule, unlike its alpha,alpha-isomer, has exact twofold symmetry through the O(1) atom. The two glucopyranosyl residues adopt a slightly distorted chair C-4(1) conformation, as defined by the Cremer & Pople puckering parameters, Q = 0.567, q2 = 0.067, q3 = 0.563 angstrom, theta = 6.8-degrees and phi2 = 159.4-degrees. The packing of the crystal is determined by a complex system of hydrogen bonds, each hydroxyl group of the sugar forming two hydrogen bonds and each water molecule forming four hydrogen bonds. The ring and the glycosidic O atoms are, however, not involved in any hydrogen bonding,