Crystal structures and thermotropic properties of alkyl alpha-D-glucopyranoside and their hydrates

Thermotropic properties and crystal structures of alkyl alpha-D-glucopyrano sides and their hydrates were estimated by X-ray, DSC and thermogravimetric measurements (TGA). Monohydrates rapidly lose their crystal water several degrees below the melting point of the anhydrous glucopyranosides. The melt ing points of the monohydrates measured in DSC pressure cells (chain length longer than seven) are lower, and the clearing points higher than those of the anhydrous glucosides. Layer distances of smectic and crystalline phase s of anhydrous compounds were established. Melting points, densities and la yer distances of the crystalline anhydrous glucopyranosides display strong even-odd effects. The strong decrease of these effects in the case of the m onohydrates can be elucidated by the results of X-ray crystal structure ana lysis. (C) 2000 Elsevier Science Ltd. All rights reserved.