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Crystal structures of methyl 6-O-acyl-α-d-galactopyranosides

✍ Scribed by Yutaka Abe; Masami Fujiwara; Kazuo Ohbu; Kazuaki Harata

Publisher
Elsevier Science
Year
1995
Tongue
English
Weight
355 KB
Volume
275
Category
Article
ISSN
0008-6215

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✦ Synopsis

The crystal structures of methyl 6-O-n-octanoyl-a-o-galactopyranoside (1) and methyl 6-O-ndecanoyl-a-D-galactopyranoside (2) were investigated by X-ray analysis. Anhydrous crystals obtained from methanol solution by slow evaporation are monoclinic, and the space group is P21 with Z = 2. The cell dimensions are as follows, 1: a = 5.774(1), b = 8.013(1), c = 19.183(1) A, /3 = 98.50(1)°; 2: a = 5.762(1), b = 8.003(1), c = 21.227(2) ,~, /3 = 93.93(1) °. The galactopyranoside ring is nearly in a 4C 1 chair conformation but slightly distorted to twist boat and the alkyl chain is in all-trans conformation. In these crystals, molecules are arranged in a bilayer structure with interdigitated alkyl chains. The hydrogen bonding linkages between sugar moieties, which are found only between the layers, form an infinite chain through the crystal. 1 and 2 show higher melting points than those of corresponding /3-o-glucopyranosides. The results indicate the important role of the sugar in the crystal.

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