Patent ID: 6124443
Filing Date: 2000-09-26
Classification: C07B,C07C,C07H

Abstract:
A process for the preparation of epimer-free sugar alcohols selected from the group consisting of xylitol, sorbitol, 4-O-.beta.-D-galactopyranosyl-.alpha.-D-sorbitol and 4-O-.alpha.-D-glucopyranosyl-.alpha.-D-sorbitol by catalytic hydrogenation of the corresponding sugars D-xylose, .alpha.-D-glucose, 4-O-.beta.-D-galactopyranosyl-.alpha.-D-glucopyranose and 4-O-.alpha.-D-glucopyranosyl-.alpha.-D-glucopyranose, respectively, in aqueous solution with hydrogen under elevated pressure and at elevated temperature, which comprises carrying out the hydrogenation continuously at a hydrogen pressure of 100 to 400 bar, and temperatures of 20 to 70.degree. C., in the fixed-bed process in a reaction zone on shaped bodies which serve as hydrogenation catalysts and have a compressive strength of 20 to 220 N, and an internal surface area of 10 to 100 m.sup.2 /g made of(i) one or more elements of the iron subgroup of subgroup VIII of the Periodic Table of the Elements (Mendeleev) which is (are) additionally alloyed with(ii) activating elements of subgroup IV and/or subgroup V.