Issue 6, 2013

Sorbitol dehydration into isosorbide in a molten salt hydrate medium

Abstract

The sorbitol conversion in a molten salt hydrate medium (ZnCl2; 70 wt% in water) was studied. Dehydration is the main reaction, initially 1,4- and 3,6-anhydrosorbitol are the main products that are subsequently converted into isosorbide; two other anhydrohexitols, (1,5- and 2,5-), formed are in less amounts and do not undergo further dehydration. Besides dehydration, depending on the temperature, sorbitol was partly epimerized into galactitol, which was further converted to anhydrohexitols or di-anhydrohexitols (mainly isoidide). Epimerization of galactitol into sorbitol was not observed. Temperature (150 to 220 °C) is a crucial factor; at low temperature the reaction rate is low but the selectivity is high, at elevated temperature (over 200 °C) the rate is high but extensive amounts of byproducts were produced. At the optimal temperature range, without using any co-catalysts, full conversion is achieved, and the isosorbide percent yield is above 85% on a molar basis; (1,5- and 2,5-) anhydrohexitols are the major byproducts. The sorbitol conversion reaction pathway has been investigated.

Graphical abstract: Sorbitol dehydration into isosorbide in a molten salt hydrate medium

Article information

Article type
Paper
Submitted
22 Nov 2012
Accepted
06 Mar 2013
First published
06 Mar 2013
This article is Open Access
Creative Commons BY license

Catal. Sci. Technol., 2013,3, 1540-1546

Sorbitol dehydration into isosorbide in a molten salt hydrate medium

J. Li, A. Spina, J. A. Moulijn and M. Makkee, Catal. Sci. Technol., 2013, 3, 1540 DOI: 10.1039/C3CY20809E

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