Investigation of Acid-Catalytic Conversion of Carbohydrates in the Presence of Aliphatic Alcohols at Mild Temperatures
V. E. TARABANKO, M. A. SMIRNOVA and M. YU. CHERNYAK
Institute of Chemistry and Chemical Technology,
Siberian Branch of the Russian Academy of Sciences,
Ul. K. Marksa 42, Krasnoyarsk 660049 (Russia) E-mail: veta@icct.ru
Pages: 551-558
Abstract
The processes of fructose and saccharose conversion catalyzed by sodium hydrosulphate and sulphuric acid in biphase water-alcohol (from butanol to octanol) systems as well as in the homogeneous alcoholic media (ethanol, butanol) at 82-102oC have been studied. It has been demonstrated by GLC-MS and 13C and 1H NMR spectroscopy methods that the main products of conversion of carbohydrates are ethers and esters of 5-hydroxymethyl furfurol and levulic acid, respectively. The total yield of ethers ranges up to 80-90 mol. %. The yield of ethers drops as the concentration of carbohydrates increases. At high concentrations of substrate, the maximum selectivity of acid-catalytic conversion of fructose declines in the following succession: biphase system (water-alcohol) - homogeneous aqueous medium - homogeneous butanol solution. An increase of alcohol molecular weight causes its alkylating capacity in the studied processes to decrease. The results arrived at demonstrate that the combination of alkylation and extraction processes with the removing of the reaction products from the catalytically active aqueous phase in alcohol-water biphase systems makes it possible to increase the yield of the desired products of the process.
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