Synthesis of erythrulose from dihydroxyacetone and formaldehyde in the presence of zeolite-like zinc imidazolate frameworks

Abstract

Aldol condensation of formaldehyde with dihydroxyacetone (DHA) in an aqueous medium (pH 7.54–8.71) was studied at 65–80 °C in the presence of zeolite-like zinc imidazolate frameworks based on 2-methylimidazole (ZIF-8) and 2-ethylimidazole (MAF-5 and MAF-6). Selectivity of the process was shown to depend on the pH of the reaction solution, which is controlled by the amount of catalyst in the reaction mixture, and on the reaction temperature. The reaction carried out at pH 8.36 and 80 °C leads to a high yield of С6-sugars. Erythrulose is formed with a high yield (39–60 %) at a temperature of 65 °C and pH 7.54-8.71. It was found that the yield of erythrulose in the presence of the catalytic systems under consideration depends on the pore radius and increases in the series MAF-6 > MAF-5 > ZIF-8. Advantages of the studied systems in comparison with the homogeneous and heterogeneous phosphate systems proposed in the literature were revealed.