GB915578A - Process for the production of esters of sugars, hexitols and anhydro-sugars - Google Patents

Abstract

A fatty acid ester or partial ester, or a mixed ester, of a sugar, hexitol or anhydrosugar is made by subjecting a fatty acid ester in which the acid radical contains from 12 to 30 carbon atoms and the alcohol residue contains from 1 to 3 carbon atoms, or a mixture of such esters, to alcoholysis with the sugar, hexitol or anhydro-sugar, in the presence of an alcoholysis catalyst in a liquid reaction medium inert under the reaction conditions and of such a kind and present in such quantity that the catalyst, and the sugar, hexitol or anhydro-sugar, are soluble, but the fatty acid ester or mixture of fatty acid esters is substantially insoluble, and intimately contacting the phases of the reaction mixture, in a thin film, under conditions such that there is rapid evaporation of the alcohol liberated in the reaction. The preferred solvents are dialkyl sulphoxides having not more than 3 carbon atoms in the alkyl groups, e.g. dimethyl sulphoxide. Sucrose, sorbitol, mannitol, dulcitol and sorbitan are suitable starting materials. The intimate contacting may be effected by maintaining vigorous turbulence of the solid and liquid phases during the reaction. The reaction may be effected in a thin-film type evaporator, such as a cyclone evaporator, a rotary film evaporator, or a calandria type of heater in which the reaction mixture is thrown across the surface of the upper part of the flask as a thin film of the mixed phases. Mixing pumps, turbo dispersers or other mixing devices may also be used in combination with means which provide a thin film of the temporarily mixed phases. Examples describe the reaction of sucrose with methyl stearate or palmitate in dimethyl sulphoxide in the presence of potassium carbonate, the reaction being carried out in a cycle evaporator fitted with a column and take-off head.