Study of the competition between homogeneous and interfacial reactions during the synthesis of surfactant sucrose hydroxyalkyl ethers in water

The study of the heterogeneous reaction of sucrose with 1,2-epoxydodecane in water showed how the emulsification can change both the reaction rates, the yields and the distribution of the products, namely sucrose monoethers, sucrose diethers, polysubstituted and oligomerisation products. The yield of sucrose ethers can thus be increased to the detriment of hydrolysis and oligomerisation reactions. From the results of the kinetic monitoring, we suggested a model explaining the competition between the different reactions depending on their location in the microheterogeneous medium. The reaction is submitted to both a physicochemical autocatalysis and a chemical autocatalysis. Macroscopic progressions of the mixtures, from emulsion stages to liquid crystals stages, are also described. (C) 2000 Elsevier Science B.V. All rights reserved.