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 i n water showed how the emulsification can change both the reaction rates, t he yields and the distribution of the products, namely sucrose monoethers, sucrose diethers, polysubstituted and oligomerisation products. The yield o f sucrose ethers can thus be increased to the detriment of hydrolysis and o ligomerisation reactions. From the results of the kinetic monitoring, we su ggested 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 autocat alysis. Macroscopic progressions of the mixtures, from emulsion stages to l iquid crystals stages, are also described. (C) 2000 Elsevier Science B.V. A ll rights reserved.