REACTION-KINETICS OF ETHOXYLATION

Ethoxylation of beta-phenylethyl alcohol and gamma-phenylpropyl alcoho l as model compounds in the presence of SbCl5 catalyst was investigate d in order to determine the kinetics of a consecutive-competitive mult istep reaction. The reaction was carried out in different solvents (di glyme, 1-4-dioxane and toluene) and at various temperatures. The molar -mass distributions of the reaction mixtures were analysed by means of HPLC. Results revealed first kinetic order in the source alcohols and second order in the catalyst. In diglyme and dioxane induction period s were observed, while in toluene the reaction set in immediately. The different behaviour of the solvents is explained by the different sol vent-catalyst complex stability. The high order in catalyst suggests a n intermediate with more than one Sb atom. The building-up of such a c omplex could justify the existence of the induction period as well. In addition activation enthalpies were estimated from the temperature de pendence of the velocity constants.