Superacids and their derivatives. X. Mechanistic studies of selective cyclodimerization of ethylene oxide by superacid ester catalysts

Abstract

Cyclodimerization of ethylene oxide (EO) to 1, 4-dioxane (DON) by using superacids and their derivatives as catalysts was examined. Results are discussed on the basis of the catalyst nature. Kinetic analyses were performed by monitoring the reaction with H- and F-NMR spectroscopy. The rate constant of initiation (ki) and the apparent one of propagation (kp) were obtained. The rate constant of propagation due to ester species (kpe) was evaluated from a model reaction. The EO consumption rate could not be explained by assuming only ester active species. It was found that in addition to the ester species oxonium active species was responsible for the EO consumption, even if they were not detected by 19F-NMR. A general scheme is presented and discussed. A model reaction of a “back-biting” process was also studied. © 1979, The Society of Polymer Science, Japan. All rights reserved.