ALKANOLYSIS OF POLYETHER POLYOLESTER BY REACTIVE DISTILLATION

摘要

A method for converting the diester of a polyether polyol (e.g., the diacetate ester of polytetramethylene ether, PTMEA) to a corresponding dihydroxy polyether polyol (e.g., polytetramethylene ether glycol, PTMEG) involving reactive distillation wherein a diester of polyether polyol is fed to the top portion of the column along with an effective amount of at least one alkali metal oxide or alkaline earth metal oxide, hydroxide or alkoxide catalyst (e.g., sodium methoxide) and with a C1 to C4 alkanol (e.g., methanol) while simultaneously adding to the bottom of the reactive distillation column hot alkanol vapor to sweep any alkanol ester formed by alkanolysis of the diester of polyether polyol upwardly. Such a process is useful for achieving high levels of conversion PTMEA to PTMEG on a commercial scale with the overhead from the column being amenable to azeotropic separation of the methyl acetate and recycle of the methanol.