Patent ID: 7674920
Filing Date: 2010-03-09
Classification: C07D,C08G

Abstract:
1. A method for preparing an oxydiphthalic anhydride which comprises contacting, under reactive and substantially anhydrous conditions in a reactor, at least one chlorophthalic anhydride containing more than 250 ppm chlorophthalide impurity, based on the chlorophthalic anhydride, with a carbonate of the formula M 2 CO 3 , wherein M is an alkali metal, in the presence of a catalytic proportion of at least one phase transfer catalyst selected from the group consisting of hexaalkylguanidinium halides and alpha,omega-bis(pentaalkylguanidinium)alkane salts, phosphonium salts, pyridinium salts, phosphazenium salts, ammonium salts, and combinations thereof; wherein the phase transfer catalyst is present in a sufficient amount to prepare the oxydiphthalic anhydride when the chlorophthalide is present in an amount that is more than 1000 ppm; and the oxydiphthalic anhydride is produced in a yield, based on the carbonate, of at least 70%.