Process for preparing diaryl oxalate

摘要

Disclosed is a process for preparing a diaryl oxalate which comprises the step of transesterifying a dialkyl oxalate or/and an alkylaryl oxalate with an aryl alcohol in the presence of a tetra(aryloxy)titanium as a catalyst, wherein the tetra(aryloxy)titanium is fed into a reaction system of the transesterification as an aryl alcohol solution of the tetra(aryloxy)titanium which is prepared by reacting a tetraalkoxy titanium and an excess amount of the aryl alcohol and removing a by-producing alkyl alcohol.

主权项

1. A process for preparing a diaryl oxalate which comprises steps of:
reacting a tetraalkoxy titanium and an excess amount of an aryl alcohol and removing a by-producing alkyl alcohol to obtain an aryl alcohol solution of a tetra(aryloxy)titanium; thereafter feeding the obtained aryl alcohol solution of a tetra(aryloxy)titanium in a reaction system of transesterification as a catalyst of the transesterification; transesterifying, in the reaction system, an alkylaryl oxalate with an aryl alcohol in the presence of the catalyst to prepare the diaryl oxalate; and making a concentration of a titanium compound of a reaction mixture containing the diaryl oxalate 10 ppm by weight or less, and then, purifying by distillation, in order to obtain a diaryl oxalate with 500 ppm or less benzofuran-2,3-diones as a coloring component, wherein a material of an apparatus contacting with a reaction solution of the transesterification is an austenitic stainless steel containing 10% by weight or more of nickel and 1 to 4% by weight of molybdenum, or containing 16.00 to 18.00% by weight of chromium; and wherein the material of an apparatus is an austenitic stainless steel substantially not containing a nitrogen atom.