Patent ID: 9174918
Filing Date: 2015-11-03
Classification: C07C,C08G

Abstract:
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.