The preparation of 2,3,3',4'-biphenyl tetracarboxylic dianhydride is as follows:In a 1000 ml three-necked flask, 18.3 g (0.1 mol) of 4-chlorophthalic anhydride and 18.3 g (0.1 mol) were added 3-chlorophthalic anhydride, 300 g of anisole as solvent, 0.13 g (0.001 mol) of nickel chloride as a catalyst, 0.198 g (0.001 mol) of C-1 as a catalyst ligand, and 0.03 g (0.0003 mol) of sodium bromide as a catalyst Auxiliary, 13 g (0.2 mol) of zinc powder was used as a reducing agent, and the reaction was stirred at 30 ° C for 8 hours under a nitrogen atmosphere. The reaction solution was filtered to remove insoluble solids in the reaction liquid. 300 g of methanol was added to the filtration mother liquor, and the product was precipitated, filtered, and dried to obtain 25.8 g of the product 2,3,3',4'-biphenyltetracarboxylic dianhydride, yield 87.7%.
