A highly efficient synthesis reaction of carboxylic anhydrides catalyzed by triphenylphosphine oxide is described for the quick synthesis of a range of symmetric carboxylic anhydrides and cyclic anhydrides under mild and neutral conditions with a high yield. The system adopts the strong reactive intermediate Ph3PCl2 as the catalyst of carboxylic acid salt; driven by catalytic reaction, the synthesis takes a relatively short time to complete
