Facile and direct synthesis of symmetrical acid anhydrides using a newly prepared powerful and efficient mixed reagent

Abstract

An efficient mixed reagent for direct synthesis of symmetrical carboxylic anhydrides from carboxylic acids has been prepared. Carboxylic acids are converted to anhydrides using triphenylphosphine/trichloroisocyanuric acid under mild reaction conditions at room temperature. Short reaction time, excellent yields of products, low cost, availability of reagents, simple experimental procedure, and easy work-up of the products are the main advantages of the presented method.

A Facile Synthetic Method for Anhydride from Carboxylic Acid with the Promotion of Triphenylphosphine Oxide and Oxaloyl Chloride

“…Anhydrides of aromatic carboxylic acids are usually prepared by rereaction of powerful acylating agents (e.g., acyl chloride) with sodium salts of the same or another carboxylic acid or by treating acyl chloride with pyridine and decomposing the reaction mixture with water . They can also be prepared by a dehydration coupling reaction of carboxylic acid, using reagents (also through dehydrating agents) such as oxalyl chloride, , thionyl chloride, triphosgene, phosphorus pentoxide, trichloroisocyanuric acid combined with triphenylphosphine, dicyclohexylcarbodiimide, , or ethoxyacetylene. , However, when using these reagent systems for the preparation of carboxylic anhydrides, there are certain disadvantages in limiting their application: high costs, low yields, harsh reaction conditions, instability, toxicity, and unwanted side effects during the preactivation of carboxylic acid. The search for a gentle and effective coupling system is therefore particularly important for the further development of synthetic carboxylic anhydrides.…”