High-energy phosphonium compounds were prepared by the oxidation of phosphorous acids and its esters with mercuric salts or halogens in pyridines, by a hydrolysis-dehydration reaction of diphenyl and triaryl phosphites or phosphonites with pyridines and also with metal salts, or by the reaction of phosphorus halides with tertiary amines. These salts are very reactive to nucleophiles, activating carboxyl, amino, or hydroxyl compounds via the corresponding phosphonium salts to yield carboxylic amides and esters in high yields on further aminolysis, alcoholysis, and acidolysis. These reactions, especially the hydrolysis-dehydration reactions with phosphites, were successfully extended to the direct polycondensation reaction of dicarboxylic acids with diamines, of free α-amino acids or dipeptides, and of carbon dioxide with diamines under mild conditions, yielding linear polymers of high molecular weight (polyamides, polypeptides, polyureas). Surprisingly high molecular weight was given by the reaction in the presence of polymer matrixes. The direct polyesterification of hydroxybenzoic acids and between dicarboxylic acids and bisphenols was achieved by the phosphonium salts derived from phosphorus halides such as hexachlorocyclotriphosphatriazene.
Dicarboxylic Acid Phosphorus Compound Polycondensation Reaction Phosphonium Salt Condensation Polymerization
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