SynopsisThe reaction of carbon dioxide with aniline using triphenyl phosphite in pyridine is greatly facilitated by the addition of hydrochlorides of tertiary amines such as pyridine and triethylamine, and has been successfully applied to the preparation of polyureas of high molecular weight from carbon dioxide and aromatic diamines. The presence of a catalytic amount of pyridine hydrochloride significantly increased the inherent viscosity of the resulting polymers, the highest value being obtained with about an equivalent of the chloride. Optimal temperatures and pressures varied with diamines used, and were M " C and 40-50 atm of carbon dioxide. The polycondensation reaction was also affected by the solvent compositions of pyridine and N-methylpyrrolidone, its optimum being dependent on diamines used.
Quaternary ammonium and pyridinium salts were found to facilitate the reaction of carboxylic acids and amines promoted by triphenyl phosphite, and the reaction was successfully applied to the direct polycondensation reaction of dicarboxylic acids and diamines. Among the salts tested, tetra ethylammonium chloride was most favorable. The reaction was extended to the direct polycondensa tion of amino acids in the presence of polyvinylpyrrolidone as a matrix: poly (ƒÀ-alanine) with high molecular weight was obtained in high yields, but polymers from a-amino acids could not be isolated due to the difficulty in separating the polymers from the polymer matrix.
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