PROCESS FOR THE PREPARATION OF P-PHENYLENEDIAMINE

摘要

1399406 p-Phenylene diamine AKZO NV 30 March 1973 [1 April 1972] 15439/73 Heading C2C p-Phenylene diamine is prepared by a process in which one or more polyesters of terephthalic acid are reacted in a first stage of the process with ammonia which contains not more than 15% by weight of water and the resulting terephthalic acid diamide is then subjected to Hofmann degradation in a second stage of the process. Ammonolyers of terephthalic acid polyesters is preferably carried out either in the liquid or in the gas phase at 50‹ to 300‹ C. and at ammonia pressures ranging from normal pressure to 300 atmospheres. Preferably ammonia which has a water content of not more than 5% by weight is used. Advantageously the Hofmann degradation is carried out using aqueous reaction mixtures at concentrations of the diamide of 3 to 5% by weight.