Reactions of phenyl isocyanate with 12 monosubstituted and 15 symmetrical disubstituted 1,3-diphenyltriazanes have been studied in tetrahydrofurane at 25°C. The found rate constants correlate with the Hammett substituent constants, the slopes being - 1.206 and - 1.682 in case of the monosubstituted and the disubstituted compounds, respectively. Under conditions of pseudomonomolecular reaction catalysis by the products and that by the catalysts used in reactions of isocyanates with amines or hydroxy compounds have not been observed. Rates of reactions of 6 substituted phenyl isocyanates with the parent 1,3-diphenyltriazane have also been measured. In this case the found rate constants correlate with the Hammett substituent constants, the slope being +1.038. The results indicate that the reaction involves rate limiting formation of a six-membered cyclic complex which successively undergoes only a rapid reorganization of electrons.
苯基
异氰酸酯与12种单取代和15种对称双取代的1,3-二苯基三氮烷在25°C下在
四氢呋喃中的反应已经研究。发现的速率常数与Hammett取代基常数相关,单取代化合物和双取代化合物的斜率分别为-1.206和-1.682。在伪单分子反应催化条件下,观察到了由产物和
异氰酸酯与胺或羟基化合物反应中使用的催化剂引起的反应。还测量了6种取代苯基
异氰酸酯与母体1,3-二苯基三氮烷的反应速率。在这种情况下,发现的速率常数与Hammett取代基常数相关,斜率为+1.038。结果表明,反应涉及限速形成一个六元环复合物,该复合物随后仅经历电子的快速
重组。