Rates and products of pyrolysis have been obtained for ten 2- nitroazidobenzenes with 4- or 5-substituents. Rate data at 100° are correlated with Hammett constants of the 4- or 5-substituents, with respect to both the azido (A) and nitro (N) reaction centres, and yield the equation log k = -3.23 + 1.20σ-/A -0.716σN. Dissection of this equation into σI and σR components was usefully attempted. The results are consistent with an electrocyclic process in which delocalization of negative charge from the innermost azido nitrogen is important at the transition state, whereas substituent effects on bridging by nitro are less important. An interpretation is made of pyrolysis rates of 4-azido-3-nitropyridine, several 2,6- dinitroazidobenzenes, and methyl 2-azidobenzoate. The rate for 4-azido- 3-nitropyridine yields a σ- value of 1.2 for the 4-aza 'substituent'.
我们获得了十种带有 4 或 5 取代基的 2-硝基叠氮苯的热解速率和产物。100° 时的速率数据与叠氮(A)和硝基(N)反应中心的 4-或 5-取代基的哈米特常数相关,并得出 log k = -3.23 + 1.20σ-/A -0.716σN。我们尝试将该方程分解为 σI 和 σR 两部分,结果非常有用。结果与电环过程一致,在电环过程中,过渡态最内层叠氮氮的负电荷脱位非常重要,而取代基对硝基桥接的影响则不那么重要。本文对 4-叠氮-3-硝基吡啶、几种 2,6-二硝基苯和 2-叠氮苯甲酸甲酯的热解速率进行了解释。4-azido-3-nitropyridine 的分解率得出 4-aza 取代基的 σ- 值为 1.2。