Pyrolysis of Aryl Azides. VII* Interpretation of Hammett Correlations of Rates of Pyrolysis of Substituted 2-Nitroazidobenzenes
Pyrolysis of Aryl Azides. VII* Interpretation of Hammett Correlations of Rates of Pyrolysis of Substituted 2-Nitroazidobenzenes
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芳基叠氮化物的热解。
DOI：
10.1071/ch9860089
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
L. K. Dyall
中科院分区：
文献类型：
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作者：
L. K. Dyall
测定了10种含4或5个取代基的2-硝基叠氮苯的热解速率和产物。在100°下的速率数据与4-或5-取代基的Hammett常数相关，对于叠氮基（A）和硝基（N）反应中心，得到方程logk = -3.23 + 1.20σ-/A-0.716 N.将该方程分解为σI和σR分量是有益的尝试。结果是一致的，其中离域的负电荷从最里面的叠氮基氮是重要的过渡态的电循环过程中，而取代基的硝基桥接的影响是不太重要的。对4-叠氮基-3-硝基吡啶、几种2，6-二硝基叠氮苯和2-叠氮苯甲酸甲酯的热解速率进行了解释。4-叠氮基-3-硝基吡啶的速率产生4-氮杂“取代基”的σ值为1.2。
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'.