Rates of pyrolysis and bond energies of substituted organic iodides (Part I).
Rates of pyrolysis and bond energies of substituted organic iodides (Part I).
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DOI：
10.1039/tf9433900019
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发表时间：
1943-01-01
影响因子：
--
通讯作者：
Polanyi, M
中科院分区：
文献类型：
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作者：
Butler, ET;Polanyi, M
有许多证据表明，在相关有机化合物的反应性的广泛变化中，化学键的性质受到取代的极大影响，这似乎与基于热化学证据的键能的加和性规则相冲突，该规则假设给定种类的键的能量是常数。本研究的目的是通过观察取代对有机键强度的影响来澄清这种情况，这种影响表现在一系列有机碘化物的热解速率上。R. A. Ogg、Ogg和Polanyi用静态法研究了一些脂肪族碘化物的热解。在他们的条件下，分解的动力学是相当复杂的，我们从下面报告的我们自己的工作中得出结论，初级键断裂过程的速率RI= R+ I不能从他们的结果中正确地推导出来。Rice和约翰斯顿使用热解作为建立键能的一种手段，他们测量了几种有机化合物分解速率的温度系数，并计算了相应的活化能。他们使用了一种流动方法，在该方法中，允许在该过程中形成的自由基去除金属镜。我们使用了类似的装置来热解有机碘化物，同时通过形成的碘（在某些情况下还有碘化氢）的量来测量反应速率。流动法的优点有两个方面：通过长时间流动产生的产品积累，可以使用
There is much evidence of an indirect nature, in the wide variation in reactivity of related organic compounds, which suggests that the nature of a chemical bond is greatly influenced by substitution, This would seem to conflict with the additivity rule of Bond Energies based on thermo chemical evidence, which assumes that the energy of a given kind of bond is a constant. The present work was begun with the object of clarifying this situation by observing the effect of substitution on organic bond strength as manifested in the rates of pyrolysis of a series of organic iodides.*R. A. Ogg and Ogg and Polanyi have studied the pyrolysis of a number of aliphatic iodides by static meth0ds. l Under their conditions the kinetics of the decomposition are rather complex, and we have come to the conclusion from our own work reported below, that the rate of the primary bond breaking process RI= R+ I cannot be deduced correctly from their results. Pyrolysis as a means of establishing bond energies was used by Rice and Johnston who measured the temperature coefficients of the rates of decomposition of several organic compounds and calculated the corresponding activation energies. They used a flow method in which the free radicals formed during the process were allowed to remove metallic mirrors. We used a similar arrangement for pyrolysing organic iodides, while measuring the rate of reaction by the amount of iodine (and in certain cases the hydrogen iodide) formed. The advantages of the flow method are twofold: by the accumulation of the product resulting from an extended period of flow it is possible to use