CHEMICAL AND ELECTROCHEMICAL REDUCTION RATES OF CYCLIC NITROXIDES (NITROXYLS)
CHEMICAL AND ELECTROCHEMICAL REDUCTION RATES OF CYCLIC NITROXIDES (NITROXYLS)
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DOI：
10.1002/jps.2600800212
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发表时间：
1991-02-01
影响因子：
3.8
通讯作者：
SWARTZ, HM
中科院分区：
文献类型：
--
作者：
MORRIS, S;SOSNOVSKY, G;SWARTZ, HM
用抗坏血酸在均相条件下测定了含不同取代基的五元吡咯烷和吡咯啉以及六元哌啶氮氧化合物(又称硝基)在均相条件下的还原速率，并在非均相条件下用电化学方法测定了还原速率。将结果与文献中的数据进行了比较。结果表明，与五元氮氧化物相比，六元氮氧化物还原速率的提高不能用电化学势的差异来解释，而可以归因于氮氧化物基团可及性的差异。五元氮氧基中的双键提高了还原速率。在任何环系中，用抗坏血酸还原氮氧化物的速率可以与诱导取代基常数相关联。在基于同一环的一系列氮氧化物中，电化学还原的半程电位与使用抗坏血酸的速率的对数和诱导常数相关。氮氧化物的单电子氧化电势与诱导常数有关。
The reduction rates of five-membered pyrrolidine and pyrroline, and six-membered piperidine nitroxides (alternatively termed nitroxyls) containing various substituents were determined under homogeneous conditions using ascorbate, and electrochemically under heterogeneous conditions. The results were compared with data from the literature. It was shown that the increased rates of reduction of six-membered nitroxides, compared with those of the five-membered nitroxides, cannot be explained on the basis of differences in electrochemical potentials but, rather, can be ascribed to differences in the accessibility of the nitroxide group. A double bond in the five-membered nitroxyls increases the reduction rate. Within any ring system, the reduction rates of nitroxides using ascorbate can be correlated with the inductive substituent constants. The half-way potentials for electrochemical reduction within a series of nitroxides based on the same ring correlate with logarithms of the rates using ascorbate and with the inductive constants. The potentials for one-electron oxidation of the nitroxides were related to the inductive constants.