RATES OF DECARBOXYLATION OF ACYLOXY RADICALS FORMED IN THE PHOTOCLEAVAGE OF SUBSTITUTED 1-NAPHTHYLMETHYL ALKANOATES
RATES OF DECARBOXYLATION OF ACYLOXY RADICALS FORMED IN THE PHOTOCLEAVAGE OF SUBSTITUTED 1-NAPHTHYLMETHYL ALKANOATES
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DOI：
10.1021/ja00007a049
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发表时间：
1991-03-27
影响因子：
15
通讯作者：
PINCOCK, JA
中科院分区：
文献类型：
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作者：
HILBORN, JW;PINCOCK, JA
对取代的1-萘甲基链烷酸酯6a-f光解形成的酰氧基自由基7a-f的脱羧速率（k（CO2）R）进行了估算。 这些速率是基于一个拟议的机制，涉及初始的碳-氧均裂键从激发单重态裂解。 产物通过两种竞争途径形成：自由基对中的电子转移以产生离子对和脱羧。 测量的产物产率沿着电子转移速率（k（ET））的估计值允许计算作为R的函数的k（CO2）R。 得到的值如下（R，k（10（9）s-1））：CH 3，< 1.3; CH 3CH 2，2.0;（CH 3）2CH，6.5;（CH 3）3C，11; PhCH 2，5.0; PhCH 2CH 2，2.3。
Rates of decarboxylation (k(CO2)R) have been estimated for the acyloxy radicals 7a-f formed in the photolysis of substituted 1-naphthylmethyl alkanoates 6a-f. These rates are based on a proposed mechanism involving initial carbon-oxygen homolytic bond cleavage from the excited singlet state. The products are formed by two competing pathways: electron transfer in the radical pair to give an ion pair and decarboxylation. Measured product yields along with an estimate of the electron-transfer rate (k(ET)) allow calculation of k(CO2)R as a function of R. The values obtained are the following (R, k (10(9) s-1)): CH3, < 1.3; CH3CH2, 2.0; (CH3)2CH, 6.5; (CH3)3C, 11; PhCH2, 5.0; PhCH2CH2, 2.3.