EXTINCTION COEFFICIENT AND RECOMBINATION RATE OF BENZYL RADICALS .1. PHOTOLYSIS OF SODIUM PHENYLACETATE
EXTINCTION COEFFICIENT AND RECOMBINATION RATE OF BENZYL RADICALS .1. PHOTOLYSIS OF SODIUM PHENYLACETATE
复制标题
DOI：
10.1021/ja00778a008
复制
发表时间：
1972-01-01
影响因子：
15
通讯作者：
MILLER, SI
中科院分区：
文献类型：
--
作者：
MEIGGS, TO;GROSSWEI.LI;MILLER, SI
苯乙酸钠在甲醇中于26 ℃光解，得到下列产物（Ⅰ）：在无氧条件下，C_6H_5CH_3（0.03）、C02（0.031），（C6 H5 CH 2）2（0.0007），C6 H5 CHO（< 0.0001）;在氧存在下，C6 H5 CH 3（<0.0001），CO2（~ 0.03），（C6 H5 CH 2）2（~ 0.0001），C6 H5 CHO（~ 0.028）。提出了在甲醇中的反应主要是生成苄基阴离子和二氧化碳，次要反应（< 5%）是苄基和羧酸根（· COr）。苯乙酸钠在水中的光解主要产生聚合物和二氧化碳，非常少的甲苯，和一些联苄;在闪光实验中，瞬态苄基自由基和水合电子是可检测的，因此，我们建议，光电离机制占主导地位。通过跟踪水中瞬变的增长和衰减，我们能够计算2000±500 M-1 cm-1处苯甲基自由基的消光系数（eB）及其复合速率常数2kR= 8 X 109 M-1秒-1。
The photolysis of sodium phenylacetate in methanol at 26 gives the following products (): in the ab-sence of oxygen, C6H5CH3 (0.03), C02 (0.031),(CeH5CH2) 2 (0.0007), C> H5CHO (< 0.0001); in the presence of oxy-gen, C6H5CH3 «0.0001), C02 (~ 0.03),(C6H5CH2) 2 «0.0001), C6H5CHO (~ 0.028). It is proposed that the pri-mary process in methanol yields benzyl anion and carbon dioxide, and that the minor path (< 5%) involves benzyl and carboxylate (· COr) radicals. The photolysis of sodium phenylacetate in water yields mostly polymer and carbon dioxide, very little toluene, and some bibenzyl; in flash experiments, transient benzyl radicals and hydrated electrons are detectable; we therefore propose that a photoionization mechanism dominates here. By following the growth and decay of the transients in water, we have been able to compute the extinction coefficient (eB) of the benzyl radical at 2000±500 M-1 cm-1and its recombination rate constant, 2kR= 8 X 109 M-1 sec-1.