Application of spin trapping technique to radical polymerization, 15. Photo-decomposition of dibenzoyl disulfide and evaluation of relative reactivities of vinyl monomers toward the benzoylthiyl radical†
Application of spin trapping technique to radical polymerization, 15. Photo-decomposition of dibenzoyl disulfide and evaluation of relative reactivities of vinyl monomers toward the benzoylthiyl radical†
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自旋捕获技术在自由基聚合中的应用，15. 二苯甲酰二硫化物的光分解和乙烯基单体对苯甲酰基自由基的相对反应性评估†
DOI：
10.1002/macp.1977.021780709
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发表时间：
1977
期刊：
影响因子：
--
通讯作者：
T. Otsu
中科院分区：
文献类型：
--
作者：
Tsuneyuki Sato;M. Abe;T. Otsu
采用2-甲基-2-亚硝基丙烷（BNO）自旋俘获技术研究了二苯甲酰二硫醚（DBDS）在苯和单体中的光分解机理，并评价了不同乙烯基单体对苯甲酰噻基自由基(4)的相对反应活性。当DBDS在22±2℃、BNO存在下在苯中光解时，4自由基和苯甲酰自由基都被捕获为它们的硝基自由基，表明DBDS在光解过程中SS键和CS键都被分解。然而，当在单体中进行光分解时，传播自由基(7)被捕获，但没有烯丙基型自由基（11）。测定了各种扩散自由基与硝基自由基的耦合常数。根据DBDS/乙烯基单体/甲基丙烯酸甲酯（作为参考）/BNO体系的ESR谱，通过计算机模拟测定了硝基[8]/[10，X = COOCH3]的相对浓度，并估计了乙烯基单体对4的相对反应活性。结果发现，这些单体的相对反应活性与其e值呈负斜率的线性关系，类似于前一篇文章中对叔丁氧基自由基的线性关系。
The mechanism of photo-decomposition of dibenzoyl disulfide (DBDS) in benzene or in monomers, and the evaluation of relative reactivities of various vinyl monomers toward the benzoylthiyl radical (4) were investigated by means of the spin trapping technique using 2-methyl-2-nitrosopropane (BNO). When DBDS photo-decomposed in benzene at 22±2°C in the presence of BNO, both 4 and benzoyl radicals were trapped as their nitroxyl radicals, indicating that both SS and CS bonds in DBDS were decomposed during its photolysis. However, when the photo-decompositions were performed in the monomers, propagating radicals (7) were trapped, but no allyl-type radicals (11). The coupling constants of the nitroxyl radicals of various propagating radicals were determined. From the ESR spectra of the systems DBDS/vinyl monomers/methyl methacrylate (as reference)/BNO the relative concentrations of the nitroxyls, [8]/[10, X = COOCH3], were determined by computer simulation, and the relative reactivities of the vinyl monomers toward 4 were estimated. It was found that the relative reactivities of these monomers are correlated with their e values to give a linear relationship with a negative slope, similar to those toward the tert-butoxyl radical found in the previous paper.