Photolysis of Dibenzyl Ketones Adsorbed on Zeolite Molecular Sieves. Correlation of Observed Cage Effects with Carbonyl 13C Enrichment Efficiencies
Photolysis of Dibenzyl Ketones Adsorbed on Zeolite Molecular Sieves. Correlation of Observed Cage Effects with Carbonyl 13C Enrichment Efficiencies
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吸附在沸石分子筛上的二苄基酮的光解。
DOI：
10.1021/ja00289a022
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发表时间：
1985
影响因子：
15
通讯作者：
P. Wan
中科院分区：
文献类型：
--
作者：
N. Turro;P. Wan
3-(4-甲基苯基)-1-苯基-2-丙酮(1)(4-MeDBK)和1,3-二苯基-2-丙酮-13C2(2')(DBK-I3C)的光解已经在几种常用沸石上进行。在几种沸石上观察到 4-MeDBK (1) 光解产物分布的显着变化。根据沸石空隙体积中光生苯甲基自由基的分子迁移率计算并合理化百分比笼效应。百分比笼效应与这些沸石上 DBK-"C 光解的“C 富集效率”以及 DBK 异构体 (PMAP) 的产率密切相关，DBK 异构体 (PMAP) 是 DBK-"C 光解中初级双子自由基对的对位偶联产物（图 3）。过去几年见证了有序系统中光化学研究的爆炸性增长。'-' 尽管光化学反应是在胶束中进行的，但微-乳液、液晶、固态和硅胶，'-' 只有少数研究涉及沸石上的光化学，其中大多数主要涉及水分解过程。s-12 然而，最近出现了关于使用沸石进行有机光物理和光化学研究的报道。I3-I5 沸石是通常具有明确结构的结晶铝硅酸盐。16 在沸石框架内是一个系统不同尺寸的通道和/或超级笼 (2-1 3 A)。16 这些通道或超级笼的确切性质取决于特定沸石的特性，对有机化学家来说，重要的是 26 A 的通道或孔径可以吸附苯和其他分子大小相似的分子。I6 因此，沸石的内部空间（或空隙体积）可以对有机光化学反应发挥拓扑控制的可能性是一个值得研究的领域，众所周知，沸石在工业化学过程中表现出择形催化和吸收特性~.~~,~~ 我们在此报告了我们对吸附在许多常用沸石中的二苄基酮的光化学行为的研究。结果表明，在沸石中进行光化学反应可以影响反应产物比例的显着变化，从而为使用这些物质作为有机光化学研究的介质开辟了道路。
The photolysis of 3-(4-methylphenyl)- 1-phenyl-2-propanone (1) (4-MeDBK) and 1 ,3-diphenyl-2-propanone-13C2 (2') (DBK-I3C) has been carried out on several commonly available zeolites. Dramatic changes in product distributions for 4-MeDBK (1) photolysis were observed on the several zeolites. Percent cage effects were calculated and rationalized in terms of molecular mobility of photogenerated benzyl radicals in the void volumes of zeolites. Percent cage effects correlate well with "C-enrichment efficiencies for DBK-"C photolysis on these zeolites and, with the yield of a DBK isomer (PMAP), the para-coupling product of the primary geminate radical pair (Figure 3) in the photolysis of DBK-"C. The past several years have witnessed an explosive increase in photochemical studies in ordered systems.'-' Although photo- chemical reactions have been performed in micelles, micro- emulsions, liquid crystals, in the solid state, and on silica gel,'-' only a small number of studies have dealt with photochemistry on zeolites, the majority of these being concerned primarily with the water-splitting process.s-12 Recently, however, reports on the use of zeolites for organic photophysical and photochemical studies have appeared.I3-I5 Zeolites are crystalline aluminosilicates of usually well-defined structure.16 Within the zeolite framework are a system of channels and/or supercages of varying dimensions (2-1 3 A).16 The exact nature of these channels or supercages depends on the identity of the particular zeolite. Of importance to the organic chemist is that channel or pore diameters of 26 A can allow the adsorption of benzene and other molecules of similar molecular size.I6 Thus, the possibility that the internal spaces (or void volumes) of zeolites can exert topological control on organic photochemical reactions is an area that warrants investigation, since it is well-known that zeolites display shape-selective catalytic and absorptive properties in industrial chemical processe~.~~,~~ We report herein our study of the photochemical behavior of dibenzyl ketones adsorbed in a number of commonly available zeolites. The results indicate that significant changes in reaction product ratios can be effected by carrying out photochemical reactions in zeolites, thus opening the way for employing these substances as a medium for organic photochemical studies. Results