CIDEP studies of the formation of cyclohexadienyl-type radicals in the photoreduction of aromatic ketones
CIDEP studies of the formation of cyclohexadienyl-type radicals in the photoreduction of aromatic ketones
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CIDEP 研究芳香酮光还原中环己二烯基型自由基的形成
DOI：
10.1021/j100409a038
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
Y. I'haya
中科院分区：
文献类型：
--
作者：
H. Hayashi;Y. Sakaguchi;H. Murai;Y. I'haya
芳香醛和酮在三重态下的吸氢反应是最基本的光化学过程之一。这些三重态的高反应活性归因于羰基的*特性2或三重态与胺的电荷转移（CT）配合物的产生。2·3通过对反应产物的分析，以及用时间分辨光学吸收（TROA） 5和化学诱导动态电子极化（CIDEP） 6技术的直接测量，已经很好地确定了这两种反应中基自由基的形成。相反，芳香醛和酮2·3的*三重态被认为比*三重态和CT配合物的反应性要低得多。另一方面，像三丁基斯坦烷这样的强氢供体，即使在*三重态也能大大提高吸氢反应的反应活性。然而，这些反应的主要过程很少用TROA8·9和CIDEP技术进行研究。最近，我们用硼氢化钠、三乙基日耳曼和三正丁基锡烷等特殊的供氢体对黄酮10 ' ' 12进行了光还原实验，首次发现在某些溶剂中形成了典型的环己二烯基。这个新反应的特征点
The hydrogen abstraction reaction by aromatic aldehydes and ketones in theirtriplet states isone of the most essential photochemical processes. 2· 3 The high reactivityof these triplet states has been ascribed toeither the* character of the carbonyl group2 or the creation of charge-transfer (CT) complexes of the triplet states with amines. 2· 3 The formationof the ketyl radicals in these two types of reactions has been well established by analysis of the reaction products4 and by direct measurement with timeresolved optical absorption (TROA) 5 and chemically induced dynamic electron polarization (CIDEP) 6 techniques. On the contrary, the* triplet states of aromaticaldehydes and ketones2· 3 have been believed to be much less reactive than the* triplet states and CT complexes. On the other hand, such a strong hydrogen donor as tri-n-butylstannane has been known to enhance very much the reactivity of the hydrogen abstraction reactions even from the* triplet states. 7 However, the primary processes of these reactions have scarcely been studied with the aids of TROA8· 9 and CIDEP techniques. Recently, we carried out CIDEP studies of the photoreduction of xanthone10" 12 with such special hydrogen donors as sodium borohydride, triethylgermane, and tri-n-butylstannane and found for the first time the formation of the cyclohexadienyl-typeradical in some solvents. The characteristic point of this new reaction