PHOTOCHEMICAL ELECTRON-TRANSFER REACTIONS OF 1,1-DIARYLETHYLENES
PHOTOCHEMICAL ELECTRON-TRANSFER REACTIONS OF 1,1-DIARYLETHYLENES
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DOI：
10.1021/ja00283a034
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发表时间：
1986-11-12
影响因子：
15
通讯作者：
FARID, S
中科院分区：
文献类型：
--
作者：
MATTES, SL;FARID, S
研究了1，1-二芳基乙烯(1)在光激发下的二聚反应、亲核加成反应和氧化反应。1，1-二苯基乙烯(1a)生成2+2和2+4环二聚体和一个脱氢二聚体，而1，1-二苯甲基乙烯(Lb)生成两个脱氢二聚体，1，1-二(4-二甲氨基)苯基)乙烯(Lc)不形成二聚体。脱氢二聚体的形成伴随着氰基菲增敏剂的还原。对于lb的二聚化，量子产率和产物比可以通过加入喹诺酮来改变。然后，对苯二酚取代还原的增敏剂。甲醇与La~(++)的亲核加成反应常数为1.6×10~9M~(-1)·S~(-1)，与Lb~(++)的亲核加成反应常数为~107M~(-1)·S~(-1)。二芳基乙烯的光氧化主要在链过程中产生相应的3，3，6，6-四芳基-1，2-二氧六环。在甲醇和氧气存在下，La主要生成1-羟基过氧基-2-甲氧基-1，1-二苯基乙烷，光诱导电子转移反应在有机光化学中备受关注。最近已经做了大量的工作来确定这些反应的范围、它们的动力学和涉及的机理。一些电子受体敏化了作为电子供体的烯烃的几个反应。这些反应包括异构化(几何和价态)、重排、二聚、混合加成、受体-给体加成、亲核加成和氧合作用。1
The dimerizations, nucleophilic additions, and oxygenation reactions of 1, 1-diarylethylenes (1), induced by photoexcited cyanoanthracenes, have been investigated. 1, 1-Diphenylethylene (la) yields 2+ 2 and 2+ 4 cyclodimers and one dehydrodimer, whereas 1, 1-dianisylethylene (lb) gives twodehydrodimers, and 1, 1-bis (4-(dimethylamino) phenyl) ethylene (lc) forms no dimers. Formation of the dehydrodimers is accompanied by reduction of the cyanoanthracene sensitizer. For the dimerizationof lb, the quantum yields and product ratios can be altered by the addition of quiñones. The hydroquinone then replaces the reduced sensitizer. The reaction constant for nucleophilic addition of methanol to la*+ is 1.6 X 109 M" 1 s'1; for addition to lb*+ it is~ 107 M" 1 s'1. Methanol does not add efficiently to lc*+. Photooxygenation of the diarylethylenes yields mainly the corresponding 3, 3, 6, 6-tetraaryl-1, 2-dioxane in a chain process. In the presence of methanoland oxygen, la yields mainly 1-hydroperoxy-2-methoxy-1, 1-diphenylethane.Photoinduced electron-transfer photoreactions are attracting much attention in organic photochemistry. Considerable work has been done recently to define the scope of these reactions, their kinetics, and the mechanisms involved. Several reactions of olefins as electron donors sensitized by a number of electron acceptors have been identified. These include isomerizations (geometric and valence), rearrangements, dimerizations, mixed additions, acceptor-donor additions, nucleophilic additions, and oxygena-tions. 1