PROPERTIES OF REACTIVE INTERMEDIATES GENERATED BY PHOTOCHEMICAL METHOD

光化学法生成的反应中间体的性能

基本信息

批准号：
10044091
负责人：
MIZUNO Kazuhiko
金额：
$ 1.92万
依托单位：
OSAKA PREFECTURE UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

Photochemical properties and direct observations of reactive species in cis-trans photoisomerizations, photorearrangements, and photocycloadditions via 1,n-biradicals and exciplexes were examined and the following results were obtained.1) Photoirradiation of 1,2-diphenylcyclopropane derivatives bearing one or two p-acetylphenyl group(s) caused cis-trans isomerization to give 45 : 55 photostationary state, accompanying with the formation of ring-opening products, 1,3-diphenylpropene derivatives. Nano-second order laser flash photolysis indicated that the photoisomerization proceeds via triplet 1,3-biradicals whose lifetimes are ca. 15 ns, and that the substituent effect at para position are negligible except for heavy atom effect by bromide group.2) Photoirradiation of cis- and trans-1-diphenylvinylidene-2,3-dimethylcyclopropane in direct or in the presense of triplet sensitizer caused cis-trans isomerization. Cis/trans ratios in photostationary states were 50 : 50 in direct irradiation, 30 : 70 in the presense of triplet sensitizer, respectively.3) Aromatic hydrocarbons such as pyrene and phenanthrene reacts with electron-deficient alkenes such as methyl cinnamate and cinnamonitrile under photoirradiation conditions, to give (2π+ 2π) photocycloadducts at 4,5-position of pyrene and 9,10-position of phenanthrene in high yields. Prolonged irradiation of a solution containing pyrene and electron-deficient alkene give 1 : 2 adduct efficiently. Intramolecular photocycloaddition of aromatic hydrocarbons connecting alkene moiety at appropriate position gave (2π+ 2π) photocycloadducts more selectively.

研究了光化学性质以及通过1,n-双自由基和激基复合物进行的顺反光异构化、光重排和光环加成反应中反应物种的直接观察，得到了以下结果。 1) 带有一个或两个p的1,2-二苯基环丙烷衍生物的光照射-乙酰苯基引起顺反异构化，产生 45 : 55 光稳态，伴随随着开环产物的形成，纳秒级激光闪光光解表明光异构化是通过寿命约为 15 ns 的三重态 1,3-双自由基进行的，并且取代基效应在对位。除了溴化物基团的重原子效应外，位置可以忽略不计。2）顺式和顺式的光照射反式-1-二苯基亚乙烯基-2,3-二甲基环丙烷在直接照射或在三线态敏化剂存在下引起顺反异构化，在直接照射下顺式/反式比例为50:50，在三线态敏化剂存在下为30:70。 3) 芳香烃，例如芘和菲在光照射条件下与缺电子烯烃如肉桂酸甲酯和肉桂腈反应，在芘的4,5位和菲的9,10位上以高产率生成(2π+2π)光环加合物。芘和缺电子烯烃可以有效地产生 1:2 分子内光环加成反应。芳香烃在适当的位置连接烯烃部分可以更选择性地产生(2π+2π)光环加合物。