[3+3] -PHOTOCYCLOADDITION OF ARENEDICARBOXYLIC ACID DERIVATIVES AND ALKYLBENZENES

本研究的目的是阐明芳二酸衍生物和烷基苯的[3+3]-光环加成反应的机理和适用性。研究结果如下：1.通过对1，2-，1，3-1，4-，2，3-或1，8-烷基苯与甲苯、二甲苯等烷基取代的1，2-，1，3-1，4-，2，3-或1，8-位分别含有酸酐、酰亚胺、二酯基和二氰基的萘衍生物与甲苯、二甲苯等烷基的光环加成反应的研究，发现[3+3]-光环加成反应普遍存在于萘环的1，8-位含有酸酐和酰亚胺基团。芳二酸衍生物的芳环加成反应中没有观察到[3+3]-光环加成反应，芳二酸衍生物的芳烃结构不同于萘，如苯、蒽或菲。烷基苯对1，8-萘二甲酸酐和1，8-萘二甲酰亚胺的荧光猝灭速率常数与[3+3]-光加成反应的发生有很好的相关性。与烷基苯单电子转移相关的自由能变化AG对芳二酸衍生物的单重态激发态起着重要的作用。较大的负值AG似乎对反应的发生是必不可少的。根据这些结果，提出了[3+3]-光环加成反应的可能机理，包括烷基苯向芳二酸衍生物的单重态激发态的电子转移，形成的自由基离子对内的质子转移，产生的自由基对内的电子转移，以及最终的阴阳离子之间的热环加成反应。反应机理合理地解释了反应的适用性和溶剂对反应的影响。

The purpose of this investigation is to clarify the mechanism and applicability of [3+3]-photocycloaddition of arenedicarboxylic acid derivatives and alkylbenzenes. The results obtained are as follows :1. From the investigations of the photoreactions of naphthalene derivatives, having acid anhydride, imide, diester, and dicyano groups at the 1,2-, 1,3- 1,4-, 2,3-, or, 1, 8-positions of the naphthalene ring, with alkylbenzenes, such as toluene, xylenes, and so on, [3+3]-photocycloaddition was found to be general in the reactions of naphthalene derivatives, having acid anhydride and imide group at the 1,8-positions of the naphthalene ring.2. No [3+3]-photocycloadditions were observed in the reactions of arenedicarboxylic acid derivatives, having arene structure other that naphthalene, such as benzene, anthracene, or phenanthrene.3. The quenching rate constants of the fluorescence of 1 , 8-naphthalenedicarboxylic anhydride and 1,8-naphthalenedicarboximide by alkylbenzenes were found to correlate well to the occurrence of the [3+3]-photoaddition.4. The free energy change AG associated with one-electron transfer from alkylbenzenes to the singlet excited states of arenedicarboxylic acid derivatives were revealed to play an important role to determine the type of the observed photoreactions. A large negative AG value seems to be essential for the occurrence of the reaction.5. From these results, possible reaction mechanism for the [3+3]-photocycloaddition, involving electron transfer from alkylbenzenes to the singlet excited states of arenedicarboxylic acid derivatives, proton transfer within the formed radical ion pair, electron transfer within the producedradical pair, and final thermal cycloaddition between the resulted anion and cation, was proposed. Applicability of the reaction and solvent effect on the reaction were reasonably explained by the reaction mechanism.