Photochemical Reactivities of Polar Molecules

研究了苯扎苯胺及其衍生物的光化学反应性。苯甲苯胺衍生物的光照射。在四氢呋喃（THE）中产生1:1的THF加合物。有效激发带是260 nm左右的吸收带，称为带II，产生单重态第二光激发态。在该系列中，反应活性高度依赖于给电子-吸电子性质和取代基的位置。反应性衍生物分为三类；4‘上有一个给电子基团，4’上有一个吸电子基团，4'上有一个卤素。在利用电解质效应、瞬态中间体观察、猝灭实验和氘同位素效应进行机理研究的基础上，分别提出了单重态第二光激发态吸氢、单重态第二光激发态连续电子和质子转移、三重态第二光激发态吸氢这三个类别的关键步骤。用半经验MO计算方法讨论了取代基效应对反应性的位置依赖性。

The photochemilcal reactivity of benzalaniline apd its derivatives has been studied. Photoirradiation of a benzalaniline derivative .in tetrahydrofuran (THE) afforded a 1 : 1 THF adduct. The effective excitation band was the absorption around 260 nm named band II giving the singlet second photoexcited state. In the series, the reactivity highly depended upon the electron donating-withdrawing property as well as the position of the substituent. The reactive derivatives have been classified into three categories ; the derivative with an electron donating group at the 4-position, with an electron withdrawing group at the 4'-position, and with a halogen at the 4-position. The individual key-steps for the three categories, namely, hydrogen abstraction at the singlet second photoexcited state, successive electron and proton transfer at the singlet second photoexcited state, and hydrogen abstraction at the triplet second photoexcited state, have been proposed, respectively, on the basis of a mechanistic study using the electrolyte effect, observation of transient intermediates, quenching experiments, and the deuterium isotope effect. The characteristic positional dependence of the substituent effect on the reactivity has been discussed using semi-empirical MO calculation.