有机化学 ›› 1993, Vol. 13 ›› Issue (4): 354-365. 上一篇    下一篇

研究论文

萘甲腈和2,3-二甲基丁烯-2-光环加成反应:三氟醋酸的效应

周原朗;张毓凰   

  1. 加拿大西蒙·弗雷泽大学化学系
  • 发布日期:1993-08-25

Photocycloaddition of naphthonitriles with 2,3-dimethyl-2-butene: effects of trifluoroacetic acid

ZHOU YUANLANG;ZHANG YUHUANG   

  • Published:1993-08-25

在低转光解情况下,1-萘甲腈(1-NpCN)和2,3-二甲基丁烯-2(DMB)在环已烷或苯中的光环加成反应主要得到环丁烷3,但2-NpCN主要得到氨杂环丁烯6和少量的环丁烷5,三氟醋酸(TFA)量增加抑制1-NpCN和DMB的光环加成反应,表明TFA与基态及单激发态1-NpCN生成非光反应的复合物,它也淬灭^*(1-NpCN-DMB)激基复合物.在低浓度范围(0.1M以下)TFA加速2-NpCN和DMB光环加成反应,但在高浓度范围(大于0.1M)时又抑制反应.这些结果被解析如下:^*(2-NpCN-DMB)激基复合物和TFA反应增加5和6的得率,反之,是由于生成非光反应的基态复合物及淬灭单激发态2-NpCN.在非极性溶剂中二种单激发态萘甲腈生成TFA激基复合物的萤光与母体^*NpCN萤光区域几乎相同.

关键词: 三氟乙酸, 萘甲腈, 丁烯 P, 加成反应, 光化学反应, 甲基, 反应机理

The photocycloaddn. of 1-naphthonitrile (1-NpCN) and 2,3-dimethyl-2-butene (DMB) in cyclohexane or benzene gave cyclobutane I primarily, but that of 2-NpCN gave azetine II as the major and cyclobutane III as the minor product in low conversion photolysis. The photocycloaddn. of 1-NpCN with DMB is retarded by increasing amts. of trifluoroacetic acid (TFA) which is shown to form non-photoreactive complexes with ground state as well as with singlet excited state 1-NpCN. It also quenches the *(1-NpCN-DMB) exciplex. The photocycloaddn. of 2-NpCN with DMB is accelerated by TFA in the low concentration range of <0.1 M but retarded in the higher concentration rangr >0.1 M. These observations were interpreted as follows: the *(2-NpCN-DMB) exciplex reacts with TFA to enhance the yields of II and III but is counter-balanced by a non-photoreactive ground state complex formation as well as quenching of singlet excited 2-NpCN. In nonpolar solvent both singlet excited naphthonitriles form TFA exciplexes that fluoresce in the nearly same region of the parent *NpCN fluorescence.

Key words: BUTENE P, PHOTOCHEMICAL REACTION, TRIFLUOROACETIC ACID, REACTION MECHANISM, ADDITION REACTION, NAPHTHONITRILE, METHYL GROUP

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