论文部分内容阅读
用高、低分辨质谱,重氢标记和亚稳跃迁研究了取代缩氨基脲和缩氨基硫脲类衍生物的质谱碎裂行为.结果表明,分子离子的丰度、基峰离子的生成方式以及碎片离子的种类、丰度和数量主要取决于取代基 R 的诱导效应和共轭效应的综合影响.质谱的碎裂特征是:(1)当 R 为 N(CH_3)_2,OH时,分子的电子云分布均匀,共轭性好,基峰为分子离子峰.(2)当 R 为 H,F 时,缩氨基脲8-N 位缺电子最甚,导致9-N 和10-C 之间键的断裂,生成的高稳定离子 p-RC_6H_4CH=N~+=NH 为基峰.但缩氨基硫脲类衍生物,因电子云分布均匀,基峰仍为分子离子峰.(3)当 R 为 Br,NO_2时,由于诱导效应强烈,分子的电子云分布不均匀,12-O(或12-S)成为缺电子最甚的原子,8-N 和9-N 之间键断裂、重排而生成的离子[HNC(NH_2)-XH]~+(X=O,S)为基峰.(4)11-NH_2基团重排到苯环3,5位上,生成离子(o-RC_6H_4NH_2)~(?)只有当 R 为 H 时,反应最易发生.R 为强给电子基或强吸电子基,对反应都不利.
Mass spectrum fragmentation behaviors of substituted semicarbazones and thiosemicarbazone derivatives were studied by high and low resolution mass spectra, deuterium labeling and metastable transitions. The results showed that the abundance of molecular ions, the generation of base peak ions and The type, abundance and amount of fragment ions depend mainly on the combined effects of the induction and conjugation effects of the substituent R. The fragmentation characteristics of the mass spectrum are: (1) when R is N (CH_3) _2, OH, (2) when R is H, F, the semicarbazone 8-N position is the most electron-deficient, resulting in between 9-N and 10-C (3) When R (superscript +) is the base peak, the generated high stable ion p-RC_6H_4CH = N ~ + = NH is the base peak. Is Br, NO 2, the electron-cloud distribution is not uniform due to the strong inducing effect, and 12-O (or 12-S) becomes the most electron-deficient atom. The bonds between 8-N and 9-N are broken and rearranged (4) 11-NH 2 group rearranges to the 3,5-position of the benzene ring to generate ions (o-RC_6H_4NH_2 ~ (X = O, S) ) ~ (?) Only when R is H, the reaction is most likely to occur Strong electron donating groups or electron withdrawing groups, are detrimental to the reaction.