多官能团分子质谱的研究(Ⅳ)——裂解机理的研究

Study on Mass Spectra of Multifunctional Group MOleeules Ⅳ—The Fragmentation Mechanism

本文对2,6—双(二甲胺甲基)—4—乙基酚二盐酸盐这一对称型分子进行了精确质量和亚稳测定,证实了:(1)由分子离子M^+经过多种裂解方式,分别形成相应碎片m/z 176、191、192、193、161的裂解机理;(2)基峰m/z 191是由M^+通过邻位效应失去HN(CH_3)_2中性分子形成的;(3)基峰m/z 191可进一步裂解,通过多种途径形成m/z 147、132、91相应碎片;(4)苯环侧链胺基中C—N键的开裂与非对称型分子相似,而与脂肪胺中C—N键稳定不开裂的过程截然相反。在对称型分子和非对称型分子裂解机理的基础上,比较了两者邻位效应的差异。

The accurate mass and metastable ion detections of symmetrical molecule 2,6—(bisdimethylaminomethyl)—4—ethyl phenol dihydrochloride demonstrated. (1) the respective fragments m/z 176, 191, 192, 193, 161 are formed from molecular ion M^+ on the fragmentation mechanism via various cleavage modes; (2)the base peak at m/z 191 is formed with the loss of a neutral molecule via the ortho effect; (3) the base peak m/z 191 may further be cleaved to form fragments m/z 147, 132, 91; (4) the cleavage of C--N bond in side chain of amine group attached to benzene ring is simillar to the symmetrical molecules and on the contrary, dissimilar to the asymmetrical molecules in which the C--N bond is stable and does not cleave. On the basis of fragmentation mechanism^([1.2]), comparison between the ortho effects of asymmetrical and symmetrical molecules showed obvious distinctions of them.