烷基环己基苯类液晶的质谱裂解规律研究

利用气相色谱质谱联用仪(GCMS)对烷基环己基苯、烷基环己基联苯两类液晶单体共72个化合物在EI离子化模式下进行分析,结果表明此两类化合物具有相同的裂解途径和裂解机理。为烷基环己基苯类衍生物的结构解析与质量监测提供参考。其裂解途径主要为与苯环连接的环己烷发生开环裂解反应,生成特征的:苯乙烯(联苯乙烯)基的奇电子离子、苯丙烯(联苯丙烯)基的偶电子离子以及卓鎓偶电子离子。当苯环部分含有乙氧基以上取代基时,分子离子及其特征离子会发生重排脱去烯烃生成对应的苯(联苯)酚离子。对于环己基联苯类化合物在特征离子生成的基础上会进一步生成质量数减少2的脱氢离子。

Fragmentation modes of alkylcyclohexylbenzene derivatives and alkylcyclohexylbiphenyl liquid crystalline derivatives

The EI mass spectra of two kinds of liquid crystals alkylcyclohexylbenzene derivatives and alkylcyclohexylbiphenyl derivatives were analyzed with the gas chromatogram/mass spectrometer, and the fragmentation rules of them were summarized in this paper. The EI mass spectra in analogy with the Alkylcyclohexylbenzene derivatives and alkylcyclohexylbiphenyl derivatives, abundant molecular ions are presented in all the spectra. They have three most characteristic ions,the odd electron ions at m/z100+R₂+R₃+R₄+R₅[m/z 175+R₂+R₃+R₄+R₅+R₆] and their satellites the even electron ions at m/z 87+R₂+R₃+R₄+R₅ and m/z 113+R₂+R₃+R₄+R₅[m/z 162+R₂+R₃+R₄+R₅+R₆、m/z 188+R₂+R₃+R₄+R₅+R₆] in the mass spectra.