利用气相色谱质谱联用仪(GCMS)对含有侧向氟取代苯并吡喃结构和侧向氟取代萘酚(苯酚)结构的16个中心桥键为含氧亚甲基的醚类液晶化合物进行分析, 结果表明此两类化合物的谱图具有明显的特征, 化合物具有相似的裂解途径。主要是与醚键相连取代基团β位的氢通过四元环过渡态重排脱去中性分子, 得到对应的侧向氟取代酚碎片离子; 萘酚(苯酚)醚类化合物当结构中有两个烷氧基取代时, 当另一个烷氧基也存在β氢时会再一次通过氢重排反应脱去烯烃, 得到特征的侧向氟取代二酚碎片离子。对于苯并吡喃醚类化合物, 当吡喃环α位有烷基取代时将通过σ键的断裂引起烷基碳碳键的裂解, 脱去烷基自由基得到相应的离子; 特殊的, 对于苯并吡喃醚类液晶化合物其可以通过吡喃环上的氢重排引起吡喃环开环从而得到对应的离子。通过对此两类含有醚键结构的液晶化合物的质谱分析可为该类液晶化合物的杂质解析与质量监测提供依据, 将有助于同类液晶衍生物的识别, 同时可为混晶的有效剖析提供参考。

The 16 kinds of Liquid crystalline (LC) compounds, with the structures of lateral fluoro-substituted benzopyran structures or naphthol (phenol), and CH2O moiety as a linkage group, were analyzed by GCMS. The results show that the spectra of the two kinds of compounds have obvious characteristics. The cleavage pathway was similar for the two kinds of compounds, which is that the ether bond connected to the β-hydrogen through the four-membered ring transition state rearrangement of neutral molecules, to obtain the corresponding lateral fluoro-substituted phenol ions. For the two alkoxy-substituted naphthols (phenol), when the other alkoxy groups also have β-hydrogen, the olefins are removed again by hydrogen rearrangement to give the characteristic lateral fluoro-substituted diol fragment ions. For the benzopyran compounds, the cleavage of the alkyl carbon-carbon bond is initiated by the cleavage of the σ bond to give the corresponding ions when the alkyl is on the pyran α-position. Specially, the benzopyranyl ether-based LC compounds can cause ring-opening of the pyran ring through the hydrogen rearrangement on the pyran ring to give the corresponding ions. Through the mass spectrometric analysis of these two kinds ether bond containing LC compounds, the basis for the analysis of impurities and quality monitoring of these LC compounds could obtained, which will help the identification of similar liquid crystal derivatives, meanwhile, it provides a reference for mixed crystal effective analysis.