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采用EI和CI电离方式下的混合样品直接进样法、EI电离条件下的气质联用技术 ,利用飞行时间质谱的精确质量及准确的元素组成 ,鉴定了改良乌尔门反应的副产物多联苯混合物的结构 ,并测定了它的相对含量分别为联苯 1 ( 70 .0 % )、三联苯异构体 2 ( 3.9% )、四联苯异构体 3( 4 .9% )和五联苯及其异构体 5 亚甲基 1 ,2 ,3,4 四苯基 1 ,3 环戊二烯 4 ( 2 1 .2 % ) .由于具有共轭大π键的多联苯分子离子结构相当稳定 ,其纯化合物的分子离子的丰度都接近 1 0 0 %或为基峰 ,可根据混合物直接进样所得质谱 (CI)中各组分分子离子的相对丰度 ,估计出组分 2、3和 4在混合物中的相对含量 .这一结论与气质联用 (EI)所测的总离子流色谱图中 2和 3的相对含量相一致 .对通过重结晶得到的主要副产物纯品联苯 1的EI TOF MS谱作了具体的裂解分析
Using the direct injection of mixed sample under EI and CI ionization mode and the GC-MS technique under EI ionization condition, by using the accurate mass and accurate elemental composition of time of flight mass spectrometry, Benzene mixture and its relative contents were determined as biphenyl 1 (70.0%), terphenyl isomer 2 (3.9%), tetraphenyl benzene isomer 3 (4.9%), Biphenyl and its isomer 5 methylene 1,2,4 3,4-tetraphenyl 1,3 cyclopentadiene 4 (21.2%) due to the conjugated π bond polybiphenyl molecular ion Its structure is quite stable. The abundances of molecular ions of the pure compounds are close to 100% or base peak, and the relative abundance of molecular ions of each component in the obtained mass spectrum (CI) 2, 3 and 4 relative to the mixture This conclusion is consistent with the relative content of 2 and 3 in the total ion chromatogram measured by the mass spectrometry (EI) The relative purity of the major byproduct obtained by recrystallization EI TOF MS spectra of Biphenyl 1 were analyzed specifically