O−˙ chemical ionization mass spectra of fluoroaromatic compounds
O−˙ chemical ionization mass spectra of fluoroaromatic compounds
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含氟芳香族化合物的 O−˙ 化学电离质谱
DOI：
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发表时间：
1993
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通讯作者：
A. G. Harrison
中科院分区：
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作者：
Kimberley Merrett;A. Young;A. G. Harrison
测量了单氟苯至五氟苯、氟甲苯和氟苯甲醚的 O−˙ 化学电离 (CI) 质谱。为了进行比较，还测量了甲苯（包括氘标记的变体）和苯甲醚的 O−˙ CI 质谱。 O−˙与氟苯的主要反应途径包括H原子置换和H夺取。随着氟化取代度的增加，H+ 提取的重要性也随之增加。对于三氟苯和四氟苯，只有当两个氢彼此邻位时，H 的夺取才重要。氟芳香族分子特有的反应通道涉及形成 [M + O – HF]−˙，对于多氟化合物，其通过消除 HF 或 CO 进一步裂解。对于氟苯甲醚，形成 FC6H4O− 以及从 [M – H]− 和 [M – 2H]−˙ 中消除 CH2O 是重要的反应通道。通过 O− 反应形成 [M + O – H]−。与甲苯的反应被证明涉及环氢的特定置换，而 [M – H]− 的形成主要涉及从甲基中夺取质子。相比之下，H的夺取是非特异性的，通过三种途径进行：（i）从芳香环中夺取两个氢，（ii）从甲基中夺取两个氢，以及（iii）从每个位置夺取一个氢；然而，结果与氢的随机选择不一致。
The O−˙ chemical ionization (CI) mass spectra of the mono- to pentafluorobenzenes, fluorotoluenes and fluoroanisoles were measured. For comparison, the O−˙ CI mass spectra of toluene (including deuterium-labelled variants) and anisole were also measured. The major reaction channels of O−˙ with fluorobenzene involve H-atom displacement and H abstraction. With increasing fluoring substitution H+ abstraction increases in importance. For the tri- and tetrafluorobenzenes H abstractions is important only when there are two hydrogen ortho to each other. Reaction channels which are unique to the fluoroaromatic molecules involve the formation of [M + O – HF]−˙, which, for polyfluoro compounds, fragments further by elimination of HF or CO. For the fluoroanisoles, formation of FC6H4O− and elimination of CH2O from [M – H]− and [M – 2H]−˙ are important reaction channels. The formation of [M + O – H]− by reaction of O−. with toluene is shown to involve specific displacement of a ring hydrogen, whereas the formation of [M – H]− involves primarily abstraction of a proton from the methyl group. By contrast, H abstraction is non-specific and proceeds by three pathways: (i) abstraction of two hydrogens from the aromatic ring, (ii) abstraction of two hydrogens from the methyl group and (iii) abstraction of one hydrogen from each position; however, the resuls are not in accord with a random selection of hydrogens.