4-氯-4’-取代-苯丁酮的低能电子轰击质谱和取代基效应的研究

The Study of Low Energy Electron Impact Mass Spectia of 4-Chloro-4’ -Substituted Benzyl Butyl Ketones and Substituent Effect

用离子动能谱探讨了9个苯环上不同取代基的4-氯-4′-取代-苯丁酮EI断裂的主要途径是:分子离子先进行Mclafferty重排,而后α-断裂。将电子能量降低至20e v,对Mclafferty重排的产物离子的α-断裂反应用Hammett方程处理,得回归线性方程lgZ/Z0=-0.37σp-0.008,线性相关系数为0.9949。由此可明显地看出质谱中单分子断裂反应的取代基效应。

The investigation of the pathway of EI fragmentation of 4-chloro-4’-substituted benzyl butyl ketones with nine different ring substituents was accomplished by means of Mass-Analyzed Ion Kinetic Energy Spectra (MIKES). The results showed that the pathway was predominantly composed of Mclafferty Rearrangement of molecular ions followed by α-dissociation. Under lower impact electron energy down to 20eV, the α-disspciation leaction of product ions of Mclafferty Rearrangement could satisfactorily correspond with Hammeit eqtation resulting in the regression linear epuationlgZ/Z0 =-0.378σp-0.008with correlation coefficient 0.9949. The substituent effect of monofnolecular dissociation in mass spectrometry was obviously shown from present work.