(2,4-二甲氧基苯基)烯丙基丙二酸二乙酯异构体的GC/MS研究

Study on Diethyl [3-(2,4-Dimethoxyphenyl)Allyl]Malonate Isomers by Gas Chromatography-Mass Spectrometry

为了研究钯催化的2,4-二甲氧基苯甲酸与烯丙基丙二酸二乙酯的脱羧Heck反应的产物结构,建立了(2,4-二甲氧基苯基)烯丙基丙二酸二乙酯同分异构体的分离与鉴定的气相色谱-离子阱质谱方法。首先通过脱羧Heck反应制得(2,4-二甲氧基苯基)烯丙基丙二酸二乙酯异构体混合物,然后利用GC/MS联用技术对混合物进行分析,得到各组分的EI和CI全扫描模式质谱信息。通过对照各组分的分子离子峰确定互为异构体的组分,再对异构体组分采用MS/MS模式获取各自的裂解碎片。通过分析异构体的不同的裂解碎片,讨论质谱裂解方式,从而确定异构体的结构。该方法省时、经济、高效,可为此类化合物的分析与鉴别提供参考。

A method applying gas chromatography-ion trap mass spectrometry （GC/MS） for the simultaneous analysis of diethyl E3-（2,4-dimethoxyphenyl）allyl]malonate isomers is de- scribed. The diethyl [-3-（2,4-dimethoxyph-enyl）allyl]malonate mixture of isomers was pre- pared by the decarboxylative Heck reaction of 2,4-dimethoxybenzoic acid with diethyl 2-al- lylmalonate firstly, and then was analyzed by GC/MS in Electron ionization （EI） and Chem- ical ionization （CI） full-scan mode. Two components were isolated by gas chromatography, and identified as isomers from the determination of the molecular ions. Next, the isomers were analyzed by tandem mass spectrometry （MS/MS） mode. Through the analysis of different cleavage fragments of the isomers in MS/MS mode, mass spectrometric fragmentation pathways of the isomers were discussed. The structures of two isomers were determined on the base of different mass characteristic fragmentation pathways. This new method of identifying isomers is a time-saving, economical and effective method, provide reference for analysis and identification of this kind of compounds.