论文部分内容阅读
利用飞行时间质谱仪的高分辨本领和离子阱串联质谱技术研究了5乙酰(苯甲酰)基4芳基3,4二氢嘧啶2(1H)酮(1-5)的电子轰击质谱的裂解规律.将所有质谱离子的精确质量数据经OpenLynx软件导出其分子离子和碎片离子的元素组成.根据质谱裂解规律,主要质谱离子得到了归属,并经离子阱串联质谱技术加以证实.化合物1-3的质谱出现了丰度很强的分子离子峰,其中1和3的分子离子为基峰,证明此类化合物的结构相当稳定.但4和5的分子离子峰却很弱(相对丰度在4%以下),这是由于嘧啶环4位上的苯环分别含有强吸电子基团-NO2(在苯环的间位才有此效应)和-Cl(苯环的2和4位均含有氯)所致.化合物1-5的主要裂解包括:分子离子失去芳基形成丰度很高的阳离子(M-Ar)+;分子离子失去羰基形成中等强度的阳离子(M-RCO)+;分子离子失去氢原子所产生的(M-H)+峰,以及消除中性分子NH=C=X的嘧啶环破裂裂解.此外,所有化合物在低质量区都发现明显的苯基阳离子Ph+(m/z77).并且还提出个别化合物的几个额外裂解过程为:化合物4(分子中苯环的3位上含有硝基)出现的基峰(M-OH)+;化合物5(分子中苯环的2和4位上都含有氯原子)出现了的基峰(M-Cl)+;化合物3和5分别出现了m/z238(16%)和m/z241(29%)的特征离子峰,它们由相应的离子消除中性分子四员内酰胺生成查耳酮离子,该离子具有共轭大Π键而稳定存在.
The electron impact mass spectra of 5-acetyl (benzoyl) 4-aryl 3,4-dihydropyrimidine 2 (1H) -one (1-5) were studied by means of high-resolution TOF mass spectrometry and ion trap tandem mass spectrometry The accurate mass data of all mass spectra ions were derived from the elemental composition of their molecular ions and fragment ions by OpenLynx software.According to the rule of mass spectrometry, the main mass spectra ions were assigned and confirmed by ion trap tandem mass spectrometry Showed strong abundance of molecular ion peaks, of which 1 and 3 molecular ion as the base peak, showing that the structure of these compounds is quite stable, but 4 and 5 molecular ion peaks are very weak (relative abundance of 4 %). This is due to the fact that the benzene rings at the 4-position of the pyrimidine ring respectively contain a strongly electron-withdrawing group -NO2 (this effect is only available at the meta-position of the benzene ring) and -Cl (both of the 2- and 4-positions of the benzene ring contain chlorine ). The main cleavages of compounds 1-5 include: the molecular ion loses the aryl group to form a highly abundant cation (M-Ar) +; the molecular ion loses the carbonyl group to form a moderate-intensity cation (M-RCO) +; the molecular ion Loss of the (MH) + peak from a hydrogen atom, and disruption of the pyrimidine ring that neutralizes the neutral molecule NH = C = X In addition, all the compounds showed obvious phenyl cation Ph + (m / z77) in the low mass region and also proposed several additional cleavage processes for the individual compounds as follows: Compound 4 (containing 3 (M-OH) +; Base peak (M-Cl) + appeared for compound 5 (chlorine atoms in the 2 and 4 positions of the benzene ring in the molecule); Compounds 3 and 5 respectively appeared The characteristic ion peaks of m / z 238 (16%) and m / z 241 (29%) which generate the chalcone ion from the corresponding ion-abolished neutral molecule four-membered lactam, .