Effect of overcrowding on mass spectra of polycyclic aromatic hydrocarbons; co-operative double cyclization of two methyl substituents at overcrowded positions
作者:Toyotoshi Ueda、Zeper Abliz、Satoshi Iwashima、Junji Aoki、Minoru Takekawa、Teruo Kan
DOI:10.1039/p29880001053
日期:——
Mass spectra of 1,10-(2) and 3,12-dimethyltetrabenzo[de,hi,op,st]pentacene (3), and 14-methyl-5-(2-methyl-1-naphthyl)-(5) and 12-methyl-5-(4-methyl-1-naphthyl)-benzo[a]perylene (6) were investigated to elucidate the effect of methyl substitution at overcrowded positions. Compound (2), showed a very strong [M– 6]i+ peak, whereas the spectra of (3), (5), and (6), which were similar to each other, showed
1,10-(2)和3,12-二甲基四苯并[ de,hi,op,st ]并五苯(3)和14-甲基-5-(2-甲基-1-萘基)-(5)的质谱和12-甲基-5-(4-甲基-1-萘基)-苯并[ a ] per(6)进行了研究,以阐明在过度拥挤的位置进行甲基取代的效果。化合物(2)表现出非常强的[ M – 6] i +峰,而彼此相似的(3),(5)和(6)的光谱则表现出强烈的[ M– 32] i +高峰。因此,仅在化合物(2)过度拥挤的情况下才发生环化反应。在类似的结构(5)的情况下,通过环平面的扭转来实现从拥挤中释放。在喹啉中加热(2)时也发生该反应。