Fragmentation selectivity in electron impact ionization mass spectra of substituted dimethoxybenzenes

✍ Scribed by Hisao Nakata; Fumie Jitsukawa; Hitomi Toyama; Yuko Kato

• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 345 KB
• Volume: 27
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/oms.1210270613

✦ Synopsis

Abstract

Several 1‐X‐sabstitirted‐3‐methoxy‐4‐trideuteromethoxybenzens were synthesized and their electron impact ionization mass spectra were measured with an ionizing energy of 20 eV. From the peak intensity ratio of [M  CD~3~ ] and [M  CH~3~] the fragmentation‐directing ability of the substituent X was evaluated. The most powerful group was found to be NH~2~, which expelled a methoxy methyl group only from its para position. The CH~3~ group and four halogen atoms, F, Cl, Br and I, exerted a moderate effect Electron‐withdrawing groups such as NO~2~, CHO and CN had only a little influence on the fragmentation selectivity. These results were interpreted in terms of the effect of X on the distribution of both the unpaired electron and the positive charge in the molecular ion.