Evaluation of nitric oxide chemical ionization mass spectra of substituted benzenes

✍ Scribed by Shigeki Daishima; Yoshio Lida; Fujihiro Kanda

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 518 KB
• Volume: 26
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/oms.1210260521

✦ Synopsis

Nitric oxide chemical ionization mass spectra of substituted benzenes obtained with the Townsend discharge technique were studied. There were four kinds of base peaks in the mass spectra, i.e. I M + NO] +', M", [ M -H 1 + and [ M -OR] + (R = H, CH,). The formation of the specific ion IM + NO] +. was highly dependent on the kind of substituent, and it was produced more abundantly in the case of substitutions involving electron-accepting groiips. The measure of IM + NO]'' production was evaluated from the value of the ratio ( M + NOl+'/M+'. In monosubstitutions, it was clarified that the ratios of [ M + NO] +'/M+* were correlated with the Hammett substituent constant cp or the electrophilic substituent constant cp+. Monosubstitutions (C,H,R) and toluene substitutions (CH,C,H,R) could be classified into six groups in terms of base peak species, [M + NO]+'/M+' ratios and substituents. In disubstitutions, the mass spectral patterns were governed by the combination of substituents. Mass spectral distinctions among ortho, meta and para isomers could be made in many cases. ~~ 1. Depending on the substituent, [M + NO]+', M+',