The reactions of some common electrophiles, CH3+, NO+, NO2+, and O2NCH2+, with monosubstituted benzenes in the gas phase

Abstract

The reactions of CH₃⁺, NO⁺, NO₂⁺, and O₂NCH₂⁺ with monosubstituted benzenes (C₆H₅X where X = H, F, Cl, CF₃, CH₃, and CH₃O) have been studied in the gas phase using a triple quadrupole mass spectrometer. Charge-exchange is the predominant process for all the ions with all the substituted benzenes. No adducts of the Wheland intermediate type were detected as major products but disproportionation products were observed with three of the primary ions [reactions (i)–(iii)]. In addition there were minor processes particular to one substituent with, CH₃⁺+ C₆H₅X → C₇H₆X (or C₇H₇)+ H₂(or HX)(i) NO₂⁺+ C₆H₅X → C₆H₅XO⁺˙+ NO (ii) O₂NCH₂⁺+ C₆H₅X → C₆H₅XNO⁺+ CH₂O (iii) one primary ion. The relevance of these gas-phase studies to the interpretation of solution-phase aromatic substitution is briefly discussed.