Electrophilic aromatic substitution under chemical ionization conditions. Methylamine and ammonia as reagent gases

For compounds C₆H₅X (X?Cl, Br, I) under chemical ionization conditions, methylamine causes ipso substitution of X by NH₂CH₃]⁺ and by NH₂]⁺˙. C₆H₅F is less reactive; it gives some C₆H₅NH₂]⁺˙. Nitrobenzene gives an adduct ion M+CH₃NH₃]⁺, a reduction product ion C₆H₅NO₂]⁺˙, and an ion at m/z93, probably a substitution product C₆H₅NH₂]⁺˙, but no C₆H₅NH₂CH₃]⁺. It is also shown that the ion m/z94, formed from nitrobenzene with ammonia as reagent gas, is a substitution product rather than a reduction product ion. Carbonyl compounds C₆H₅. CO. X give adduct ions and some substitution, mainly C₆H₅NH₂]⁺˙.