Addition reaction with 2-methyl-2-nitrosopropane and pressure dependence of ionized picoline N-oxides in the gas phase

Abstract

The equilibrium of the addition reaction of ionized picoline N-oxides with 2-methyl-2-nitrosopropane as an ion-trapping reagent was determined at various temperatures in the gas phase. From the thermodynamic properties of the addition reaction, the structures of the addition products are discussed. In connection with the addition reaction, the pressure dependence of the mass spectra of picoline N-oxides is discussed, and it is concluded that the pressure dependence is caused by the effect of the charge transfer reaction between the (M– O)⁺ species and a neutral molecule of picoline N-oxide through an intermediate ion (M₂– O)⁺. Upon the formation of this intermediate ion, picoline N-oxides acted as ion-trapping reagents in a similar manner to 2-methyl-2-nitrosopropane.