Gas-phase ion-molecule reactions in organophosphorus esters

Self-condensation ion-molecule reactions of trimethyl phosphite, triethyl p hosphite, dimethyl phosphonate, trimethyl phosphate and 2,2-dichlorovinyl d imethyl phosphate (dichlorvos) mere investigated by ion trap mass spectrome try and Fourier transform ion cyclotron resonance mass spectrometry. Reacti on paths for the main processes observed were elucidated by parent ion sele ction and for reaction times up to 500 ms. In parallel, high-resolution mea surements were performed in order to determine the composition of the princ ipal ions, Among the compounds under examination, trimethyl phosphite and t riethyl phosphite mainly give [M + H](+) and [M + (RO)(2)P](+) (R = CH3, C2 H5) adduct ions, whereas trimethyl phosphate and dimethyl phosphonate displ ay [2M + H](+) ions, as the only abundant products, formed by reaction of [ M + H](+) and M. 2,2-Dichlorovinyl dimethyl phosphate mostly shows fragment ation processes, The reaction patterns of the compounds examined were relat ed to their different structural features. Gas-phase basicities of the phos phoryl compounds were also determined or re-examined, Copyright (C) 1999 Jo hn Wiley & Sons, Ltd.