Gas-phase ion-molecule reactions in organophosphorus esters

Gas‐phase reactivity of the OP(OCH3)2+ phosphonium ion with aliphatic esters in a quadrupole ion trap. Spontaneous elimination of ketenes

“…Three major products ions are formed between isolated phosphonium ions O P(OCH 3 ) 2 + ( m/z 109) and aliphatic esters RR′CHCOOR″: (i) an addition product [RR′CHCOOR″, O P(OCH 3 ) 2 ] + , (ii) an ion at m/z 141 with esters 2a–2d (R″ = CH 3 ) or at m/z 155 with ester 2e (R″ = CH 3 CH 2 ), these ions corresponding to the loss of C n H 2 n −2 O from the adducts and (iii) an ion at m/z 127. In fact, the last ion is the result of the addition of background water to the m/z 109 ion 13–16. The structure of the m/z 127 ion corresponds to a protonated dimethyl phosphate, [(CH 3 O) 2 P(OH) 2 ] + .…”

“…Such a reaction has also been reported for the OP(OCH 3 ) 2 + species formed upon electrospray ionization of TMPA in an LCQ ion trap mass spectrometer 14. Self‐condensation ion–molecule reactions of organophosphorus esters have been investigated by recently Gal et al 15 Ion–molecule reactions between the OP(OH) 2 + phosphonium ions and methanol or aromatic hydrocarbons (ArHs) were also performed in a QIT mass spectrometer. The OP(OCH 3 ) 2 + phosphonium ions were found to react with methanol via three consecutive reactions, via sequential methanol addition–water elimination, to yield protonated TMPA 16, 17.…”

“…The O P(OCH 3 ) 2 + cations were generated from TMPI upon EI. The experiments were performed in a QIT mass spectrometer, which is proving to be an effective device for studying ion–molecule reactions 12, 13, 15–21. A theoretical study using density functional theory (DFT) was carried out in order to investigate the potential energy surface (PES) for the reaction between O P(OCH 3 ) 2 + and ester 2a .…”

Charge permutation reactions in tandem mass spectrometry

“…191 In both the equilibrium and bracketing methods, a proton is transferred from a monocation, MH C , to a neutral base species, B, with known gas-phase basicity, according to the Reaction (2.2). The free-energy change for this reaction, G rxn , is the difference in gas-phase basicities of M and B, 196,197 Other tools, such as triple-quadrupole instruments, 198 quadrupole ion traps 199,200 and guided ion beam mass spectrometers, 201 have also been employed. 'Flow reactor' or 'flow tube' techniques, including flowing afterglow (FA) and selected ion flow drift tube (SIFDT), have been used for the determination of thermodynamic values associated with proton transfer.…”

Gas‐phase reactivity of the OP(OCH3)2+ phosphonium ion towards α,β‐unsaturated esters in a quadrupole ion trap

“…Self‐condensation ion–molecule reactions of organophosphorus esters have been recently investigated by Gal et al 15 Ion–molecule reactions between the OP(OH) 2 + phosphonium ions and methanol were also performed in a QIT mass spectrometer. The OP(OH) 2 + phosphonium ions, formed by EI from neutral TMPI, react with methanol according to three consecutive reactions, via sequential methanol addition–water elimination, to yield protonated TMPA 16, 17.…”