Mechanisms of reactions between ammonia and methylene oxonium ions: immonium ion formation versus transfer of the oxygen substituent

Exploring the intrinsic polar [4 + 2+] cycloaddition reactivity of gaseous carbosulfonium and carboxonium ions

“…Under the present reaction conditions, gaseous 2a fails to form any detectable intact adduct with butadiene, isoprene, ethyl vinyl ketone and 1,3‐cyclohexadiene, forming only minor [M + CH] + product ions with thiophene and furan (Table ). To investigate the cause of such lack of polar cycloaddition reactivity, and the possibility of isomerization during ion formation, gaseous 2a was also formed via EI with less energetic electrons (15 eV) or via dimetoxymethane and dimethyl ether self‐CI 20c . No major difference in reactivity was observed for gaseous 2a generated by these more gentle methods.…”

“…Carboxonium (R 1 R 2 C = O + ‐R) ions and their S‐analogue ions, the carbosulfonium ions (R 1 R 2 C = S + ‐R), which are formally carbenium ions with α‐(thio)alkoxy groups, constitute ubiquitous classes of stable gaseous ions and their ambident reactivity – characteristic of both carbenium and sulfonium/oxonium ions (Scheme ) – and physico‐chemical properties have been largely exploited both in the condensed and gas phase . However, surprisingly, there have been very few reports on polar cycloaddition reactivity for carboxonium and carbosulfonium ions, both in solution and gas phase.…”

Gas‐phase electrophilic addition promoted by CH3S+ CH2 ions on aromatic systems

“…Ion–molecule reactions of CH 3 O + CH 2 with NH 3 and CH 3 NH 2 are known to proceed by methylene insertion to yield the corresponding protonated imines, CH 2 NH 2 + and CH 3 NH + CH 2 , respectively, with rate constants comparable to the collision rate constants 10. The mechanism for the NH 3 reaction has been previously explored by computational chemistry9, 28 and the calculated energy surface is similar to those presented in Figs 3, 4 and 6. Similar reactions have also been observed in our laboratories with CH 3 S + CH 2 as the reagent ion 29…”

“…The methoxymethyl cation, CH 3 O + CH 2 , is a ubiquitous species in gas‐phase ion chemistry whose reactivity has been explored by several research groups using a variety of experimental techniques 1–10. Four types of ion–molecule reactions have been well established for the CH 3 O + CH 2 cation depending on the nature of the neutral organic substrate (M):11 (1) addition followed by elimination of methanol to yield an [M + CH] + ion; (2) methylation leading to an [M + CH 3 ] + ion; (3) direct addition with the subsequent formation of an adduct ion; and (4) hydride abstraction to yield an [M − H] + ion.…”

The Oxidative Power of Protonated Hydrogen Peroxide

“…Bimolecular reactions between HOOH 2 + and alkanes were investigated using a Fourier transform ion cyclotron resonance (FT‐ICR) mass spectrometer using conditions described in detail elsewhere 16. Briefly, HOOH 2 + ions were produced in an external ion source, transferred to the cell of the instrument, isolated, thermalized, reacted with the alkane, and the reaction rates were determined by recording FT‐ICR mass spectra at different reaction times.…”