The gas phase reactivity of chloronium ions by high pressure mass spectroscopy

Abstract

The reactions of CH3ClCH3+ (I) and CH3ClCH2Cl+ (II) with a range of bases have been studied in a high pressure ion source. Reactant ion monitoring has been used to obtain the relative reactivities. Transfer of CH3+ from I and CH2Cl+ from II are the only reactions observed with N- and O-containing bases. Following addition of CH2Cl+ from II, the lower alkyl aromatics (ArH) yield either ArHCH2Cl+ or the benzyl ions ArCH2+ and ArCHCl+ while CH3+ transfer leads only to ArHCH3+. The reactivities of the alkyl aromatics increase with increasing exothermicity (benzene → mesitylene) and there is an increasingly negative temperature coefficient of reactivity in the same order.

Ethyl cation transfer from diethylchloronium to alkyl aromatics studied by high pressure mass spectrometry

“…For B = benzene the reaction efficiency increases with increasing temperature (positive temperature coefficient) while for B = toluene or isopropylbenzene the reaction efficiency decreases with increasing temperature (negative temperature coefficient). A series of relative rate determinations for B = benzene, toluene, and mesitylene for which reaction exothermicity increases in the order given suggested that the magnitude of the negative temperature dependence increases with increasing exothermicity (6).…”

“…The order of reactivity of the different bases should be, according to the model, the same for (C2HJ2C1+ and (CH3)2C1+ but the temperature coefficients should change with change of AEO. (C2~5)2Cl+ is the exclusive long-lived ion in C2H5C1/CH4 mixtures under most ion source conditions whereas CH3C1/CH4 mixtures lead to both (CH3)2C1+ and C2H5C1CH:, each of which reacts with aromatics, the latter ion forming BC2Hf (4,6). The ion chemistry resulting from C2Hf addition may be followed using C2H5C1/CH4 mixtures without the complications resulting from a concurrent reaction.…”

An ICR mass spectrometry study of ion/molecule reactions between ethyl chloride and alkylamines

“…On the other hand, the enthalpy change of reaction [6] depends on the structure of the CSHl4N+ species, but if it corresponds to [(C3H7)NH2-(C2HS)]+, which is likely, then the heat of reaction would be slightly exothermic by = -21 kJ mol-'. As mentioned previously, reaction [6] which occurs in pure propylamine with a low rate constant (<lo-j2 cm3 s-I) (14) might be real, or may reflect the presence of small amounts of impurities. Thus, the contribution from reaction [5] must be quite significant in this system.…”

“…Dialkylhalonium ions have been used as alkylating agents in both gas and liquid phase reactions (3)(4)(5)(6)(7), and it is expected that diethylchloronium ions will react similarly. Such alkylation processes are bimolecular nucleophilic displacement reactions and are usually highly exothermic for bases such as dimethyl ether, ethanol, ammonia, and many aromatic bases (5,7,8).…”

The gas phase reactions of the trichloromethylium ion with alkyl aromatics, studied by high pressure mass spectrometry

“…If the arenium ion has a structure analogous to III, with NO, meta to the site of the proton, then its destabilizing influence should not be too much greater than that of CC13 since at this site only the inductive effect is operative (19 We have previously reported (20) that when CH3+ or C2Hs+ adds to mesitylene, the resulting arenium ion does transfer a proton, albeit slowly, to mesitylene. We have repeated that experiment with the results shown in Fig.…”