The gas-phase methylation of benzene and toluene

Spectroscopic Characterization of the Product Ions Formed by Electron Ionization of Adamantane

“…o-pt is computed to be 5.7 kJ/mol higher in energy than the para isomer, which is the lowest energy isomer considered here. [33,45,[49][50][51] Our infrared spectroscopic assignment can best be compared with a mass spectrometric gas-phase titration study of C 7 H 9 + ions formed by electron ionization of two monoterpenes, a-pinene and limonene (two C 10 H 16 isomers of adamantane). Significant contributions by other protonated non-aromatic isomers are unlikely, as these are thermodynamically far more unfavorable.…”

Toluenium and Other Gaseous Methylbenzenium Ions: Complex Interplay of Protonated Arenes and Cyclo‐olefins

“…The recent report by Wang, Bierbaum and their associates disclosed an important and detailed complementation of the half-century-long studies of the bimolecular formation of toluenium and xylenium ions by electrophilic attack of methyl cations on benzene and toluene, respectively (Wang et al, 2018). This reaction has always been and will remain prototypical for electrophilic aromatic substitution processes and Friedel-Crafts reactions, in particular (Dewar, 1946;Taylor, 1990;Olah, 1971;March, 1992).…”

“…▪ KUCK recent calculations by Wang,2p) (Wang et al, 2018). In fact, ions i-[1+H] + can be considered a key species of the overall fragmentation of gaseous C 7 H 9 + ions by both 1,2-elimination of H 2 and by 1,1-elimination of CH 4 .…”

“…In view of such an extended series of experimental and theoretical studies, it is satisfying to note that experimental work on the bimolecular formation of toluenium ions under flow-tube conditions, that is, in the "dense" gas phase, has been accomplished recently in great detail (Wang et al, 2018). In fact, this work on the C 7 H 9…”

“…+ manifold has a decades-long background (see a remark in the Acknowledgments). In that project, Wang, Bierbaum, DePuy and their associates studied both the reaction of the methyl cation with benzene and that of the phenyl cation with methane by flowing afterglow/selected ion flow/drift tube (FA-SIFT-Drift) mass spectrometry (Bierbaum, 2015;Wang et al, 2018). The C 7 H 9 + ions formed from the encounter of CH 3 + and benzene were found to eliminate H 2 and CH 4 and to lose CH 3…”