title: Chemical and thermal stability of N-heterocyclic ionic liquids in catalytic C-H activation reactions.
abstract: (1)H-NMR spectrum analyses are applied to study the chemical and thermal stability of selected N-heterocyclic ionic liquids within the reaction system that can highly efficiently activate a C-H bond of methane and convert it into the C-O bond in methanol. Our results indicate that under such reaction conditions involving using a powerful Pt-based catalyst and strong acidic solvent, the aromatic ring of an imidazolium cation becomes unstable generating an ammonium ion (NH(4)(+)). Our results also suggest that the instability of the imidazolium ring is more chemically (participation in reactions) than thermally based. Modifications of the aromatic ring structure such as pyrazolium and triazolium cations can increase the chemical/thermal stability of ionic liquids under these reaction conditions.
authors.affiliation: School of Environment Science and Engineering, Tianjin University, Tianjin, 300072, China; State Key Laboratory of Engines, Tianjin University, Tianjin, 300072, China.
authors.forename: Guanyi
authors.initials: G
authors.lastname: Chen
authors.forename: Shujuan
authors.initials: S
authors.lastname: Kang
authors.forename: Qisheng
authors.initials: Q
authors.lastname: Ma
authors.forename: Weiqun
authors.initials: W
authors.lastname: Chen
authors.forename: Yongchun
authors.initials: Y
authors.lastname: Tang
keywords: 1H-NMR; C-H activation; chemical stability; ionic liquid; thermal stability