The protonation of cyclopropane by gaseous Bronsted acids of varying strength in radiolytic experiments at atmospheric pressure leads to two distinct C3H7+ isomers that have been sampled by their reaction with benzene. The neutral end products, nC(3)H(7)-C6H5 and iC(3)H(7)-C6H5, arise from the electrophilic aromatic substitution reaction with the cC(3)H(7)(+) and iC(3)H(7)(+) ions, respectively. Their relative abundance was studied as a function of pressure, temperature, and the presence of additives in the gaseous systems; the results indicate a large extent of isomerization to the thermodynamically favored iC(3)H(7)(+) from the protonation by strong acids. The presence of a kinetic barrier prevents any thermal isomerization from taking place in the time frame of 10(-8) s. In the peculiar case in which protonated benzene is the Bronsted acid, C3H7+ ions are formed in the presence of neutral benzene within the same ion - molecule complex. The ensuing reaction shows that cC(3)H(7)(+) ions are formed exclusively and react in the 10(-10) s(-1) estimated lifetime of the complex. Still, such cC(3)H(7)(+) ions undergo complete randomization of their hydrogen atoms; this points to a low kinetic barrier for the process. Agreement is found between the reported experimental results and updated computations of the relevant species in the C3H7+ potential energy surface.

The protonation of gaseous cyclopropane / Chiavarino, Barbara; Crestoni, Maria Elisa; Andrey A., Fokin; Fornarini, Simonetta. - In: CHEMISTRY-A EUROPEAN JOURNAL. - ISSN 0947-6539. - STAMPA. - 7:13(2001), pp. 2916-2921. [10.1002/1521-3765(20010702)7:13<2916::aid-chem2916>3.0.co;2-0]

The protonation of gaseous cyclopropane

CHIAVARINO, Barbara;CRESTONI, Maria Elisa;FORNARINI, Simonetta
2001

Abstract

The protonation of cyclopropane by gaseous Bronsted acids of varying strength in radiolytic experiments at atmospheric pressure leads to two distinct C3H7+ isomers that have been sampled by their reaction with benzene. The neutral end products, nC(3)H(7)-C6H5 and iC(3)H(7)-C6H5, arise from the electrophilic aromatic substitution reaction with the cC(3)H(7)(+) and iC(3)H(7)(+) ions, respectively. Their relative abundance was studied as a function of pressure, temperature, and the presence of additives in the gaseous systems; the results indicate a large extent of isomerization to the thermodynamically favored iC(3)H(7)(+) from the protonation by strong acids. The presence of a kinetic barrier prevents any thermal isomerization from taking place in the time frame of 10(-8) s. In the peculiar case in which protonated benzene is the Bronsted acid, C3H7+ ions are formed in the presence of neutral benzene within the same ion - molecule complex. The ensuing reaction shows that cC(3)H(7)(+) ions are formed exclusively and react in the 10(-10) s(-1) estimated lifetime of the complex. Still, such cC(3)H(7)(+) ions undergo complete randomization of their hydrogen atoms; this points to a low kinetic barrier for the process. Agreement is found between the reported experimental results and updated computations of the relevant species in the C3H7+ potential energy surface.
gas phase kinetics; gas-phase reactions; ion-molecule complexes; isomerization; proton transfer reactions; proton transport; radiolysis; reaction mechanism; structure elucidation
01 Pubblicazione su rivista::01a Articolo in rivista
The protonation of gaseous cyclopropane / Chiavarino, Barbara; Crestoni, Maria Elisa; Andrey A., Fokin; Fornarini, Simonetta. - In: CHEMISTRY-A EUROPEAN JOURNAL. - ISSN 0947-6539. - STAMPA. - 7:13(2001), pp. 2916-2921. [10.1002/1521-3765(20010702)7:13<2916::aid-chem2916>3.0.co;2-0]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/251846
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