Methane activation and oxidation in sulfuric acid

Goeppert, Alain (author)

Dinér, Peter (author): Organic Chemistry Department of Chemistry Göteborg University

Ahlberg, Per (author)

Sommer, Jean (author)

(creator_code:org_t)

2002
2002
English.
In: Chemistry - A European Journal. - 0947-6539 .- 1521-3765. ; 8:14, s. 3277-3283

Related links:: https://urn.kb.se/re...; show more...; https://doi.org/10.1...; show less...

Abstract Subject headings

The H/D exchange observed when methane is contacted with D(2)SO(4) at 270-330 degrees C shows that the alkane behaves as a sigma base and undergoes rapid and reversible protonation at this temperature. DFT studies of the hydrogen exchange between a monomer and a dimer of sulfuric acid and methane show that the transition states involved in the exchange are bifunctional, that is one hydrogen atom is transferred from a hydroxy group in sulfuric acid to methane, while one hydrogen atom is abstracted from methane by a non-hydroxy oxygen atom in sulfuric acid. All the transition states include a CH(5) moiety, which shows similarities to the methanium ion CH(5) (+). The calculated potential activation energy of the hydrogen exchange for the monomer is 174 kJ mol(-1), which is close to the experimental value (176 kJ mol(-1)). Solvation of the monomer and the transition state of the monomer with an extra sulfuric acid molecule, decrease the potential activation energy by 6 kJ mol(-1). The acid-base process is in competition, however, with an oxidative process involving methane and sulfuric acid which leads to CO(2), SO(2), and water, and thus to a decrease of acidity and loss of reactivity of the medium.

By the author/editor: Goeppert, Alain; Dinér, Peter; Ahlberg, Per; Sommer, Jean

About the subject

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