Methyl bisulfate

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Methyl bisulfate is CH₃OSO₃H. This compound is the combination of the hypothetical methyl cation and the bisulfate anion, written HSO₄^- but better described with the formula HOSO₃^-. The significance of (CH₃)HSO₄ is that it is an intermediate in the hydrolysis of the important reagent dimethyl sulfate, (CH₃)₂SO₄:

(CH₃)₂SO₄ + H₂O → (CH₃)HSO₄ + CH₃OH

Methyl bisulfate is an acid:

(CH₃)HSO₄ → (CH₃)SO₄^- + H⁺

Methyl bisulfate came into the public view in 1998 with the discovery that certain platinum complexes catalyze the reaction of CH₄ by SO₃ and O₂:

CH₄ + SO₃ 1/2 O₂ → (CH₃)HSO₄

This discovery pointed to a possible method for upgrading inexpensive and abundantly available methane (natural gas) into methanol, which is both a more useful chemical and more easily shipped than methane. The process is proposed to proceed via an intermediate containing the Pt-CH₃ group.

Salts of (CH₃)SO₄^- are commercially available, e.g. tris(2-hydroxyethyl)methylammonium methylsulfate (CAS #29463-06-7).

[edit] References

Robertson, R. E.; Sugamon, S.E. "The Hydrolysis of Dimethyl Sulfate and Diethyl Sulfate in Water" Canadian Journal of Chemistry, volume 44 (1966) page 1728–1730.
Hristov, I. H.; Ziegler, T. "The Possible Role of SO₃ as an Oxidizing Agent in Methane Functionalization by the Catalytica Process. A Density Functional Theory Study" Organometallics (2003), volume 22, pages 1668-1674.
Periana, R. A.; Mirinov, O.; Taube, D. J.; Gamble, S "High Yield Conversion of Methane to Methyl Bisulfate Catalyzed by Iodine Cations" Chemical Communications (2002), pages 2376-2377.
Wolf, D. "High Yields of Methanol from Methane by C-H Bond Activation at Low Temperatures" Angewandte Chemie, International Edition (1999), volume 37, 3351-3353.
Periana, R. A.; Taube, D. J.; Gamble, S.; Taube, H.; Satoh, T.; Fujii, H. "Platinum Catalysts for the High-Yield Oxidation of Methane to a Methanol Derivative" Science (1998), volume 280, pages 560-564.