Douglas J. Taube

A Mercury-Catalyzed, High-Yield System for the Oxidation of Methane to Methanol

A homogeneous system for the selective, catalytic oxidation of methane to methanol via methyl bisulfate is reported. The net reaction catalyzed by mercuric ions, Hg(II), is the oxidation of methane by concentrated sulfuric acid to produce methyl bisulfate, water, and sulfur dioxide. The reaction is efficient. At a methane conversion of 50 percent, 85 percent selectivity to methyl bisulfate (∼43 percent yield; the major side product is carbon dioxide) was achieved at a molar productivity of 10–7 mole per cubic centimeter per second and Hg(II) turnover frequency of 10–3 per second. Separate hydrolysis of methyl bisulfate and reoxidation of the sulfur dioxide with air provides a potentially practical scheme for the oxidation of methane to methanol with molecular oxygen. The primary steps of the Hg(II)-catalyzed reaction were individually examined and the essential elements of the mechanism were identified. The Hg(II) ion reacts with methane by an electrophilic displacement mechanism to produce an observable species, CH3HgOSO3H, 1. Under the reaction conditions, 1 readily decomposes to CH3OSO3H and the reduced mercurous species, Hg22+ The catalytic cycle is completed by the reoxidation of Hg22+ with H2SO4 to regenerate Hg(II) and byproducts SO2 and H2O. Thallium(III), palladium(II), and the cations of platinum and gold also oxidize methane to methyl bisulfate in sulfuric acid.

Regioselective hydrophenylation of olefins catalyzed by an Ir(III) complex

Abstract The novel, anti-Markovnikov, arylation of olefins with benzene to produce straight-chain alkylbenzenes with higher selectivity than branched alkylbenzenes is catalyzed by [Ir(μ-acac-O,O′,C3)(acac-O,O′)(acac-C3)]2 (acac=acetylacetonato), 1 [J. Am. Chem. Soc. 122 (2000) 7414]. The reaction of benzene with propylene gave n-propylbenzene and cumene in 61 and 39% selectivities, respectively. The reaction of benzene and styrene afforded 1,2-diphenylethane in 98% selectivity. Considering the anti-Markovnikov regioselectivity and lack of inhibition by water, we propose that the reaction does not proceed via a Friedel–Crafts, carbocation, mechanism. Complex 1, amongst the various transition metal complexes examined, is the most efficient for catalyzing the anti-Markovnikov olefin arylation. The crystal structure of complex 1 was solved and is consistent with a binuclear Ir(III) structure with three different types of coordinated acac ligands as reported by earlier solution IR and NMR analyses. [Ir(μ-acac-O,O′,C3)(acac-O,O′)Cl]2, 2, was prepared by the reaction of complex 1 with benzoyl chloride, and the crystal structure was also reported.

Reactivities of activated metal carbonyl clusters. Ligand substitution kinetics of the ruthenium methoxycarbonyl adduct Ru3(CO)11(CO2CH3)

La reaction de Ru 3 (CO) 11 (CO 2 CH 3 ) − avec le phosphite de trimethyle en solution sous CO, donne des produits neutres Ru 3 (CO) 11 P(OCH 3 ) 3 ou Ru 3 (CO) 10 (P(OCH) 3 ) 3 ) 2 suivant les conditions. Mecanisme de ces substitutions

High yield conversion of methane to methyl bisulfate catalyzed by iodine cations

Iodine in 2% oleum is an efficient catalyst for the selective, high yield oxidation of methane to methyl bisulfate.

A Novel, High Yield System for the Oxidation of Methane to Methanol*

Abstract The selective oxidation of methane to methanol is an important scientific and commercial objective. A novel, homogeneous system for the selective, catalytic oxidation of methane to methanol via methyl bisulfate is reported. The net reaction catalyzed by mercuric ions, Hg(II), is the oxidation of methane by concentrated sulfuric acid to produce methyl bisulfate, water, and sulfur dioxide. The reaction is efficient. At a methane conversion of 50%, 85% selectivity to methyl bisulfate (˜43% yield, the major side product is carbon dioxide) was achieved at a molar productivity of 10 -7 mol/cm 3 .s and Hg(II) turnover frequency of 10 -3 s -1 Separate hydrolysis of methyl bisulfate and reoxidation of the sulfur dioxide with air provides a potentially practical scheme for the oxidation of methane to methanol with molecular oxygen. This is the highest single-pass yield of methanol so far reported for a catalytic methane oxidation. The primary steps of the Hg(II)-catalyzed reaction were individually examined and the essential elements of the mechanism were identified. The Hg(II) ion reacts with methane by an electrophilic displacement mechanism to produce an observable species, CH 3 HgOSO 3 H, 1. Under the reaction conditions, 1 readily decomposes to CH 3 OSO 3 H and the reduced mercurous species, Hg 2 2+ . The catalytic cycle is completed by the reoxidation of Hg 2 2+ with H 2 S0 4 to regenerate Hg(II) and byproducts SO 2 and H 2 O. Thallium(III), palladium(II), and the cations of platinum and gold also oxidize methane to methyl bisulfate in sulfuric acid.

High Yield, Low Temperature Oxidation of Methane to Methanol

Developing methods for the direct oxidation of alkanes to fuel and chemicals will lead to a paradigm shift in the manufacture of chemicals and fuels in the 21st century. We wish to report the development of novel catalysts that allow the direct, low temperature, oxidative conversion of methane to a methanol equivalent product in 70% one-pass yield. To our knowledge, this is the highest one-pass yield ever reported for methane oxidation to a methyl product. The keys to achieving this high yield are: A) the development of novel catalysts that are stable and active for the oxidation of the CH bonds of methane at temperatures as low as 100°C and B) the chemical “protection” of the methanol product from over-oxidation by esterification. The catalysts utilized are novel ligated Pt complexes based on the bidiazine ligand family. A particularly effective oxidation system is based on 20mM solutions of (bipyrimidine)PtC12 in concentrated sulfuric acid. Reaction of methane at 500 psig at 250°C with this solution results in 90% conversion of methane to methyl bisulfate in 80% selectivity (70% one-pass yield) based on added methane.