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 ( approximately 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, 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)SO(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.

Potentials for the thermal cell (25°C) normalAg‐normalAgCl/normalKCl/normalAgCl‐normalAgfalse(T°Cfalse) as a function of the concentration of normalKCl false(0.0050–0.505Mfalse) and temperature false(T=25°–275°Cfalse) are reported. The thermal cell potentials are combined with isothermal potentials for the silver‐silver chloride electrode at elevated temperatures to calibrate external normalAg/normalAgCl electrodes as pseudothermodynamic standards for the investigation of electrochemical processes in high temperature aqueous systems.

The use of palladium hydride electrodes (Pd black on Pd, Pt, and Au) for the measurement of pH in high temperature aqueous systems (298°–548°K) is described. The electrodes were calibrated against boric acid/lithium hydroxide buffer solutions, whose pHT vs. temperature profiles have been calculated using known dissociation constants for the components. Linear potentialvs. pH correlations are observed for all temperatures studied. However, the gradients of the correlations deviate from the predicted Nernstian values. Furthermore, thermodynamic analyses of the systems demonstrate that above 373°K the observed potential deviates significantly from the equilibrium values calculated on the supposition that the potential‐determining reaction is H++e−⇄Hfalse(normalPd,α+βfalse) . Possible reasons for the observed deviation from ideal behavior are identified.