Solution-phase Oxidation Research Articles

Oxidation of benzaldehyde in films by Oxo-Cr(V) salen derivatives at solid/liquid interface

The oxidation of benzaldehyde as a film on a solid surface by various substituted oxochromium(V) salen in solution has been studied by monitoring the change in contact angle of the oxidant at the film/liquid interface utilizing a Teflon cell of known hydrodynamics and controlled convection/diffusion. The kinetics of the redox reaction in bulk has been monitored by measuring the change in absorbance of the oxidant solution. The interfacial study permits analysis of adsorption of the oxidant followed by the oxidation of the substrate under pseudo-first-order conditions. A comparison of the independent surface-averaged kinetic data with those obtained in the solution phase oxidation reaction is made and a model is presented for the mechanism of the interfacial reaction. The kinetic investigation shows that the rate of oxidation is accelerated in the presence of an electron-withdrawing group and is faster at the solid/liquid interface compared to the bulk. The probable mechanism of the redox reaction is discussed.

Unequivocal determination of metal atom oxidation state in naked heme proteins: Fe(III)myoglobin, Fe(III)cytochrome c, Fe(III)cytochrome b5, and Fe(III)cytochrome b5 L47R

Unambiguous determination of metal atom oxidation state in an intact metalloprotein is achieved by matching experimental (electrospray ionization 9.4 tesla Fourier transform ion cyclotron resonance) and theoretical isotopic abundance mass distributions for one or more holoprotein charge states. The iron atom oxidation state is determined unequivocally as Fe(III) for each of four gas-phase unhydrated heme proteins electrosprayed from H 2O: myoglobin, cytochrome c, cytochrome b5, and cytochrome b5 L47R (i.e., the solution-phase oxidation state is conserved following electrospray to produce gas-phase ions). However, the same Fe(III) oxidation state in all four heme proteins is observed after prior reduction by sodium dithionite to produce Fe(II) heme proteins in solution: thus proving that oxygen was present during the electrospray process. Those results bear directly on the issue of similarity (or lack thereof) of solution-phase and gas-phase protein conformations. Finally, infrared multiphoton irradiation of the gas-phase Fe(III)holoproteins releases Fe(III)heme from each of the noncovalently bound Fe(III)heme proteins (myoglobin, cytochrome b5 and cytochrome b5 L47R), but yields Fe(II)heme from the covalently bound heme in cytochrome c.

Formation and Measurement of Ozone and Nitric Acid in a High Voltage DC Negative Metallic Point-to-Aqueous-Plane Continuous Corona Reactor

AbstractOzone and nitric acid were formed when high voltage was applied across a metal (stainless steel) point and liquid (water) plane at atmospheric pressure and room temperature. Ozone was observed in the gas-phase and nitric acid in the liquid-phase. The gas-phase concentration of ozone reached a power-dependent steady-state whereas the nitric acid concentration in solution increased linearly with time. The rate of formation of ozone increased with increasing current. Aqueous solutions of potassium iodide were exposed to corona discharge to determine the amount of gas-phase ozone available to oxidize liquid-phase solutes. The result of the test with KI suggests that ozone is the major oxidant in the solution phase. An optimum point-to-plane distance of 1.5 cm was observed for both ozone production and solution phase oxidation. Corona discharge effectively destroyed both non-volatile organic compounds such as methylene blue and volatile compounds such as carbon tetrachloride in aqueous solutions.

Oxidation chemistry of chloric acid in NOx/SOx and air toxic metal removal from gas streams

AbstractChloric acid, HClO3, is a new oxidizer which has recently been shown to be an effective agent in the simultaneous removal of NOx and/or SOx from combustion flue gases and various chemical processes, including nitrations and metal pickling. Aqueous chloric acid readily reacts with NO and SO2 even in dilute solutions at ambient temperatures. Chlorine dioxide, ClO2, is formed as a chemical intermediate in the solution phase oxidation reactions. The oxidation by‐products of NO include NO2 and nitric acid. The ClO2 generated from the solution phase reactions also participates in gas phase oxidation reactions with NO and NO2. The combined solution phase and fast gas phase reaction chemistries provide the means for creating a new type of high performance NOx/SOx removal process. Wet scrubber based pilot plant tests have demonstrated up to 99% removal of NO.Additional recent research work has shown that chloric acid is an effective reagent for the removal of air toxic metals, such as elemental mercury, which are present in the waste gas output streams from incinerators, hydrogen from mercury cell chlor‐alkali plants, and flue gases of coal‐fired power plants. Work in this area is being conducted by Argonne National Laboratories and Olin.This paper discusses the oxidation chemistry of chloric acid and its unique solution and gas phase reactions with NO, SO2, and air toxics in wet scrubber type process equipment.

Kinetic modeling of manganese(II) oxidation by chlorine dioxide and potassium permanganate

Oxidation of Mn(II) by potassium permanganate and chlorine dioxide was investigated for the environmental conditions of pH, temperature, and initial Mn(II) concentrations typically observed in water treatment. For the conditions examined, oxidation reactions are rapid, with completion of the reactions within ∼30 s. A kinetic model based on solution-phase oxidation, adsorption, and surface oxidation mechanisms was developed that successfully simulates experimental data

Low-temperature, specific methane oxidation

The first example of catalytic, low-temperature, solution-phase oxidation of methane to a methanol derivative has come from the lab of chemistry professor Ayusman Sen of Pennsylvania State Universi...

Low-temperature, palladium(II)-catalyzed, solution-phase oxidation of methane to methanol derivative

On propose un mecanisme electrophile plutot qu'un mecanisme radicalaire pour l'oxydation etudiee

Applications of oxygen polarography to drug stability testing and formulation development: solution-phase oxidation of hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors.

The kinetics of oxidation of the HMG-CoA reductase inhibitors lovastatin, simvastatin, L-157,012, and L-647,318 were studied in an aqueous surfactant solution. A thermally labile free radical initiator was used to attain measurable reaction rates at 40 degrees C and rate constants were determined by measuring oxygen consumption using an oxygen electrode. The stability of the drugs was found to increase in the order lovastatin = simvastatin less than L-157,012 less than L-647,318. The addition of butylated hydroxyanisole (BHA) was found to stabilize the drugs. For the oxidation of lovastatin, the effectiveness of antioxidants increased in the order propyl gallate less than BHA less than alpha-tocopherol. It is concluded that the stability of oxidizable drugs can be rapidly and conveniently assessed by the techniques described herein.