Colorimetric determination of trace levels of oxygen in gases with the photochemically generated methyl viologen radical-cation

Abstract

for 1M anion and 1M solvating agent concentrations. The varying magnitudes of these extraction constants may be attributed to the increasing acidity of the proton of the solvating species in the order chloroform < -amyl alcohol < pzerz-butylphenol.Effect of ZVjiV-Dimethylcaprylamide on Solvating Agent.It was of interest to determine if the schematic model postulated in Case I was reasonable. This was done by utilizing an electron donor solvating agent. This agent would not be expected to enhance partitioning of the ion pair. An experiment was carried out using fixed concentrations of dextromethorphan, bromide ion, and /z-zerz-butylphenol but adding increasing amounts of dimethylcaprylamide to the organic phase. The results shown in Figure 8 indicate that the addition of the amide actually reduced the partition coefficient. These results would suggest that the amide did not act as a solvating agent even when present in rather high concentrations. Further, the decrease in partitioning at constant p-ZerZ-butylphenol could be expected, since in previous studies in these laboratories it has been shown that phenols formed strong association complexes with disubstituted aliphatic amides (11). Therefore, the addition of the amide resulted in the complexation of the phenolic solvating agent and essen-(11) E. G. Shami, unpublished Ph.D. thesis, University of Wisconsin, 1964.

Acridines, Deazaflavins, Andtris(2,2'‐bipyridine)ruthenium as Catalysts for Photoproduction of Hydrogen From Organic Compounds

“…No attempt was made to determine the absolute quantum yield. Sweetser (1967) reported that photoreduction of methyl viologen by EDTA at p H 6 at 450 nm with catalytic quantities of proflavin had a quantum yield of 0.6. For each catalyst the rate of reduction of methyl viologen with the same intensity of the same incident light source was determined.…”

Electron Paramagnetic Resonance of Nitrogenase and Nitrogenase Components from Clostridium pasteurianum W5 and Azotobacter vinelandii OP

“…The vacuum system included a liquid-nitrogencooled trap, and the inert gas (argon) was scrubbed to below 1 ppm 02 by passage over H2-activated BTS catalyst (Kontes Qlass Co.) at 200'C. Oxygen in the inert gas stream was measured by the method of Sweetser (16). The serum cap and stopcock on the sidearm of the Thunberg-EPR tube allows one to degas the system empty, with five or more cycles of gassing and evacuation, with the sidearm stopcock open.…”

The Purification and Characterization of the o-type Cytochrome Oxidase from Methylophilus methylotrophus, and its Reconstitution into a 'Methanol Oxidase' Electron Transport Chain

“…O2 -according to the manufacturer) led to a 50% decrease in activity of the oxidase, thus indicating that the K , value for the pure oxidase must be very low (probably less than 1 p~). Complete removal of O2 by passing the N2 through the solution of Sweetser (1967) prior to sparging the reaction mixture completely prevented oxidation of cytochrome c by the added oxidase.…”