Showing papers on "Redox published in 1968"
TL;DR: In this paper, the role of holes and electrons in the mechanism of semiconductor electrodes being oxidized and reduced is discussed, with the main emphasis on the roles of holes in the reaction mechanism.
180 citations
TL;DR: Reduction of sulfate to sulfide in waterlogged soils was dependent on soil redox potential and pH, and little or no sulfide accumulated with aredox potential above -150 millivolts.
Abstract: Reduction of sulfate to sulfide in waterlogged soils was dependent on soil redox potential and pH. Little or no sulfide accumulated with a redox potential above -150 millivolts, or with a pH outside the range 6.5 to 8.5.
178 citations
143 citations
TL;DR: In this article, the anodic dissolution of GaP was investigated in both acid and acid solutions, and it was shown that surface states are involved in certain redox reactions, and the electroluminescence produced by applying a field between the electrode and a redox electrolyte was explained by assuming a radiative transition via surface states.
121 citations
TL;DR: In this paper, it was shown that 2-hydroxyadamantane is formed by a 1,2-hydride shift of the 1-adamantsyl cation.
82 citations
TL;DR: In this paper, the number-average molecular weights of the grafts were calculated based on the PAN and the COOH contents of the grafted cellulose, and a theoretical method to calculate the number average molecular weights was proposed.
Abstract: The ceric ion-cellulose redox system has been studied for grafting acrylonitrile on cotton fibers. Grafting yields are very high as compared to the persulfate-thiosulfate redox system reported earlier. Traces of copper sulfate in the reaction mixture do not increase grafting yields, unlike the persulfate-thiosulfate system. The high polymerization rate on cotton fibers is shown to be due to the reducing action of cellulose and not to the large surface area of cotton fibers. The Ce+4 consumption during grafting is higher than during oxidation of cellulose, indicating formation of homopolymer during the grafting reaction. Studies on the consumption of Ce+4 by model compounds such as D-glucose and α-methyl-D-glucoside show that the hemiacetal group in D-glucose is responsible for a faster rate of Ce+4 consumption. Formation of a Ce+4-alcohol complex also contributes to the initial fast rate of Ce+4 consumption. Studies on the oxidation of cellulose by Ce+4 indicate that the initial oxidative attack occurs on carbon atom 2, with the formation of a >CO group. On further oxidation, cleavage of the C2-C3 bond occurs as shown by the presence of glycol aldehyde determined chromatographically. Cellulose-polyacrylonitrile grafts have been isolated by an acetolysis treatment followed by extraction with dimethylformamide. Number-average molecular weights of the isolated fractions are approximately 50,000–55,000. A theoretical method to calculate the number-average molecular weights, based on the PAN and the COOH contents of the grafted cellulose, is described.
68 citations
TL;DR: In this paper, the authors showed that the dependence on noble metal substrates work functions in solution containing Cl ion or sulfate ion, noting anion effects, and that the anion effect is independent of the noble metal substrate.
Abstract: Electrodic redox reaction rates dependence on noble metal substrates work functions in solution containing Cl ion or sulfate ion, noting anion effects
65 citations
TL;DR: In this paper, carbon and redox balances including thirteen substances are presented in good agreement with the concept that the biosynthesis of I g. (dry matter) of yeast gives rise to the formation of about 6 mmoles of glycerol.
Abstract: Compared to alcoholic fermentation, the biosynthesis of a yeast cell is an oxidation process. To maintain the redox balance, this oxidation is counterbalanced by reduction of dihydroxyacetone phosphate to glycerol. Many other substances affecting the redox balance of the yeast cell are also formed as by-products of alcoholic fermentation. Carbon and redox balances including thirteen substances are presented in this paper; they are in good agreement with the concept that the biosynthesis of I g. (dry matter) of yeast gives rise to the formation of about 6 mmoles of glycerol.
58 citations
49 citations
TL;DR: In this article, the standard potential (reduction) of the system O2 + 2H+ + 2e = H2O2 is investigated. And it appears that the oxide system having potential E 0 lower than E′ 0 is a poor catalyst.
49 citations
TL;DR: In this paper, a potential-determining reaction exists for platinum electrodes which do not carry a deposit of ferric oxide (as is generally required in experiments of this type).
Abstract: Experiments in iron-rich interstitial water taken from sediment of Linsley Pond, Connecticut have shown that a potential-determining reaction exists for platinum electrodes which do not carry a deposit of ferric oxide (as is generally required in experiments of this type). The stable redox potentials were more negative than predicted by the equation Eh=0.965-0.177pH-0.059 log a Fe ++ by about 100 mv. The oxide layer on the electrode, where present, disappeared slowly in this water as its potential drifted down from an initial value close to the ferrous ion-ferric oxide Nernst potential. Current-potential curves revealed several electroactive substances, none of which could be positively identified with Fe (super ++) ion.
TL;DR: In this paper, the relationship between spectral transitions in complexed ions with redox potentials and activation energies of redox processes is discussed. And the spectral transitions are compared with existing experimental data.
TL;DR: Complexity constants for Hg(II)Cl− complexes have been determined at 25°C in 1 M NaClO4 ionic medium by potentiometric methods.
TL;DR: The electrochemical properties of NiO in the form of mosaic crystals have been examined in this paper, where voltammetry of this oxide in H 2 SO 4, HCl, HClO 4, and NaOH reveals a reversible peak at 0.9 V(he).
01 Jan 1968
TL;DR: The present discussion will center on a different type of reaction in which oxygen participates in many mammalian cells, which have been termed mixed function oxidation reactions — reactions which are catalyzed by a unique hemoprotein called cytochrome P-450.
Abstract: The central role of oxygen in many metabolic reactions of the cell is the general theme of this colloquium. Prof. Lubbers [1] has described the role of the hemoproteins, hemoglobin and myoglobin in oxygen transfer reactions whereas Prof. Chance [2] has presented his elegant experiments on the reduction of oxygen by the mitochondrial respiratory chain. The present discussion will center on a different type of reaction in which oxygen participates in many mammalian cells. These reactions are those which have been termed [3] mixed function oxidation reactions — reactions which are catalyzed [4] by a unique hemoprotein called cytochrome P-450.
TL;DR: In this paper, it was shown that trichloromethyl radicals are captured by ferrous chloride in a subsequent fast reaction, giving a carbenoid complex which decomposes bimolecularly into ferric chloride and tetrachloroethylene.
Abstract: The oxidation of ferrous chloride by carbon tetrachloride has been studied spectrophotometrically by initial-rate measurements of FeCl4– formation in acetonitrile as solvent and in the presence of an excess of chloride ion. A transient violet intermediate appears upon mixing of the reagents, considered to be a charge-transfer complex between ferrous chloride and carbon tetrachloride, which decomposes into FeCl4– and a trichloromethyl radical. This decomposition is the rate-determining step in the overall oxidation to ferric chloride. Trichloromethyl radicals are captured by ferrous chloride in a subsequent fast reaction, giving a carbenoid complex which decomposes bimolecularly into ferric chloride and tetrachloroethylene. in the presence of an olefin, dichlorocyclopropanes are also formed. The overall reaction is first-order in ferrous chloride and has a rate constant of 2·10–4l. mole–1 sec.–1 at 22°. The fast interaction of ferrous chloride and trichloromethyl radicals, and the subsequent reactions of the complex formed, are recognized as the main mode of termination in the radical-chain addition of carbon tetrachloride to olefins in a redox transfer-system. The rate constant of the reaction between cuprous chloride and carbon tetrachloride (CCl4+ CuCl[graphic omitted]CuCl2+·CCl3) is about 40 times smaller than the corresponding constant for the ferrous chloride reaction. The reaction reaches a quasi-equilibrium already at conversions into cupric chloride as low as 1·5%.
TL;DR: When supplemented with alpha-oxoglutarate and EDTA, homogenates readily adjust the redox state of the beta-hydroxybutyrate dehydrogenase system after it has been upset by the addition of either acetoacetate or beta-Hydroxy butyrate, taken to indicate that the reduction of aceto acetate in the homogenate was not an energy-linked process.
Abstract: 1. The redox state of the NAD couple of rat liver mitochondria, as measured by the [beta-hydroxybutyrate]/[acetoacetate] ratio, rapidly changed in the direction of oxidation during the preparation of homogenates in a saline medium. The value of the [beta-hydroxybutyrate]/[acetoacetate] ratio fell from 2.3 to 0.15 in 10min. EDTA diminished the fall and succinate prevented it. 2. The redox state of the rat liver cytoplasm, as measured by the [lactate]/[pyruvate] ratio, changed slightly in the direction of reduction during the preparation of homogenate. This was prevented by succinate. 3. In unsupplemented homogenates the differences in the redox states of mitochondria and cytoplasm decreased. Succinate and EDTA together maintained the differences within the physiological range. A measure of the ability of the mitochondria to maintain different redox states in mitochondria and cytoplasm is the value of the expression [lactate][acetoacetate]/[pyruvate][beta-hydroxybutyrate]. If there are no differences in the redox states of the NAD in the two cell compartments the value of the expression is 444 at 37 degrees . The value in the intact rat liver is between 4.7 and 21. 4. alpha-Oxoglutarate or glutamate were still more effective than succinate in maintaining high [beta-hydroxybutyrate]/[acetoacetate] ratios in the homogenates because these substrates supply a reducing agent of NAD(+) and, through succinate, an inhibitor of the oxidation of NADH. 5. When supplemented with alpha-oxoglutarate and EDTA, homogenates readily adjust the redox state of the beta-hydroxybutyrate dehydrogenase system after it has been upset by the addition of either acetoacetate or beta-hydroxybutyrate. 6. Amytal and rotenone raised the value of the [beta-hydroxybutyrate]/[acetoacetate] ratio. This is taken to indicate that the reduction of acetoacetate in the homogenates was not an energy-linked process. 7. 2,4-Dinitrophenol shifted the [beta-hydroxybutyrate]/[acetoacetate] ratio in the presence of succinate in favour of oxidation because it inhibited the oxidation of succinate and accelerated the oxidation of NADH. 8. Rotenone increased the rate of ketone-body formation of liver homogenates, though it decreased the rate of oxygen uptake.
TL;DR: Vitamin K 5 proved to have a preferential specificity toward cytochrome b as shown by its polarographic response to the addition of reagents that alter the electron transfer characteristics of the mitochondria.
TL;DR: In this article, a statistical review of all the current data available on the homogeneous oxidation of ammonia indicates that the activation energy is more precisely 37·7 ± 2·6 kcal mole−1.
TL;DR: In this article, the 2-mercaptosuccinic acid was studied in the pH range 2·4-4·4 at temperatures from 0-25° with a stopped-flow technique.
Abstract: The oxidation of 2-mercaptosuccinic acid by the oxy-ions of vanadium(V) has been studied in the pH range 2·4–4·4 at temperatures from 0–25° with a stopped-flow technique. The reaction proceeds via the formation of a coloured intermediate complex followed by a slower electron-transfer step. The intermediate has a stability constant of ten and at 15° the observed rate constant for its formation may be expressed as kobs=[44·5 + 465(T)] sec.–1 where T= 2-mercaptosuccinic acid. At the same temperature the rate constant for the redox process may be written as k1obs=[5·0 + 40(T)] sec.–1. The acid dissociation constants for 2-mercaptosuccinic acid have also been measured. Reaction of the intermediate leads to the formation of the disulphide, and a mechanism for the process is proposed. In the range studied, temperature has no significant effect on the rates.
Patent•
22 Jul 1968
TL;DR: A METAL SULFATE is converted to a METAL OXIDE and a metal dioxide by SUBJECTing it to a series of REDUCTION and OXIDATION STEPS.
Abstract: A METAL SULFATE IS CONVERTED TO A METAL OXIDE AND SULFUR DIOXIDE BY SUBJECTING IT TO A SERIES OF REDUCTION AND OXIDATION STEPS. DURING THE REDUCTION STEPS, THE SULFATE PRESENT IS CONVERTED TO SULFUR DIOXIDE, THE METAL SULFIDE AND THE METAL OXIDE. THE SUBSEQUENT OXIDIZING STEP CONVERTS THE METAL SULFIDE TO SULFUR DIOXIDE, METAL OXIDE, AND A SMALL AMOUNT OF METAL SULFATE. THE SULFUR DIOXIDE IS COLLECTED TO ANY SUITABLE MANNER, AND THE REDUCTION AND OXIDATION SYCLE IS REPEATED UNTIL A METAL OXIDE OF DESIRED PURITY IS OBTAINED.
TL;DR: In this article, a thermodynamic discussion of the Pt/O2 electrode in molten NaOH shows that the redox potential depends on po2, pH2O, ao22− and ao2−.
TL;DR: In this article, the standard exchange cd for IrCl62−, IrCl63− in 0·5 N HCl was determined at an anthracene electrode to be i0s = 1·5 - 7 × 10−3 A/cm2.
TL;DR: In this paper, the initial-stages of the reaction 2Fe(CN)63−+ 21−= 2Fe[CN)64−+ l2 have been measured and the suggested mechanism is in agreement with the observed kinetic form.
Abstract: Kinetics of the initial-stages of the reaction 2Fe(CN)63–+ 21–= 2Fe(CN)64–+ l2 have been measured. The reaction normally observed is a cation-catalysed process, although specific ion effects caused by both cations and anions may be present. The rate of reaction is relatively insensitive to general ionic-strength effects. The suggested mechanism is in agreement with the observed kinetic form, and we are able to include the interpretation of previously published data.
TL;DR: In this article, the reactions of pentacarbonyliron in liquid hydrogen chloride with the halogens, nitrosyl chloride, boron trichloride, and phosphorus pentafluoride were described.
Abstract: This paper describes the reactions of pentacarbonyliron in liquid hydrogen chloride with the halogens, nitrosyl chloride, boron trichloride, and phosphorus pentafluoride. Salts of the new cationic species, Fe(CO)5H+, Fe(CO)5Cl+, Fe(CO)5Br+, and Fe(CO)5NO+ were prepared and isolated. The structure of these cations is discussed in terms of their infrared and ultraviolet absorption spectra and magnetic properties.
TL;DR: In this paper, the authors measured the reaction between dichromate and iodide in acid solution under a variety of conditions and found that the initial reaction is accurately of the first order in acid chromate ion and of second order in both iodide and hydrogen ion.
Abstract: Kinetics of the reaction between dichromate and iodide in acid solution have been measured under a variety of conditions. By taking account of the equilibria present in the system we find that the initial reaction is accurately of the first order in acid chromate ion and of second order in both iodide and hydrogen ion. At a relatively early stage however the rate falls below that indicated by the initial kinetics. The redox potentials for the CrVI/CrIII and l0/l–1 couples show that there can be no overall detectable position of equilibrium; and the fall seems to be due to a reversible step in the mechanism involving l2 and CrIV. A satisfactory complete rate equation is thereby obtained.
TL;DR: In this article, the authors studied the rate of oxidation of malic acid by cobaltic ions in the range 0-21° by a stopped-flow technique and showed that two changes in absorbance are seen, namely, an initial increase associated with the formation of an intermediate followed by a slower decrease when the intramolecular electron transfer occurs.
Abstract: The rate of oxidation of malic acid by cobaltic ions has been studied in the range 0–21° by a stopped-flow technique. During the reaction, two changes in absorbance are seen, namely, an initial increase associated with the formation of an intermediate followed by a slower decrease when the intramolecular electron transfer occurs. The spectrum of the intermediate has been obtained in the range 250–300 mµ. The rate constants k1 and k2 for the reactions Co3++ HA [graphic omitted] CoHA3+ and CoOH2++ HA [graphic omitted] CoOHHA2+(where HA = malic acid) are 5·4 ± 1·2 and 70 ± 10 mole–1 sec.–1, respectively, at 7° and an ionic strength of 0·25M. The observed rate constant for the oxidation reaction may be expressed as kobs=[0·11 + 0·20/(H+)] at 12·7° and an ionic strength of 1·0M. Temperature studies yield activation energies of 15·3 ± 1·0 and 25·1 ± 1·0 kcal./mole for the oxidations involving CoHA3+ and CoOHHA2+ respecitively. The mechanisms of the reactions are discussed.