Kinetics of Decomposition of Nitric Oxide at Elevated Temperatures. I. Rate Measurements in a Quartz Vessel

1952 ◽  
Vol 20 (1) ◽  
pp. 22-24 ◽  
Author(s):  
Henry Wise ◽  
Maurice F. Frech
Keyword(s):  
Nitric Oxide ◽  
Elevated Temperatures ◽  
Kinetics Of Decomposition ◽  
Kinetics Of

Kinetics of Decomposition of Nitric Oxide

1953 ◽  
Vol 21 (4) ◽  
pp. 751-751 ◽  
Author(s):  
Frederick Kaufman ◽  
John R. Kelso
Keyword(s):  
Nitric Oxide ◽  
Kinetics Of Decomposition ◽  
Kinetics Of

Synthesis and kinetics of decomposition of some novel S-nitrosothiols

1999 ◽  
Vol 77 (5-6) ◽  
pp. 550-556 ◽  
Author(s):  
Andrew P Munro ◽  
D Lyn H. Williams
Keyword(s):  
Nitric Oxide ◽  
Room Temperature ◽  
Alternative Pathway ◽  
Copper Catalysis ◽  
Induction Periods ◽  
Kinetics Of Decomposition ◽  
Initial Generation ◽  
Kinetics Of ◽  
Reaction Schemes

TheS-nitrosothiols 2-acetamido-2-deoxy-S-nitroso-1-thio-β-D-glucopyranose 3,4,6-triacetate (GPSNO) and S-nitroso-N-carbamyl-D,L-penicillamine (SNCP) were synthesized by S-nitrosation of the corresponding thiols, isolated, and fully characterized. The nitrosothiol (TGSNO) from 1-thioglycerol was obtained as a red gelatinous liquid, which decomposed rapidly at room temperature and so was not characterized. The kinetics of decomposition of GPSNO showed that there is a surprisingly large thermal pathway overlaid with a Cu2+/RS- catalyzed reaction. The results strongly suggest that the product disulfide complexes Cu2+ (for which there is some spectral evidence), leading to incomplete conversion by that route. Ascorbate also acts as a Cu2+ reductant. Another S-nitroso sugar, S-nitroso-1-thio-β-D-glucose (SNTG), behaved very similarly from solutions generated and used in situ. The decomposition of TGSNO shows induction periods suggesting that slow initial generation of Cu+ (the true catalyst) is taking place. There appears to be also a significant alternative pathway (analogous to that found for GPSNO), where the rate appears to be independent of [Cu2+], but very unusually this pathway is effectively halted by addition of EDTA either at the start of the reaction or at a later time. Reaction schemes are put forward to account for these unusual reaction characteristics.Key words: S-nitrosothiols, nitric oxide, ascorbate, copper catalysis.

Kinetics and Mechanism of Decomposition of 1,3-Bis(4-methylphenyl)triazene Catalyzed with Substituted Benzoic Acids in 25% Aqueous Methanol-General or Specific Catalysis?

1994 ◽  
Vol 59 (9) ◽  
pp. 2029-2041
Author(s):  
Oldřich Pytela ◽  
Taťjana Nevěčná
Keyword(s):  
Benzoic Acids ◽  
Hammett Equation ◽  
Aqueous Methanol ◽  
Mechanism Of Decomposition ◽  
Kinetics Of Decomposition ◽  
Independent Variable ◽  
Amino Derivatives ◽  
Substituted Benzoic Acids ◽  
The Individual ◽  
Kinetics Of

The kinetics of decomposition of 1,3-bis(4-methylphenyl)triazene catalyzed with 13 substituted benzoic acids of various concentrations have been measured in 25 vol.% aqueous methanol at 25.0 °C. The rate constants observed (297 data) have be used as values of independent variable in a series of models of the catalyzed decomposition. For the catalytic particles were considered the undissociated acid, its conjugated base, and the proton in both the specific and general catalyses. Some models presumed formation of reactive or nonreactive complexes of the individual reactants. The substituent effect is described by the Hammett equation. The statistically best model in which the observed rate constant is a superposition of a term describing the dependence on proton concentration and a term describing the dependence on the product of concentrations of proton and conjugated base is valid with the presumption of complete proton transfer from the catalyst acid to substrate, which has been proved. The behaviour of 4-dimethylamino, 4-amino, and 3-amino derivatives is anomalous (lower catalytic activity as compared with benzoic acid). This supports the presumed participation of conjugated base in the title process.

On the use of Ozawa/Flynn/Wall method to determine aging activation energy for elastomers

2021 ◽  
pp. 009524432110203
Author(s):  
Sudhir Bafna
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Weight Loss ◽  
Oxygen Consumption ◽  
Dwell Time ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Degradation Mechanism ◽  
Kinetics Of ◽  
Wall Method

It is often necessary to assess the effect of aging at room temperature over years/decades for hardware containing elastomeric components such as oring seals or shock isolators. In order to determine this effect, accelerated oven aging at elevated temperatures is pursued. When doing so, it is vital that the degradation mechanism still be representative of that prevalent at room temperature. This places an upper limit on the elevated oven temperature, which in turn, increases the dwell time in the oven. As a result, the oven dwell time can run into months, if not years, something that is not realistically feasible due to resource/schedule constraints in industry. Measuring activation energy (Ea) of elastomer aging by test methods such as tensile strength or elongation, compression set, modulus, oxygen consumption, etc. is expensive and time consuming. Use of kinetics of weight loss by ThermoGravimetric Analysis (TGA) using the Ozawa/Flynn/Wall method per ASTM E1641 is an attractive option (especially due to the availability of commercial instrumentation with software to make the required measurements and calculations) and is widely used. There is no fundamental scientific reason why the kinetics of weight loss at elevated temperatures should correlate to the kinetics of loss of mechanical properties over years/decades at room temperature. Ea obtained by high temperature weight loss is almost always significantly higher than that obtained by measurements of mechanical properties or oxygen consumption over extended periods at much lower temperatures. In this paper, data on five different elastomer types (butyl, nitrile, EPDM, polychloroprene and fluorocarbon) are presented to prove that point. Thus, use of Ea determined by weight loss by TGA tends to give unrealistically high values, which in turn, will lead to incorrectly high predictions of storage life at room temperature.

scholarly journals Influence of Heterointerfaces on the Kinetics of Oxygen Surface Exchange on Epitaxial La1.85Sr0.15CuO4 Thin Films

2021 ◽  
Vol 11 (9) ◽  
pp. 3778
Author(s):  
Gene Yang ◽  
So-Yeun Kim ◽  
Changhee Sohn ◽  
Jong K. Keum ◽  
Dongkyu Lee
Keyword(s):  
Thin Films ◽  
Oxygen Vacancies ◽  
Elevated Temperatures ◽  
Surface Exchange ◽  
Electrical Conductivity Relaxation ◽  
Exchange Kinetics ◽  
Relaxation Curves ◽  
Kinetics Of ◽  
Oxygen Surface Exchange ◽  
Oxygen Surface

Considerable attention has been directed to understanding the influence of heterointerfaces between Ruddlesden–Popper (RP) phases and ABO3 perovskites on the kinetics of oxygen electrocatalysis at elevated temperatures. Here, we report the effect of heterointerfaces on the oxygen surface exchange kinetics by employing heteroepitaxial oxide thin films formed by decorating LaNiO3 (LNO) on La1.85Sr0.15CuO4 (LSCO) thin films. Regardless of LNO decoration, tensile in-plane strain on LSCO films does not change. The oxygen surface exchange coefficients (kchem) of LSCO films extracted from electrical conductivity relaxation curves significantly increase with partial decorations of LNO, whereas full LNO coverage leads to the reduction in the kchem of LSCO films. The activation energy for oxygen exchange in LSCO films significantly decreases with partial LNO decorations in contrast with the full coverage of LNO. Optical spectroscopy reveals the increased oxygen vacancies in the partially covered LSCO films relative to the undecorated LSCO film. We attribute the enhanced oxygen surface exchange kinetics of LSCO to the increased oxygen vacancies by creating the heterointerface between LSCO and LNO.

scholarly journals Kinetics of electron transfer from NADH to the Escherichia coli nitric oxide reductase flavorubredoxin

FEBS Journal ◽  
2006 ◽  
Vol 274 (3) ◽  
pp. 677-686 ◽  
Author(s):  
João B. Vicente ◽  
Francesca M. Scandurra ◽  
João V. Rodrigues ◽  
Maurizio Brunori ◽  
Paolo Sarti ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Escherichia Coli ◽  
Electron Transfer ◽  
Nitric Oxide Reductase ◽  
Kinetics Of
Sign in / Sign up

Export Citation Format

Share Document