scispace - formally typeset
Search or ask a question
Topic

Elementary reaction

About: Elementary reaction is a research topic. Over the lifetime, 2972 publications have been published within this topic receiving 76110 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: In this paper, the rate of reaction of muonium atoms with bromine molecules in an argon moderator gas at a atm and 23°C was measured and the bimolecular rate constant was k = (2.4±0.3) ×1011 l/mole−sec, ten times higher than that for the analogous reaction of hydrogen atoms.
Abstract: We report a precise measurement of the rate of reaction of muonium atoms with bromine molecules in an argon moderator gas at a atm and 23 °C. The bimolecular rate constant is k= (2.4±0.3) ×1011 l/mole‐sec, ten times higher than that for the analogous reaction of hydrogen atoms. Since muonium can properly be treated as a light isotope of hydrogen, this comparison has potential significance for the theory of reaction rates. The technique is described and the results discussed.

33 citations

Journal ArticleDOI
TL;DR: It is demonstrated that mass spectrometry can play an important role in predicting the chemical solution phase transformations of 2-pyrimidinyloxy-N-arylbenzyl amine derivatives.

33 citations

Journal ArticleDOI
TL;DR: In this paper, the authors studied the autoxidation of benzaldehyde in glacial acetic acid catalyzed by cobalt salts and determined the relative contributions of these reactions to the decay of the peracid concentration.
Abstract: The autoxidation of benzaldehyde in glacial acetic acid catalyzed by cobalt salts has been studied by kinetic and analytical methods. In the initial phase of the reaction the oxygen reacts quantitatively with the aldehyde to form perbenzoic acid, but as the reaction proceeds the peracid concentration falls below that of the oxygen absorbed due to ( a ) the catalyzed decomposition of the perbenzoic acid, and ( b ) the reaction of the perbenzoic acid with benzaldehyde to give benzoic acid. The relative contributions of these reactions to the decay of the peracid concentration has been determined. The initiating reaction has been shown to be the interaction of the cobaltic ion with the aldehyde according to Co 3+ + C 6 H 5 CHO → Co 2+ + C 6 H 5 CO·. (1) Direct measurements of the rate of this reaction agreed with the value of the rate of initiation determined by an analysis of the kinetics of the rate of the inhibited oxidation. The overall rate of oxidation may be fully explained by the following kinetic scheme: C 6 H 5 CO· + O 2 → C 6 H 5 COOO· (2) C 6 H 5 COOO· + C 6 H 5 CHO → C 6 H 5 COOOH + C 6 H 5 CO· } (propagation), (3) 2C 6 H 5 COOO → inert products (termination). (4) The chain length and the activation energies of the elementary reactions have been determined. The oxidation was inhibited by hydroquinone, diphenylamine and β -napthol and retarded by benzoquinone. The rate of the retarded oxidations satisfied the relation rate of oxidation = k9 / k" + [benzoquinone]· By considering the reaction which is responsible for the retardation, C 6 H 5 COOO· + C 6 H 4 O 2 → inert products, (5) in conjunction with the normal termination reaction (4) it is shown that at retarder con­centrations below 10 -3 M radical-radical termination is the more important reaction, but at 10 -1 M retarder concentration radical-radical interaction contributes only 1% to the termination process.

33 citations

Journal ArticleDOI
01 Jan 2005
TL;DR: In this paper, the thermal reactions of methylcyclopentadiene diluted in argon were studied behind reflected shock waves in a 2-in. i.d. pressurized driver single-pulse shock tube over the temperature range 1070-1270 K and overall densities of ∼3-×-10−5 mol/cm3.
Abstract: The thermal reactions of methylcyclopentadiene diluted in argon were studied behind reflected shock waves in a 2 in. i.d. pressurized driver single-pulse shock tube over the temperature range 1070–1270 K and overall densities of ∼3 × 10−5 mol/cm3. A plethora of products resulting from decompositions and ring expansion were found in the post-shock samples. They were, in order of decreasing abundance, cyclopentadiene, benzene, methane, ethane, naphthalene, acetylene, ethylene, C4H4, toluene, C3H4, and indene. Very minute yields of some other compounds were also observed. Production of all the products involves free radical reactions. The initiation of the free radical mechanisms in the decomposition of methylcyclopentadiene takes place via ejection of hydrogen atoms from SP3 carbons and dissociation of the methyl group attached to the ring. The H atoms and the methyl radicals initiate free radical reactions by abstraction of hydrogen atoms from SP3 carbons and by dissociative recombination of H atom and removal of a methyl group from the ring. In addition to these dissociations, there are several reactions that involve β-cleavage in the five-membered ring radical intermediates to produce open chain intermediates that then decompose to stable and unstable fragments. The ring expansion process that leads to the production of high yield of benzene takes place mainly from the methylene cyclopentadienyl intermediate. Ring expansion from methylcyclopentadiene itself does not take place. The total decomposition of methylcyclopentadiene in terms of a first-order rate constant is given by ktotal = 1011.31 exp (−46.6 × 103/RT) s−1. A reaction scheme containing 40 species and 105 elementary reactions was composed and computer simulation was performed over the temperature range 1050–1300 K at 25 K intervals. The agreement between the experimental results and the model prediction for most of the products is satisfactory.

33 citations

Journal ArticleDOI
01 Jan 1992
TL;DR: In this article, the effects of CO/H 2 O/O/O 2 radicals with hydrocarbons (RH) and general mechanistic inhibition behavior at temperatures near 1000 K were studied.
Abstract: The moist carbon monoxide oxidation reaction perturbed by small quantities of hydrocarbons is studied to yield information on the reactions of H, O, OH, and HO 2 radicals with hydrocarbons (RH) and on general mechanistic inhibition behavior at temperatures near 1000 K. In particular, the inhibiting action of CH 4 , C 2 H 6 , C 3 H 8 , C 2 H 4 , C 3 H 6 , and C 2 H 2 at pressures below the second explosion limit of CO/H 2 O/O 2 mixtures are reported over the temperature range 1026–1140 K at 1 atm . The kinetics of these mixtures are shown to complement mechanistic studies on RH/O 2 mixtures for the development and validation of hierarchical hydrocarbon oxidation reaction mechanisms. Considering all the hydrocarbons studied, the general ranking of effectiveness as an inhibitor was found to follow the order: propene>propane >methane>ethane>ethene>acetylene. In fact, acetylene was observed to always promote the oxidation of moist CO, thus emphasizing the importance of O-atom radical attack rather than OH attack on acetylene. Methodologies are also described which permit assessment of elementary reaction rates from inhibition effects. In order to evaluate the potential of these techniques to yield information on rates of H and HO 2 attack on hydrocarbons, these methods were applied to constrained moist CO oxidation inhibitions where RH+OH is most important. In the case of the well studied methane reaction and the lesser studied propene reaction, inhibition studies lead to rate constants of 1.6×10 12 cm 3 /mol-s at 1026 K for CH 4 and 8×10 12 cm 3 /mol-s at 1020 K for C 3 H 6 , respectively. These values are in good agreement with literature data from other more direct techniques. These results show promise of the approach for determining lesser studied elementary reactions at these temperatures, particularly under reaction conditions where HO 2 and H reactions dominate the reaction inhibition characteristics.

33 citations


Network Information
Related Topics (5)
Catalysis
400.9K papers, 8.7M citations
83% related
Hydrogen
132.2K papers, 2.5M citations
82% related
Adsorption
226.4K papers, 5.9M citations
80% related
Aqueous solution
189.5K papers, 3.4M citations
79% related
Combustion
172.3K papers, 1.9M citations
79% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202321
202229
202185
202088
201971
201871