Rate constants for reaction of hydrogen atoms in aqueous solutions

1971 ◽  
Vol 75 (4) ◽  
pp. 449-454 ◽  
Author(s):  
Robert H. Schuler ◽  
Pedatsur Neta ◽  
G. R. Holdren
Keyword(s):  
Aqueous Solutions ◽  
Rate Constants ◽  
Hydrogen Atoms

An electron spin resonance study of the reactions of hydrogen atoms with halocarbons

1986 ◽  
Vol 64 (11) ◽  
pp. 2192-2195 ◽  
Author(s):  
William E. Jones ◽  
Joseph L. Ma
Keyword(s):  
Rate Constants ◽  
Gas Flow ◽  
Esr Spectroscopy ◽  
Flow System ◽  
Electron Spin Resonance Study ◽  
Absolute Rate ◽  
Hydrogen Atoms ◽  
Vinyl Halides ◽  
Spin Resonance ◽  
Spin Resonance Study

The absolute rate constants for the reaction of H atoms with methyl- and vinyl-halides have been determined using esr spectroscopy and a conventional gas flow system. The rate constants determined at 298 ± 2 K at a pressure of 0.55 Torr are methane, (1.7 ± 0.3) × 10−17; ethane, (2.3 ± 0.5) × 10−17; methylfluoride, (4 ± 3) × 10−15; methylchloride, (8 ± 2) × 10−16; methylbromide, (2.1 ± 0.6) × 10−14; vinylfluoride, (1.47 ± 0.02) × 10−13; vinylchloride, (1.66 ± 0.08) × 10−13; and vinylbromide (4.07 ± 0.73) × 10−13 in units of cm3 molecule−1 s−1.

scholarly journals Tunnelling dominates the reactions of hydrogen atoms with unsaturated alcohols and aldehydes in the dense medium

2018 ◽  
Vol 617 ◽  
pp. A25 ◽  
Author(s):  
V. Zaverkin ◽  
T. Lamberts ◽  
M. N. Markmeyer ◽  
J. Kästner
Keyword(s):  
Functional Groups ◽  
Rate Constants ◽  
Aldehyde Group ◽  
Dense Medium ◽  
Hydrogen Atoms ◽  
Hydrogen Addition ◽  
Reaction Rate Constants ◽  
Quantum Chemical Methods ◽  
Experimental Findings ◽  
Recombination Reactions

Hydrogen addition and abstraction reactions play an important role as surface reactions in the buildup of complex organic molecules in the dense interstellar medium. Addition reactions allow unsaturated bonds to be fully hydrogenated, while abstraction reactions recreate radicals that may undergo radical–radical recombination reactions. Previous experimental work has indicated that double and triple C–C bonds are easily hydrogenated, but aldehyde –C=O bonds are not. Here, we investigate a total of 29 reactions of the hydrogen atom with propynal, propargyl alcohol, propenal, allyl alcohol, and propanal by means of quantum chemical methods to quantify the reaction rate constants involved. First of all, our results are in good agreement with and can explain the observed experimental findings. The hydrogen addition to the aldehyde group, either on the C or O side, is indeed slow for all molecules considered. Abstraction of the H atom from the aldehyde group, on the other hand, is among the faster reactions. Furthermore, hydrogen addition to C–C double bonds is generally faster than to triple bonds. In both cases, addition on the terminal carbon atom that is not connected to other functional groups is easiest. Finally, we wish to stress that it is not possible to predict rate constants based solely on the type of reaction: the specific functional groups attached to a backbone play a crucial role and can lead to a spread of several orders of magnitude in the rate constant.

scholarly journals KINETICS OF OZONE REACTIONS WITH ADENINE AND CYTOSINE IN AQUEOUS SOLUTIONS

2020 ◽  
Vol 63 (10) ◽  
pp. 17-22
Author(s):  
Aigul A. Maksyutova ◽  
Elvina R. Khaynasova ◽  
Yuriy S. Zimin
Keyword(s):  
Aqueous Solutions ◽  
Rate Constants ◽  
Correlation Coefficients ◽  
Activation Parameters ◽  
Second Order ◽  
Order Kinetic ◽  
Temperature Dependences ◽  
Ozone Reactivity ◽  
Kinetics Of ◽  
Ozone Reactions

The ultraviolet spectroscopy method has been applied to study the kinetics of the ozone reactions with nitrogenous bases (NB), namely adenine and cytosine in aqueous solutions. At the first research stage, the range of NB working concentrations has been determined. It was found that linear dependences between optical densities and concentrations of nitrogenous bases aqueous solutions are quite reliable, with correlation coefficients r ≥ 0.998, are satisfied up to [NB] = 2.3 ∙ 10–4 mol/l. According to the Bouguer-Lambert-Beer law, adenine and cytosine extinction coefficients in aqueous solutions were determined and subsequently used to calculate their residual concentrations. At the next stage, the kinetics of nitrogenous bases ozonized oxidation was studied with equal initial concentrations of the starting substances ([NB]0 = [О3]0). The results revealed that the kinetic consumption curves of the starting reagents are fairly well linearized (r ≥ 0.996) in the second-order reaction equation coordinates. As found with the bubbling installation, 1 mol of the absorbed ozone falls on 1 mol of the used NB. Thus, the reactions of ozone with adenine and cytosine explicitly proceed according to the second-order kinetic laws (the first – according to О3 and the first – according to NB). The rate constants were calculated by the integral reaction equations, the values of which indicate a higher ozone reactivity in relation to nitrogen bases. The temperature dependences of the second-order rate constants was studied ranging 285-309 K, and the activation parameters (pre-exponential factors and activation energies) of the ozone reactions with adenine and cytosine in aqueous solutions were determined.

Reactions of hydrogen atoms in aqueous solutions. Some amino acids

1968 ◽  
Vol 72 (10) ◽  
pp. 3394-3400 ◽  
Author(s):  
Wynn A. Volkert ◽  
Robert R. Kuntz
Keyword(s):  
Amino Acids ◽  
Aqueous Solutions ◽  
Hydrogen Atoms
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