scholarly journals Elementary rate constants for hydrogen atoms. Final report, 1974--1975

1977 ◽  
Author(s):  
Keyword(s):  
Rate Constants ◽  
Final Report ◽  
Hydrogen Atoms ◽  
Elementary Rate Constants

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.

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

Rate constants for the reactions of hydrogen atoms with SiHnF4 − n (n = 4, 3, 2)

1990 ◽  
Vol 173 (2-3) ◽  
pp. 235-240 ◽  
Author(s):  
Mitsuo Koshi ◽  
Fumitaka Tamura ◽  
Hiroyuki Matsui
Keyword(s):  
Rate Constants ◽  
Hydrogen Atoms
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