Hydrogen atoms as convenient synthetic reagents: mercury-photosensitized dimerization of functionalized organic compounds in the presence of molecular hydrogen

1991 ◽  
Vol 113 (6) ◽  
pp. 2233-2242 ◽  
Author(s):  
Cesar A. Muedas ◽  
Richard R. Ferguson ◽  
Stephen H. Brown ◽  
Robert H. Crabtree
Keyword(s):  
Organic Compounds ◽  
Molecular Hydrogen ◽  
Hydrogen Atoms

Photodissociation of H2 near Threshold Energies

1970 ◽  
Vol 25 (2) ◽  
pp. 237-242 ◽  
Author(s):  
F. J. Comes ◽  
U. Wenning
Keyword(s):  
Electric Field ◽  
Cross Section ◽  
Configuration Interaction ◽  
Atomic Hydrogen ◽  
Molecular Hydrogen ◽  
Hydrogen Atoms ◽  
Dissociation Cross Section ◽  
Excited Molecules ◽  
Threshold Energies ◽  
Near Threshold

Abstract Measurements of the atomic hydrogen fluorescence (Lyα) yield important information on the dissociation behavior of molecular hydrogen under photon impact. Under certain assumptions the dissociation cross section of the molecule can be deduced from such experiments. By applying an appropriate electric field in the observation region those dissociations leading to the formation of metastable hydrogen atoms can be quantitatively determined. This information opens the possibility to describe the predissociation of the excited H2-molecules in the C-, D-and B″-states. The experiments show that the excited molecules in these particular states dissociate into H(1S) and H(2S) by configuration interaction with the B′-state.

scholarly journals Abiotic Synthesis of Methane and Organic Compounds in Earth’s Lithosphere

Elements ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 25-31 ◽  
Author(s):  
Eoghan P. Reeves ◽  
Jens Fiebig
Keyword(s):  
Organic Matter ◽  
Organic Compounds ◽  
Molecular Hydrogen ◽  
Inorganic Carbon ◽  
Organic Molecules ◽  
Laboratory Simulations ◽  
Abiotic Synthesis ◽  
Extensive Analysis ◽  
Isotope Analyses ◽  
Ubiquitous Presence

Accumulation of molecular hydrogen in geologic systems can create conditions energetically favorable to transform inorganic carbon into methane and other organic compounds. Although hydrocarbons with a potentially abiotic origin have been proposed to form in a number of crustal settings, the ubiquitous presence of organic compounds derived from biological organic matter presents a challenge for unambiguously identifying abiotic organic molecules. In recent years, extensive analysis of methane and other organics in diverse geologic fluids, combined with novel isotope analyses and laboratory simulations, have, however, yielded insights into the distribution of specific abiotic organic molecules in Earth’s lithosphere and the likely conditions and pathways under which they form.

Electron loss from hydrogen atoms incident on molecular hydrogen, nitrogen and oxygen

1971 ◽  
Vol 36 (3) ◽  
pp. 189-190
Author(s):  
K.C. Mathur ◽  
A.N. Tripathi ◽  
S.K. Joshi
Keyword(s):  
Molecular Hydrogen ◽  
Electron Loss ◽  
Hydrogen Atoms

A heteroelectrode structure for solar water splitting: integrated cobalt ditelluride across a TiO2-passivated silicon microwire array

2017 ◽  
Vol 7 (7) ◽  
pp. 1488-1496 ◽  
Author(s):  
Behrouz Bazri ◽  
Yu-Chen Lin ◽  
Tzu-Hsiang Lu ◽  
Chih-Jung Chen ◽  
Elaheh Kowsari ◽  
...  
Keyword(s):  
Water Splitting ◽  
Molecular Hydrogen ◽  
Active Sites ◽  
Hydrogen Atoms ◽  
Proton Reduction ◽  
Solar Water Splitting ◽  
Surface Hydrogen ◽  
Silicon Microwire ◽  
Passivated Silicon ◽  
Combine Surface

CoTe2@TiO2-Si-MWs provide active sites for proton reduction and combine surface hydrogen atoms into molecular hydrogen.

scholarly journals THE REACTION OF HYDROGEN ATOMS WITH ISOBUTANE

1942 ◽  
Vol 20b (11) ◽  
pp. 255-264 ◽  
Author(s):  
W. Harold White ◽  
C. A. Winkler ◽  
B. J. Kenalty
Keyword(s):  
Activation Energy ◽  
Discharge Tube ◽  
Low Temperatures ◽  
Molecular Hydrogen ◽  
Methane Content ◽  
Hydrogen Atoms ◽  
Dehydrogenation Reaction ◽  
Temperature Range ◽  
Secondary Reactions

The reaction of hydrogen atoms with isobutane has been investigated by the Wood–Bonhoeffer discharge tube method, over a temperature range 30° to 250 °C. An activation energy of 10.5 ± 1.5 kcal. was obtained for the reaction.The nature of the products at a given temperature was found to depend upon the concentration of hydrogen atoms present. With low atom concentrations (5 to 9%) methane was essentially the only product at temperatures below 170 °C. At 250 °C., ethane was formed to the extent of approximately one-half the amount of methane. With higher atom concentrations (14 to 24%) ethane was formed in appreciable quantities at 140° to 170 °C., and exceeded the methane content at 250 °C. Small amounts of propane were formed at the higher temperatures.The results at low temperatures appear to be satisfactorily explained by assuming a primary dehydrogenation reaction:[Formula: see text]followed by a series of "atomic cracking" reactions. To account for the behaviour at higher temperatures, additional secondary reactions, involving decomposition of radicals and their reaction with molecular hydrogen, are assumed.

The action of X-rays on ferrous and ferric salts in aqueous solutions

1952 ◽  
Vol 211 (1106) ◽  
pp. 375-398 ◽  
Keyword(s):  
Molecular Hydrogen ◽  
Ph Dependence ◽  
Oh Radicals ◽  
Specific Rate ◽  
X Rays ◽  
Ferrous Ions ◽  
Hydrogen Atoms ◽  
Hydrogen Molecules ◽  
Specific Rate Constant ◽  
Theoretical Considerations

The action of X-rays on the ferrous-ferric system has been studied under a variety of conditions. The H atoms and OH radicals formed primarily by the action of the radiation on the water react according to Fe 3+ + H → Fe 2+ + H + and Fe 2+ + OH → Fe 3+ + OH - . Experiments carried out in the presence of molecular hydrogen, where the latter reaction competes with the reaction H 2 + OH → H 2 O + H, permit us to deduce that the specific rate constant of the reaction between OH radicals and ferrous ions is about five times greater than that of the corresponding reaction with hydrogen molecules. The study of the pH dependence of the reaction has led to the assumption that molecular hydrogen ions, H + 2(hydr.) , intervene in this process undergoing the reaction Fe 2+ + H + 2(hydr.) → Fe 3+ + H 2 , and that these ions exist in the equilibrium: H + H + (hydr.) ⇌ H + 2(hydr.) . Experimental evidence and some theoretical considerations which have led to the assumption of H + 2 in aqueous systems have been discussed in detail. In the presence of molecular oxygen the hydrogen atoms react according to H + O 2 → HO 2 , followed by reactions of the latter radical (cf. Haber & Weiss 1934). A comparison of the experimentally determined yields under different conditions with the absolute (chemical) yields as derived from the proposed mechanism has led to the estimation of the energy ( W H 2 O ) required for the production of a radical pair (H + OH) by the action of X-rays on water. This has been found to be W H 2 O = 19⋅4 ± 0⋅4 eV.

Predictions by Correlations

2007 ◽  
Author(s):  
James Wei
Keyword(s):  
Polychlorinated Biphenyls ◽  
Organic Compounds ◽  
Aromatic Compounds ◽  
Hydrogen Atoms ◽  
Saturated Hydrocarbons ◽  
Chlorine Atoms ◽  
Boiling Points

After searching the literature and making predictions based on theory without getting sufficient satisfactory results, the next move would be to make estimates. We need the property y of substances pi from a population P that has not been investigated and reported in the literature. Fortunately, there exists a subset S of P that has been investigated, and we have the values for the property y. For instance, we may want the boiling points of all the hydrocarbons, but we have only the boiling points of the normal paraffins from 1 to 20 carbon atoms. Can we use this piece of information on normal paraffins to estimate the boiling points for the rest of the hydrocarbon population? How much effort would be involved and how accurate would the results be? The number of isomers of paraffin is very large; see table 5.1. We see that the iso-paraffins are not as well investigated as the normal paraffins. We have the boiling points of all three isomers of pentane, but not the 75 isomers of decane. It is inevitable that we have to resort to estimations. When we have obtained a good correlation for normal paraffins, we would naturally want to know if we can extend this to the branched paraffins, and onward to the population of all the saturated hydrocarbons (by including the cyclic paraffins), and onward to the population of all hydrocarbons (by including olefins, acetylenes, and aromatic compounds), and then onward to the population of all organic compounds (by including compounds with heteroatoms, such as O, N, Cl). A correlation that applies accurately to a larger domain is more useful than one that works only for a smaller domain. Another example is polychlorinated biphenyls (PCBs), which have 10 hydrogen atoms that can be substituted by chlorine atoms. There are three types of site: the four α sites near the bridge between the two phenyl fragments, the four β sites farther away from the bridge, and the two γ sites that are the farthest away from the bridge. The number of isomers is shown in table 5.2.

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