The Far Ultraviolet Photolysis of Alkenes: The Use of Hydrogen Sulfide as a Radical Scavenger

1972 ◽  
Vol 50 (15) ◽  
pp. 2391-2399 ◽  
Author(s):  
Guy J. Collin ◽  
Patrick M. Perrin ◽  
Christian M. Gaucher
Keyword(s):  
Hydrogen Sulfide ◽  
The Other ◽  
Radical Scavenger ◽  
Methyl Ethyl ◽  
Hydrogen Atoms ◽  
Radical Species ◽  
Alkyl Radicals ◽  
Vinyl Radicals ◽  
Ultraviolet Photolysis ◽  
Far Ultraviolet

The far u.v. photolysis of cis-2-butene, n-1-pentene, and cis-2-pentene was carried out in the presence of various quantities of hydrogen sulfide. We showed that in these systems, hydrogen atoms add to the double bond and are not scavenged by 5–10% hydrogen sulfide. On the other hand, alkyl radicals such as methyl, ethyl, s-butyl, and s-pentyl react with hydrogen sulfide, and the formation of the corresponding alkanes may be used to measure the absolute yields of the radical species. The same holds true for vinyl radicals. We also report some experiments published elsewhere. In particular, in the case of 1,3-butadiene, identification of the principal radicals is possible; however, measurement of absolute yields becomes more difficult.

NO, CO and H2S based pharmaceuticals in the mission of vision (eye health): a comprehensive review

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jan Mohammad Mir ◽  
Ram Charitra Maurya ◽  
Mohd Washid Khan
Keyword(s):  
Nitric Oxide ◽  
Carbon Monoxide ◽  
Human Physiology ◽  
Hydrogen Sulfide ◽  
The Other ◽  
Normal Functioning ◽  
Comprehensive Review ◽  
Molecular Systems ◽  
Eye Health ◽  
Highly Sensitive

Abstract A set of well defined signaling molecules responsible for normal functioning of human physiology including nitric oxide along with carbon monoxide and hydrogen sulphide are referred as “gasotransmitters”. Due to their involvement in almost every system of a human body, the care of highly sensitive organs using these molecules as drugs represents highly fascinating area of research. In connection with these interesting aspects, the applied aspects of these gaseous molecules in maintaining healthy eye and vision have been targeted in this review. Several examples of eye-droppers including NORMs like latanoprost and nipradiol, CORMs like CORM-3 and CORM-A1, and Hydrogen sulfide releasing system like GYY4137 have been discussed in this context. Therefore the relation of these trio-gasotransmitters with the ophthalmic homeostasis on one hand, and de-infecting role on the other hand has been mainly highlighted. Some molecular systems capable of mimicking gasotransmitter action have also been introduced in connection with the titled theme.

Hydrogen Sulfide Stress Cracking in a Q345R Welded Joint

2021 ◽  
Vol 1035 ◽  
pp. 486-491
Author(s):  
Yan Han ◽  
Jing Bin Luo ◽  
An Qing Fu ◽  
Cheng Xian Yin
Keyword(s):  
Hydrogen Sulfide ◽  
Welded Joint ◽  
Chemical Properties ◽  
Test Method ◽  
Hydrogen Atoms ◽  
Stress Cracking ◽  
Micro Cracks ◽  
Sulfide Stress ◽  
Macroscopic Observation ◽  
Metal Microstructure

In this paper the failure reason of Q345R Welded Joint was studied through macroscopic observation, chemical properties, metallurgical analysis, scanning electron microscope (SEM) and EDS test method. The results showed that there were a large number of micro-cracks in the fracture surface. The reason of cracking is severe banded structure in base metal microstructure, which provided opportunity for hydrogen atoms to enter into the internal of steel when contact with wet hydrogen sulfide environment. The existence of tensile stress promotes the entry of hydrogen atoms and the propagation of cracks. The welding products of this procedure are not suitable for use under sour conditions.

The vacuum ultraviolet photolysis of hydrogen chloride. The role of the hot hydrogen atoms

1981 ◽  
Vol 55 (1-2) ◽  
pp. 9-15 ◽  
Author(s):  
A. Jówko ◽  
S. U. Pavlova ◽  
H. Baj ◽  
B. G. Dzantiev ◽  
M. Foryś
Keyword(s):  
Hydrogen Chloride ◽  
Vacuum Ultraviolet ◽  
Hydrogen Atoms ◽  
Ultraviolet Photolysis

Behavior Analysis of Environmental Hydrogen in High-Magnesium Al-Mg Alloys by Hydrogen Microprint Technique

2007 ◽  
Vol 539-543 ◽  
pp. 475-480 ◽  
Author(s):  
T. Izumi ◽  
Goroh Itoh
Keyword(s):  
Stress Corrosion ◽  
Behavior Analysis ◽  
Stress Corrosion Cracking ◽  
Mg Alloys ◽  
The Other ◽  
Corrosive Environment ◽  
Silver Particles ◽  
Nacl Solution ◽  
Hydrogen Atoms ◽  
Al Mg Alloys

High-magnesium Al-Mg alloys are known to be sensitive to stress corrosion cracking involving environmental hydrogen, hydrogen invading from the corrosive environment. In this study, the behavior of the environmental hydrogen in Al-6%Mg and Al-8%Mg binary alloy sheets stretched by 10% during exposure to 3.5%NaCl solution has been investigated by means of hydrogen microprint technique. Microprint image is observed on one surface while the other surface is exposed to the solution. In both alloys, the silver particles corresponding to the sites where hydrogen atoms are emitted from the inside of the sheets are shown on the slip lines. It is shown that the hydrogen atoms are transported with moving dislocations in the alloys.

Reactions of hydrogen atoms with hexafluoroacetone

1978 ◽  
Vol 56 (20) ◽  
pp. 2638-2645 ◽  
Author(s):  
D. W. Grattan ◽  
K. O. Kutschke
Keyword(s):  
Rate Constant ◽  
Cross Sections ◽  
The Other ◽  
Hydrogen Atoms ◽  
Kinetics Of

Attempts were made to study the kinetics of the reaction of atomic H with (CF3)2CO vapour (HFA). Atomic H was generated from H2 by mercury photosensitization in the presence of C2H4 and HFA but the system was complicated by the loss of C2H5 radicals by addition to HFA and the kinetic results were intractable. When atomic H was generated from C3H8, the kinetics again were obscured by some unidentified reaction(s) which became more important at higher [HFA]/[C3H8]. An estimate of the rate constant for the addition of H to HFA obtained at low [HFA]/[C3H8] yielded k9 = 8.5 × 105 l mol−1 s−1. Trifluoroacetaldehyde was identified with some reliability but many of the other heavier products formed in the H2 + HFA reaction could not be identified. Quenching cross-sections were determined for C2H4, C3H8, C4H10, and HFA relative to that for N2O.

scholarly journals Electron-induced ionization of undeuterated and deuterated benzoic acid isopropyl esters and nicotinic acid isopropyl esters: Some implications for the mechanism of the McLafferty rearrangement

2019 ◽  
Vol 26 (1) ◽  
pp. 3-24
Author(s):  
Joachim Opitz ◽  
A Stephen K Hashmi ◽  
Burkhard Miehlich ◽  
Michael Wölfle
Keyword(s):  
Benzoic Acid ◽  
Nicotinic Acid ◽  
Ethyl Ester ◽  
Methyl Groups ◽  
Aliphatic Chain ◽  
Methyl Ethyl ◽  
Hydrogen Atoms ◽  
Isopropyl Esters ◽  
Mclafferty Rearrangement ◽  
Ester Chain

Electron ionization mass spectra, ionization, and appearance energies and bond energies (as dissociation energies) are reported for benzoic acid-1-methyl-ethyl ester (BAIPE), benzoic acid-1-deutero-1-methyl-ethyl ester (BAIPED1), benzoic acid-2,2,2-trideutero-1-trideuteromethyl-ethyl ester (BAIPED6) as well as nicotinic acid-1-methyl-ethyl ester (NAIPE), nicotinic acid-1-deutero-1-methyl-ethyl ester (NAIPED1), and nicotinic acid-2,2,2-trideutero-1-trideuteromethyl-ethyl ester (NAIPED6). Ionization energies of 9.39 eV for BAIPE, 9.40 eV for BAIPED1, 9.26 eV for BAIPED6 as well as 9.70 eV for NAIPE, 9.79 eV for NAIPED1, and 9.65 eV for NAIPED6 were determined. A gas-phase formation enthalpy of [Formula: see text] = (−4.10 ± 0.1) eV for BAIPE is calculated as well as [Formula: see text] = (−3.35 ± 0.1) eV for NAIPE. Molecular ions show two main fragmentation pathways. The first is a classical McLafferty rearrangement, characterized by the transfer of one γ-hydrogen atom from the isopropyl ester chain leading to the ions of the corresponding acid and neutral propene. The second is the double hydrogen transfer from the ester chain leading to the formation of the protonated acid and a C3H5√ allyl radical. For BAIPE, both hydrogen atoms originate from the methyl groups of the aliphatic chain with a probability of ≥98%, whereas the C-1-hydrogen is transferred with a probability of ≤2%. For NAIPE, both hydrogen atoms originate from the methyl groups of the aliphatic chain with a probability of 90%. Experimental proton affinities of PA = (8.75 ± 0.2) eV for benzoic acid and PA = (8.43 ± 0.2) eV for nicotinic acid are derived. For the protonation of the carbonyl group, B3LYP DFT calculations yielded PA = 8.66 eV for benzoic acid and PA = 8.41 eV for nicotinic acid. The overall fragmentation mechanism is explained with the initial formation of a 1,5-distonic ion by transfer of the first hydrogen. For the transfer of the second hydrogen, an intermediate ion/neutral complex is formulated.

Intra-articular injection of hydrogen sulfide decreased the progression of gonarthrosis

2019 ◽  
Vol 97 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Kürşad Aytekin ◽  
Selma Şengiz Erhan ◽  
Züleyha Erişgin ◽  
Cem Zeki Esenyel ◽  
Selçuk Takır
Keyword(s):  
Anterior Cruciate Ligament ◽  
Hydrogen Sulfide ◽  
Synovial Fluid ◽  
Scoring System ◽  
Cruciate Ligament ◽  
The Other ◽  
Sodium Hydrosulfide ◽  
Medial Meniscectomy ◽  
Anterior Cruciate

Hydrogen sulfide (H2S) is found in both the plasma and synovial fluid of patients with gonarthrosis. In the present study, we investigated whether intra-articular injection of sodium hydrosulfide (NaSH) (1 mM, 30 μL), a H2S donor, might affect gonarthrosis in rats. Gonarthrosis was induced surgically in the left knees of rats and left for 6 weeks for the development of disease. Then, intra-articular injections of NaSH or methylprednisolone (1 mg/kg, 30 μL) were administered to rats. Half of each group was sacrificed at the end of the first day and the other half was sacrificed at the end of 4 weeks to evaluate early and later effects of injections on gonarthrosis. The injury induced by anterior cruciate ligament resection and medial meniscectomy in rats caused the development of gonarthrosis. As the duration lengthened after gonarthrosis induction, the progression of the disease continued. According to the modified Mankin Scoring System, intra-articular injection of NaSH histopathologically slowed the progression of gonarthrosis, whereas methylprednisolone was ineffective. In addition, NaSH decreased apoptosis in rat knees with gonarthrosis. Each treatment did not cause injury to healthy knees. Our results lead to the consideration that intra-articular NaSH administration may be effective in the progression of gonarthrosis.

The homogeneous conversion of methane to higher hydrocarbons in the presence of ethylene in the temperature range 925–1023 K

1991 ◽  
Vol 69 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Alain R. Bossard ◽  
Margaret H. Back
Keyword(s):  
Hydrogen Abstraction ◽  
Homogeneous System ◽  
Catalytic Reactions ◽  
The Other ◽  
Methyl Radicals ◽  
Temperature Range ◽  
Vinyl Radicals ◽  
Conversion Of Methane ◽  
Radical Distribution ◽  
Higher Hydrocarbons

Mixtures of ethylene and methane have been pyrolyzed in the temperature range 925–1023 K for the purpose of converting methane to higher hydrocarbons. Addition of methane to thermally-reacting ethylene increases the rate of formation of propylene but decreases the rates of formation of the other major products, ethane, acetylene, and butadiene. Hydrogen abstraction from methane is a major propagation reaction and causes a shift in the radical distribution from ethyl and vinyl radicals, the main radicals in the pyrolysis reactions of ethylene alone, to methyl radicals, which lead to the formation of propylene. At 1023 K with a pressure of ethylene of 6.5 Torr and of methane of 356 Torr, 1.5 mol of methane is converted to higher molecular weight products for every mole of ethylene reacted. The rate of conversion of methane in the homogeneous system is lower than in catalytic reactions but the product is entirely hydrocarbon and no methane is lost to carbon monoxide or carbon dioxide. Key words: methane, ethylene, kinetics, pyrolysis, fuels.

Photometric investigations of alkali metals in hydrogen flame gases - II. The study of excess concentrations of hydrogen atoms in burnt gas mixtures

1956 ◽  
Vol 235 (1200) ◽  
pp. 89-106 ◽  
Keyword(s):  
Hydroxyl Radicals ◽  
Alkali Metals ◽  
Equilibrium Constants ◽  
The Other ◽  
Large Excess ◽  
Hydrogen Atoms ◽  
Free Hydrogen ◽  
Hydrogen Flame ◽  
Photometric Measurements ◽  
Oxygen Flame

Photometric measurements on alkali metals in hydrogen-oxygen flame gases, diluted with various proportions of nitrogen, are interpreted as giving a measure of the concentration of free hydrogen atoms, which persist in these gases for several milliseconds after primary combustion. These concentrations are well in excess of those expected from thermodynamic equilibrium, especially towards the lower end of the range of temperatures studied (2400 to 1600°K). Two kinds of measurement have been made. (i) Comparison of the intensities of the Na D lines and the Li resonance doublets, for equal traces of the two elements present in the gases. The amount of free lithium is modified by the balanced process, Li + H 2 O ⇌ LiOH + H, whereas corresponding reactions for sodium are negligible. Using estimated equilibrium constants for these reactions, [H] can be obtained. (ii) Measurements of the change in intensity of the Na D lines when 0∙01 to 0∙5% of chlorine or its compounds (a large excess over the sodium) are added to the flame gases. NaCl is considered to be formed by the balanced reactions Na + HCl ⇌ NaCl + H. The concentration of HCl, the most important chlorine compound in the hydrogen-rich flame gases, may be obtained from the total chlorine added. Using estimated equilibrium constants for the above reaction, [H] can again be obtained. The agreement between the [H] values obtained by these two independent methods is good. The decrease of [H] with height in the gases is consistent with ternary recombination towards full equilibrium. A general discussion of excess radical concentrations in hydrogen flame gases is given, for hydroxyl radicals and oxygen atoms as well as hydrogen atoms. The conclusions reached are supported by experimental evidence. A further discussion of the way in which the amounts of chlorine used in the experiments may affect the other radical concentrations is given.

Secondary Bonding Interactions in Some Dichloroanilinium Chlorides

2002 ◽  
Vol 57 (1) ◽  
pp. 73-82 ◽  
Author(s):  
Lilian Gray ◽  
Peter G. Jones
Keyword(s):  
Hydrogen Bonds ◽  
Layer Structure ◽  
The Other ◽  
Hydrogen Atoms ◽  
Ribbon Structure ◽  
Bonding Systems ◽  
Ribbon Structures ◽  
Chloride Hydrate ◽  
Positively Charged ◽  
Secondary Bonding

Of the six structures presented here, five involve clearly defined hydrophilic layers built up from classical hydrogen bonding systems. Of three solvent-free structures, 2,4- and 3,5-dichloroanilinium chlorides both form ribbon structures involving annelated R24 (8) rings with NH2 donors (two hydrogen atoms from the positively charged NH3 groups) and chloride acceptors. The ribbons are linked by weaker interactions to form layers. 2,5-Dichloroanilinium chloride forms a layer structure directly, with rings R36 (12) exactly analogous to those previously observed in 2-chloroanilinium chloride. 2,6-Dichloroanilinium chloride methanol solvate forms a different type of ribbon structure, with alternating R24 (8) and R46 12) rings; the latter involve two chlorides, two NH2 groups and two methanols. These ribbons too are linked to form layers. 2,3-Dichloroanilinium chloride hydrate forms layers with two types of ring R35 (10); one involves two NH2, two chlorides and the OH part of a water, whereas in the other, an NH2 is replaced by OH2. In all these structures the aromatic groups project approximately perpendicular to the layers to form hydrophobic regions; for all except 3,5-dichloroanilinium chloride, neighbouring layers are linked by weaker interactions such as C-H···Cl hydrogen bonds or Cl···Cl contacts. The final structure, 3,5-dichloroanilinium chloride 1/4-hydrate, is completely different; it involves two types of columns, one built up from quadrilaterals of Cl···Cl contacts between cations and the other consisting of “nanotubes ’ of NH3 groups and chloride anions linked by two- and three-centre hydrogen bonds. The columns are in turn linked by cation-anion Cl···Cl interactions.

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