Reactions of Thiyl Radicals. X. Photolysis of Ethyl Sulfide Vapor

1973 ◽  
Vol 51 (5) ◽  
pp. 780-786 ◽  
Author(s):  
Conrad S. Smith ◽  
Arthur R. Knight
Keyword(s):  
Reaction Rates ◽  
Quantum Yields ◽  
Minor Role ◽  
Primary Decomposition ◽  
Primary Process ◽  
Temperature Reaction ◽  
Reaction Products ◽  
Thiyl Radicals ◽  
Pressure Time ◽  
A Minor

The photolysis of ethyl sulfide vapor at 2537 Å has been investigated as a function of substrate and CF4 pressure, time, and temperature. Reaction products with quantum yields in parentheses are ethyl disulfide (0.178), ethane (0.138), butane (0.086), ethanethiol (0.096), 4-methyl-3-thiahexane (0.034) and 4-methyl-3,5-dithiaheptane.Ethyl and ethylthiyl radicals are formed in the primary process and the product yields indicate a net primary decomposition quantum yield of 0.48. A reaction mechanism involving subsequent reactions of the primary fragments is proposed and explains the observed products and the observed variation in rates. Excited radicals and hot radical combination products play a minor role in this system, in contrast to the behavior of lower molecular weight sulfides. Secondary photolysis of the disulfide produced and consumption of ethanethiol are important factors in determining the time dependence of reaction rates in this system.

Reactions of thiyl radicals. XII. Triplet mercury photosensitized decomposition of ethyl sulfide in the gas phase

1976 ◽  
Vol 54 (8) ◽  
pp. 1290-1295 ◽  
Author(s):  
Conrad S. Smith ◽  
Arthur R. Knight
Keyword(s):  
Quantum Yield ◽  
Gas Phase ◽  
Quantum Yields ◽  
Second Step ◽  
Primary Process ◽  
Reaction Products ◽  
Process Comparison ◽  
Thiyl Radicals ◽  
Ethyl Radicals ◽  
High Sulfide

The triplet mercury photosensitized decomposition of ethyl sulfide vapour has been studied at 25 °C. The reaction products include C2H4 (Φ0 = 0.075), C2H6 (Φ0 = 0.043), C4H10 (Φ0 = 0.011), C2H5SH (Φ0 = 0.068), 4-methyl-3-thiahexane (Φ0 = 0.011), and C2H5SSC2H5 (Φ0 = 0.175). The overall decomposition quantum yield is 0.38 at high sulfide pressures. The initial decomposition gives principally ethyl radicals and ethylthiyl radicals; a second step which yields ethylene and ethanethiol may account for up to 20% of the primary process. Comparison of the direct and sensitized decompositions indicates that both likely originate in the triplet manifold of ethyl sulfide.Primary decomposition quantum yields have been accurately redetermined for the direct, 254 nm, photolysis of methyl sulfide (0.51), methylethyl sulfide (0.46), and ethyl sulfide (0.49).

THE Hg 6(3P1) PHOTOSENSITIZATION OF CHLORODIFLUOROMETHANE

1965 ◽  
Vol 43 (5) ◽  
pp. 1022-1029 ◽  
Author(s):  
M. G. Bellas ◽  
O. P. Strausz ◽  
H. E. Gunning
Keyword(s):  
Incident Light ◽  
Strong Dependence ◽  
Quantum Yields ◽  
Primary Process ◽  
Reaction Products ◽  
Light Intensities ◽  
Principal Reaction ◽  
Bond Scission ◽  
Circulatory Apparatus ◽  
Cl Atoms

The reaction was studied in a circulatory apparatus under a variety of conditions. The sole primary process occurring is C—Cl bond scission. The Cl atoms formed in the primary step, through an abstractive attack on the substrate, generate chlorodifluoromethyl radicals (CF2Cl) All principal reaction products, CF2H2, CF2Cl2, CF2ClCF2Cl, CF2HCF2H, and CF2HCF2Cl, can be accounted for by the combination–disproportionation reactions of the CF2H• and CF2Cl• radicals. The observed strong dependence of the primary quantum yields on the incident light intensities has been ascribed to a rapid substrate-reforming step.

Copper Corrosion Mechanisms of Polysulfides

1997 ◽  
Vol 492 ◽  
Author(s):  
Anne M. Chaka ◽  
John Harris ◽  
X. P. Li
Keyword(s):  
Density Functional ◽  
Copper Surface ◽  
Minor Role ◽  
Copper Corrosion ◽  
Dramatic Decrease ◽  
Functional Theory ◽  
Hartree Fock ◽  
Thiyl Radicals ◽  
Corrosion Mechanisms ◽  
A Minor

ABSTRACTCorrosive behavior of commercial organopolysulfides of the type R-(S)n-R is known to increase dramatically towards copper-based alloys when n ≥ 4, whereas di- and trisulfides are essentially inert. Three possible reasons for this behavior are examined using local and nonlocal density-functional theory as well as post-Hartree-Fock theory at the MP2 level. The hypotheses are: the shorter chains are protected from the surface by steric hindrance of the terminal organic groups, longer polysulfides can chelate copper atoms and remove them from the surface, and S-S bonds become weaker and more reactive as the polysulfide chains become longer. We find the predominant reason for the increase in corrosive behavior to be a dramatic decrease in S-S bond dissociation energy when n ≥ 4 due to stabilization of the unpaired electron via delocalization in RSS• thiyl radicals. The thiyl radicals are thus the species which is capable of attacking and corroding the copper surface. Chelation is eliminated as a possible mechanism, and steric protection and oil solubility afforded by the organic terminal groups are found to play a minor role.

Reactions of Thiyl Radicals. VII. Photolysis of Methyl Sulfide Vapor

1972 ◽  
Vol 50 (6) ◽  
pp. 844-852 ◽  
Author(s):  
P. M. Rao ◽  
A. R. Knight
Keyword(s):  
Wavelength Range ◽  
Sulfur Hexafluoride ◽  
Quantum Yields ◽  
Primary Process ◽  
Methyl Radicals ◽  
Methyl Sulfide ◽  
Thiyl Radicals ◽  
Several Variables ◽  
Bond Scission ◽  
Function Of Several Variables

The photolysis of methyl sulfide vapor has been investigated as a function of substrate pressure, exposure time, and temperature in the wavelength range 2000 to 2300 Å. The effects of added propane, sulfur hexafluoride, and 2-methylpentane have been studied. The principal products of the decomposition are CH4, C2H6, CH3SSCH3, and CH3SH. The data indicate direct C—S bond scission in the primary process giving rise to "hot" CH3 and CH3S radicals. A mechanism in which disproportionation of methylthiyl radicals is a very minor process is proposed.The reactions of CH3 and CH3S radicals with methyl sulfide have been examined also by photolyzing CH3SSCH3 and CH3COCH3 in the presence of CH3SCH3. Quantum yields at 2288 Å have been determined as a function of several variables. A number of rate parameters for the reactions of methyl radicals and methylthiyl radicals have been calculated.

scholarly journals Towards a better understanding of the HTL process of lignin-rich feedstock

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Benedetta Ciuffi ◽  
Massimiliano Loppi ◽  
Andrea Maria Rizzo ◽  
David Chiaramonti ◽  
Luca Rosi
Keyword(s):  
Spectroscopic Analysis ◽  
Operating Conditions ◽  
Industrial Plant ◽  
Minor Role ◽  
Spectroscopic Techniques ◽  
Reaction Products ◽  
Batch Mode ◽  
H Nmr ◽  
Different Temperatures ◽  
A Minor

AbstractThe hydrothermal liquefaction reactions (HTL) in subcritical conditions of a lignin residue has been studied on a lab scale. The starting material was a lignin rich residue co-produced by an industrial plant situated in Northern Italy producing lignocellulosic bioethanol. The reactions were carried out in batch mode using stainless steel autoclaves. The experiments were under the following operating conditions: two different temperatures (300–350 °C), the presence of basis catalysts (NaOH, and NH4OH) in different concentrations and the presence/absence of capping agent 2,6-bis-(1,1-dimethylethyl)-4-methylphenol (BHT). Lignin residue and reaction products were characterized by analytical and spectroscopic techniques such as CHN-S, TGA, GC–MS, EPR, and 1H-NMR with (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (T.E.M.P.O.). The addition of BHT did not significantly affect the yield of char which is formed by radical way. Spectroscopic analysis indicated that the level of radicals during the reaction was negligible. Therefore, the results obtained experimentally suggest that the reaction takes place via an ionic route while radical species would play a minor role.

The Effect of Path Length and Display Size on Memory for Spatial Information

2012 ◽  
Vol 59 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Katherine Guérard ◽  
Sébastien Tremblay
Keyword(s):  
Path Length ◽  
Potential Role ◽  
Spatial Information ◽  
Recall Performance ◽  
Minor Role ◽  
Length Effect ◽  
Serial Memory ◽  
Fixed Reference ◽  
A Minor

In serial memory for spatial information, some studies showed that recall performance suffers when the distance between successive locations increases relatively to the size of the display in which they are presented (the path length effect; e.g., Parmentier et al., 2005) but not when distance is increased by enlarging the size of the display (e.g., Smyth & Scholey, 1994). In the present study, we examined the effect of varying the absolute and relative distance between to-be-remembered items on memory for spatial information. We manipulated path length using small (15″) and large (64″) screens within the same design. In two experiments, we showed that distance was disruptive mainly when it is varied relatively to a fixed reference frame, though increasing the size of the display also had a small deleterious effect on recall. The insertion of a retention interval did not influence these effects, suggesting that rehearsal plays a minor role in mediating the effects of distance on serial spatial memory. We discuss the potential role of perceptual organization in light of the pattern of results.

Use of Different Tissue Thromboplastins in the Control of Anticoagulant-Therapy

1958 ◽  
Vol 02 (05/06) ◽  
pp. 462-480 ◽  
Author(s):  
Marc Verstraete ◽  
Patricia A. Clark ◽  
Irving S. Wright
Keyword(s):  
Prothrombin Time ◽  
Anticoagulant Therapy ◽  
Factor Vii ◽  
Rabbit Brain ◽  
Minor Role ◽  
Rabbit Lung ◽  
Coagulation Mechanism ◽  
Time Test ◽  
The One ◽  
A Minor

SummaryAn analysis of the results of prothrombin time tests with different types of thromboplastins sheds some light on the problem why the administration of coumarin is difficult to standardize in different centers. Our present ideas on the subject, based on experimental data may be summarized as follows.Several factors of the clotting mechanism are influenced by coumarin derivatives. The action of some of these factors is by-passed in the 1-stage prothrombin time test. The decrease of the prothrombin and factor VII levels may be evaluated in the 1-stage prothrombin time determination (Quick-test). The prolongation of the prothrombin times are, however, predominantly due to the decrease of factor VII activity, the prothrombin content remaining around 50 per cent of normal during an adequate anticoagulant therapy. It is unlikely that this degree of depression of prothrombin is of major significance in interfering with the coagulation mechanism in the protection against thromboembolism. It may, however, play a minor role, which has yet to be evaluated quantitatively. An exact evaluation of factor VII is, therefore, important for the guidance of anticoagulant therapy and the method of choice is the one which is most sensitive to changes in factor VII concentration. The 1-stage prothrombin time test with a rabbit lung thromboplastin seems the most suitable method because rabbit brain preparations exhibit a factor VII-like activity that is not present in rabbit lung preparations.

Produktivkraft als Versprechen

2016 ◽  
Vol 46 (185) ◽  
pp. 621-638 ◽  
Author(s):  
Christian Siefkes
Keyword(s):  
Private Consumption ◽  
Minor Role ◽  
Progressive Reduction ◽  
Internal Forces ◽  
A Minor

The ‘Fragment on Machines’ from Marx’s Grundrisse is often cited as an argument that the internal forces of capitalism will lead to its doom. But the argument that the progressive reduction of labor must doom capitalism lacks a proper foundation, as a comparison with the ‘Schemes of Reproduction’ given in Capital II shows. The latter, however, aren’t fully convincing either. In reality, more depends on the private consumption of capitalists than either model recognizes. Ultimately, most can be made of the ‘Fragment on Machines’ by reading it not as an exposure of capitalism’s internal contractions, but as a discussion of a possible communist future where labor (or work) will play but a minor role.

Effects of Myo-inositol Alone and in Combination with Seleno-Lmethionine on Cadmium-Induced Testicular Damage in Mice

2019 ◽  
Vol 12 (4) ◽  
pp. 311-323 ◽  
Author(s):  
Salvatore Benvenga ◽  
Antonio Micali ◽  
Giovanni Pallio ◽  
Roberto Vita ◽  
Consuelo Malta ◽  
...  
Keyword(s):  
Structural Changes ◽  
Natural Antioxidants ◽  
Minor Role ◽  
Positive Role ◽  
Testosterone Levels ◽  
Tnf Α ◽  
Testicular Lesions ◽  
A Minor ◽  
Immunohistochemical Analyses

Background: Cadmium (Cd) impairs gametogenesis and damages the blood-testis barrier. Objective: As the primary mechanism of Cd-induced damage is oxidative stress, the effects of two natural antioxidants, myo-inositol (MI) and seleno-L-methionine (Se), were evaluated in mice testes. Methods: Eighty-four male C57 BL/6J mice were divided into twelve groups: 0.9% NaCl (vehicle; 1 ml/kg/day i.p.); Se (0.2 mg/kg/day per os); Se (0.4 mg/kg/day per os); MI (360 mg/kg/day per os); MI plus Se (0.2 mg/kg/day); MI plus Se (0.4 mg/kg/day); CdCl2 (2 mg/kg/day i.p.) plus vehicle; CdCl2 plus MI; CdCl2 plus Se (0.2 mg/kg/day); CdCl2 plus Se (0.4 mg/kg/day); CdCl2 plus MI plus Se (0.2 mg/kg/day); and CdCl2 plus MI plus Se (0.4 mg/kg/day). After 14 days, testes were processed for biochemical, structural and immunohistochemical analyses. Results: CdCl2 increased iNOS and TNF-α expression and Malondialdehyde (MDA) levels, lowered glutathione (GSH) and testosterone, induced testicular lesions, and almost eliminated claudin-11 immunoreactivity. Se administration at 0.2 or 0.4 mg/kg significantly reduced iNOS and TNF-α expression, maintained GSH, MDA and testosterone levels, structural changes and low claudin-11 immunoreactivity. MI alone or associated with Se at 0.2 or 0.4 mg/kg significantly reduced iNOS and TNF-α expression and MDA levels, increased GSH and testosterone levels, ameliorated structural organization and increased claudin-11 patches number. Conclusion: We demonstrated a protective effect of MI, a minor role of Se and an evident positive role of the association between MI and Se on Cd-induced damages of the testis. MI alone or associated with Se might protect testes in subjects exposed to toxicants, at least to those with behavior similar to Cd.

Extraction of strontium and barium salts by the nitrobenzene solution of dicarbolide in the presence of glymes

1985 ◽  
Vol 50 (3) ◽  
pp. 581-599 ◽  
Author(s):  
Petr Vaňura ◽  
Emanuel Makrlík
Keyword(s):  
Stability Constants ◽  
Organic Phase ◽  
Equilibrium Constants ◽  
Minor Role ◽  
Nitrobenzene Solution ◽  
Ligand Structure ◽  
Stability Constants Of Complexes ◽  
Separation Factors ◽  
The Stability ◽  
A Minor

Extraction of microamounts of Sr2+ and Ba2+ (henceforth M2+) from the aqueous solutions of perchloric acid (0.0125-1.02 mol/l) by means of the nitrobenzene solutions of dicarbolide (0.004-0.05 mol/l of H+{Co(C2B9H11)2}-) was studied in the presence of monoglyme (only Ba2+), diglyme, triglyme, and tetraglyme (CH3O-(CH2-CH2O)nCH3, where n = 1, 2, 3, 4). The distribution of glyme betweeen the aqueous and organic phases, the extraction of the protonized glyme molecule HL+ together with the extraction of M2+ ion and of the glyme complex with the M2+ ion, i.e., ML2+ (where L is the molecule of glyme), were found to be the dominating reactions in the systems under study. In the systems with tri- and tetraglymes the extraction of H+ and M2+ ions solvated with two glyme molecules, i.e., the formation of HL2+ and ML22+ species, can probably play a minor role. The values of the respective equilibrium constants, of the stability constants of complexes formed in the organic phase, and the theoretical separation factors αBa/Sr were determined. The effect of the ligand structure on the values of extraction and stability constants in the organic phase is discussed.

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