Reactions of Thiyl Radicals. XI. Further Investigations of Thiol–Disulfide Photolyses in the Liquid Phase

1973 ◽  
Vol 51 (9) ◽  
pp. 1410-1415 ◽  
Author(s):  
Donna D. Carlson ◽  
Arthur R. Knight
Keyword(s):  
Liquid Phase ◽  
Room Temperature ◽  
Liquid Mixtures ◽  
Quantum Yields ◽  
Chain Reaction ◽  
Photochemical Process ◽  
High Quantum Efficiency ◽  
Thiyl Radicals ◽  
Exchange Processes ◽  
A Chain

The photolysis of C2H5SH liquid at 2537 Å has been shown to give H2 and C2H5SSC2H5 at equal rates with a quantum yield of 0.25. The photolysis of ethanethiol – methyl disulfide liquid mixtures leads, via a chain reaction involving propagation by attack of thiyl radicals on the disulfide S—S bond, to the formation with high quantum efficiency of CH3SH, C2H5SSC2H5 and, as an intermediate that is consumed after long exposures, CH3SSC2H5. The net result of the sequence of exchange processes is the essentially irreversible conversion of the methyl disulfide into methanethiol. The same overall reaction occurs thermally at room temperature, but the rate is appreciably less than that of the photochemical process. The quantum yields of formation of the unsymmetrical disulfides arising from the photochemically initiated exchange reaction in equimolar mixtures of CH3SSCH3 + n-C3H7SSC3H7 and C2H5SSC2H5 + n-C3H7SSC3H7 have been shown to be 6.9 and 4.4, compared to 355 for CH3-SSCH3 + C2H5SSC2H5 mixtures. In all three types of system examined in this investigation all thiyl radicals can be accounted for stoichiometrically on the basis of exchange and combination reactions alone, indicating negligible disproportionation of these species in condensed phase.

Photoisomerization of 2-Alkenes in the Presence of Hydrogen Sulfide

1972 ◽  
Vol 50 (15) ◽  
pp. 2400-2406 ◽  
Author(s):  
Guy J. Collin ◽  
Patrick M. Perrin
Keyword(s):  
Hydrogen Sulfide ◽  
Liquid Phase ◽  
Quantum Yields ◽  
Chain Mechanism ◽  
Thiyl Radicals ◽  
Trans Isomerization ◽  
A Chain ◽  
Effect Of Oxygen

In far u.v. photochemistry, the radicals formed react with hydrogen sulfide to give, amongst others, thiyl radicals (HS•). These radicals initiate the cis–trans isomerization of 2-olefins in a chain mechanism. We have tried to demonstrate that the thiyl radicals are also chain carriers. Quantum yields for the isomerization of cis to trans compound are probably of the order of 6–7 × 103 and the length of the chain, of the order of 4.7 × 103. We have also studied the radiolysis of these reactions in the liquid phase. The effect of oxygen and of conjugated di-olefins, such as 1,3-butadiene and 1,3-pentadiene is also discussed.

The Quantum Yield of Oxidation of Hevea Rubber and GR-S

1948 ◽  
Vol 21 (3) ◽  
pp. 639-653 ◽  
Author(s):  
E. J. Hart ◽  
M. S. Matheson
Keyword(s):  
Quantum Yield ◽  
Room Temperature ◽  
Wave Length ◽  
Radical Reaction ◽  
Quantum Yields ◽  
Initial Reaction ◽  
Free Radical Reaction ◽  
Stable Intermediate ◽  
A Chain ◽  
Reaction Chain

Abstract The initial quantum yields of photoöxidation for purified Hevea rubber have been measured for various mercury arc lines in the wave length region 2537– 17,400 A˚. All experiments were carried out at room temperature and at an oxygen pressure of one atmosphere. At the outset of irradiation all quantum yields of combined oxygen are less than unity, although the quantum efficiency rises above 1.0 at 2537 and 3130 A˚. as photoöxidation proceeds. The low quantum yield suggests that in its initial stages (less than 0.1 per cent oxygen combined on the rubber) photoöxidation is not a chain reaction. It is postulated as the first step in rubber photoöxidation that the light activated rubber group reacts with oxygen to give a relatively stable intermediate which does not immediately dissociate to give a free radical reaction chain. The quantum yields of photoöxidation of purified GR-S were also measured under the same conditions as used for rubber. At each wave length the quantum yield was lower than for rubber, indicating formation of a stable intermediate in the initial reaction also.

High efficiency photoresist-free lithography of UO3 patterns from amorphous films of uranyl complexes

1998 ◽  
Vol 13 (5) ◽  
pp. 1379-1389 ◽  
Author(s):  
M. Gao ◽  
Ross H. Hill
Keyword(s):  
Uranium Oxide ◽  
High Efficiency ◽  
Optical Lithography ◽  
Silicon Surfaces ◽  
Quantum Yields ◽  
Chain Reaction ◽  
Amorphous Films ◽  
Chain Reactions ◽  
A Chain ◽  
Primary Photochemical Reaction

The solid state photochemistry of uranyl carboxylate complexes is presented with the purpose of developing methods for optical lithography of uranium oxide films. These complexes of the general formula, UO2(OOCR)2 (R = i-C3H7, C5H11, CH2C6H5, CH2OC2H5, C2H4OC2H5), were all photosensitive as thin amorphous films. The primary photochemical reaction for each of these complexes was the extrusion of a CO2 from the ligand and the production of radicals which initiated a chain reaction. The nature of this chain reaction was dependent upon the identity of the organic substituents, R. In some cases the chain reaction required a photochemical step while others were entirely thermal in nature. Of importance are the potentially high quantum yields which can be associated with thermal chain reactions. Some of the systems presented here exhibit quantum yields in excess of 1. This process was shown to be compatible with optical lithography by the patterning of the uranium oxide product on silicon surfaces.

Notiz: A Molecular Source of CF2(X̃) at Room Temperature

1994 ◽  
Vol 49 (6) ◽  
pp. 730-732
Author(s):  
W. Hack ◽  
M. Wagner
Keyword(s):  
Room Temperature ◽  
Molecular System ◽  
Single Step ◽  
Production Mechanism ◽  
Chain Reaction ◽  
Step Process ◽  
Molecular Source ◽  
A Chain

Abstract In the molecular system of F2 and C3O2 a fast formation of CF2 (X̃) was detected directly via LIF. The CF2 (X̃) production mechanism could be a single step process but also how­ ever a chain reaction via F atoms.

Radiation Chemistry of Carbohydrates, X* γ-Radiolysis of Crystalline D-Glucose and D-Fructose

1977 ◽  
Vol 32 (2) ◽  
pp. 213-224 ◽  
Author(s):  
M. Dizdaroglu ◽  
D. Henneberg ◽  
K. Neuwald ◽  
G. Schomburg ◽  
C. Von Sonntag
Keyword(s):  
Aqueous Solution ◽  
Solid State ◽  
Dose Rate ◽  
Gluconic Acid ◽  
Room Temperature ◽  
Radiation Chemistry ◽  
Chain Reaction ◽  
A Chain ◽  
Reaction Schemes

α-D-Glucose and β-D-fructose were γ-irratiated in the solid (polycrystalline) state at room temperature at doses of 3.5 · 1020-4.2 · 1021 eV g-1 (dose rate 1.16 · 1018 eV g-1 min-1). Carbohydrate products containing ≤ 6 carbon atoms were identified and their G-values (in parentheses) measured.Glucose: Dihydroxyacetone (1) (0.05), 3-deoxy-tetrose (2) (0.015), 1,4-dideoxy-2-pentulose (3) (0.05), 2,4-dideoxy-pentose (4) (0.085), 2,4-dideoxy-pentonic acid (5), 2,3-dideoxypentos-4-ulose (6) (together 0.035), threose (7), erythrulose (8), erythrose (9), erythronic acid (10) (together 0.04), 1-deoxy-2-pentulose (11) (0.005), 2-deoxy-ribose (12) (0.25), 3-deoxy-pentosulose (18) (0.02), 3,5-dideoxy-hexonic acid (14) (0.02), 2,3-dideoxy-hexonic acid (15) (0.01), arabinose (16) (0.25), ribose (17), ribonic acid (18) (together 0.02), 2-deoxy-2-C-hydroxymethyl-pentonic acid (19) (0.06), 5-deoxy-gluconic acid (20), 2deoxy-5-keto-glucose (21), 2-deoxy-gluconic acid (22), 2-deoxy-3-keto-glucose (28), 3-deoxy-glucosone (24), 3-deoxy-gluconic acid (25), 3-deoxy-4-keto-glucose (26), 3-deoxymannonic acid (27) (together 0.4). Identified but nor measured quantitatively were glucosone (28), 3-keto-glucose (29), 4-keto-glucose (30), 5-keto-glucose (31) and gluconic acid (82). G(H2) = 5.75; G(CO2) = 0.7.Fructose: 7-9 (together 0.65), 3-deoxy-pentonic acids (37), 3-deoxy-pentosulose (88) (together 0.3), arabonic acid (89) (0.1), 18 (0.05), 6-deoxy-2,5-hexodiulose (40) (40). Identified but not measured quantitatively were glyceraldehyde (34), butanone-(3)-diol-(1,2) (35) and 2- and 3-deoxy-hexodiuloses. G(H2) = 4.75, G(CO2) = 0.05.Reaction schemes are proposed to account for the formation of the products. The scission of the hemiacetal bond and of the C-Η and C-C bonds next to it appears to be typical for solid state irradiations. The formation of deoxy-compounds is observed both in the solid state and in aqueous solution. The formation of dideoxy-compounds is only prominent in the solid state. In polycrystalline fructose a chain reaction is induced leading to 6-deoxy-2,5-hexodiulose (40).

Observations on a Relationship between Steroid Metabolism and the Concentration of Plasma Fibrinogen

1963 ◽  
Vol 10 (02) ◽  
pp. 400-405 ◽  
Author(s):  
B. A Amundson ◽  
L. O Pilgeram
Keyword(s):  
Blood Coagulation ◽  
Methyl Ether ◽  
Broad Spectrum ◽  
Human Subjects ◽  
Plasma Fibrinogen ◽  
Steroid Metabolism ◽  
Specific Site ◽  
Chain Reaction ◽  
Normal Human ◽  
A Chain

SummaryEnovid (5 mg norethynodrel and 0.075 mg ethynylestradiol-3-methyl ether) therapy in young normal human subjects causes an increase in plasma fibrinogen of 32.4% (P >C 0.001). Consideration of this effect together with other effects of Enovid on the activity of specific blood coagulatory factors suggests that the steroids are exerting their effect at a specific site of the blood coagulation and/or fibrinolytic system. The broad spectrum of changes which are induced by the steroids may be attributed to a combination of a chain reaction and feed-back control.

Data-Driven Many-Body Models with Chemical Accuracy for CH4/H2O Mixtures

2020 ◽  
Author(s):  
Marc Riera ◽  
Alan Hirales ◽  
Raja Ghosh ◽  
Francesco Paesani
Keyword(s):  
Liquid Phase ◽  
Quantitative Description ◽  
Liquid Mixtures ◽  
Many Body ◽  
Energy Functions ◽  
Potential Energy Functions ◽  
Dynamics Simulations ◽  
Body Potential ◽  
Small Clusters ◽  
Many Body Interactions

<div> <div> <div> <p>Many-body potential energy functions (PEFs) based on the TTM-nrg and MB-nrg theoretical/computational frameworks are developed from coupled cluster reference data for neat methane and mixed methane/water systems. It is shown that that the MB-nrg PEFs achieve subchemical accuracy in the representation of individual many-body effects in small clusters and enables predictive simulations from the gas to the liquid phase. Analysis of structural properties calculated from molecular dynamics simulations of liquid methane and methane/water mixtures using both TTM-nrg and MB-nrg PEFs indicates that, while accounting for polarization effects is important for a correct description of many-body interactions in the liquid phase, an accurate representation of short-range interactions, as provided by the MB-nrg PEFs, is necessary for a quantitative description of the local solvation structure in liquid mixtures. </p> </div> </div> </div>

The Reactivity of Different Active Forms of Sodium Carbonate with Respect to Sulfur Dioxide

1992 ◽  
Vol 57 (11) ◽  
pp. 2302-2308
Author(s):  
Karel Mocek ◽  
Erich Lippert ◽  
Emerich Erdös
Keyword(s):  
Thermal Decomposition ◽  
Liquid Phase ◽  
Sulfur Dioxide ◽  
Specific Surface ◽  
Surface Area ◽  
Sodium Carbonate ◽  
Room Temperature ◽  
Active Form ◽  
The Other ◽  
Kinetics Of

The kinetics of the reaction of solid sodium carbonate with sulfur dioxide depends on the microstructure of the solid, which in turn is affected by the way and conditions of its preparation. The active form, analogous to that obtained by thermal decomposition of NaHCO3, emerges from the dehydration of Na2CO3 . 10 H2O in a vacuum or its weathering in air at room temperature. The two active forms are porous and have approximately the same specific surface area. Partial hydration of the active Na2CO3 in air at room temperature followed by thermal dehydration does not bring about a significant decrease in reactivity. On the other hand, if the preparation of anhydrous Na2CO3 involves, partly or completely, the liquid phase, the reactivity of the product is substantially lower.

scholarly journals Preparation of Li3PS4–Li3PO4 Solid Electrolytes by Liquid-Phase Shaking for All-Solid-State Batteries

2021 ◽  
Vol 2 (1) ◽  
pp. 39-48
Author(s):  
Nguyen H. H. Phuc ◽  
Takaki Maeda ◽  
Tokoharu Yamamoto ◽  
Hiroyuki Muto ◽  
Atsunori Matsuda
Keyword(s):  
Solid Solution ◽  
Solid State ◽  
Liquid Phase ◽  
Room Temperature ◽  
Reaction Medium ◽  
Magic Angle Spinning ◽  
Resonance Spectroscopy ◽  
Synthesis Methods ◽  
Magic Angle ◽  
Angle Spinning

A solid solution of a 100Li3PS4·xLi3PO4 solid electrolyte was easily prepared by liquid-phase synthesis. Instead of the conventional solid-state synthesis methods, ethyl propionate was used as the reaction medium. The initial stage of the reaction among Li2S, P2S5 and Li3PO4 was proved by ultraviolet-visible spectroscopy. The powder X-ray diffraction (XRD) results showed that the solid solution was formed up to x = 6. At x = 20, XRD peaks of Li3PO4 were detected in the prepared sample after heat treatment at 170 °C. However, the samples obtained at room temperature showed no evidence of Li3PO4 remaining for x = 20. Solid phosphorus-31 magic angle spinning nuclear magnetic resonance spectroscopy results proved the formation of a POS33− unit in the sample with x = 6. Improvements of ionic conductivity at room temperature and activation energy were obtained with the formation of the solid solution. The sample with x = 6 exhibited a better stability against Li metal than that with x = 0. The all-solid-state half-cell employing the sample with x = 6 at the positive electrode exhibited a better charge–discharge capacity than that employing the sample with x = 0.

scholarly journals Pathogenesis and Management of COVID-19

2021 ◽  
Vol 11 (2) ◽  
pp. 77-93
Author(s):  
Khalid O. Alfarouk ◽  
Sari T. S. AlHoufie ◽  
Samrein B. M. Ahmed ◽  
Mona Shabana ◽  
Ahmed Ahmed ◽  
...  
Keyword(s):  
Multiple Organ Failure ◽  
Human Body ◽  
Inflammatory Mediators ◽  
Expression Patterns ◽  
Multiple Organ ◽  
Cytokine Storm ◽  
Chain Reaction ◽  
Road Map ◽  
A Chain ◽  
Global War

COVID-19, occurring due to SARS-COV-2 infection, is the most recent pandemic disease that has led to three million deaths at the time of writing. A great deal of effort has been directed towards altering the virus trajectory and/or managing the interactions of the virus with its subsequent targets in the human body; these interactions can lead to a chain reaction-like state manifested by a cytokine storm and progress to multiple organ failure. During cytokine storms the ratio of pro-inflammatory to anti-inflammatory mediators is generally increased, which contributes to the instigation of hyper-inflammation and confers advantages to the virus. Because cytokine expression patterns fluctuate from one person to another and even within the same person from one time to another, we suggest a road map of COVID-19 management using an individual approach instead of focusing on the blockbuster process (one treatment for most people, if not all). Here, we highlight the biology of the virus, study the interaction between the virus and humans, and present potential pharmacological and non-pharmacological modulators that might contribute to the global war against SARS-COV-2. We suggest an algorithmic roadmap to manage COVID-19.

Sign in / Sign up

Export Citation Format

Share Document