Radiation Induced Oxidation of Methanol

1991 ◽  
Vol 46 (7) ◽  
pp. 625-629 ◽  
Author(s):  
Hak-Jin Jung ◽  
Nikola Getoff
Keyword(s):  
Reaction Mechanism ◽  
Oxalic Acid ◽  
Formic Acid ◽  
Carboxylic Acids ◽  
Glycolic Acid ◽  
Absorbed Dose ◽  
Pure Oxygen ◽  
Oxidation Of Methanol ◽  
Glyoxalic Acid ◽  
Radiation Induced

The radiolysis of methanol in the presence of air as well as of pure oxygen (1 to 5atm) was investigated, the yields of the major products: carboxylic acids (by far predominantly formic acid), oxalic acid, formaldehyde and glycolaldehyde were determined as a function of the absorbed dose. In addition small amounts (G≤0.05) of glyoxal, glyoxalic acid and glycolic acid were also detected. Based on the results a possible reaction mechanism is presented.

Aerobic oxidation of methanol to formic acid on Au20−: a theoretical study on the reaction mechanism

2012 ◽  
Vol 14 (9) ◽  
pp. 3103 ◽  
Author(s):  
Karan Bobuatong ◽  
Sangita Karanjit ◽  
Ryoichi Fukuda ◽  
Masahiro Ehara ◽  
Hidehiro Sakurai
Keyword(s):  
Reaction Mechanism ◽  
Formic Acid ◽  
Theoretical Study ◽  
Aerobic Oxidation ◽  
Oxidation Of Methanol

scholarly journals Boosting the H2 Production Efficiency via Photocatalytic Organic Reforming: The Role of Additional Hole Scavenging System

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1423
Author(s):  
Yamen AlSalka ◽  
Osama Al-Madanat ◽  
Amer Hakki ◽  
Detlef W. Bahnemann
Keyword(s):  
Reaction Mechanism ◽  
Oxalic Acid ◽  
Formic Acid ◽  
Environmental Remediation ◽  
Production Efficiency ◽  
Isotopic Labeling ◽  
Hydrogen Yield ◽  
Organic Substrates ◽  
H2 Evolution ◽  
Flow Monitoring

The simultaneous photocatalytic H2 evolution with environmental remediation over semiconducting metal oxides is a fascinating process for sustainable fuel production. However, most of the previously reported photocatalytic reforming showed nonstoichiometric amounts of the evolved H2 when organic substrates were used. To explain the reasons for this phenomenon, a careful analysis of the products and intermediates in gas and aqueous phases upon the photocatalytic hydrogen evolution from oxalic acid using Pt/TiO2 was performed. A quadrupole mass spectrometer (QMS) was used for the continuous flow monitoring of the evolved gases, while high performance ion chromatography (HPIC), isotopic labeling, and electron paramagnetic resonance (EPR) were employed to understand the reactions in the solution. The entire consumption of oxalic acid led to a ~30% lower H2 amount than theoretically expected. Due to the contribution of the photo-Kolbe reaction mechanism, a tiny amount of formic acid was produced then disappeared shortly after the complete consumption of oxalic acid. Nevertheless, a much lower concentration of formic acid was generated compared to the nonstoichiometric difference between the formed H2 and the consumed oxalic acid. Isotopic labeling measurements showed that the evolved H2, HD, and/or D2 matched those of the solvent; however, using D2O decreased the reaction rate. Interestingly, the presence of KI as an additional hole scavenger with oxalic acid had a considerable impact on the reaction mechanism, and thus the hydrogen yield, as indicated by the QMS and the EPR measurements. The added KI promoted H2 evolution to reach the theoretically predictable amount and inhibited the formation of intermediates without affecting the oxalic acid degradation rate. The proposed mechanism, by which KI boosts the photocatalytic performance, is of great importance in enhancing the overall energy efficiency for hydrogen production via photocatalytic organic reforming.

Ligand-Enabled γ-C(sp3)–H Olefination of Free Carboxylic Acids

2020 ◽  
Author(s):  
Kiron Kumar Ghosh ◽  
Alexander Uttry ◽  
Francesca Ghiringhelli ◽  
Arup Mondal ◽  
Manuel van Gemmeren
Keyword(s):  
Reaction Mechanism ◽  
Carboxylic Acids ◽  
Michael Addition ◽  
Kinetic Studies ◽  
Wide Range ◽  
Palladium Catalyzed

We report the ligand enabled C(sp3)–H activation/olefination of free carboxylic acids in the γ-position. Through an intramolecular Michael-addition, δ-lactones are obtained as products. Two distinct ligand classes are identified that enable the challenging palladium-catalyzed activation of free carboxylic acids in the γ-position. The developed protocol features a wide range of acid substrates and olefin reaction partners and is shown to be applicable on a preparatively useful scale. Insights into the underlying reaction mechanism obtained through kinetic studies are reported.<br>

scholarly journals EANM position paper on the role of radiobiology in nuclear medicine

2021 ◽  
Author(s):  
An Aerts ◽  
Uta Eberlein ◽  
Sören Holm ◽  
Roland Hustinx ◽  
Mark Konijnenberg ◽  
...  
Keyword(s):  
Nuclear Medicine ◽  
Absorbed Dose ◽  
Added Value ◽  
External Irradiation ◽  
Executive Summary ◽  
Dose Rates ◽  
Biological Responses ◽  
Medical Physicists ◽  
Radiation Induced

Executive SummaryWith an increasing variety of radiopharmaceuticals for diagnostic or therapeutic nuclear medicine as valuable diagnostic or treatment option, radiobiology plays an important role in supporting optimizations. This comprises particularly safety and efficacy of radionuclide therapies, specifically tailored to each patient. As absorbed dose rates and absorbed dose distributions in space and time are very different between external irradiation and systemic radionuclide exposure, distinct radiation-induced biological responses are expected in nuclear medicine, which need to be explored. This calls for a dedicated nuclear medicine radiobiology. Radiobiology findings and absorbed dose measurements will enable an improved estimation and prediction of efficacy and adverse effects. Moreover, a better understanding on the fundamental biological mechanisms underlying tumor and normal tissue responses will help to identify predictive and prognostic biomarkers as well as biomarkers for treatment follow-up. In addition, radiobiology can form the basis for the development of radiosensitizing strategies and radioprotectant agents. Thus, EANM believes that, beyond in vitro and preclinical evaluations, radiobiology will bring important added value to clinical studies and to clinical teams. Therefore, EANM strongly supports active collaboration between radiochemists, radiopharmacists, radiobiologists, medical physicists, and physicians to foster research toward precision nuclear medicine.

scholarly journals Oxidation of Glyoxylic Acid to Oxalic Acid by Glycolic Acid Oxidase

1961 ◽  
Vol 236 (5) ◽  
pp. 1280-1284
Author(s):  
K.E. Richardson ◽  
N.E. Tolbert
Keyword(s):  
Oxalic Acid ◽  
Glycolic Acid ◽  
Glyoxylic Acid ◽  
Acid Oxidase

Dosimetry of High-Energy Photon Beams Based on Standards of Absorbed Dose to Water: Abstract

2001 ◽  
Vol 1 (1) ◽  
pp. 8-8 ◽  
Author(s):  
K. Hohlfeld ◽  
P. Andreo ◽  
O. Mattsson ◽  
J. P. Simoen
Keyword(s):  
Reference Conditions ◽  
International Comparisons ◽  
Absorbed Dose ◽  
High Energy ◽  
National Standards ◽  
Photon Radiation ◽  
Photon Beams ◽  
Radiation Induced ◽  
Absorbed Dose To Water ◽  
Primary Standards

This report examines the methods by which absorbed dose to water can be determined for photon radiations with maximum energies from approximately 1 MeV to 50 MeV, the beam qualities most commonly used for radiation therapy. The report is primarily concerned with methods of measurement for photon radiation, but many aspects are also relevant to the dosimetry of other therapeutic beams (high-energy electrons, protons, etc.). It deals with methods that are sufficiently precise and well established to be incorporated into the dosimetric measurement chain as primary standards (i.e., methods based on ionisation, radiation-induced chemical changes, and calorimetry using either graphite or water). The report discusses the primary dose standards used in several national standards laboratories and reviews the international comparisons that have been made. The report also describes the reference conditions that are suitable for establishing primary standards and provides a formalism for determining absorbed dose, including a discussion of correction factors needed under conditions other than those used to calibrate an instrument at the standards laboratory.

A computational study on the mechanism of ynamide-mediated amide bond formation from carboxylic acids and amines

2017 ◽  
Vol 15 (30) ◽  
pp. 6367-6374 ◽  
Author(s):  
Song-Lin Zhang ◽  
Hai-Xing Wan ◽  
Zhu-Qin Deng
Keyword(s):  
Reaction Mechanism ◽  
Carboxylic Acids ◽  
Computational Study ◽  
Bond Formation ◽  
Amide Bond ◽  
Reactivity Pattern ◽  
Amide Bond Formation ◽  
Coupling Reagent ◽  
Catalytic Effects ◽  
Acid Substrate

A detailed computational study is presented on the reaction mechanism of ynamide-mediated condensation of carboxylic acids with amines to produce amides, which elucidates the reactivity pattern of the coupling reagent ynamide and discloses crucial bifunctional catalytic effects of the carboxylic acid substrate during aminolysis.

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