Probing the Reactivity of the Potent AgF2 Oxidizer. Part 1: Organic Compounds

2008 ◽  
Vol 73 (12) ◽  
pp. 1729-1746 ◽  
Author(s):  
Dorota Grzybowska ◽  
Przemysław Malinowski ◽  
Zoran Mazej ◽  
Wojciech Grochala
Keyword(s):  
Organic Compounds ◽  
Room Temperature ◽  
Bimolecular Reaction ◽  
Intramolecular Rearrangement ◽  
Triflic Acid ◽  
Experimental Conditions ◽  
Lewis Bases ◽  
Gaseous Products ◽  
Aliphatic Nitriles ◽  
High Degree

The reactivity of Ag(II)F2 towards a variety of organic compounds of a high degree of fluorination has been investigated. AgF2 readily fluorinates P(C6F5)3 to PF2(C6F5)3, and attacks the isothiocyanate functional group, -NCS, yielding Ag2S. Perfluorinated aliphatic nitriles resist the action of AgF2, but aromatic C6F5CN undergoes a radical-initiated oligomerization; byproducts include C6F6CN• and C6F5N2• (after intramolecular rearrangement following the bimolecular reaction). AgF2 oxidizes higher fluorosulfonic acids (C4F9SO3H, C8F17SO3H) at or close to the room temperature and triflic acid (CF3SO3H) at its boiling point to the corresponding peroxides. CF3COOH and CF3CONH2 are also decomposed in redox reactions, but the gaseous products have not been identified. Surprisingly, AgF2 is kinetically inert to perfluorinated aromatic hydrocarbons and to CCl4, but it decomposes CBr4 with vigorous elimination of Br2. CI4 decomposes explosively in the presence of AgF2. C6F5OH and CF3COOH are readily oxidized with AgF2 but, surprisingly, t-C4F9OH is kinetically resistant under similar conditions. Coordination complexes of perfluorinated aza and oxa Lewis bases (including perfluorinated 15-crown-5 ether) and AgF2 are not formed under the experimental conditions.

scholarly journals Gaseous products and Secondary Organic Aerosol formation during long term oxidation of isoprene and methacrolein

2014 ◽  
Vol 14 (16) ◽  
pp. 22507-22545 ◽  
Author(s):  
L. Brégonzio-Rozier ◽  
F. Siekmann ◽  
C. Giorio ◽  
E. Pangui ◽  
S. B. Morales ◽  
...  
Keyword(s):  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Oh Radicals ◽  
Aerosol Formation ◽  
Experimental Conditions ◽  
Gaseous Products ◽  
Oxidation Rates ◽  
Chamber Studies ◽  
High Degree

Abstract. First- and higher-generation products from the oxidation of isoprene and methacrolein with OH radicals in the presence of NOx have been studied in a simulation chamber: (1) significant oxidation rates have been maintained for up to 7 h allowing the study of highly oxidized products, (2) gas-phase products distribution and yields are provided, and show good agreement with previous studies. Secondary organic aerosol (SOA) formation resulting from these experiments has also been investigated. Among the general dispersion exhibited by SOA mass yields from previous studies, the mass yields obtained here were consistent with the lowest values found in the literature, and more specifically in agreement with studies carried out with natural light or artificial lamps with emission spectrum similar to the solar one. An effect of light source is hence proposed to explain, at least in part, the discrepancies observed between different studies in the literature for both isoprene- and methacrolein-SOA mass yields. A high degree of similarity is shown in the comparison of SOA mass spectra from isoprene and methacrolein photooxidation, thus strengthening the importance of the role of methacrolein in SOA formation from isoprene photooxidation under our experimental conditions (i.e. presence of NOx and long term oxidation). Overall, if these results are further confirmed, SOA mass yields from both isoprene and methacrolein in the atmosphere could be lower than suggested by most of the current chamber studies.

A Reinvestigation of the Deceptively Simple Reaction of Toluene with ●OH, and the Fate of the Benzyl Radical. I. a Combined Thermodynamic and Kinetic Study on the Competition Between ●OH Addition and Hydrogen Abstraction Reactions.

2019 ◽  
Author(s):  
Zoi Salta ◽  
Agnie M. Kosmas ◽  
Marc E. Segovia ◽  
Martina Kieninger ◽  
Oscar Ventura ◽  
...  
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Hydrogen Abstraction ◽  
Reaction Rates ◽  
Composite Model ◽  
Alternative Mechanism ◽  
Radical Intermediate ◽  
Experimental Conditions ◽  
Methyl Group ◽  
Benzyl Radical

This work reports density functional and composite model chemistry calculations performed on the reactions of toluene with the hydroxyl radical. Both experimentally observed H-abstraction from the methyl group and possible additions to the phenyl ring were investigated. Reaction enthalpies and heights of the barriers suggest that H-abstraction is more favorable than ●OH addition to the ring. The calculated reaction rates at room temperature and the radical-intermediate product fractions support this view. This is somehow contradictory with the fact that, under most experimental conditions, cresols are observed in a larger concentration than benzaldehyde. Since the accepted mechanism for benzaldehyde formation involves H-abstraction, a contradiction arises that begs for an explanation. In this first part of our work we give the evidences that support the preference of hydrogen abstraction over ●OH addition and suggest an alternative mechanism which shows that cresols can actually arise also from the former reaction and not only from the latter.

A Reinvestigation of the Deceptively Simple Reaction of Toluene with ●OH, and the Fate of the Benzyl Radical. I. a Combined Thermodynamic and Kinetic Study on the Competition Between ●OH Addition and Hydrogen Abstraction Reactions.

2019 ◽  
Author(s):  
Zoi Salta ◽  
Agnie M. Kosmas ◽  
Marc E. Segovia ◽  
Martina Kieninger ◽  
Oscar Ventura ◽  
...  
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Hydrogen Abstraction ◽  
Reaction Rates ◽  
Composite Model ◽  
Alternative Mechanism ◽  
Radical Intermediate ◽  
Experimental Conditions ◽  
Methyl Group ◽  
Benzyl Radical

This work reports density functional and composite model chemistry calculations performed on the reactions of toluene with the hydroxyl radical. Both experimentally observed H-abstraction from the methyl group and possible additions to the phenyl ring were investigated. Reaction enthalpies and heights of the barriers suggest that H-abstraction is more favorable than ●OH addition to the ring. The calculated reaction rates at room temperature and the radical-intermediate product fractions support this view. This is somehow contradictory with the fact that, under most experimental conditions, cresols are observed in a larger concentration than benzaldehyde. Since the accepted mechanism for benzaldehyde formation involves H-abstraction, a contradiction arises that begs for an explanation. In this first part of our work we give the evidences that support the preference of hydrogen abstraction over ●OH addition and suggest an alternative mechanism which shows that cresols can actually arise also from the former reaction and not only from the latter.

Manganese Oxide Photodeposited onto Titanium Dioxide as a New Environmental Catalyst

2005 ◽  
Vol 480-481 ◽  
pp. 117-122 ◽  
Author(s):  
Ayumu Tateoka ◽  
Yoshika Sekine ◽  
Takamasa Tsuda ◽  
Takanobu Ohashi
Keyword(s):  
Carbon Dioxide ◽  
Titanium Dioxide ◽  
Manganese Oxide ◽  
Organic Compounds ◽  
Uv Irradiation ◽  
Room Temperature ◽  
Complex Oxide ◽  
Environmental Catalysis ◽  
Environmental Catalyst ◽  
Formaldehyde In Air

Authors have successfully synthesized a new environmental catalysis which reacted with harmful formaldehyde in air at room temperature. Although manganese oxide is practically used for a major ingredient of formaldehyde removing materials, intermediates such as formate formed on the surface reduced the removal efficiency. Then, manganese oxide was photodeposited onto the surface of titanium dioxide particles which could decompose certain organic compounds with UV irradiation. It was confirmed that the complex oxide decomposed formaldehyde into carbon dioxide at room temperature. Moreover, UV irradiation enhanced the production of the carbon dioxide.

scholarly journals Silver Enhances Hematite Nanoparticles Based Ethanol Sensor Response and Selectivity at Room Temperature

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 440
Author(s):  
Daniel Garcia-Osorio ◽  
Pilar Hidalgo-Falla ◽  
Henrique E. M. Peres ◽  
Josue M. Gonçalves ◽  
Koiti Araki ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Gas Sensors ◽  
Room Temperature ◽  
Gas Sensing ◽  
Ethanol Vapor ◽  
Oxide Semiconductor ◽  
Charge Carrier Density ◽  
Ethanol Sensor ◽  
Volatile Organic

Gas sensors are fundamental for continuous online monitoring of volatile organic compounds. Gas sensors based on semiconductor materials have demonstrated to be highly competitive, but are generally made of expensive materials and operate at high temperatures, which are drawbacks of these technologies. Herein is described a novel ethanol sensor for room temperature (25 °C) measurements based on hematite (α‑Fe2O3)/silver nanoparticles. The AgNPs were shown to increase the oxide semiconductor charge carrier density, but especially to enhance the ethanol adsorption rate boosting the selectivity and sensitivity, thus allowing quantification of ethanol vapor in 2–35 mg L−1 range with an excellent linear relationship. In addition, the α-Fe2O3/Ag 3.0 wt% nanocomposite is cheap, and easy to make and process, imparting high perspectives for real applications in breath analyzers and/or sensors in food and beverage industries. This work contributes to the advance of gas sensing at ambient temperature as a competitive alternative for quantification of conventional volatile organic compounds.

scholarly journals Responses of quinoa (Chenopodium quinoa Willd.) seeds stored under different germination temperatures

2017 ◽  
Vol 39 (1) ◽  
pp. 83 ◽  
Author(s):  
Andressa Strenske ◽  
Edmar Soares de Vasconcelos ◽  
Vanessa Aline Egewarth ◽  
Neusa Francisca Michelon Herzog ◽  
Marlene De Matos Malavasi
Keyword(s):  
Room Temperature ◽  
Storage Time ◽  
Chenopodium Quinoa ◽  
Seed Vigor ◽  
Continuous Darkness ◽  
Experimental Conditions ◽  
Growing Seasons ◽  
Germinating Seeds ◽  
Germinated Seeds ◽  
Plot Design

In this experiment, we assessed the germination and vigor of quinoa seeds packed in paper bags and stored at room temperature for 36, 85, 119, 146, 177 and 270 days. The seeds were harvested under experimental conditions in Marechal Candido Rondon, Paraná, during the 2012/13 growing seasons. Four replicates of 100 seeds each were established for each storage time, and the seeds were evaluated, on paper, based on the BOD under the following experimental temperature conditions: alternating temperatures of 20 and 30°C and a constant temperature of 25°C. The seeds from both treatments were subject to seven-hour photoperiods and 25°C under continuous darkness. The germinated seeds were counted daily for eight days after sowing, and we evaluated the percentages of normal and abnormal seedlings and the germination index. The experimental design was completely randomized using a split-plot design. Increasing the storage time decreased the percentage of germinated seeds and seed vigor due to the increased number of abnormal seedlings. Over the 430-day study period, quinoa seed germination completely declined under the experimental conditions. The final number of germinating seeds should be evaluated 7 days after the beginning of the germination test. 

scholarly journals Electroless and Electrodeposition of Silver from a Choline Chloride-Based Ionic Liquid

2015 ◽  
Vol 58 (2) ◽  
pp. 66-73
Author(s):  
Muhammad Rostom Ali ◽  
Muhammad Ziaur Rahman ◽  
Siddhartha Sankar Saha
Keyword(s):  
Ionic Liquids ◽  
Room Temperature ◽  
Choline Chloride ◽  
Dip Coating ◽  
Constant Current ◽  
Electrolytic Deposition ◽  
Cathodic Current ◽  
Experimental Conditions ◽  
Constant Potential ◽  
Potential Methods

The electroless and electrolytic deposition of silver from a solution containing silver nitrate in either an ethylene glycol (EG)-choline chloride based or a urea-choline chloride based ionic liquids has been carried out onto steel and copper cathodes by simple immersion, constant current and constant potential methods at room temperature. It has been found that electroless silver deposits of up to several micronshave been obtained by dip coating from both urea and EG based ionic liquids without the use of catalysts. The influences of various experimental conditions on electrodeposition and morphology of the deposited layers have been investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). It has been observed that crack free bright metallic coloured silver coatings can be obtained from both EG and urea based ionic liquids at the applied deposition potentials up to -0.40 V and applied deposition current densities up to -5.0 A m-2 at room temperature. The cathodic current efficiency for the deposition of Ag is about 99%.

scholarly journals Room-temperature autonomous self-healing glassy polymers with hyperbranched structure

2020 ◽  
Vol 117 (21) ◽  
pp. 11299-11305 ◽  
Author(s):  
Hao Wang ◽  
Hanchao Liu ◽  
Zhenxing Cao ◽  
Weihang Li ◽  
Xin Huang ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Room Temperature ◽  
Glassy State ◽  
Glassy Polymers ◽  
Self Healing ◽  
External Branch ◽  
Healing Efficiency ◽  
High Degree ◽  
External Stimuli ◽  
Hyperbranched Structure

Glassy polymers are extremely difficult to self-heal below their glass transition temperature (Tg) due to the frozen molecules. Here, we fabricate a series of randomly hyperbranched polymers (RHP) with high density of multiple hydrogen bonds, which showTgup to 49 °C and storage modulus up to 2.7 GPa. We reveal that the hyperbranched structure not only allows the external branch units and terminals of the molecules to have a high degree of mobility in the glassy state, but also leads to the coexistence of “free” and associated complementary moieties of hydrogen bonds. The free complementary moieties can exchange with the associated hydrogen bonds, enabling network reconfiguration in the glassy polymer. As a result, the RHP shows amazing instantaneous self-healing with recovered tensile strength up to 5.5 MPa within 1 min, and the self-healing efficiency increases with contacting time at room temperature without the intervention of external stimuli.

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