7782-44-7Relevant articles and documents
Measurements of the absorption line strength of hydroperoxyl radical in the ν3 band using a continuous wave quantum cascade laser
Sakamoto, Yosuke,Tonokura, Kenichi
, p. 215 - 222 (2012)
Mid-infrared absorption spectroscopy has been applied to the detection of the hydroperoxyl (HO2) radical in pulsed laser photolysis combined with a laser absorption kinetics reactor. Transitions of the ν3 vibrational band assigned to the O-O stretch mode were probed with a thermoelectrically cooled, continuous wave mid-infrared distributed feedback quantum cascade laser (QCL). The HO2 radicals were generated with the photolysis of Cl2/CH3OH/O2 mixtures at 355 nm. The absorption cross section at each pressure was determined by three methods at 1065.203 cm-1 for the F1, 131,13 ← 141,14 transition in the ν3 band. From these values, the absolute absorption cross section at zero pressure was estimated. The relative line strengths of other absorptions in the feasible emitting frequency range of the QCL from 1061.17 to 1065.28 cm-1 were also measured, and agreed with values reproduced from the HITRAN database. The ν3 band absorption strength was estimated from the analytically obtained absolute absorption cross section and the calculated relative intensity by spectrum simulation, to be 21.4 ± 4.2 km mol-1, which shows an agreement with results of quantum chemical calculations.
Investigation of the radical product channel of the CH3OCH 2O2 + HO2 Reaction in the Gas Phase
Jenkin,Hurley,Wallington
, p. 408 - 416 (2010)
The reaction of CH3OCH2O2 with HO 2 has been investigated at 296 K and 700 Torr using long path FTIR spectroscopy, during photolysis of Cl2/CH3OCH 3/CH3OH/air mixtures. The branching ratio for the reaction channel forming CH3OCH2O, OH, and O2 has been determined from experiments in which OH radicals were scavenged by addition of benzene to the system, with subsequent formation of phenol used as the primary diagnostic for OH radical formation. The dependence of the phenol yield on the initial peroxy radical precursor reagent concentration ratio, [CH 3OH]0/[CH3OCH3]0, is consistent with prompt OH formation resulting mainly from the reaction of CH3OCH2O2 with HO2, such that the inferred prompt yield of OH is well-correlated with that of CH 3OCH2OOH, a well-established product of the CH 3OCH2O2 + HO2 reaction. The system was fully characterized by simulation, using a detailed chemical mechanism which included other established sources of OH in the system. This allowed a branching ratio of k2c/k2 = 0.19 ± 0.08 to be determined. The results therefore provide strong indirect evidence for the participation of the radical-forming channel of the title reaction.
Prompt HO2 formation following the reaction of OH with aromatic compounds under atmospheric conditions
Nehr, Sascha,Bohn, Birger,Wahner, Andreas
, p. 6015 - 6026 (2012)
The secondary formation of HO2 radicals following OH + aromatic hydrocarbon reactions in synthetic air under normal pressure and temperature was investigated in the absence of NO after pulsed production of OH radicals. OH and HOx (=OH + HO2) decay curves were recorded using laser-induced fluorescence after gas-expansion. The prompt HO2 yields (HO2 formed without preceding NO reactions) were determined by comparison to results obtained with CO as a reference compound. This approach was recently introduced and applied to the OH + benzene reaction and was extended here for a number of monocyclic aromatic hydrocarbons. The measured HO2 formation yields are as follows: toluene, 0.42 ± 0.11; ethylbenzene, 0.53 ± 0.10; o-xylene, 0.41 ± 0.08; m-xylene, 0.27 ± 0.06; p-xylene, 0.40 ± 0.09; 1,2,3-trimethylbenzene, 0.31 ± 0.06; 1,2,4-trimethylbenzene, 0.37 ± 0.09; 1,3,5- trimethylbenzene, 0.29 ± 0.08; hexamethylbenzene, 0.32 ± 0.08; phenol, 0.89 ± 0.29; o-cresol, 0.87 ± 0.29; 2,5-dimethylphenol, 0.72 ± 0.12; 2,4,6-trimethylphenol, 0.45 ± 0.13. For the alkylbenzenes HO2 is the proposed coproduct of phenols, epoxides, and possibly oxepins formed in secondary reactions with O2. In most product studies the only quantified coproducts were phenols whereas only a few studies reported yields of epoxides. Oxepins have not been observed so far. Together with the yields of phenols from other studies, the HO2 yields determined in this work set an upper limit to the combined yields of epoxides and oxepins that was found to be significant (≥0.3) for all investigated alkylbenzenes except m-xylene. For the hydroxybenzenes the currently proposed HO2 coproducts are dihydroxybenzenes. For phenol and o-cresol the determined HO2 yields are matching the previously reported dihydroxybenzene yields, indicating that these are the only HO 2 forming reaction channels. For 2,5-dimethylphenol and 2,4,6-trimethylphenol no complementary product studies are available.
Production of H2O radical in the Track of High-Energy Carbon Ions
La Verne, Jay A.,Schuler, Robert H.
, p. 4171 - 4173 (1985)
The radiation chemical yields of H2O radical produced by irradiating water with 12C ions of 37-100-MeV initial energy have been determined. these data have been combined with previous values for lower energy carbon and helium ions to obtain the differential yields over the range 2-102 eV/Angstroem.The close similarly between the yields for helium and carbon ions of the same LET suggests that the reaction volume of interest extrends somewhat beyond the track core, especially for helium.LET appears to be a useful parameter to describe the production of H2O radicals in the tracks of heavy particles.
Mechanistic Investigation of the HO+HO2 Reaction
Kurylo, Michael J.,Klais, Odo,Laufer, Allan H.
, p. 3674 - 3678 (1981)
A steady-state photolysis experiment including mass-spectrometric end-product analysis was used to conduct a mechanistic investigation of the H(18)O+HO2 reaction system.The results obtained do not support the existence of a linear adduct reaction intermediate as suggested by a proposed pressure dependennce for the title reaction: HO+HO2->H2O+O2 (k1).An elaborate modeling analysis of the experiment best matches the observed product yields for values of k1 in the range 1*10-10-2*10-10 cm3 molecule-1 s-1.
Posey, Jessica,Sherwell, John,Kaufman, Myron
, p. 476 - 479 (1981)
Milligan, D. E.,Jacox, M. E.
, p. 2627 - 2631 (1963)
Reaction of O2 with the hydrogen atom in water up to 350 °C
Janik, Ireneusz,Bartels, David M.,Marin, Timothy W.,Jonah, Charles D.
, p. 79 - 88 (2007)
The reaction of the H atom with O2, giving the hydroperoxyl HO2 radical, has been investigated in pressurized water up to 350 °C using pulse radiolysis and deep-UV transient absorption spectroscopy. The reaction rate behavior is highly non-Arrhenius, with near diffusion-limited behavior at room temperature, increasing to a near constant limiting value of ~5 × 1010 M-1 s -1 above 250 °C. The high-temperature rate constant is in near-perfect agreement with experimental extrapolations and ab initio calculations of the gas-phase high-pressure limiting rate. As part of the study, reaction of the OH radical with H2 has been reevaluated at 350 °C, giving a rate constant of (6.0 ± 0.5) × 108 M-1 s-1. The mechanism of the H atom reaction with the HO2 radical is also investigated and discussed.
Time-resolved Study of Hydrogen Atoms in the H2-O2 System under Conditions close to Criticality
Hanning-Lee, Mark A.,Pilling, Michael J.,Warr, Jonathan F.
, p. 2907 - 2912 (1991)
A time-resolved study has been performed at conditions close to criticality in the H2-O2 system.Reaction was initiatd by the exciplex laser flash photolysis of O2 at 193.3 nm.H was monitored using time-resolved resonance fluorescence and showed an approximately biexponential time dependence.Near the explosion limit, the long-time behaviour is dominated by the competition between the branching and terminating H + O2 channels.Rate coefficients for these channels were inferred from this time dependence over the ranges 800 T/K 850 and 100 P/Torr 243.
Superoxide: Base, Nucleophile, Radical, or Electron Transfer Reagent?
Purrington, Suzanne T.,Kenion, Grant B.
, p. 731 - 732 (1982)
In contrast with the reaction in dimethylformamide, dichlorocarbene is formed from the superoxide ion and chloroform in benzene.
Hoare, D. E.,Walsh, A. D.
, p. 1102 - 1110 (1957)
Jen, C. K.,Foner, S. N.,Cochran, E. L.,Bowers, V. A.
, p. 1169 - 1182 (1958)
Laser photolysis of O3/H2 mixtures: The yield of the H + O3 -> HO2 + O reaction
Force, A.P.,Wiesenfeld, J.R.
, p. 1718 - 1723 (1981)
The collisional deactivation of O(21D2) by H2 and D2 was found to proceed with a rate constant 1.0 +/- 0.1 * 10-10 cm3 molecule-1 sec-1.The hydrogen atoms produced by O(21D2) + H2 -> OH + H were observed to react with the O3 source molecule with the rate coefficient 3*10-11 cm3 molecule-1 sec-1.Oxygen atoms were seen to be formed with a similar rate and approximately 40percent of the reactive encounters of H with O3, were estimated to result in the production of oxygen atoms instead of the expected OH and O2.Possible mechanisms involving collisionally induced dissociation of O3 by vibrationally excited hydroxyl radicals do not appear to account for the observed oxygen atom kinetics in this system, thus suggesting that H + O3 -> HO2 + O may indeed be a significant pathway in the reaction of hydrogen atoms with ozone.
Zabel, F.,Sahetchian, K. A.,Chachaty, C.
, p. 433 - 437 (1987)
Properties of chemically generated π-radical cations and molecules of (meso-phenyl-β-octaethylporphyrinato)rhenium(V) with axial molecular oxygen
Bichan,Tyulyaeva,Lomova
, p. 1445 - 1453 (2014)
The state of existence and reactions of stable rhenium(V) complexes with β-octaethylporphin (O=Re(OPh)OEP, O=Re(Cl)OEP) and its meso-diphenyl-substituted derivatives (O=Re(Cl)5,15DPOEP) in concentrated H2SO4 at 318-348 K were studied. It was found that O=Re(Cl)5,15DPOEP undergoes slow single-electron oxidation at the aromatic ligand to give π-radical cation. The oxidation is accompanied by replacement of the axial Cl- ligand by the hydrogen sulfate ion present in excess. Full kinetic description of the intricate oxidation reaction of the complex involving atmospheric oxygen was obtained and parameters of simple reactions that constitute the intricate process were determined. In the case of O=Re(Cl)OEP and O=Re(OPh)OEP, the reaction stops after the formation of the cationic complex with axially coordinated oxygen and outer-sphere chloride ion O=Re(O2)OEP+ Cl-. The effect of the nature of axial and macrocyclic ligands in rhenium(V) porphyrins on the processes in sulfuric acid solutions of these compounds was established.
Kinetics of the reaction of HO2 with ozone
Zahniser, Mark S.,Howard, Carleton J.
, p. 1620 - 1626 (1980)
Rate constants were measured for the reaction HO2 + O3 -> OH + 202(k1) using a discharge-flow system with laser magnetic resonance detection of both HO2 and OH. k1 was determined directly from the first order decay of HO2 in excess O3 when C2F3Cl was added to scavenge the OH product and prevent interference from the faster reaction OH + O3 -> HO2 + O2(k2).The ratio k2/k1 was independently determined from the steady-state / ratio obtained without C2F3Cl.Results from the scavenger method are given by k1 = (1.4+/-0.4)x10-14 exp cm3s-1 for 245 K a directly measured value of k2 = (6.5 +/- 1.0)x10-14 cm3s-1 at 300 K.These measurements are compared with other studies and some implications for stratospheric ozone chemistry are discussed.
ESR study of the thermal decomposition of di-tert-butoxy-tert-butyl alumotrioxide formed in the reaction of tri-tert-butoxyaluminum with tert-butyl hydroperoxide
Stepovik, L. P.,Martinova, I. M.,Dodonov, V. A.,Cherkasov, V. K.
, (2002)
Tri-tert-butoxyaluminum reacts with tert-butyl hydroperoxide to produce di-tert-butoxy-tert-butyl alumotrioxide, which decomposes heterolytically to form singlet dioxygen and homolytically with the O-O bond cleavage. The ButOO , (But
Smith, R. C.,Wyard, S. J.
, p. 897 - 898 (1961)
Stoichiometry and Rate of Reaction of Hydrogen Atoms with Oxygen
Pratt, Graham L.,Wood, Stephen W.
, p. 2597 - 2604 (1983)
The reaction of hydrogen atoms (1E-6-1E-5mol dm-3) with oxygen (0-1E-5mol dm-3) in excess argon has been studied in a fast flow-discharge tube at total pressures from 2 to 10 Torr and temperatures from 231 to 512 K using mass spectrometry and gas chromatography for final-product analysis.A method of measuring small concentrations of water (ca. 1E-7mol dm-3) has been developed which enabled the relative rates of reactions (2) and (3) to be determined, reaction (4) being negligible:+Ar->HO2+Ar (1); H+HO2->(2); H+HO2->2OH (3); H+HO2->H2O+O.Over the range 231(errors throughout are standard deviations.An improved Arrhenius expression for reaction (1) has been determined: .Previous evaluations of rate data for step (3) are discussed and revised values suggested:.
Measurements and modeling of HO2 formation in the reactions of n-C3H7 and i-C3H7 radicals with O2
Estupinì?aì?n, Edgar G.,Klippenstein, Stephen J.,Taatjes, Craig A.
, p. 8374 - 8387 (2005)
The formation of HO2 in the reactions of C2H 5, n-C3H7, and i-C3H7 radicals with O2 is investigated using the technique of laser photolysis/long-path frequency-modulation spectroscopy. The alkyl radicals are formed by 266 nm photolysis of alkyl iodides. The formation of HO2 from the subsequent reaction of the alkyl radicals with O2 is followed by infrared frequency-modulation spectroscopy. The concentration of I atoms is simultaneously monitored by direct absorption of a second laser probe on the spin-orbit transition. The measured profiles are compared to a kinetic model taken from time-resolved master-equation results based on previously published ab initio characterizations of the relevant stationary points on the potential-energy surface. The ab initio energies are adjusted to produce agreement with the present experimental data and with available literature studies. The isomer specificity of the present results enables refinement of the model for i-C3H7 + O2 and improved agreement with experimental measurements of HO2 production in propane oxidation. ? 2005 American Chemical Society.
Rate Constant and Possible Pressure Dependence of the Reaction OH+HO2
DeMore, W. B.
, p. 121 - 126 (1982)
The technique of laser-induced fluorescence has been used to measure steady-state OH concentrations in the photolysis of water vapor at 184.9 nm and 298 K, with O2 added in trace amounts.He or Ar was present at total pressures in the range 75-730 torr.The results were used to derive the rate-constant ratio k1/k51/2, where k1 and k5 are the rate constants for the reactions OH+HO2->H2O+O2 and HO2+HO2->O2, respectively.When currently available values for k5 are used, the results give k1=(1.2+/-0.4)x10-10 cm3s-1 at 1-atm pressure, with evidence of a decline of k1 at lower pressures.No water-vapor effect on k1 was observed.
Kinetics of O(3PJ) Reactions with H2O2 and O3
Wine, P. H.,Nicovich, J. M.,Thompson, R. J.,Ravishankara, A. R.
, p. 3948 - 3954 (1983)
The kinetics of the reactions O(3PJ) + H2O2 -> products (k1) and O(3PJ) + O3 -> 2O2 (k2) have been investigated as a function of temperature over the temperature ranges 298-386 and 237-377 K, respectively.O(3PJ) was produced in the absence of other reactive free radicals by 532-nm pulsed laser photolysis of O3 and detected by time-resolved resonance fluorescence spectroscopy.The following Arrhenius expressions adequately describe the experimental results: k1=(1.13 +/- 0.54)*10-12 exp and k2=(5.6 +/- 2.1)*10-12 exp (units are cm3 molecule-1 s-1, errors are 2?).
Role of interstitial voids in oxides on formation and stabilization of reactive radicals: Interstitial HO2 radicals in F2-laser- irradiated amorphous SiO2
Kajihara, Koichi,Hirano, Masahiro,Skuja, Linards,Hosono, Hideo
, p. 5371 - 5374 (2006)
A procedure to produce stable hydroperoxy radicals (HO2 .) in bulk amorphous SiO2 (a-SiO2) has been developed. Oxygen molecules incorporated in the interstitial voids in a-SiO 2 react with mobile hydrogen atoms (H0) generated by the photolysis of silanol (SiOH) groups with F2-laser light (λ = 157 nm, hν = 7.9 eV), resulting in the efficient creation of interstitial HO2.. The high yield of HO2. suggests that the collisions of the reaction intermediate with the void wall play an important role in dissipating the excess energy of the intermediate instead of the triple collision observed in the gas phase reaction. The resultant HO2. is thermally stable up to 100 °C.
Rate Constants for the Reaction HO2 + NO2 + N2 -> HO2NO2 + N2: The Temperature Dependence of the Falloff Parameters
Kurylo, Michael J.,Ouellette, Philip A.
, p. 3365 - 3368 (1987)
Rate constants for the title reaction were measured by flash photolysis ultraviolet absorption spectroscopy at N2 pressures of 25, 50, and 100 Torr over the temperature range 228-358 K.The data were fit to an expression suitable for describing the pressure dependence of reactions in the falloff region with the temperature dependence of the falloff parameters given by k0,N2(T) = k0,N2(300K)-n and kinfinite(T) = kinfinite(300K)-m.The inert gas pressures in this study were low enough to permit a precise determination of n (which describes the temperature dependence of the low-pressure, limiting third-order rate constant).The same rate constant data, however, were less sensitive to the determination of m (associated with the limiting high-pressure rate constant).For this reason, our final analysis utilizes a composite fit of our temperature dependent data along with similar data at 100 and 700 Torr of N2 obtained by Sander and Peterson to yield k0,N2(T) = 1.8 * 10-31-(3.2+/-0.4) cm6 molecule-2 s-1 and kinfinite(T) = 4.7 * 10-12-(1.4+/-1.0) cm3 molecule-1 s-1.
Rate Constants for H +O2 + M at 298 K for M = He, N2, and H2O
Hsu, K.-J.,Durant, J. L.,Kaufman, F.
, p. 1895 - 1899 (1987)
The rate constants of the three-body recombination reaction H + O2 + M (M = He, N2, H2O) were measured from 4.79 to 30.1 Torr at room temperature by the discharge-flow technique.The respective rate constants obtained are (2.6 +/- 0.2)E-32, (6.1 +/- 0.9)E-32, and (6.4 +/- 0.8)E-31 cm6s-1.Although the rates for He and N2 can be rationalized in terms of existing theory, that for H2O implies a collision efficiency greater than 1.This situation can be rectified by use of the total quantum mechanical scattering cross section instead of the Lennard-Jones cross section commonly used.
Nanoscale Metal-Organic Frameworks Stabilize Bacteriochlorins for Type i and Type II Photodynamic Therapy
Luo, Taokun,Ni, Kaiyuan,Culbert, August,Lan, Guangxu,Li, Zhe,Jiang, Xiaomin,Kaufmann, Michael,Lin, Wenbin
supporting information, p. 7334 - 7339 (2020/08/21)
Herein we report the design of a bacteriochlorin-based nanoscale metal-organic framework, Zr-TBB, for highly effective photodynamic therapy via both type I and type II mechanisms. The framework of Zr-TBB stabilizes 5,10,15,20-tetra(p-benzoato)bacteriochlorin (TBB) ligands toward oxygen and light via geometrical constraint. Upon 740 nm light irradiation, Zr-TBB efficiently generates various reactive oxygen species, including singlet oxygen, superoxide anion, hydrogen peroxide, and hydroxyl radicals, to afford superb antitumor efficacy on mouse models of breast and colon cancers, with cure rates of 40% and 60%, respectively.
Precursor-mediated synthesis of Cu2-xSe nanoparticles and their composites with TiO2 for improved photocatalysis
Gahlot, Sweta,Jeanneau, Erwann,Dappozze, Frederic,Guillard, Chantal,Mishra, Shashank
supporting information, p. 8897 - 8905 (2018/07/25)
The direct synthesis of copper selenide nanoparticles from the reaction of ditertiarybutyl selenide tBu2Se with copper(ii) trifluoroacetate Cu(TFA)2 under mild conditions is reported. The isolation of a molecular species d