3031-74-1Relevant articles and documents
Temperature and pressure Dependence of the C2H4 Yield from the Reaction C2H5 + O2
Kaiser, E. W.
, p. 707 - 711 (1995)
The yield of C2H4 from the reaction (1) has been investigated as functions of temperature (260-530 K) and pressure (50-1500 Torr) at nonambient temperature using a relative rate technique.This yield has a non-Arrhenius temperature dependence, increasing slowly at a gas density of 4.9 x E18 molecules cm-3 with an apparent activation energy of 1.1 +/- 0.25 kcal in the temperature range 250-400 K and then increasing sharply as reaction 1 becomes reversible.These results are consistent with the formation of C2H4 via rearrangement of an excited adduct (C2H5O2*) with an energy barrier less than 1.1 cal.The yield follows a P-0.75 dependence at temperatures below 400 K.The pressure dependence becomes less pronounced at higher temperature (P-0.32 at 529 +/- 10 K).Rate constants of the coupled mechanism for C2H4 formation developed by Wagner et al. provide reasonable agreement with these data to within the experimental error.The overall rate constant of reaction 1 was determined as a function of temperature (260-460 K) at 580 Torr relative to that of C2H5 + Cl2 -> C2H5Cl + Cl (3).No temperature dependence is observed in the range 260-380 K 1 = (8.1 +/- 0.3) x E-12 cm3 molecule-1s-1>.At 460 K, the rate constant decreases ca. 35percent.
The Ethylperoxy Radical: Its Ultraviolet Spectrum, Self-Reaction, and Reaction with HO2, Each Studied as a Function of Temperature
Fenter, Frederick F.,Catoire, Valery,Lesclaux, Robert,Lightfoot, Phillip D.
, p. 3530 - 3538 (1993)
The ultraviolet spectrum of the ethylperoxy radical (C2H5O2) and the reactions C2H5O2 + C2H5O2 --> products (1) and C2H5O2 + HO2 --> C2H5O2H + O2 (5) have been studied using the flash photolysis/UV absorption technique.The spectrum was taken between the wavelengths of 210 and 290 nm and at the temperatures of 298 and 600 K.The room temperature spectrum is found to be in good agreement with previous determinations, with a maximum cross section ?max = (4.89 +/- 0.60) * 10-18 cm2 molecule-1 at 240 nm.The temperature dependence of the broadness of the spectrum as well as the value of ?max is analyzed by fitting the data to a Gaussian function that predicts the temperature behavior of broad, structureless UV absorptions.Our results on the C2H5O2 self-reaction are also in good agreement with previous studies, with k1/cm3 molecule-1 s-1 = (6.7 +/- 0.6) * 10-14 exp for the temperature range 248-460 K.At higher temperatures, we observe non-second-order kinetic behavior which can be attributed to the thermal decomposition of the ethoxy radical, a product of reaction 1.Our results for the reaction C2H5O2 + HO2 are significantly different from the only previous determination of its temperature dependence, especially at and below room temperature, with k5/cm3 molecule-1 s-1 = (1.6 +/- 0.4) * 10-13 exp over the temperature range of 248-480 K; our room temperature rate constant is about a factor of 2 greater than the currently accepted value of k5, with k5(298)/cm3 molecule-1 s-1 * 10-11.This result holds implications for the understanding of the reactivity of RO2 species with HO2, which is important for the chemical modeling of the troposphere.
A Kinetic Study of the Reaction between Ethylperoxy Radicals and HO2
Maricq, M. Matti,Szente, Joseph J.
, p. 2078 - 2082 (1994)
Flash photolysis-time-resolved UV spectroscopy is used to measure the rate constant for the C2H5O2 + HO2 reaction over the temperature range of 210-363 K.The radicals are generated by photolysis of F2 in the presence of H2 and ethane.The rate constant for the F + C2H6 reaction is measured relative to the F + H2 reaction to be k1 = (7.1+2.1-1.6)*10-10e(-347+/-69)/T cm3 s-1.In order to ascertain time-resolved concentrations, the HO2 UV absorption cross section and its self-reaction rate constant have been remeasured.The UV cross section is in good agreement with previous reports, with ?max = 0.041 Angstroem2 at 203 nm.The self-reaction rate constant of k5 = (2.8+/-0.5)*10-13e(594+/-55)/T cm3 s-1 is in excellent agreement with the currenty recommended value.The rate constant for the C2H5O2 + HO2 reaction is k7 = (6.9+2.1-1.6)*10-13e(702+/-69)/T cm3 s-1.This result is discussed with regard to the discrepancy which exists between the two previous measurements of this rate constant.
A new method for the synthesis of primary hydroperoxides. A useful application of bis(tributyltin) oxide in the hydrolysis of peroxyesters
Baj, Stefan,Chrobok, Anna
, p. 623 - 624 (2001)
Hydrolysis of peroxyesters in the presence of bis(tributyltin) oxide provides a new method for the synthesis of hydroperoxides including methyl and ethyl hydroperoxide.
Infrared matrix isolation and theoretical study of the initial intermediates in the reaction of ozone with cis-2-Butene
Clay, Mary,Ault, Bruce S.
, p. 2799 - 2805 (2010)
Matrix isolation studies combined with infrared spectroscopy of the twin jet codeposition of ozone and cis-2-butene into argon matrices have led to the first observation of several early intermediates in this ozonolysis reaction. Specifically, evidence is presented for the formation and identification of the long sought-after Criegee intermediate, as well as confirming evidence for earlier reports of the primary and secondary ozonides. These species were observed after initial twin jet deposition, and grew upon annealing to 35 K. Extensive isotopic labeling (18O and 16,48O mixtures) experiments provided important supporting data. Detailed theoretical calculations at the B3LYP/6-311++G(d,2p) level were carried out as well to augment the experimental work, Merged jet (flow reactor) experiments followed by cryogenic trapping in solid argon led to the formation of "late", stable oxidation products. Photochemical, reactions of ozone with cis-2-butene was studied as well, as was the photochemical behavior of the primary and secondary ozonides.
Kinetics and branching ratio studies of the reaction of C2H 5O2 + HO2 using chemical ionisation mass spectrometry
Teresa Raventos-Duran,Percival, Carl J.,McGillen, Max R.,Hamer, Paul D.,Shallcross, Dudley E.
, p. 4338 - 4348 (2007)
The overall rate coefficient for the reaction of C2H 5O2 with HO2 was determined using a turbulent flow chemical ionization mass spectrometer (TF-CIMS) system over the pressure range of 75 to 200 Torr and temperatures between 195 and 298 K. The temperature dependence of the overall rate coefficient for the reaction between C 2H5O2 and HO2 was fitted using the following Arrhenius expression: k(T) = (2.08-0.62+0.87) × 10-13 exp [(864 ± 79)/T] cm-3 molecule -1 s-1. The upper limits for the branching ratios for reactive channels leading to O3 and OH production were quantified for the first time. A tropospheric model has been used to assess the impact of the experimental error of the rate coefficients determined in this study on predicted concentrations of a number of key species, including O3, OH, HO2, NO and NO2. In all cases it is found that the propagated error is very small and will not in itself be a major cause of uncertainty in modelled concentrations. However, at low temperatures, where there is a wide discrepancy between existing kinetic studies, modelling using the range of kinetic data in the literature shows a small but significant variation for [C2H5O2], [C2H 5OOH], [NOx] and the HO2:OH ratio. Furthermore, a structure-activity relationship (SAR) was developed to rationalise the reactivity of the reaction between RO2 and HO2. the Owner Societies.
Highly efficient visible-light photocatalytic ethane oxidation into ethyl hydroperoxide as a radical reservoir
Zhu, Yao,Fang, Siyuan,Chen, Shaoqin,Tong, Youjie,Wang, Chunling,Hu, Yun Hang
, p. 5825 - 5833 (2021/05/07)
Photocatalytic ethane conversion into value-added chemicals is a great challenge especially under visible light irradiation. The production of ethyl hydroperoxide (CH3CH2OOH), which is a promising radical reservoir for regulating the oxidative stress in cells, is even more challenging due to its facile decomposition. Here, we demonstrated a design of a highly efficient visible-light-responsive photocatalyst, Au/WO3, for ethane oxidation into CH3CH2OOH, achieving an impressive yield of 1887 μmol gcat?1in two hours under visible light irradiation at room temperature for the first time. Furthermore, thermal energy was introduced into the photocatalytic system to increase the driving force for ethane oxidation, enhancing CH3CH2OOH production by six times to 11?233 μmol gcat?1at 100 °C and achieving a significant apparent quantum efficiency of 17.9% at 450 nm. In addition, trapping active species and isotope-labeling reactants revealed the reaction pathway. These findings pave the way for scalable ethane conversion into CH3CH2OOH as a potential anticancer drug.
Room temperature and atmospheric pressure aqueous partial oxidation of ethane to oxygenates over AuPd catalysts
Felvey, Noah,Gurses, Sadi,Kronawitter, Coleman X.,Wang, Yu Lei
, p. 6679 - 6686 (2020/11/16)
New modes of chemical manufacturing based on small-scale, distributed facilities have been proposed to supplement many existing production operations in the chemical industry, including the synthesis of value-added products from light alkanes. Motivated by this prospect, herein the aqueous partial oxidation of ethane over unsupported AuPd nanoparticle catalysts is investigated, with emphasis on outcomes for reactions occurring at 21 °C and 1 bar ethane. When H2O2 is used as an oxidant, the system generates numerous C2 oxygenates, including ethyl hydroperoxide/ethanol, acetaldehyde, and acetic acid. Ethyl hydroperoxide is found to be the primary product resulting from the direct oxidation of ethane: it is produced with 100% selectivity in batch reactions with short durations and with low initial H2O2 concentrations. At longer times or in more oxidizing conditions, deeper product oxidations expectedly occur. In batch experiments, the maximum observed yield of oxygenates is 7707 μmol gAuPd-1 h-1. Product distributions differ when H2O2 is replaced by H2 and O2 in the headspace. Additionally, to simulate a scenario wherein H2O2 is produced on-site and to study ethane oxidation in steady, low H2O2 concentrations over 50 h, a semi-batch configuration facilitating continuous injection of dilute H2O2 was implemented. These efforts showed that H2O2 can serve as an oxygenate-selective oxidant of ethane when its concentration is kept low during reaction. These and other experimental results, as well as initial computational results using density functional theory, suggest that paths forward for aqueous ethane conversion exist, and systems should be engineered to emphasize product stabilization.
The Role of Copper Speciation in the Low Temperature Oxidative Upgrading of Short Chain Alkanes over Cu/ZSM-5 Catalysts
Armstrong, Robert D.,Peneau, Virginie,Ritterskamp, Nadine,Kiely, Christopher J.,Taylor, Stuart H.,Hutchings, Graham J.
, p. 469 - 478 (2018/01/27)
Partial oxidative upgrading of C1–C3 alkanes over Cu/ZSM-5 catalysts prepared by chemical vapour impregnation (CVI) has been studied. The undoped ZSM-5 support is itself able to catalyse selective oxidations, for example, methane to methanol, using mild reaction conditions and the green oxidant H2O2. Addition of Cu suppresses secondary oxidation reactions, affording methanol selectivities of up to 97 %. Characterisation studies attribute this ability to population of specific Cu sites below the level of total exchange (Cu/Al0.5). These species also show activity for radical-based methane oxidation, with productivities exceeding those of the parent zeolite supports. When tested for ethane and propane oxidation reactions, comparable trends are observed.
Partial oxidation of ethane to oxygenates using Fe- and Cu-containing ZSM-5
Forde, Michael M.,Armstrong, Robert D.,Hammond, Ceri,He, Qian,Jenkins, Robert L.,Kondrat, Simon A.,Dimitratos, Nikolaos,Lopez-Sanchez, Jose Antonio,Taylor, Stuart H.,Willock, David,Kiely, Christopher J.,Hutchings, Graham John
supporting information, p. 11087 - 11099 (2013/08/23)
Iron and copper containing ZSM-5 catalysts are effective for the partial oxidation of ethane with hydrogen peroxide giving combined oxygenate selectivities and productivities of up to 95.2% and 65 mol kgcat -1 h-1, respectively. High conversion of ethane (ca. 56%) to acetic acid (ca. 70% selectivity) can be observed. Detailed studies of this catalytic system reveal a complex reaction network in which the oxidation of ethane gives a range of C2 oxygenates, with sequential C-C bond cleavage generating C1 products. We demonstrate that ethene is also formed and can be subsequently oxidized. Ethanol can be directly produced from ethane, and does not originate from the decomposition of its corresponding alkylperoxy species, ethyl hydroperoxide. In contrast to our previously proposed mechanism for methane oxidation over similar zeolite catalysts, the mechanism of ethane oxidation involves carbon-based radicals, which lead to the high conversions we observe.
