The effect of oxygen pressure on the tropospheric oxidation of diethyl ether, H-atom elimination from the 1-ethoxyethoxy radical

Cheema, Shahbaz A.; Holbrook, K. A.; Oldershaw, G. A.; Starkey, Darren P.; Walker, Robert

doi:10.1039/a902243k

Cited by 9 publications

(18 citation statements)

References 6 publications

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“…For example, compare: k(OH+CH 3 OCH 3 ) = 2.8x10 -12 with k(OH+CH 3 CH 3 ) = 0. acetaldehyde and formaldehyde. [60][61][62][63] The reaction proceeds mainly by H-atom abstraction from the -CH 2 -groups followed by reaction with O 2 to give a peroxy radical which reacts with NO to form the alkoxy radical C 2 H 5 OC(O)HCH 3 . It has been shown in chamber studies that a substantial fraction of these alkoxy radicals are formed chemically activated.…”

Section: Aliphatic Ethers Polyethers Cyclic Ethers Alkoxy Alcohols and Alkoxy Estersmentioning

confidence: 99%

Atmospheric Chemistry of Oxygenated Volatile Organic Compounds: Impacts on Air Quality and Climate

2015

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International audienceIt is hard to overstate the importance of oxygenated organiccompounds in atmospheric chemistry. Oxygenated organiccompounds are emitted into the atmosphere from natural andman-made sources, and they are formed in the atmosphere asoxidation products of all hydrocarbons present in theatmosphere. Oxygenated volatile organic compounds(OVOCs) are generally more reactive than the alkanes fromwhich they are derived. OVOCs play an active role in thesequence of chemical reactions responsible for troposphericozone formation in both polluted and remote environments

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Section: Aliphatic Ethers Polyethers Cyclic Ethers Alkoxy Alcohols and Alkoxy Estersmentioning

confidence: 99%

Atmospheric Chemistry of Oxygenated Volatile Organic Compounds: Impacts on Air Quality and Climate

2015

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“…where Y (AA) and Y (AAn) are the fractional molar yields of AA and AAn, respectively; D is a scaling term that accounts for sources of AAn other than from reaction (21); k 20 is the Þrst-order rate coefÞcient for reaction (20); and k 21 is the second-order rate coefÞ-cient for reaction (21). Least-squares Þtting of the data measured at 298 K to this expression yields k 20 /k 21 = 1.2 × 10 20 molecule cm −3 , with D = 0.72 (see Fig.…”

Section: Ethyl Formate Loss (Molecule CMmentioning

confidence: 99%

“…Although it is now apparent that the α-ester rearrangement occurs more rapidly for larger and more highly substituted alkoxy radicals, there is still limited information available regarding the energetics and dynamics of this process for the suite of atmospherically relevant esters. In this paper, we describe an environmental chamber study of the oxidation of ethyl formate and ethyl acetate, the major products of the atmospheric oxidation of diethyl ether [16,18,20,31]. These studies were carried out over a range of temperatures (249-325 K) and O 2 partial pressures (50-700 Torr) to examine competition, under conditions relevant to the lower atmosphere, between the α-ester rearrangement and the reaction with O 2 for HC(O)OCH(O • )CH 3 and CH 3 C(O)OCH(O • )CH 3 derived from ethyl formate and ethyl acetate.…”

Section: Introductionmentioning

confidence: 99%

The atmospheric oxidation of ethyl formate and ethyl acetate over a range of temperatures and oxygen partial pressures

Tyndall

2010

Int J of Chemical Kinetics

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The Cl-atom-initiated oxidation of two esters, ethyl formate [HC(O)OCH 2 CH 3 ] and ethyl acetate [CH 3 C(O)OCH 2 CH 3 ], has been studied at pressures close to 1 atm as a function of temperature (249-325 K) and O 2 partial pressure (50-700 Torr), using an environmental chamber technique. In both cases, Cl-atom attack at the CH 2 group is most important, leading in part to the formation of radicals of the type RC(O)OCH(O • )CH 3 [R = H, CH 3 ]. The atmospheric fate of these radicals involves competition between reaction with O 2 to produce an anhydride compound, RC(O)OC(O)CH 3 , and the so-called α-ester rearrangement that produces an organic acid, RC(O)OH, and an acetyl radical, CH 3 C(O). For both species studied, the α-ester rearrangement is found to dominate in air at 1 atm and 298 K. Barriers to the rearrangement of 7.7 ± 1.5 and 8.4 ± 1.5 kcal/mole are estimated for CH 3 C(O)OCH(O • )CH 3 and HC(O)OCH(O • )CH 3 , respectively, leading to increased occurrence of the O 2 reaction at reduced temperature. The data are combined with those obtained from similar studies of other simple esters to provide a correlation between the rate of occurrence of the α-ester rearrangement and the structure of the reacting radical. C

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“…The mechanism of the atmospheric oxidation of diethyl ether has been explored in the laboratory by three groups. [5][6][7] The major product of the oxidation at 298 K in the presence of NO x is ethyl formate, while lower yields of ethyl acetate and acetaldehyde have also been reported. The oxidation is thought to proceed predominantly via the formation of the 1-ethoxyethoxy radical, CH 3 CH 2 OCH(O )CH 3 , following OH attack at the -CH 2 -groups in the parent ether:…”

Section: Introductionmentioning

confidence: 99%

“…Their data indicated that pathways (3), (5), and (6) were occurring with respective yields of 66 AE 14%, 8 AE 2%, and 4 AE 3% per 1-ethoxyethoxy formed. The product yield data of Cheema et al 7 in air in the presence of NO x are consistent with those reported earlier (65 AE 5% ethyl formate yield, 13 AE 5% acetaldehyde yield, and 7 AE 3% ethyl acetate yield from the OH-initiated oxidation; 79 AE 9% ethyl formate yield, 11 AE 3% acetaldehyde yield, 7 AE 1% ethyl acetate yield from the Cl-atom initiated oxidation), confirming the dominance of reaction (3) in air at 298 K. However, these workers also studied the O 2 dependence of the product yields, and found the data to be inconsistent with the exclusive occurrence of reaction (3), (5), and (6). More specifically, the yield of ethyl acetate did not change dramatically with O 2 and did not tend to zero at low O 2 as would be expected if reaction (6) were its sole source.…”

Section: Introductionmentioning

confidence: 99%

The atmospheric oxidation of diethyl ether: chemistry of the C2H5–O–CH(O˙)CH3 radical between 218 and 335 K

Orlando

2007

Phys. Chem. Chem. Phys.

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The products of the Cl atom initiated oxidation of diethyl ether (DEE) were investigated at atmospheric pressure over a range of temperatures (218-335 K) and O(2) partial pressures (50-700 Torr), both in the presence and absence of NO(x). The major products observed at 298 K and below were ethyl formate and ethyl acetate, which accounted for approximately equal to 60-80% of the reacted diethyl ether. In general, the yield of ethyl formate increased with increasing temperature, with decreasing O(2) partial pressure, and upon addition of NO to the reaction mixtures. The product yield data show that thermal decomposition reaction 3, CH(3)CH(2)-O-CH(O.)CH(3)--> CH(3)CH(2)-O-CH=O + CH(3), and reaction 6 with O(2), CH(3)CH(2)-O-CH(O.)CH(3) + O(2)--> CH(3)CH(2)-O-C(=O)CH(3) + HO(2) are competing fates of the CH(3)CH(2)-O-CH(O )CH(3) radical, with a best estimate of k3/k6 approximately equal to 6.9 x 10(24) exp(-3130/T). Thermal decomposition via C-H or C-O bond cleavage are at most minor contributors to the CH(3)CH(2)-O-CH(O.)CH(3) chemistry. The data also show that the CH(3)CH(2)-O-CH(O.)CH(3) radical is subject to a chemical activation effect. When produced from the exothermic reaction of the CH(3)CH(2)-O-CH(OO.)CH(3) radical with NO, prompt decomposition via both CH(3)- and probably H-elimination occur, with yields of about 40% and < or =15%, respectively. Finally, at temperatures slightly above ambient, evidence for a change in mechanism in the absence of NO(x), possibly due to chemistry involving the peroxy radical CH(3)CH(2)-O-CH(OO.)CH(3), is presented.

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The effect of oxygen pressure on the tropospheric oxidation of diethyl ether, H-atom elimination from the 1-ethoxyethoxy radical

Cited by 9 publications

References 6 publications

Atmospheric Chemistry of Oxygenated Volatile Organic Compounds: Impacts on Air Quality and Climate

Atmospheric Chemistry of Oxygenated Volatile Organic Compounds: Impacts on Air Quality and Climate

The atmospheric oxidation of ethyl formate and ethyl acetate over a range of temperatures and oxygen partial pressures

The atmospheric oxidation of diethyl ether: chemistry of the C2H5–O–CH(O˙)CH3 radical between 218 and 335 K

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