Troposphere ethers

Unsaturated Ethers, Tropospheric degradation, Kinetics, OH radicals, NO3 radicals. Ozone Introduction... 

Tuazon et al. (1984a) investigated the atmospheric reactions of TV-nitrosodimethylamine and dimethylnitramine in an environmental chamber utilizing in situ long-path Fourier transform infared spectroscopy. They irradiated an ozone-rich atmosphere containing A-nitrosodimethyl-amine. Photolysis products identified include dimethylnitramine, nitromethane, formaldehyde, carbon monoxide, nitrogen dioxide, nitrogen pentoxide, and nitric acid. The rate constants for the reaction of fV-nitrosodimethylamine with OH radicals and ozone relative to methyl ether were 3.0 X 10 and <1 x 10 ° cmVmolecule-sec, respectively. The estimated atmospheric half-life of A-nitrosodimethylamine in the troposphere is approximately 5 min. 

Eberhard, J., C. Muller, D. W. Stocker, and J. A. Kerr, The Photo-oxidation of Diethyl Ether in Smog Chamber Experiments Simulating Tropospheric Conditions Product Studies and Proposed Mechanism, lnt. J. Chem. Kinet., 25, 639-649 (1993). 

Dimethyl ether has been increasingly used as a propellant in aerosol formulations to replace chloro-fluorocarbons, which are found to destroy the ozone layer of the atmosphere. Dimethyl ether is nontoxic and easily degrades in the troposphere. Although about 90% of the major current U.S. aerosol industry uses hydrocarbon-based propellants (mostly isobutane and propane), DME could become a more widely used propellant in the coming years. Several aerosol-based... 

The fractions of the 1-ethoxyethoxy radicals undergoing reactions 1-4 are shown in Tables and compared with previous FllR studies and with theoretical estimates. Although diethyl ether is rapidly photo-oxidised, its contribution to tropospheric ozone formation is limited as one of the major products is ethyl formate which is relatively unreactive in the troposphere. This is also confirmed from the NO-NO2 oxidation stoichiometry, ca, 1 mole NO is oxidised per mole diethyl ether reacted. 

The project has resulted in a considerable extension of the kinetic data base for the reactions of OH radicals with the VOC classes of aliphatic ethers and of aromatic compounds. Such data are essential in the determination of tropospheric lifetimes of the VOC. 

The photo-oxidation of diethyl ether in smog chamber experiments simulating tropospheric conditions product studies and proposed mechanism,... 

Tropospheric oxidation mechanism of dimethyl ether and methyl formate ... 

Aryl halides tend to be chemically unreactive and include persistent environmental pollutants such as dichloro-diphenyl-trichloroethane (DDT), polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and polybrominated diphenyl ethers (PBDEs). Many studies of the photochemistry of halogenated aromatic compounds have been stimulated by environmental concerns, the goal often being to understand whether photolysis is an important sink for these compounds in natural waters - or in the atmosphere.The photochemistry of aryl halides causes problems in this context because many aryl halides have minimal absorption in the region of the tropospheric solar spectrum (>295 nm), and experiments at environmentally irrelevant wavelengths such as 254 nm are... 

Alwe HD, Walavalkar MP, Sharma A, Dhanya S, Naik PD. Tropospheric oxidation of cyclic unsaturated ethers in the day-time comparison of the reactions with Cl, OH and O3 based on the determination of their rate coefficients at 298 K. Atmos Environ. 2014 82 113-120. 

Reaction of ethyl vinyl ether with OH, O3, and NO3 are all of potential importance, and limit the lifetime of this species to less than 1 h under most tropospheric conditions. 

On the basis of the data of Thiault and Mellouki (2006) for the OH reaction, and data presented earlier for other vinyl ethers, the tropospheric lifetimes of isobutyl and tert-butyl vinyl ethers will likely be quite short (< 1 h under most conditions), and will be controlled by reaction with NO3, OH, and O3. Major end products of the OH-, O3-, and NO3-initiated oxidation will be CH2O and either isobutyl or tert-butyl formate. 

Cheema, S.A., K.A. Holbrook, GA. Oldershaw, D.P. Starkey, and R.W. Walker (1999), The effect of oxygen pressure on the tropospheric oxidation of diethyl ether, H-atom elimination from the 1-ethoxyethoxy radical, Phys. Chem. Chem. Phys., 1, 3243-3245. 

Good, D.A., and J. S. Francisco (2000), Tropospheric oxidation mechanism of dimethyl ether and methyl formate, J. Rhys. Chem. A, 104, 1171-1185. 

Stemmier, K., W. Mengon, and J.A. Kerr (1997a), Hydroxy-radical-initiated oxidation of isobutyl isopropyl ether under laboratory condtions related to the troposphere Product studies and proposed mechanism, J. Chem. Soc., Faraday Trans., 93, 2865-2875. 

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