Theoretical studies of the reactions of methyl radical with dimethyl ether and 1,2-ethanediol

The mercury-photosensitized decomposition of dimethyl ether was investigated from 200 to 300 °C and over the pressure range 3 to 600 mm Hg. Measurements were made of the initial rates of formation of the products of reaction, which are CO, H2, C2H6, CH4, CH3OC2H5, and CH3OCH2CH2OCH3. It is concluded that the primary step involves a C—H split; there is no evidence for a primary C—O split. Over the range 200 to 300 °C the methoxymethyl radical, CH3OCH2, decomposed to give formaldehyde and a methyl radical, whereas at 30 °C no decomposition of the CH3OCH2 radical was detected. The mass balance is consistent with the mechanism proposed. The homogeneity of the reaction conditions was examined by varying the concentration of mercury in the reaction vessel.

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Individual rate constants of methyl radical reactions in the pyrolysis of dimethyl ether

Canadian Journal of Chemistry ◽

10.1139/v77-585 ◽

1977 ◽

Vol 55 (23) ◽

pp. 4128-4134 ◽

Cited By ~ 32

Author(s):

Andrew M. Held ◽

Kim C. Manthorne ◽

Philip D. Pacey ◽

Howard P. Reinholdt

Keyword(s):

Dimethyl Ether ◽

Rate Constants ◽

Flow System ◽

Average Concentration ◽

Radical Reactions ◽

Methyl Radical ◽

Warm Up ◽

Secondary Reactions ◽

Ultraviolet Absorption Spectroscopy ◽

Individual Rate

Dimethyl ether was pyrolyzed in a flow system at 10 to 80 Torr and 1005 K. The average concentration of CH3 radicals in the reactor was measured by ultraviolet absorption spectroscopy. Product yields were measured by gas chromatography. The system was simulated using a computer program, taking into account the warm-up of the entering gas and the occurrence of secondary reactions. Rate constants were varied to find values consistent with experimental observations. The limiting, high pressure rate constant for the recombination of CH3 was estimated to be 1010.5 ± 0.5ℓ mol−1 s−1. Estimated rate constants for the reactions[Formula: see text]were 107.12 ± 0.2ℓ mol−1 s−1 and 107.5 ± 0.4ℓ mol−1 s−1, respectively.

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Matrix isolation infrared and density functional theoretical studies of cryogenic reactions of silicon atoms with dimethyl ether and methanol: new route to generation and stabilization of transient silanones

Journal of Organometallic Chemistry ◽

10.1016/s0022-328x(99)00632-4 ◽

2000 ◽

Vol 595 (2) ◽

pp. 248-260 ◽

Cited By ~ 23

Author(s):

Valery N. Khabashesku ◽

Konstantin N. Kudin ◽

John L. Margrave ◽

Leif Fredin

Keyword(s):

Dimethyl Ether ◽

Density Functional ◽

Matrix Isolation ◽

Theoretical Studies

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Mercury-photosensitized decomposition of dimethyl ether. Part II. The thermal decomposition of the methoxymethyl radical

Canadian Journal of Chemistry ◽

10.1139/v67-449 ◽

1967 ◽

Vol 45 (22) ◽

pp. 2767-2773 ◽

Cited By ~ 28

Author(s):

Leon F. Loucks ◽

Keith J. Laidler

Keyword(s):

Carbon Dioxide ◽

Dimethyl Ether ◽

Pressure Range ◽

High Pressures ◽

Rate Coefficient ◽

Rate Coefficients ◽

Methyl Radical ◽

Lower Efficiency ◽

First Order ◽

Order Rate

The decomposition of the methoxymethyl radical, generated in the mercury-photosensitized decomposition of dimethyl ether, has been investigated over the temperature range 200 to 300 °C and the pressure range 3 to 600 mm Hg. The radical decomposes to give a formaldehyde molecule and a methyl radical. The effects of pressure and temperature on the first-order rate coefficient for the decomposition of the methoxymethyl radical have been examined in detail. The rate coefficient shows a pressure dependence over the full pressure range studied. The order of the decomposition is about 1.4 at the middle of the pressure range studied, with a lower order at higher pressures and a higher order at lower pressures. At 100 mm Hg the observed activation energy for the decomposition of the methoxymethyl radical is 24.8 kcal/mole.The first-order and second-order rate coefficients, k∞ and k0, corresponding to the limiting conditions of high pressures and low pressures respectively, have been evaluated as [Formula: see text]Kassel integrations have been carried out for the methoxymethyl radical and have been fitted to the experimental data. It is concluded that 8 or 9 normal modes contribute to the energization of the radical. The rate coefficient is increased by the presence of carbon dioxide, but carbon dioxide has a lower efficiency than dimethyl ether for the transfer of energy in the energization process.

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