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Flash photolysis of dimethyl oxalate produced the radicals CH3, CH30, and COOCH3. Thermally equilibrated methoxycarbonyl radicals did not decompose during radicalradical reactions in the presence of 40-tom cyclohexane in the temperature range 298-448 K. Cyclohexyl radicals were also generated during the flash photolysis of the reaction mixture. Rate coefficients of radical-radical reactions were calculated from the amounts of stable products determined by gas chromatography: CO, COz, CHI, CH3C6H11, and CH30C6Hll. Calculations were performed using an iterative computer integration program. Absolute values of rate coefficients were based on the rate coefficient of the reaction between methyl radicals, k l = 2.7 x 10" dm3 mo1-l sK1, measured with the same equipment.CzH4, CzHfj, CH20, CH,OH, CH3OCH3, HCOOCH,, CH3COOCH3, CH3OCOOCH3,The rate coefficients for reactions (5)-(8) are: k5 = (3.1 + 0.5) X 10" dm3 mol-' s -' k6 = (2.1 + 0.2) X 10" dm3 mol-'s-' k7 = (2.3 + 0.1) x 10" dm3 m o l -'~-~

The flash photolysis of biacetyl produces CO, CZH6, and CH3COCH3 as main products, and in small amounts COz, CzH4, and CH3CHO. The rate constants of reactions (2) and (3) (1)of' thermally equilibrated radicals were calculated from the amounts of products: k z = (2.98 + 0.17) lo'* dm3/mol. s k 3 = (2.43 f 0.14) 1O1O dm3/mol. s

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