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Kinetic study of the reaction of O2(1[delta]g) with some olefins and amines

University of British Columbia

O2(1[delta]g) was produced in a discharge flow system and used to study the kinetics of its interaction with a number of olefins, amines and a sulfide. Rate constants were determined for the removal of O2(1[delta]g) by a series of olefins at a total pressure of 1.0 torr. The values obtained were: 1.1 x 10(7) 1mol(-1) sec(-1) by cyclopentadiene; 3.5 x 10(6) 1mol(-1) sec(-1) by 2,5-dimethylfuran; 1.6 x 10(6) 1mol(-1) sec(-1) by 2,3-dimethyl-2-butene; 1.0 x 10(5) 1mol(-1) sec(-1) by 2-methyl-2-butene; 3.2 x 10(4) 1mol(-1) sec(-1) by cis-2-butene; 1.3 x 10(4) 1mol(-1) sec(-1) by trans-2-butene. Some correlation was found between the ionization energy of the olefin and the magnitude of the rate constant. For some of the olefins the rate constants were found to increase with increasing pressure. A detailed study of this trend using 2,3-dimethyl-2-butene, 2-methyl-2-butene and cis-2-butene showed that the interaction could be analyzed into the following second order and third order processes: O2(1[delta]g) + Olefin [formula omitted] hydroperoxide; O2(1[delta]g) + Olefin [formula omitted] + Olefin; O2(1[delta]g) + Olefin + [formula omitted] + Olefin. From the kinetic measurements and a determination of the ratio of peroxide formed to O2(1[delta]g) removed the following rate constants were calculated: ( Reactant ) [formula omitted]; 2,3-Dimethyl 0.98 x 10(6) 0.3 x 10(6) 1.26 x 10(10); -2-butene; 2-Methyl 1.1 x 10(4); 1 x 10(5) 1.4 x 10(9); -2-butene The study was extended to include triethylamine, diethylamine and diethylsulfide, where complications are more easily avoided since no chemical reaction is observed. For these quenching species the following rate constants were obtained: Quencher [formula omitted]; Triethyl- 1 x 10(6) 3.5 x 10(10) 2 x 10(10) 1.5 x 10(10); amine; Diethyl- 5.9 x 10(4) 2.7 x 10(8); amine; Diethylsulfide- 8.7 x 10(9). Taking into account some earlier quenching studies conducted in the condensed phase and the relative efficiencies of different third bodies, a set of elementary processes has been proposed which involves the participation of a weakly bound complex between O2(1[delta]g) and the quenchers which displays a third order quenching process.

Text

2011-04-18

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http://hdl.handle.net/2429/33725

Chemistry

University of British Columbia

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