Kinetic flash spectroscopic study of the CH3O2CH3O2 and CH3O2SO2 reactions

✍ Scribed by Charles S. Kan; Robert D. McQuigg; Michael R. Whitbeck; Jack G. Calvert

• Publisher: John Wiley and Sons
• Year: 1979
• Tongue: English
• Weight: 676 KB
• Volume: 11
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550110811

✦ Synopsis

Methylperoxy radicals were generated by the flash photolysis of azomethane-oxygen mixtures. The observed broadband spectrum of the CH302 radical is similar, but not identical to those reported previously. The CH:302 decay followed second-order kinetics a t high CH:jOz concentrations with k4, = (2.5 f 0.3) X lo8 liter/mol.sec (23 f 2OC); 2CH302products ( 4 ) .

Because of the potential loss of CH302 through the reactions with H02 and CHRO radicals subsequently formed in this system, simulations suggest that the true k4 is in the range: 2.5 X 10x Z k 4 2 2.3 X lo8 liter/mol-sec. Deviations from linearity of the plot of the reciprocal of the CH:{Oz absorbance versus time were seen at long times and were attributed to the reaction ( ) with an apparent rate constant k y = (1.6 f 0.4) X lo5 liter/mol-sec; CH302 + Me2N2 product (5). The CH302-SO2 reaction, CH:%02 + SO2products ( ), was studied by observing C H R O ~ decay in flashed mixtures of Me2N2, 0 2 . and Son. The results gave the apparent second-order rate constant k l w rr (6.4 f 1.4) X lo6 liter/mol.sec. It appears likely that each occurrence of reaction ( ) and ( ) is followed by the loss of an additional CH:<02 radical and that k5 N k y / 2 and k16 = klw/2. Our findings suggest that a significant fraction of the SO2 oxidation in a sunlight-irradiated NO, -RH-polluted atmosphere, may occur by reaction with CH:@:! as well as from the HO and HOz reactions.