Journal of Physical Chemistry A, Vol.111, No.13, 2547-2554, 2007
Atmospheric chemistry of a model biodiesel fuel, CH3C(O)O(CH2)(2)OC(O)CH3: Kinetics, mechanisms, and products of Cl atom and OH radical initiated oxidation in the presence and absence of NOx
Relative rate techniques were used to study the kinetics of the reactions of Cl atoms and OH radicals with ethylene glycol diacetate, CH3C(O)O(CH2)(2)OC(O)CH3, in 700 Torr of N-2/O-2 diluent at 296 K. The rate constants measured were k(Cl + CH3C(O)O(CH2)(2)OC(O)CH3) = (5.7 +/- 1.1) x 10(-12) and k(OH + CH3C(O)O(CH2)(2)OC(O)CH3) = (2.36 +/-0.34) x 10(-12) cm(3) molecule(-1) s(-1). Product studies of the Cl atom initiated oxidation of ethylene glycol diacetate in the absence of NO in 700 Torr of O-2/N-2 diluent at 296 K show the primary products to be CH3C(O)OC(O)CH2OC(O)CH3, CH3C(O)OC(O)H, and CH3C(O)OH. Product studies of the Cl atom initiated oxidation of ethylene glycol diacetate in the presence of NO in 700 Torr of O-2/N-2 diluent at 296 K show the primary products to be CH3C(O)OC(O)H and CH3C(O)OH. The CH3C(O)OCH2O center dot radical is formed during the Cl atom initiated oxidation of ethylene glycol diacetate, and two loss mechanisms were identified: reaction with O-2 to give CH3C(O)OC(O)H and alpha-ester rearrangement to give CH3C(O)OH and HC(O) radicals. The reaction of CH3C(O)OCH2O2 center dot with NO gives chemically activated CH3C(O)OCH2O center dot radicals which are more likely to undergo decomposition via the alpha-ester rearrangement than CH3C(O)OCH2O center dot radicals produced in the peroxy radical self-reaction.