ATMOSPHERIC FATE OF SEVERAL ALKYL NITRATES .1. RATE COEFFICIENTS OF THE REACTIONS ALKYL NITRATES WITH ISOTOPICALLY LABELED HYDROXYL RADICALS

The rate coefficients for the reaction of OH radical with CH3ONO2 (k(1 )), CD3ONO2 (k(6)), C2H5ONO, (k(2)) and 2-C3H7ONO2 (k(3)) between 220 and 410 K were measured to be: k(1) = (8.2 +/- 1.6) x 10(-13) exp{-(10 20 +/- 60)/T}, k(6) = (1.6 +/- 0.2)(8.2 +/- 1.6) x 10(-13) exp{-(1020 +/- 60)/T}, k(6) = (1.6 +/- 0.2) x 10(-12) exp{-(1730 +/- 40)/T}, k(2) =3.68 x 10(-12) exp(-1077/T) + 5.32 x 10(-14) exp(126/T) and k(3)=4.3 x 10(-12) exp(-1250/T) + 2.5 x 10(-13) exp(-32/T) cm(3) molecule(-1)s( -1). The quoted errors in the Arrhenius expressions are at the 95% con fidence limit and include estimated systematic errors. The measured ra te coefficients for the reactions of (OH)-O-18 were roughly the same a s those for (OH)-O-16 reactions while the rate constants for OD reacti ons were slightly (ca. 10-15%) higher than those for OH reactions. The hydroxyl radicals were generated by pulsed laser photolysis and detec ted by pulsed laser induced fluorescence. The observed large primary k inetic isotope effect(k(1)/k(6) = 4.5 at 298 K), the independence of t he measured rate coefficients on the gas composition, and the trend in the reactivity with the alkyl group suggests that the above reactions proceed via abstraction of an H atom from the alkyl group. Our result s are compared with those from previous studies.