Reaction between ozone and allene in the gas phase

The kinetics of the reaction between ozone and allene (A) were studied in the range of 226 to 325°K in the gas phase. Initial O 3 pressures varied from 0.01 to 0.7 torr and allene pressures varied from 0.05 to 6 torr. At the higher initial O 3 pressures the most important product was O 2 followed by CO, H 2 O, CO 2 , and C 2 H 4 . Oxygen balances averaging about 110% were obtained, which implies that no important oxygenated products were missed. However, carbon balances were only about 50% and hydrogen balances were even less, so that unidentified hydrocarbons were presumably formed. The rate law found was − d [O 3 ]/ dt = k 1 [O 3 ][A] + k 2a [O 3 ] 2 [ A ]/[O 3 ] 0 where log k 1 ( M −1 sec −1 ) = 6.0 ± 0.7 − (5500±1000)/2.30 RT and log k 2a ( M −1 sec −1 ) = 6.9 ± 0.7 − (6200 ± 800/2.30 RT ). A mechanism is proposed which accounts for the rate law and the observed stoichiometry of O 2 formed–O 3 used. This involves a heterogeneous catalyzed decomposition of O 3 . The rate constant k 1 is identified with the primary addition reaction A + O 3 → AO 3 , and this rate constant is compared with those from other O 3 addition reactions.