The reaction of ozone with thiophene in the gas phase

Publisher Website
Google Scholar
Abstract
The reaction between ozone and thiophene was studied from 30 to 125°C over a pressure range of 0.005‐0.3 torr ozone and 0.1‐1 torr thiophene. The most abundant product was O2 with smaller amounts of CO2 and SO2. The mass balance was 100% for oxygen and approached 100% for sulfur at the higher values of [O3]0. The carbon balance, however, was only 25% and no H‐containing products were found, suggesting that the missing product is a hydrocarbon which may be a polymer. The rate law found was ‐d[O3]/dt = k1[Th] [O3] + k2 [Th] [O3]2 where log k1(M−1 · sec−1) = 7.8 ± 0.5 ‐ (8400 ± 700)/2.3RT, and log k2(M−2 · sec−1) = 12.4 ± 0.4 ‐ (4700 ± 400)/2.3RT. Added O2 had no effect on k1 but reduced k2 to a limiting value. It is thus not possible to measure the primary rate constant in this system by measuring the overall rate in the presence of oxygen, and this restriction may also apply to other ozone systems. A mechanism is postulated involving two chain sequences, one of which is inhibited by added O2. A comparison with other ozone systems is made, and the chain lengths are far greater for ozone + thiophene than other systems, under the conditions employed. Possible intermediates in the mechanism are discussed.

This publication has 14 references indexed in Scilit: