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The reaction of ozone with thiophene in the gas phase
Author(s) -
Kaduk Bruce A.,
Toby Sidney
Publication year - 1977
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550090513
Subject(s) - chemistry , ozone , thiophene , torr , reaction rate constant , oxygen , hydrocarbon , analytical chemistry (journal) , sulfur , limiting , organic chemistry , kinetics , thermodynamics , mechanical engineering , physics , quantum mechanics , engineering
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 O 2 with smaller amounts of CO 2 and SO 2 . The mass balance was 100% for oxygen and approached 100% for sulfur at the higher values of [O 3 ] 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 [O 3 ]/ dt = k 1 [Th] [O 3 ] + k 2 [Th] [O 3 ] 2 where log k 1 ( M −1 · sec −1 ) = 7.8 ± 0.5 ‐ (8400 ± 700)/2.3 RT , and log k 2 ( M −2 · sec −1 ) = 12.4 ± 0.4 ‐ (4700 ± 400)/2.3 RT . Added O 2 had no effect on k 1 but reduced k 2 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 O 2 . 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.