A flash photolysis–resonance fluorescence kinetics study of the reactions of ground-state sulfur atoms. V. Rate parameters for the reaction of S(3P)with cis-2-butene and tetramethylethylene

✍ Scribed by D. D. Davis; R. B. Klemm

• Publisher: John Wiley and Sons
• Year: 1973
• Tongue: English
• Weight: 837 KB
• Volume: 5
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550050511

✦ Synopsis

Abstract

Rate parameters for the reaction of ground‐state atomic sulfur, S(^3^P), with the olefins cis‐2‐butene and tetramethylethylene have been determined over a temperature range of ∽280°K. A major finding of this study was that the rate constants for both reactions showed negative temperature dependencies. When k is expressed in the form of an Arrhenius equation, this necessarily leads to negative activation energies: k~1~ = (4.68 ± 0.70) × 10^−12^ exp ^(+0.23 ± 0.09 kcal/mole)/RT^ (219°‐500°K) k~2~ = (4.68 ± 1.70) × 10^−12^ exp ^(+1.29 ± 0.23 kcal/mole)/RT^ (252°‐500°K) Units are cm^3^ molec^−1^s^−1^. When a threshold energy of 0.0 kcal/mole is assumed for reaction (2), the temperature dependence of the preexponential term has a value of T^−2^. Making the usual simplifying assumptions, neither collision theory nor transition state theory leads to a preexponential factor with a strong enough negative temperature dependence. A comparison of these results with those derived from studies of the reactions of atomic oxygen, O(^3^P), with the same olefins shows that in both studies simple bimolecular processes were being examined. Also discussed are the possible experimental and theoretical ramifications of these new results.