Laser flash photolysis and integral equation theory to investigate reactions of dilute solutes with oxygen in supercritical fluids
- Auburn Univ., AL (United States)
- Univ. of Notre Dame, IN (United States)
The absolute reactivity of triplet benzophenone ({sup 3}BP) and benzyl free radical (PhCH{sub 2}) toward molecular oxygen (O{sub 2}) in supercritical CO{sub 2} and CHF{sub 3} has been measured by laser flash photolysis (LFP). The transient reactants may be considered to be infinitely dilute solutes reacting with a gaseous cosolvent in a supercritical fluid mixture. Both reactants were found to undergo kinetically controlled reactivity with O{sub 2} and the measured bimolecular rate constants (k{sub hi}) were found to decrease with a decrease in solvent density at reduced pressures between 1.0 and 2.5. These results are consistent with solute reactivity with a `nonattractive` cosolvent. The results are compared with those previously obtained for the reaction of {sup 3}BP with an `attractive` cosolvent, 1,4-cyclohexadiene, in supercritical CO{sub 2} and CHF{sub 3}, in which enhanced {sup 3}BP reactivity was observed due to preferential cosolvent/solute solvation. Integral equation theory has also been applied to model these ternary systems, and the results indicate how the strengths of local solvation forces can influence kinetically controlled reactions in supercritical fluids. 36 refs., 8 figs., 3 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 81397
- Journal Information:
- Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 24 Vol. 117; ISSN JACSAT; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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