title: Reaction dynamics of excited ketoprofen with triethylamine.
abstract: The reaction dynamics of ketoprofen (KP) with and without triethylamine (TEA) in methanol both in the ground and the excited states was studied by laser flash photolysis and the pump-probe emission spectroscopy. After the excitation, triplet KP abstracted a hydrogen atom from methanol to form KP ketyl radical (KPH). In the presence of TEA, the acid-base equilibrium state was found to be KP + TEA right arrow over left arrow KP- + TEAH+ in the ground state. The equilibrium constant was determined to be 32 +/- 7. Excited KP- rapidly underwent decarboxylation to form a carbanion resonant with the 3-ethylbenzophenone ketyl biradical anion (3-EBP-), followed by a proton-transfer reaction with TEAH+ to produce the 3-ethylbenzophenone ketyl biradical (3-EBPH). Furthermore, 3-EBPH was found to make a complex with TEA, whose equilibrium constant was obtained to be 18 +/- 2 M(-1). The complex formation ability of 3-EBPH was discussed compared with benzophenone ketyl radical (BPH).
authors.affiliation: Department of Chemistry and Materials Science, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro, Tokyo 152-8551, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Suzuki
authors.forename: Tadashi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Teijiro
authors.initials: T
authors.lastname: Ichimura
authors.forename: Koichi
authors.initials: K
authors.lastname: Ikesue
authors.forename: Michinori
authors.initials: M
authors.lastname: Sakai
mesh_terms: D005021:Ethylamines / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D007660:Ketoprofen / Q000737:chemistry*; D015394:Molecular Structure
chemical_list: D005021:Ethylamines; D007477:Ions; D007660:Ketoprofen; C016162:triethylamine