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|Title:||Chemiluminescence of Dimethyldioxetanone|
|Author(s):||Schmidt, Steven Paul|
|Department / Program:||Chemistry|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||Dimethyldioxetanone undergoes two distinct thermal reactions which generate electronically excited states. The unimolecular decomposition at 30.0(DEGREES)C produces excited singlet and triplet acetone, with efficiencies of 0.1 and 1.5% respectively. The composite activation energy for formation of singlet acetone is 3-4 kcal/mol greater than the activation energy for the thermal disappearance of dimethyldioxetanone. This result is interpreted in terms of two parallel competitive pathways for dioxetanone decomposition, the more highly activated one of which leads to excited acetone.
The primary light-generating reaction of dimethyldioxetanone results from a chemically initiated electron-exchange luminescence (CIEEL) path. A wide range of fluorescent electron donors, including aromatic hydrocarbons and amines, catalyze the chemiluminescence. In general, the magnitude of the catalytic rate constant, and the effectiveness of excited state generation correlate well with the one electron oxidation potential of the donor. Exceptions of this correlation are several zinc and magnesium porphyrins, including chlorophyll a, for which their chemiluminescent catalysis is much greater than predicted by their oxidation potentials. The critical role of the central metal atom in eliciting this unusual behavior was evaluated by determining the catalytic rate constants and the initial chemiluminescence intensity of several non-metallated as well as differently metallated porphyrins. These results suggest that formation of a ground state complex between dimethyldioxetanone and certain metalloporphyrins is the cause of the unusual catalysis. Spectroscopic evidence of a ground state complex between zinc tetraphenyl porphyrin and tetramethyldioxetane, a model for dimethyldioxetanone, has been obtained. Also, the special catalysis may be inhibited by the addition of competitive complexing agents. Infrared chemiluminescence is observed from the YbTPPacac-catalyzed reaction of dimethyldioxetanone.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1981.
|Date Available in IDEALS:||2014-12-13|