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Effects of Chemical Environment on the Photochemical Behavior of Alkoxy Carbonyl Azides and 2-benzoyl-3-methyl-2H-Azirine

Murthy, Rajesh S.

Abstract Details

2007, PhD, University of Cincinnati, Arts and Sciences : Chemistry.

In this thesis we have investigated the photochemical reactivity of alkoxy carbonyl azides 1-4 and 2-Benzoyl-3-Methyl-2H-Azirine 39 in different chemical environments. Our results show that photolyzing azides 1-4 in methanol results in intramolecular energy transfer to form triplet alkoxy carbonyl nitrenes 1n-4n that decay mainly by H-atom abstraction from the solvent. Our data also support the postulate that triplet nitrenes 1n-4n absorb another photon and cleave to form alkoxy radicals that abstract an H-atom from the solvent to form the corresponding alcohols 8-12. Photolyzing azides 1-3 in argon matrices at cryogenic temperature yields isocyanic acid from secondary photolysis of triplet nitrenes 1n-3n. Similarly, photolyzing azide 4 in matrices yields isocyanate 4i via secondary photolysis of triplet nitrene 4n. Thus, triplet alkoxy carbonyl nitrenes can be formed selectively via intramolecular photosensitization, but these intermediates are themselves highly photoreactive.

The solid state photochemistry of azide 3 reveals a unique bimolecular reactivity leading to the formation of 34. We speculate that formation of 34 can be explained in terms of both singlet as well as triplet nitrene reactivity. We have selectively formed an oxaziridine ring via solid state reactivity, which is the discovery of a new chemical reaction for alkoxy carbonyl azides. In case of azide 4, we observed a different reaction pathway of the nitrene in the solid state as compared to its solution photolysis.

We investigated the photoreactivity of 2-benzoyl-3-methyl-2H-azirine (39) and found that irradiation above 300 nm selectively cleaves the C-N bond to form triplet vinyl nitrene 42, which decays into 40. In comparison irradiation with light below 300 nm breaks the C-C bond to form ylide 41, which yields 46 as the final product. Laser flash photolysis (wavelength = 355 nm) produces a transient with wavelength of maximum absorption at 400 nm that we assign to 42, whereas laser flash photolysis with a 266 nm irradiation generates ylide 41 (wavelength of maximum absorption = 380 nm). We photolyzed 39 in a low temperature argon matrix and found that light above 340 nm causes the formation of ketene imine 43, which is formed by 1,2 methyl shift in 1n.

Dr. Anna Gudmundsdottir (Advisor)
175 p.

Recommended Citations

Citations

  • Murthy, R. S. (2007). Effects of Chemical Environment on the Photochemical Behavior of Alkoxy Carbonyl Azides and 2-benzoyl-3-methyl-2H-Azirine [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1175296082

    APA Style (7th edition)

  • Murthy, Rajesh. Effects of Chemical Environment on the Photochemical Behavior of Alkoxy Carbonyl Azides and 2-benzoyl-3-methyl-2H-Azirine. 2007. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1175296082.

    MLA Style (8th edition)

  • Murthy, Rajesh. "Effects of Chemical Environment on the Photochemical Behavior of Alkoxy Carbonyl Azides and 2-benzoyl-3-methyl-2H-Azirine." Doctoral dissertation, University of Cincinnati, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1175296082

    Chicago Manual of Style (17th edition)