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|Title:||A Study of Reactive Intermediates Generated by One-Electron Transfers (Diazoalkane, Cieel, Chemiluminescence, Carbene, Peroxide)|
|Author(s):||Little, Charles Bernard|
|Department / Program:||Chemistry|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||Part I. 1-Phenyl-2-mesityl diazoethane, 1 is a unique example of a diazoalkane whose oxidative and non-oxidative decompositions are clearly distinguishable from the formation of mutually exclusive sets of products. In the thermolysis of photolysis of 1, steric hindrance provided by the mesityl group prevents bimolecular reactions while the 1,2-migrations normally observed for diazoethanes remain facile, giving only stable monomeric olefins as decomposition products. In the diazoalkane radical cation, 1('+), formed by chemical or elecro- chemical oxidation of 1, these migrations do not compete with fast bimolecular reactions. Reaction between 1('+) and neutral 1 gives the corresponding ketazine in a catalytic process. The principle fate of 1('+), however, is radical cation dimerization, giving stoichiometric amounts of stable, dehydrodimeric products by loss of two protons and two nitrogen molecules from the initially formed dication. No evidence was found to support the intermediacy of a carbene radical cation in these reactions. Electro-transfer quenching of the excited singlet state of 1,4-dicyanonaphthalene (DCN) by 1 was found by nanosecond transient absorption spectroscopy to generate DCN('-) and another short-lived species whose (lamda)(,max) occurs at ca. 520 nm. This absorption is tentatively assigned to 1('+).
Part II. Acylation of 4-nitroperoxybenzoic acid with diphenic anhydride provides the linear diacyl peroxide, 2-(2-carboxyphenyl)- 4'-nitrobenzoyl peroxide, 65. Treatment of 65 with various insoluble bases (KOH, NaOH) in the presence of easily oxidized aromatic hydrocarbons leads to chemiluminescence by the chemically initia- ted electron-exchange luminescence (CIEEL) mechanism under heterogeneous conditions. The carboxylate 67 initially formed from 65 does not itself undergo CIEEL decomposition by accepting an electron from the aromatic hydrocarbons as was originally proposed. Instead, the insoluble carboxylate slowly forms a soluble chemilumi- nescent intermediate, presumed to be diphenoyl peroxide, which then undergoes CIEEL decomposition. Replacing the carboxylic acid moiety in 65 with a 2-trimethylsilylethyl ester gives the analo- gous peroxide 66, treatment of which with various fluoride sources to generate carboxylate 67 leads, again, to chemiluminescence in the presence of a CIEEL activator.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1986.
|Date Available in IDEALS:||2014-12-15|