I. The Biogenesis of Phenazine Pigments. II. β-Ferrocenyl Carbonium Ions. III. Chemical Shift and π-Electron Densities

Citation

Carter, Robert Everett (1962) I. The Biogenesis of Phenazine Pigments. II. β-Ferrocenyl Carbonium Ions. III. Chemical Shift and π-Electron Densities. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/GM3C-6N32. https://resolver.caltech.edu/CaltechTHESIS:07292011-081826791

Abstract

Part I: The biogenesis of phenazine pigments in bacteria has been studied by the use of radioactive substrates. The results indicate that the pigment of Pseudomonas chlororaphis originates in the dimerization of precursors derived from anthranilic acid. The structures of all the other known phenazine pigments are compatible with such a derivation.

Part II: β-Ferrocenyl carbonium ions have been studied in solvolytic experiments with β-ferrocenyl ethyl and β-ferrocenylisopropyl tosylates. A deuterium-labelling experiment with the ethyl compound indicates the absence of cyclopentadienyl ring participation. The isotope effect in the solvolysis (in 80% acetone) of β-ferrocenylethyl-a,a-d_2 tosylate was determined. The racemization of optically active β-ferrocenylisopropyl tosylate in 60% acetone at pH 6.9 is discussed; it is suggested that the racemization may come about through a special iron-carbon interaction which leads to a symmetrical carbonium ion. A simple diagram of a β-ferrocenyl carbonium ion stabilized by iron participation is presented and discussed to scrutinize the plausibility of such participation.

Part III: The use of the equation δ = π which relates the chemical shift (δ) of an aromatic proton to the excess π-electron density q on the carbon to which the proton is attached is discussed and illustrated by examples from the current literature.

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