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Part One. Photochemical cis-trans isomerization of beta-strylnaphthalene. Part Two. Photochemistry of N-methyl-4-pyridone and N-methyllutidone

Citation

Shim, Sang Chul (1967) Part One. Photochemical cis-trans isomerization of beta-strylnaphthalene. Part Two. Photochemistry of N-methyl-4-pyridone and N-methyllutidone. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-10072002-103918

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. PART ONE. Photochemical cis[...]trans isomerization of [beta]-styrylnaphthalene is studied by direct irradiation with light of various wavelengths and irradiation in the presence of sensitizers. A very unusual "negative" wavelength effect on quantum yields of trans[...]cis isomerization by direct irradiation is observed. The interpretation of this observation is presented in terms of multiple conformers of electronically excited states which are not interconvertible. The study of fluorescence spectra confirms the interpretation. Sensitizers transfer triplet energy quite efficiently to [beta]-styrylnaphthalene. However, benzophenone whose triplet energy is considered to be high transfers triplet excitation preferentially to the cis isomer. Quenching constants, both k[subscript qc] and k[subscript qt], were expected to be diffusion controlled. However, the study of the photostationary states and quantum yields of sensitized isomerization indicates the opposite for the benzophenone. A significant quantum waste is observed and interpreted in terms of localization of excitation in the naphthalene chromophore. The effect was far more pronounced in direct isomerization perhaps because the excited singlets are shorter lived than triplets made by energy transfer. Definitely a singlet mechanism is involved, perhaps in conjunction with other mechanisms, in direct isomerization. This is confirmed by the studies of quantum yields, photostationar y states, and side reactions. The studies of solvent effect and concentration effect on quantum yields in direct isomerization are also presented. [Superscript 60]Co [...]-ray radiolysis of [beta]-styrylnaphthalene in benzene indicates that the triplet mechanism is responsible for the isomerization of [beta]-styrylnaphthalene in the radiolysis of benzene solution. The detailed study of G values and radiostationary states are presented with the discussions of the nature of the reaction. The implications of above studies in the study of other photoreactions are presented. PART TWO. The photochemistry of the model compounds for pyrimidine bases, N-methyl-4-pyridone and N-methyllutidone, is reported. Spectroscopic and chemical studies on the irradiations of these compounds in aqueous solutions indicate that the hydration occurs at the [alpha]-position and leads to ring opening. The products obtained from ring opening undergo some unknown reactions, perhaps photo-oxidations and polymerizations.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Restricted to Caltech community only
Research Advisor(s):
  • Hammond, George Simms
Thesis Committee:
  • Unknown, Unknown
Defense Date:25 May 1967
Record Number:CaltechETD:etd-10072002-103918
Persistent URL:http://resolver.caltech.edu/CaltechETD:etd-10072002-103918
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3947
Collection:CaltechTHESIS
Deposited By: Imported from ETD-db
Deposited On:08 Oct 2002
Last Modified:26 Dec 2012 03:04

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