Date of Award
12-1984
Document Type
Dissertation - Restricted
Degree Name
Doctor of Philosophy (PhD)
Department
Chemistry
First Advisor
Sheldon E. Cremer
Second Advisor
William A. Donaldson
Third Advisor
Norman E. Hoffman
Fourth Advisor
Michael A. McKinney
Fifth Advisor
Charles A. Wilkie
Abstract
Part I. The synthesis and characterization of twelve compounds in the 3-stannabicyclo[3.2.1]octane and -oct-6-ene series are described.
3,3-Dimethyl-3-stannabicyclo[3.2.l]octane (2) was successfully synthesized in 50% yield. It was converted to the monochloro derivative (Sb) by reaction with mercuric chloride. Other derivatives of 3-stannabicyclo[3.2.1]octane were synthesized by the reaction of 5b with an appropriate reagent. Most of these reactions were clean, and afforded a good yield of the desired product. Moreover, no ring cleavage of 5b was observed. The structures of these compounds were supported through two or more of the following methods: C,H-analysis, IR, 1H NMR, 13C NMR, 119Sn NMR, and mass spectra. The results were consistent with known organotin compounds as well as their silicon counterparts. Tentative endo/exo stereochemical assignments of some of these compounds were made from the 1H NMR chemical shift of the Sn-CH3 group.
According to the literature, the alkyl-, hydrido-, and aryl-derivatives (2-4, 8, and 9} are monomers whereas the ch oro-, acetato-, benzoato-, fluoro-, azido-, and methoxy-derivatives (5-7, 10-12) are probably polymers. Attempts to separate the isomers of the 3-methyl-3-phenylderivative (9) were not successful. The compounds which are polymers are not suitable for stereochemical studies (reaction at the tin atom). The monomers 8 and 9 will be more suitable if their isomers can be separated.
Part II. Each phosphonium salt: exo-3-methoxy-endo-3-phenyl3-phosphoniabicyclo[3.2.1]oct-6-ene tetrafluoroborate (14) and its isomer (15), and trans-1-methoxy-4-tert-butyl-1-phenylphosphorinanium hexafluorophosphate (16) and its isomer (17), was hydrolyzed with varying amounts of water in acetonitrile solution to afford the corresponding phosphine oxides; the results ranged from nearly complete retention to predominant inversion. It appeared from oxygen-18 labeling experiments that aqueous hydrolyses of 14 and 17 occurred via exclusive P-0 bond cleavage whereas the hydrolyses of 15 and 16 occurred via P-0 and C-0 bond cleavage.
A kinetic study of homogeneous hydrolysis of each salt 14-17 was carried out in acetonitrile solution (constant temperature) and the resultant pseudo-first-order reaction was followed by 1H NMR spectroscopy. The rate constant of hydrolysis and the stereochemical outcome were affected by the concentration of water, the acidity of the solution, and the geometry of the salts. Attempts to control the pH of the solution during the hydrolyses of 14 and 17 by the following methods were only partially successful: (1) addition of an equivalent of an organic base to neutralize the HBF4 or HPF6 generated during the hydrolysis, (2) performing the hydrolysis in a buffer solution, or (3) addition of excess HBF4 to keep the pH of the solution constant.
Mechanisms for homogeneous aqueous hydrolysis of 14-17 were proposed. Comparison of the stereochemical outcome as well as the rate constant of the hydrolysis of 14-17 were made. Possible isomerization of the phosphonium salts 2~-2~ and the corresponding phosphine oxides were monitored by control experiments.