Multi-functional homogeneous catalysts /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1990.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | We have synthesized, characterized and used soluble polyethylene-, polystyrene-, and poly(ethylene glycol)-bound tin halides as catalysts for the reduction of alkyl halides using a suspension of sodium borohydride in toluene and a crown ether as a phase-transfer catalyst. The polyethylene- and polystyrene-bound tin chloride catalysts were synthesized by the anionic oligomerization of ethylene or styrene followed by electrophilic substitution of the resulting "living oligomer" with various organic tin halides including tin tetrachloride, n-butyltin trichloride, di-n-butyltin dichloride, and diphenyltin dichloride. Poly(ethylene glycol)-bound diphenyltin bromide was synthesized by the reaction of the PEG alkoxy anion with iodomethyltriphenyltin, which was then cleaved by bromine. The resulting oligomer-bound reagents were characterized by [^1]H and [^119]Sn NMR spectroscopy, and the tin content of the oligomers was analyzed by ICP analysis. Typically the tin reagents were used as cocatalysts (ca. 20%) along with 10-20% of a crown ether as a phase-transfer catalyst in reductions of primary, secondary, and aryl halides using a suspension of sodium borohydride in hot toluene at 110 °C. Kinetic studies showed that the reaction rate was dependent on the concentration of the tin catalyst and that secondary halides reacted slightly faster than primary halides. Yields of reduced products were typically greater than 90%. The oligomer-bound tin reagents were reused at least 4 times. Poly(ethylene glycol)-bound N,N-dimethyl-p-aminobenzene azobenzoates of various sizes (Mn of 550, 750, 2000, and 5000 g/mol) were synthesized by reacting the corresponding poly(ethylene glycol) monomethyl ether with N,N-dimethyl-p-amino azobenzoic acid. These soluble polymers were then used as a base and were allowed to react with insoluble cross-linked sulfonated polystyrene resin (acid catalyst). The rates of these reactions were studied by UV-visible spectroscopy. It was found that by increasing the size of PEG, the rate of reaction decreased. These reactions were carried out at room temperature. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Chemistry." |
| Physical Description: | xii, 123 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |