Date of Award

Fall 1981

Degree Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Chemistry

First Advisor

Regen, Steven

Second Advisor

Cremer, Sheldon

Third Advisor

Pollard, Bruce D.

Abstract

Alumina supports were activated with potassium thiocyanate and tested in converting oxiranes to the corresponding thiirane. In addition to activation by three different methods, parameters such as molar ratio of support to substrate, temperature, and stirring were investigated for neutral alumina. Activated charcoal support was impregnated with potassium thiocyanate and determined not as effective as neutral alumina. Solvents such as di~ethoxyethane and tetrahydrofuran were used to dissolve the inorganic salt and increase the activity. A control was also tested with the substrate and potassium thiocyanate in toluene. An ideal support, silica gel, was found to give excellent activity in preparing thiiranes. Water which was adsorbed on the silica gel's surface caused changes in activity of the support. The best results were obtained for dry silica gel hydrated with 7.5~ water and impregnated with potassium thiocyanate. With this hydrated reagent, various thiiranes were prepared in isolated yields better than previous literature methods. The sterochemistry of the reagent was studied with cis and trans-5-decene oxide and showed a retention in configuratian. The reaction mechanism was thought to proceed through a double Walden inversion. The silica gel/ potassium thiocyanate was found to give a higher conversion rate for a terminal oxirane over a non-terminal. The rate difference affords a higher selectivity than several literature methods.

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