Part I. Several 1,4-substituted bicyclo{2.2.0}hexanes are synthesized and their thermal isomerization to 1,5-hexadienes are studied. The (DELTA)(DELTA)G('+)'s of the substituted compounds (as compared to the parent bicyclo{2.2.0}hexane) are in good agreement with values of the radical stabilization energies of the substituents determined by other methods. The (DELTA)(DELTA)G('(NOT=)) value of a 1,4-disubstituted bicyclo{2.2.0}hexane is found to be a sum of the radical stabilization energies of the individual substituents in the 1 and 4 positions. The evidence supports a biradical intermediate in the ring opening of substituted bicyclohexanes. Finally, the 50.7 kcal/mole strain energy reported for a bicyclo{2.2.0}hexane moiety gives calculated values of (DELTA)H(,f) that agree to within (+OR-)3 kcal/mole of the experimental value, which has been determined by DSC.
Part II. The thermal behavior of cis-dialkyldiazenes is studied by UV kinetics and their heat of isomerization to the more stable trans isomers is measured. The results support the semilinearization mechanism of isomerization for symmetric cis-dialkyldiazenes. Depending on structure, the cis diazenes are observed to isomerize, decompose, or undergo both process simultaneously. A kinetic isotope effect is observed for the reactive radicals obtained by thermolysis of cis-azo-1-adamantane and cis-azo-1-bicyclo{2.2.2}octane. The solvent cage effect is also determined.
| Identifer | oai:union.ndltd.org:RICE/oai:scholarship.rice.edu:1911/15735 |
| Date | January 1983 |
| Creators | BAUGHMAN, SHARON ANN |
| Source Sets | Rice University |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | application/pdf |
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