The Kamlet-Taft solvatoohromic comparison method has been used to characterize the dipolarity/polarizability ((pi)*) and hydrogen-bond accepting basicity ((beta)) of supercritical carbon dioxide at various densities. The fluid medium is shown to be less polar (and/or polarizable) than cyclohexane by the (pi)* parameter. As the density of the medium is decreased the (pi)* parameter decreases on a smooth curve toward the gas phase value of (pi)*. Variation between the gas phase value of (pi)* and the value of (pi)* in supercritical carbon dioxide at different densities is quantitatively accounted for by a function of the refractive index which has been shown to be directly proportional to the dispersion force contribution to the free energy of interaction in solution. / The solvatochromism of the internal charge transfer absorption band of 4-diethylamino-4'-nitroazobenzene, DENAB, correlates linearly with the (pi)* parameter in conventional solvents and in supercritical carbon dioxide at various densities. The free energy of activation, (DELTA)G('(tau)), for the thermal cis to trans relaxation of DENAB correlates roughly with (pi)* in conventional solvents, however, this same correlation fails to continue in supercritical carbon dioxide. A correlation between (DELTA)G('(tau)) and (pi)* is found in supercritical carbon dioxide and two conventional non-polar solvents. This correlation has a much smaller slope than the rough correlation found in conventional polar aprotic solvents, and is of opposite sign. The change in behavior of (DELTA)G('(tau)) as a function of (pi)* is interpreted as indication a change of mechanism on going from polar to non-polar solvents. / The decomposition of phenylazotriphenylmethane (PAT) has been studied in supercritical carbon dioxide. PAT gives a poor material balance upon decomposition even though the solvent does not appear to be reacting with the radical species formed during the decomposition. The observed rate of decomposition is intermediate to that in cyclohexane and the proposed "zero" viscosity rate. / The decompositions of two secondary diacyl peroxides have been studied in supercritical carbon dioxide, cyclobutanecarboxoyl- m-chlorobenzoyl peroxide and isobutyryl peroxide. Experiments with ('13)C labels in the acyl moiety of the peroxides show that an exchange of 13CO2 groups with carbon dioxide solvent molecules occurs during carboxy-inversion. (Abstract shortened with permission of author.) / Source: Dissertation Abstracts International, Volume: 48-02, Section: B, page: 0446. / Thesis (Ph.D.)--The Florida State University, 1986.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_76046 |
| Contributors | SIGMAN, MICHAEL EDGAR., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 215 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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