Chemistry and Chemical Biology ETDs

Don J. Temer

Publication Date

7-29-1970

Abstract

As part of a comprehensive study of the thermodynamics of conformational changes of n-alkyl groups in aqueous solution, the equilibrium constants, enthalpy changes, and entropy changes have been measured for the stepwise formation of bis(n-alkylamino)silver(I) complex ions at 25° in dilute aqueous solution. The attachment of the charged Ag+ to the end of the amine molecule is thought to cause changes in the conformation of the n-alkyl chain. The effects of these conformational changes on the formation constants, enthalpy changes, and entropy changes of the Ag+ complexes are discussed and compared with the effects on the formation constants, enthalpy changes, and entropy changes for the formation of the protonated n-alkylamines. The n-alkylamines studied were methylamine, ethylamine, n-propylamine, n-butylamine, n-pentylamine, and n-hexylamine. The equilibrium constants were determined from pH measurements and the enthalpy changes were determined from calorimetric measurements. Three effects are put forth as possible explanations for the effects of the hydrocarbon chain length on the thermodynamic values of the Ag+ complexes. These three effects are due to (1) the repulsion of the n-alkyl chain by the charge, (2) the formation of a clathrate hydrate structure of water molecules around the neutral amine molecule, and (3) the orientation of water about the metal ion. Each of these effects is described with respect to the results obtained in this study. In comparing the proton and silver ion, it was found that they exhibit the same general pattern with respect to the effects of alkyl chain length on the thermodynamic values but differ in detail (i.e., distance over which the effects are observed and magnitude of the effects).

Language

English

Document Type

Thesis

Degree Name

Chemistry

Level of Degree

Masters

Department Name

Department of Chemistry and Chemical Biology

First Committee Member (Chair)

Lee Duane Hansen

Second Committee Member

Robert Edwin Tapscott

Third Committee Member

Raymond N. Castle

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