Three studies in ion thermodynamics

Author

Daniel Nathan Sorensen

Date of Award

8-1994

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Chemistry

Major Professor

John E. Bartmess

Abstract

This work is actually three different projects, each addressing a problem in ion thermodynamics. The first project addresses equilibrium affinity scales. These scales contain many Hess cycles which may not be numerically close due to experimental uncertainties. Experimenters needed an unbiased estimator to evaluate the affinity of one compound with respect to another. To rectify this problem, the programs LADDER and GRAPHLDR were developed. These programs take a set of data, analyze it under three different algorithms to ascertain the best fit, and then graph the scale. Partitioning of the data into subsets simplifies the analysis. Traditional least squares analysis is considered the best unbiased estimate toward fitting the data. The iterative smoothing algorithm tends to reproduce the least squares solution. The least trimmed squares algorithm locates possible suspect data within the fusion set. The least trimmed squares algorithm works best for subsets of four to ten compounds. The second project evaluated sulfonates and phenyl–dimethylsilyl enol ethers for use as precursors undergoing dissociative attachment in ion-molecule chemistry. Two silyl enol ethers were synthesized from isobutyraldehyde and cyclohexanone. Each compound was verified by its NMR spectra, but complete separation from solution was not feasible. It was not possible to verify whether the observed enolate ions were from dissociative attachment or whether they were from secondary ion processes. Dimethyl sulfate yielded the methyl sulfate anion. Methyl methanethiosulfonate cleaved at the sulfur-sulfur bond to produce MeSO₂^-. The gas phase basicity for Me₂^- was bracketed between ClCH₂CO₂^- and CF₃CO₂^-. The third project involved traditional solution calorimetry on selected anilines. Neutral solvation enthalpies were obtained from the heat of reaction of the neutral anilines into aqueous acid. The solvation enthalpies for five anilinium ions were calculated. The electrostatic term of the solvation enthalpy is highly correlated with the proton affinity. The effect of the electrostatic term toward solvation was greater in ring-substituted compounds than in successive alkylations of the nitrogen.

Recommended Citation

Sorensen, Daniel Nathan, "Three studies in ion thermodynamics. " PhD diss., University of Tennessee, 1994.
https://trace.tennessee.edu/utk_graddiss/10582