Chemistry and Chemical Biology ETDs

Publication Date

4-29-1972

Abstract

A study of the solvent effects of sulfolane (tetrahydrothiophene 1, 1-dioxide, tetramethylene sulfone) upon a series of acids and several bases has been conducted. A procedure is presented for purifying sulfolane which results in a solvent of very low water content (5 x 10-4 M) and very few impurities, as shown by its cooling curve. Potentiometric and conductometric measurements of additions of acids and bases to purified sulfolane and of various acid-base titrations were made. The series of carboxylic acids included benzoic, orthomethoxybenzoic, and three different monochlorobenzoic acids. The bases investigated included sodium methoxide, pyridine, and diphenylguanidine. Interpretation of the data from the potentiometric monitoring of the acid-base titrations of diphenylguanidine with the previously mentioned acids gave the following order of increasing acidity:

ΦCOOH < o-MeOՓCOOH < m-ClՓCOOH < o-ClՓCOOH < p-ClՓCOOH.

Potentiometric measurements of the addition of the acids and bases suggested that the ionic species which exists in sulfolane is not monomeric, but is more probably oligomeric. The characteristic shape of the conductometric acid-base response curve confirmed the indication of polymeric ionic forms existing in sulfolane. The interpretation of the addition and titration data leads to the proposal that the model which most closely approximates the behavior of acids in sulfolane is:

3 HX ⇄ (HX)3 ⇄ H2X+ + HX-2.

Interpretation of the addition curves from the conductometric measurements was attempted by means of three methods used separately and in combination. The methods chosen were graphical extrapolation, semi-empirical curve fitting, and summation of ionic-equivalent conductances. The second of the three approaches, the semi-empirical curve fitting, appeared to be the most productive in dealing with the limited data available. Possible ionization constants for the acids in this study are: (benzoic acid, 2.7 x 10-11; orthochlorobenzoic acid, 2.1 x 10-11, metachlorobenzoic acid, 1.2 x 10-11; parachlorobenzoic, 1.9 x 10-10; and orthomethoxybenzoic, 3.9 x 10-11. It is pointed out that a more definitive set of ionization constants could be obtained if the homoconjugation constants of the acids were known.

Language

English

Document Type

Thesis

Degree Name

Chemistry

Level of Degree

Masters

Department Name

Department of Chemistry and Chemical Biology

First Committee Member (Chair)

Nicholas Ernest Vanderborgh

Second Committee Member

Guido Herman Daub

Third Committee Member

Milton Kahn

Fourth Committee Member

James E. Sattizahn

Fifth Committee Member

Jere D. Knight

Sixth Committee Member

Darleane C. Hoffman

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