Hope, James

2018-03-29T12:17:13Z

2018-03-29T12:17:13Z

1940

1. The conductivities, densities and viscosities at at 18°C. and 25°C. of aqueous solutions of the following acids have been determined over a wide range of concentration:- p-toluene sulphonic acid, phenanthrene-2- and -3-sulphonic acids, 9-chloroand 9-bromo-phenanthrene-3-sulphonic acids.

2. The conductivity data indicate that: (a) In sufficiently dilute solutions all the acids are present mainly as simple ions, with a small proportion of ion-pairs of the Bjerrum type. (b) The mobility of the phenanthrene sulphonate ion is considerably greater than that of a paraffin-chain sulphonate ion containing the same number of atoms. (c) p-toluene sulphonic acid behaves throughout the given concentration range as a simple strong electrolyte whose ions associate to some extent to form ion-pairs, (d) The phenanthrene sulphonic acids under consideration are colloidal electrolytes, their anions aggregating to form micelles to an extent dependent upon the concentration, the temperature, and the chemical constitution of the acid. (e) The tendency to form micelles in dilute solution increases in the order:- unsubstituted 3-acid < unsubstituted 2-acid < chloro-acid < bromo-acid. (f) Phenanthren sulphonate ions show less tendency to form micelles than similar paraffin-chain ions with the same number of carbon atoms. (g) No minimum occurs in the conductivity curve for clear (isotropic) solutions of the halogenated phenanthrene sulphonic acids

3. The viscosity curves for dilute solutions of the phenanthrene sulphonic acids undergo inflection at concentrations in the neighbourhood of those at which micelle-formation becomes prominent, as indicated by the conductivity data. It is suggested that the observed enhancement of viscosity is due to an increase in the Coulomb attractive forces resulting from the ion-aggregation.

4. The viscosity data show that:- (a) Concentrated isotropic solutions of the halogenated phenanthrene sulphonic acids are very much more viscous than corresponding solutions of the unsubstituted 3-acid. (b) Despite their high viscosity, there is no evidence of "structural viscosity" in concentrated isotropic solutions of the halogenated phenanthrene sulphonic acids, (c) Concentrated isotropic solutions of the chloro-phenanthrene sulphonic acid are more viscous than corresponding solutions ' of the bromo-acid.

5. The observation of Sandqvist that the region of anisotropic behaviour commences at a lower concentration in the case of the chloro-phenanthrene sulphonic acid than in that of the bromine derivative has been confirmed.

6. It is suggested that- the high viscosity of concentrated isotropic solutions of the halogenated phenanthrene sulphonic acids is due to the presence of aggregates which take the form of ultramicroscopic liquid crystals. These differ from the micelles in dilute solutions in that they include water molecules.

7. Sandqvlst's observation that the addition of hydrochloric acid to solutions of the halogenated phenanthrene sulphonic acids produces a remarkable increase in viscosity has been confirmed, the effect being greater for the chloro-acid. It Is found that the mixed solutions possess "structural viscosity".

8. The density curves for solutions of the phenanthrene sulphonlc acids show no breaks such as observed with paraffin-chain colloidal electrolytes, and which therefore appear to be characteristic of these compounds.

http://hdl.handle.net/1842/29160

The University of Edinburgh

Annexe Thesis Digitisation Project 2018 Block 17

The properties of aqueous solutions of the phenanthrene sulphonic acids: a contribution to the study of colloidal electrolytes

Thesis or Dissertation

Doctoral

PhD Doctor of Philosophy