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Luckcock, Ronald George (1963) Studies in the solubilities of hydrogen chloride in oxygen-containing organic compounds. Doctoral thesis, Northern Polytechnic.
Hydrogen chloride solubilities have been measured in carboxylic esters, phosphates, carbonates, alkyl borates, alkoxy boroxoles, alkoxysilanes, aldehydes and ketones, mostly below 0°C. The solubility appeared to be largely controlled by the available electron density on the oxygen atoms. An attempt was made to relate solubility with structure. Solubilities in polyoxygen compounds were discussed in terms of the moles of hydrogen chloride per mole of solvent per oxygon atom and related to the solubility in n-butanol. Thus in tetraalkoxysilanes, the solubility per oxygen atom was about the same as for n-butanol while for trialkyl borates and trialkoxy boroxoles the solubility per oxygen atom was very much loss than for n-butanol. The low value for the boron compounds can be attributed to the delocalisation of electron density on the oxygen atoms by back-coordination to the electrophilic boron atom.
Solubilities were determined by a bubbler technique which is described in detail. Certain disadvantages of the bubbler method were pointed out such as entrainment of volatile solvent in the hydrogen chloride gas stream and the necessity of a titration technique at sub-zero temperatures. A direct weighing procedure using snail quarts balances, so that a single sample of solvent would suffice for a continuous measurement of solubility over a wide range of temperature, was devised. Measurements were made with quarts spring balances on n-butanol using static absorption and a description was given of the construction of a magnetically controlled quarts beam balance.
The saturation vapour pressure of hydrogen chloride over its solution in a number of solvents has been measured. Over a small range of concentration there was a linear relationship between log vapour pressure and the reciprocal of the absolute temperature. from the slope of these curves differential enthalpies were calculated. Differential entropies of solution wore also calculated from the intercepts of the curves for n-butanol, ethyl acetate and n-butyl acetate. The entropies of solution for those solvents were similar but the enthalpies of solution were in the same order as the saturation hydrogen chloride solubilities. The change in Gibbs function for solution in n-butanol was used to give an estimate of the equilibrium constant for the complexing of hydrogen chloride with n-butanol in solution, and the conclusion is that practically every molecule of hydrogen chloride is complexed (hydrogen bonded).
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