Extensive measurements have been made of the solubilities of the five gases helium, hydrogen, argon, oxygen, and carbon dioxide, in ethanol/water and in t-butanol/water mixtures over the whole of their concentration range, and throughout the temperature interval 4°C to 61°C. The measurements were carried out by the less usual flowing-film technique, which has been described in detail. It depends on the rapid establishment of equilibrium between a gas and its solvent while the liquid flows in a stable, thin film down the walls of a tube enclosing the gas. Results were reproducible, corroborated at relevant points by results obtained by other workers from the other more common mixing techniques. These solubility measurements were used to investigate the effects of foreign molecules on the structure of liquid water. To this end standard thermodynamic functions were calculated for each of the solubilities, having programmed a computer to carry out the arithmetic. Graphs were drawn to show the relationship of the functions to the gas dissolved, the alcohol mixed with the water, and the temperature. Most information was obtained from the enthalpy and entropy changes in the systems, and certain features of their dependence on the concentration of the alcohol. A mixture model for water structure has been described, and some aspects of it elucidated. The size of any molecule introduced into water has been shown to be an important factor in its influence on the water structure. A quantitative estimate has been made of the effect of temperature on the mole fraction of water molecules which are completely hydrogen-bonded, called "icebergs" or "clusters". An estimate has also been made of the relative amounts of different-sized clusters at various temperatures, and it has been concluded that as the temperature rises, there is a selective and progressive destruction of the largest clusters. Finally, a mechanism has been suggested for the stabilisation of clusters by added solute molecules, which depends on their efficiency at preventing thermal disruption of the clusters.

This study is concerned with the association characteristics of solutions of alcohols in some non-polar solvents. The permittivities at 2 MHz and 25°C for solutions of the straight chain octanols in cyclohexane, carbon tetrachloride and benzene have been examined over the entire solute concentration range, with particular attention -1 being paid to the range below 0.1 molℓ⁻¹ By applying the Kirkwood- Fröhlich equation to these data, the apparent dipole moments of the alcohols as a function of concentration have been evaluated. These concentration dependencies have been correlated with infrared absorption results on the same systems to provide information on the sizes and configurations of the proposed hydrogen bonded multimers. It is concluded that, at very low solute concentrations, the alcohol molecules exist as monomers; but with increasing concentration, two types of hydrogen bonded multimers are formed, the first (at low concentrations) being of high dipole moment and the second (at higher concentrations) being of low dipole moment. At high concentrations, the molecules associate to form a three-dimensional network. Attempts have been made to determine equilibrium parameters for molecular models which are consistent with the qualitative understanding of the association behaviour. These parameters were obtained by applying least-squares, curve-fitting techniques to the low concentration permittivity data. A similar investigation has been conducted on solutions of 2,3,4-trimethyl-3-pentanol in the same solvents. The steric hindrance around the hydroxyl group of this alcohol modifies the association behaviour so that a three-dimensional network does not form at high solute concentrations. Proton magnetic resonance chemical shifts for the hydroxyl proton of this alcohol in carbon tetrachloride solutions have been measured. Attempts have also been made to determine equilibrium parameters which describe formation of the hydrogen bonded multimers. To extend this study to include solutes other than octanols, similar experiments have been conducted on solutions of t-butanol in hexadecane, a system which has recently been investigated by other workers using different experimental techniques. The association behaviour of this system is qualitatively similar to that of the straight-chain octanols. The combination of permittivity and infrared measurements, although proving extremely powerful in interpreting the association characteristics of dilute alcohol solutions, is less adequate at high solute concentrations. Attention was therefore directed towards dielectric relaxation and viscosity studies to investigate concentrated solutions. The relaxation times at 20°C of the low frequency dispersion have been measured for solutions of 1-propanol, 1-butanol, 1-hexanol, 1-octanol and 1-decanol in cyclohexane using time domain reflectometry techniques. Similar measurements have also been made on solutions of 1-butanol and 1-octanol in carbon tetrachloride and in benzene. The concentration dependence of the viscosities of certain of these systems has also been examined in an independent study. The ratio of the dielectric relaxation time to the viscosity, the "reduced relaxation time", is qualitatively similar for each system studied. This similarity leads to an explanation of the molecular process responsible for the low frequency dispersion in terms of the proximity of the hydroxyl groups in concentrated alcohol solutions and the fraction of the groups which are not involved in hydrogen bonding.

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This study investigated the reduction reaction of ruthenium tetroxide by various aliphatic alcohols in acidic medium. UV-Vis spectroscopy still plays an essential role in the analysis and study of volatile ruthenium tetroxide and was used in this study to collect kinetic data. This data was analyzed using graphical and computational methods, such as Mauser diagrams and kinetic simulation software. From the results obtained it is proposed that the reaction occurs by the following two-step reaction model: Ru(VIII) k1 Ru(VI) Ru(VI) k2 k-2 Ru(III) Molar extinction coefficients and conditional rate constants were calculated using kinetic simulating software and a hydride transfer mechanism was proposed. The temperature dependence of this reduction reaction was also investigated and thermodynamic parameters calculated. Ruthenium concentrations were determined using a method employing UV-Vis spectroscopy. The method proved to be a reliable, sensitive and simple technique.

Tertiary alcohols are a common functional group in many natural products, pharmaceuticals and agrochemicals. The ability to produce highly enantiomerically pure tertiary alcohols is therefore an important goal in synthetic chemistry. The synthesis of chiral tertiary alcohol precursors has been achieved via enzymatic desymmetrisation with the lipase Amano L, AK to generate (S)-(2-(hydroxymethyl)oxiran-2-yl)methyl acetate in 42% isolated yield and 97% enantiomeric excess. The reaction was also attempted with an immobilised lipase from R. miehei yielding the product in 82-90% yield and up to 89% ee. The enantioselective ring-opening of the epoxide using different amines has been developed in high yields generating enantiomerically pure β-amino tertiary alcohol products. However, an undesired intramolecular migration of the acetyl group was observed during the epoxide opening with aliphatic primary amines resulting in prochiral triol products. To avoid such an intramolecular migration a TBS-protected derivative has been used to prepare the tertiary alcohol products with primary amines in good yields (43%-83%), without any loss of enantiomeric excess of the formed 'pseudo'-enantiomer .(S)-(2-(hydroxymethyl)oxiran-2-yl)methyl acetate has the potential to generate a large diversity of compounds; this reagent was also used as the starting material to generate azetidines in high yields.

The catalytic conversion of cyclohexanol to cyclohexanone using a combination of rhodium trichloride trihydrate and ferric chloride in the presence of molecular oxygen was investigated. No conversion to cyclohexanone occurred in the absence of rhodium trichloride trihydrate, but some degree of conversion was found in the absence of ferric chloride. The optimum conditions for catalytic oxidation were produced by using a combination of rhodium trichloride trihydrate and ferric chloride, and under these conditions the rate of conversion to the ketone declined steadily, until the mixture contained approximately U0% cyclohexanone. For a fixed amount of cyclohexanol and rhodium trichloride trihydrate it was found that there was an optimum amount of ferric chloride necessary to produce the maximum yield in the shortest possible time. Addition of ferric chloride in excess of this optimum amount tended to suppress the rate of conversion to the ketone. This can probably be explained by the additional production of water and cyclohexene (see below). Using a cyclohexanol/ferric chloride ratio in the optimum range at a given temperature, increasing the rhodium trichloride trihydrate concentration beyond a certain level did not significantly increase the final yield, or the reaction rate. The oxidation reaction occurred under acidic conditions, this acidity being the result of interaction between ferric chloride and cyclohexanol (and cyclohexanone) , The acidity of a typical system was found to decline rapidly as the reaction progressed. Cyclohexene was produced in a side reaction, together with water. This is presumably the result of cyclohexanol undergoing an elimination reaction under acidic conditions. Using the optimum cyclohexanol/ferric chloride ratio at 100deg, the the cyclohexene content remained at less than 10%, during the course of the reaction. Introduction of cyclohexene in amounts in excess of 20 % greatly suppressed the conversion to cyclohexanone, presumably due to strong complexation of the olefin with a rhodium species. water was produced during the catalytic oxidation in amounts greater than could be accounted for by production of cyclohexene. This additional water content of the reaction mixture in a closed system was in good agreement with that predicted on the basis of the equation: [ ] The presence of water in the reaction mixture tended to suppress the oxidation of cyclohexanol to cyclohexanone. Using the optimum ratio of components, very little conversion to the ketone occurred in the presence of oxygen, at temperatures below 50deg. Increasing the temperature from 100deg to 150deg increased the rate of oxidation but had little effect on the final yield of cyclohexanone. , Oxygen was found to be necessary for catalytic oxidation to occur. The measured oxygen absorption for a reaction mixture containing an optimum ratio of components, was found to be in good agreement with that predicted by the above equation. Using an optimum ratio of components in the presence of oxygen, the conversion to cyclohexanone was limited to approximately 40%. This limit was probably due to an interaction between cyclohexanone and some active rhodium species essential for catalytic activity. / Science, Faculty of / Chemistry, Department of / Graduate

Bibliography: pages 220-231. / A series of crystalline Cholic acid inclusion compounds were studied with a view to understanding the role of guest molecules in inducing and stabilizing a particular Cholic acid (host) lattice structure. Alcohols in the series CH₃(CH₂nOH (n= 0 to 3 and 2-propanol) were employed as guest molecules and enclathrated in the host lattice of Cholic acid during crystallization. Single crystal structure analyses were performed by X-ray diffraction. Two types of molecular packing were identified. Cholic acid inclusion compounds with methanol, ethanol and 1-propanol are characterized by a 3-D host and guest molecule network stabilized by hydrogen bonds with symmetry of P2₁2₁2₁ space group. The guest molecules 2- propanol and 1-butanol, by nature of their size, induce a molecular packing with a larger guest cavity than that in the P2₁2₁2₁ space structures. Symmetrically defined by the P6₅22 space group, the crystal lattice is characterized by a helix of Cholic acid molecules generated by the six-fold screw axis through the origin and parallel to the c axis. The lattice is stabilized by an intricate hydrogen bonding scheme. The conformation of Cholic acid (particularly that of the flexible side-chain) in the two types of molecular packing was studied. The size and shape of the guest cavities created by the host lattices were examined. Thermal analyses (Thermogravimetric analysis and Differential Scanning Calorimetry) were performed on these compounds to examine the guest content and the strength of host-guest interactions. ₁₂₃₅

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