The relative rates of chromic acid oxidation of eight aryltrifluoromethylcarbinols were determined in 77.2% acetic acid medium. The primary deuterium isotope effects for these alcohols ranged from 7.40 for p-tolyltrifluoromethylcarbinol to 12.93 for 3,5-dinitrophenyltrifluoromethylcarbinol at 25°. The rates fitted a Hammett plot best when modified ϭ⁺ substituent values were used and a modified ̎rho ̎value of -1.01 was observed. The rates of oxidation of several halogenated-2-propanols as well as their corresponding 2-d analogttas were also determined in 77.2% acetic acid and in 50.1% sulfuric acid. Results indicated that while the isotope effect varied with changes in the nature of the alcohol being oxidized, it was constant for a particular alcohol in solutions of varying acidity. The thermodynamic parameters for the oxidation of two different alcohols under a variety of conditions were determined and found to be approximately the same, ΔH# = 9 kcal/mole, ΔS# = -40 cal/mole deg. An extensive investigation of the oxidation of alcohols in sulfuric acid solutions ranging from 5 to 95% was conducted and a spectroscopic study was made of the behavior of chromium VI in this entire region, A ϭ* value was obtained for the CF₃ group and this was used to determine the "true rate constant", k = kobs /K, for the chromic acid oxidation of a series of primary alcohols. A Taft ϭ*- e* plot then yielded a e* value of -0.92 for the rate determining step of this reaction. A spectroscopic investigation of the variation of the pKa of chromic acid with changes in the identity of the mineral acid solvents was made, and the results were applied to explain observed variations in the rate of oxidation of isopropyl alcohol in solutions of different mineral acids all having the same acidity. The H₀ acidity function for nitric and phosphoric acid systems with a 1:1 molar ratio of sodium perchlorate was also determined. / Science, Faculty of / Chemistry, Department of / Graduate

An investigation of the oxidation of carbon by lead oxide-silica melts was undertaken. The carbon specimens utilised in this investigation were spectroscopic graphite,, petroleum coke (baked at 900°C) and spectroscopic carbon. The kinetics of the reactions were studied for different geometric surface areas over a wide range of concentrations of lead oxide and at different temperatures. In all cases the rate of oxidation was found to be directly proportional to the geometric surface area of the carbon sample used. The rate was also proportional to the square of the activity of lead oxide or equilibrium pressure of O₂ obtained from the dissociation of PbO in the melt. The experimental rate constant k values were calculated. The values of k for the oxidation of graphite, petroleum coke and carbon at 1000°C were found to be 1.35 x 10⁻², 1.31 x 10⁻² and 0.97 x 10⁻² gm.C/cm²/min. respectively. The values of the experimental activation energies of the oxidation of graphite, petroleum coke and carbon were found to be 33* 28 and 22 kilo-calories per mole respectively. In all cases carbon dioxide was the product gas. The results obtained in the present investigation indicated that the stoichiometry of the reaction is two molecules of lead oxide and an atom of carbon to produce metallic lead and carbon dioxide. / Applied Science, Faculty of / Mining Engineering, Keevil Institute of / Graduate

Cell free extracts of glucose grown cultures of P. aeruginosa were prepared by exposure to sonic vibration. These sonicates were capable of oxidizing glucose-6-phosphate, ribose-5-phosphate, glucose, gluconic acid and gluconolactone. Treatment of the sonicate with (NH₄)₂S0₄ resulted in the formation of precipitates which possessed the ability to oxidize glucose, gluconolactone and gluconic acid. After (NH₄)₂SO₄ treatment neither the supernatant nor the precipitate could oxidize the phosphorylated compounds. Since 30.0% (NH₄)₂SO₄ or centrifugation for one half hour at 25,000X g precipitated the enzymes they were considered to be insoluble. Precipitation with different concentrations of (NH₄)₂S0₄ and MnSO₄ failed to separate the glucose and gluconate enzymes from one another. Extraction with bile salts solubilized the gluconate enzyme, but precipitated the glucose enzyme along with a high proportion of the gluconate system. An increase in concentration of the bile salts destroyed the glucose enzyme while a reduction left a large percentage in solution. The addition of glycine to the sonicate solubilized the enzymes but did not aid in their separation. When added before the sonic treatment, the enzymes became labile to protein precipitants. Ethyl alcohol, dioxane and acetone destroyed glucose oxidizing and gluconate oxidizing enzyme activity while ethyl ether destroyed only the glucose system. The use of a growth substrate other than glucose resulted in the formation of a reduced gluconic acid system, but the results were not uniform in that the gluconate enzyme frequently was very active. The glucose system was sensitive to KCN and NaN₃, and 8-hydroxy-quinoline but not to NaF. The 8-hydroxy-quinoline inhibition could be overcome by Mg⁺⁺. Adenosinetriphosphate, flavine adenine dinucleotide, diphosphopyridinonucleotide, triphosphopyridinonucleotide, had no effect on the glucose oxidizing system. Methylene blue, brilliant cresyl blue and pyocyanin had no ability to act as a hydrogen acceptor. However 2.6 dichlorobenzenoneindophenol stimulated the reaction. When this dye was added in the presence of MgS0₄ a 300.0% increase was noted. The product of the reaction was determined by paper chromatography to be gluconic acid. These data indicate that the glucose dehydrogenase differs from any previously described glucose dehydrogenase and that some unknown hydrogen transport system apparently functions in the transport of electrons to the cytochromes. The data support earlier conclusions that the reaction does not involve phosphorylation. / Land and Food Systems, Faculty of / Graduate

The effect of stress on the electrode potential of copper in aerated cupric sulphate and in aerated cupric chloride solutions was studied. The influence of the variables time, temperature, concentration, magnitude of stress, mechanical condition of the metal, and pH was considered. The potential difference between two size #22B&S copper wires was continuously recorded on a type G speedomax automatic recorder. Weights were added to one of the wires and the change in the potential difference between the two wires from the pre-stress potential difference value was taken as the strain potential. At least six runs, using fresh pairs of wire for each run, were carried out to illustrate each specific point and to show the results have statistical significance and are reproducible. The following results were obtained: (A) Electronegative strain potentials have been obtained for copper metal in copper sulfate solution; these changes achieve a maximum at the instants of stressing and then decay with time. The magnitude of the electronegative strain potential for a given stress increased exponentially with the absolute temperature and decreased significantly for concentration changes from 0.0005 N to 0.500 N. (B) Experimental evidences were obtained to support the postulate that strain potentials of copper metal in copper sulfate solution and their time dependence parallel film rupture and repair. (C) Both electronegative and electropositive strain.potentials were obtained with size #22B&S soft copper wire in cupric chloride solution; the sign of the strain potential was negative for a concentration of 0.500 N and the sign of the strain potential was positive for concentrations of 0.100, 0.050, and 0.005. The magnitude of the strain potential did not vary with concentration as for the case of copper wire in copper sulfate solution. The electronegative change, obtained in 0.500 N cupric chloride lasted for less than three seconds whereupon the change in the potential difference between the two wires shifted rapidly to a positive value. An attempt was made to explain these results on the basis of the stability of Cu₂O and CuCl films using potential-pH diagrams. The magnitude of the strain potential for a given stress was found to vary exponentially with the absolute temperature between the range 298°K to 338°K. / Science, Faculty of / Chemistry, Department of / Graduate

To complement the data, on the aqueous oxidation of sulphide minerals, that is, treatment of sulphides in aqueous solution at elevated temperatures under oxygen pressure, a study was undertaken of the aqueous oxidation of galena in sodium hydroxide solution. It was hoped by the study of the kinetics of the reaction to learn something of the mechanism involved. The reaction was followed by means of a cathoderay polarograph. A crystal of galena was mounted in a small autoclave equipped with suitable electrodes, and during the course of the reaction photographs were taken at intervals of the current-voltage curves. From the height of the lead wave relative concentrations could be recorded, and after a suitable time the run was stopped and the solution assayed to give absolute values to the wave heights. The variables of oxygen partial pressure agitation, sodium hydroxide concentration, temperature, silicate-ion, and electrical potential were investigated. It was found that the polarograph under these conditions gave reproducible results. On the basis of the experimental results three alternative mechanisms for the reaction were proposed. One of these was too indefinite to treat quantitatively, but the other two were examined by calculations using the theory of absolute reaction rates. One was found to give agreement in rate with experiment, a model in which desorption accompanied by hydration and ionization was the rate controlling step. The experimental results were reviewed in the light of this mechanism and appeared to show no serious contradictions, so this model is put forward as a postulate of the reaction of galena with oxygen in sodium hydroxide solution. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

The mechanism of permanganate oxidation of benzhydrol has been investigated between pH 7.00 and H₀ -2.46. The deuterium isotope effect, kH/kD, obtained by studying the oxidation rate of benzhydrol α-d, was found to fall from 7.3 at pH 7.00 to 1.08 at H₀ -1.22. Between pH 7.00 and H₀ 0.20, the reaction is of second order, first order in each of the reactants. Beyond H₀-0.50 the reaction becomes first order in carbinol and zero order in permanganate, and in this region the reaction is strongly acid-catalyzed. A study of eight substituted benzhydrols shows an excellent Hammett correlation with α⁺,ρ⁺ being -1.02. The rate-determining step at higher acidities is believed to be the scission of protonated carbinol to carbonium ion, which then reacts with permanganate in a fast step. This idea is supported by the results of a study of the rate of ionization of p-methoxybenzhydrol under conditions similar to those of the oxidation reaction. The mechanism of chromic acid oxidation of benzhydrol has been studied between H₀ 0.50 and -4.20. The reaction is acid-catalyzed in this region and was found to be of second order, first order in each of the reactants. The deuterium isotope effect with benzhydrol α-d at H₀ -1.00 is 6.81. A Hammett plot, obtained from the study of five substituted benzhydrols, shows σ to be the operative substituent constant, ρ being -0.54. The rate-determining step is believed to be the unimolecular decomposition of a chromate ester. The permanganate oxidation of triphenylcarbinol has been investigated in the region of acidity of H₀ -0.60 to -1.93. The reaction was found to be acid-catalyzed in this region and to produce benzophenone and phenol. The order of reaction was found to be the same as in the case of benzhydrol, i.e., first order in carbinol and zero order in permanganate. A study of nine substituted triphenylcarbinols gave a good Hammett correlation with σ⁺,ρ⁺+ being -1.39. As in the case of benzhydrol, the rate-determining step is believed to be the ionization of the carbinols. The chromic acid oxidation of triphenylcarbinol has been investigated between HR -2.80 and -7.48. Acid-catalysis was observed for the reaction in this region. The reaction was found to be of second order, first order in each of the reactants, as in the case of benzhydrol. The reaction gave a quantitative yield of benzophenone, phenol also being formed. A Hammett correlation with σ⁺+ was obtained from a study of eleven substituted triphenylcarbinols, ρ⁺+ was found to be -0.879. The rates of oxidation of the triarylcarbinols were also studied in the presence of added manganous ions, which showed an almost uniform reduction in rate for all the carbinols, the value of ρ⁺ in this case being -0.906. The migration aptitudes of the substituted aryl groups were determined and ρ⁺ for migration was found to be -1.44. A chromate ester mechanism, similar to that proposed for benzhydrol and other secondary alcohols, is believed to be operative in this case, except that the decomposition of the ester takes place by migration of the electron-rich ring. It is suggested that the chromic acid oxidation of primary and secondary alcohols may take place by an analogous rearrangement reaction of a chromate ester. In these cases the migrating group would be hydrogen. Permanganate oxidation of benzhydrol was also studied in frozen system between pH 1.50 and 12.40. A large increase in rate, compared to that in the liquid system, was observed. The deuterium isotope effect, kH/kD, of 7.2 to 7.5 was found in this system. The reactions are of second order, as in the liquid system. The acceleration in rate appears to be due to an increase in concentration of the reactants in the liquid phase between ice crystals. / Science, Faculty of / Chemistry, Department of / Graduate

An investigation of the oxidation of solid iron by lead oxide-silica melts was undertaken between 850°C and 1000°C over a wide range of oxidising potentials. The experimental reaction rates were measured by a technique of electrical resistance measurements. In the intermediate range of concentration investigated (80-88 % wgt.PbO) the rate of oxidation was found to be proportional to the mole fraction of lead oxide in the melt, in other words, to the lead ion concentration. The rate determining step of iron oxidation by lead oxide-silica melts is supposed to involve lead cations in contrast with the oxidation of carbon where oxygen ions are involved. The apparent activation energy was found to be 50 ± 7 Kcal/mole. Two sets of activity data concerning the lead oxide in PbO-SiO₂ melts were available and were compared by processing the present results on iron oxidation and previous results on carbon oxidation by similar melts. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

Chairman: Professor G.G.S. Dutton Periodate Oxidation Products of Some Partially Methylated Hexoses and Hexitols Complete periodate oxidation of 2,3-di-O-methyl-D-glucitol and 2,3-di-O-methyl-D-mannitol produced 2,3-di-O-methyl-L-threose and 2,3-di-0-methyl-D-erythrose respectively. Reduction with sodium borohydride produced the corresponding tetritols, 2,3-di-O-methyl-L-threitol and 2,3-di-0-methyl-erythritol. Incomplete periodate oxidation of the two hexitols lead to the formation of large amounts of the respective pentoses, 3,4-di-0-methyl-L-xylose and 3,4-di-O-methyl-D-arabinose. Attempts to prepare 4-0-methyl-D-threose from methyl 6-0-methyl-αβ-D-galactofuranoside and 2-0-methyl-D-erythrose from methyl 4-0-methyl-α-D-mannopyranoside by periodate oxidation were only partially successful. Although the oxidation proceeded smoothly, the cleavage of the oxidized product could not be readily effected with mineral acid, methanolysis or mercaptolysis without extensive degradation taking place. Reduction of the aldehydes generated by periodate oxidation allowed the facile preparation of the corresponding tetritols. A scheme to correlate the original aldehyde structure to the reduced tetritol is proposed. The structure of an unknown component in the hydrolysis of methyl 2,3-di-0-methyl-α-D-glucopyranoside in the presence of 2,3-di-0-methyl-D-glucitol was shown to be 1,4-anhydro-2,3-di-0-methyl-D-glucitol. The paper chromatographic characteristics of the prepared tetroses, tetritols and pentoses in the two most commonly used solvent systems have been recorded. / Science, Faculty of / Chemistry, Department of / Graduate

Titanium oxidation was studied between 400 and 800°C with oxygen partial pressures over the range 760 to 10⁻⁵ mm Hg and times up to 20,000 minutes. Oxidation rates were measured with a Cahn electrobalance after sophisticated metal preparation and experimental procedures. Growth effects in the oxide film were thoroughly examined at time intervals by removing specimens for metallographic observation. Films were stripped from these specimens for transmission electron microscope examination. The morphology development was then related to the rate curves. In all cases the rate curves were complex functions of temperature, pressure, specimen preparation, and oxidation procedure. In spite of the numerous rate transitions with time, reproducibility under a specific set of conditions was excellent. As the oxide grows from a thin film to a thick scale, an intermediate period of peculiar network formation, most pronounced at 500°C, is observed. The networks consist of thousands of small crystallites, approximately 100 to 5000 Angstroms in size, and arranged in random and oriented patterns of accelerated and suppressed growth areas. Two different types of whisker formation were observed in addition to the network phenomena. The complex rate data associated with periods of network growth do not conform to any of the simple rate laws reported by previous investigators. Since the network structures violated all of the assumptions associated with current transport theories regarding planar homogeneous films, it was concluded that these theories were inadequate to describe the growth kinetics. Surface diffusion is probably the main growth mechanism during network formation although orientation and epitaxial effects may have some influence. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

A four-part investigation was described in which first, the use of thiolignin and lignosulfonate to remove a factor involved in growth limitation in hydrocarbon fermentation was investigated; secondly, the performance of the Cyelone-fermenter in hydrocarbon fermentation was evaluated; thirdly, continuous hydrocarbon fermentation with reference to hydrocarbon, nitrogen, thiolignin and dilution rate was studied; and fourthly, the mechanism of n-decane oxidation was studied manometrically and gas chromatographically. The addition of polymerized lignosulfonate and thiolignin into the hydrocarbon fermentation media greatly, increased the fermentation rate and the yield of biomass. Lignin itself did not appear to be decomposed during the fermentation. Resting cell studies of Pseudomonas desmolytica S(11) indicated that the oxygen consumption increased with the decreasing n-alkane carbon number and did not parallel the production of total biomass. The greatest biomass occurred using n-undecane and decreased sharply with lower and higher n-alkanes. The individual n-alkanes in kerosene were not degraded uniformly, the lower ones were used preferentially. Thiolignin not only increased the rate of utilization of these lower n-alkanes but also extended microbial acceptability to the higher n-alkanes. Gas chromatographic analyses revealed that five monocarboxylic fatty acids corresponding to C(8), C(9), C(10, C(11), and C(12) were present in the fermentation fluid. The Cyclone-fermenter was found to be very suitable for hydrocarbon fermentation. The hydrocarbon, kerosene, was fermented with a pure bacterial culture in a continuous process for 250 hours without any noticeable change in the culture behavior. Moreover, the addition of various culture medium ingredients could be optimized to produce maximum cell yield or maximum acid production. Manometric and gas chromatographic studies revealed that cell-free extracts of 2(11) oxidized n-decane to n-decanol and n-decanoic acid, whereas the partially purified hydrocarbon-oxidizing enzyme only oxidized n-decane to decanol. The n-decane-oxidizing enzyme could be precipitated by 30% (NH4)2 SO4 and had a narrow optimal pH around 7.0. The enzyme also required a dialyzed, heat stable 60% (NH4)2 SO4 supernatant fraction and NAD for maximum enzyme activity. Ferrous, manganous and calcium ions did not stimulate the enzyme activity. It seemed that the enzymatic attack on n-decane occurred primarily at the terminal carbon atom and this was manifested by the fact that n-decanol, n-decanal and n-decanoic acid supported good growth for S(11). / Land and Food Systems, Faculty of / Graduate