201 results for 1960, Doctoral

  • Aspects of the biology of some New Zealand echinoderms : feeding, growth and reproduction in the asteroids, Patiriella regularis (Verrill, 1867) and Coscinasterias calamaria (Gray, 1840).

    Crump, Robin (1969)

    Doctoral thesis
    University of Otago

    192 leaves :illus. ; 30 cm. Bibliography: p.138-147. The author's "The flight response in Struthiolaria papulosa giges Sowerby", reprinted from the New Zealand journal of marine and freshwater research, v.2, no.3, Sept., 1968, in pocket. University of Otago department: Zoology

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  • Some aspects of molybdenum halide chemistry

    Gainsford, G.J. (1969)

    Doctoral thesis
    University of Canterbury Library

    Chemical and X-ray crystallographic studies of molybdenum(II) halides, which are based on the well-known (Mo₆Cl₈)⁴⁺ cluster, have been carried out. Contrary to previous reports, the reactions of 2,2'-bipyridyl with the halides (Mo₆Cl₈)Cl₄ and (Mo₆Cl₈)I₄ yield, even under mild conditions, bipyridylium salts of chloromolybdic(II) and iodomolybdic(II) acids respectively: (BipyH)₂((Mo₆Cl₈)X₆) where X = Cl, I and Bipy = 2,2'-bipyridyl. The reactions are complicated by the formation of mixtures of products, which are mainly various crystalline forms of the bipyridylium salts. An amorphous product may be a true mono-bipyridyl complex. An unusual oxidation occurs during the reactions of triphenylphosphine (Ph₃P) and triphenylarsine (Ph₃As) with (Mo₆Cl₈)Cl₄ and (Mo₆Cl₈)I₄. Infra-red spectral and X-ray powder photographic studies show that the oxidized ligand complexes, (Mo₆Cl₈)X₄(Ph₃Z0)₂ (X = Cl, I; Z = As,P), are formed except under conditions in which both molecular and chemically-bound oxygen is rigorously excluded. The conditions required to coordinate more than two neutral unidentate ligands to the (Mo₆Cl₈)⁴⁺ cluster have been examined. It proved possible to obtain new ionic complexes under a range of conditions. The six-fold coordination of the (Mo₆Cl₈)⁴⁺ cluster is maintained in these compounds (e.g. ((Mo₆Cl₈)I₃(triphenylphosphine oxide)₂(pyridine))⁺I⁻) by the ionization of one or more of the terminal halogen atoms in the molybdenum(II) halide starting material (e.g.(Mo₆Cl₈)I₄). The X-ray single crystal structures of two isomorphous salts, (BipyH)₂(( (Mo₆Cl₈)X₆) (X = Cl,I), have been solved using the difference Patterson method. To solve another crystalline modification of the chloro-salt, the (Mo₆Cl₈) cluster was constrained to its established geometry with its centroid fixed at the origin of the unit cell. This rigid group of atoms was then rotated by the least-squares refinement of the three orientation-defining angles. The three structures contain discrete ((Mo₆Cl₈)X₆)²⁻(X = Cl,I) and (C₁₀H₉N₂)⁺ (bipyridylium) ions. The anions consist of highly-symmetric (Mo₆Cl₈) clusters (Mo-Mo = 2.606, Mo-Cl = 2.48 Ao), with six terminal halogen atoms (X) bound by single covalent bonds to the molybdenum atoms (Mo-Cl = 2.423, Mo-I = 2.737 Ao). The bipyridylium cations are twisted from perfect cis conformations in all three structures. The average dihedral angle between the two rings is 13 degrees. Further details of the geometries of the anion and cation are discussed. The ionic packing in the three crystals is dominated by the bulky anions. These are arranged in expanded "hexagonal close-packed" layers with the cations centred on approximately trigonal holes in this array. The two crystalline modifications of the chloro-salt differ in the orientation of the bipyridylium cations in these layers.

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  • Uranium luminescence

    Nicholas, J.V. (1966)

    Doctoral thesis
    University of Canterbury Library

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  • Lower ionospheric irregularities

    Vincent, R.A. (1967)

    Doctoral thesis
    University of Canterbury Library

    This thesis is a study of the structure of that part of the ionosphere lying between 60 and 120 km. In the usual terminology the ionized parts of the atmosphere in this altitude range are called the ionospheric D and E regions, the boundary between them occurring at a height of 90 km. Above this height the E region extends upwards to 140 km, the base of the F region. Since the ionization below 50 km is not enough to effect the propagation or radio waves this height effectively marks the bottom of the D region. There is also another system of nomenclature based on the neutral gas temperatures of the atmosphere. The mesosphere lies in the altitude range 50 to 85 km, which is a region of decreasing temperature with height. Because they refer to the same height range the terms mesosphere and D region are often used synonymously in the following work. Above 90 km the temperature increases, rapidly at first and then more slowly, in the thermosphere.

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  • A study of low valency states of transition metals

    Hickford, Jeanette Helen (1967)

    Doctoral thesis
    University of Canterbury Library

    This is a study of certain aspects of the chemistry of low valency states of the two group VIIa elements, technetium and rhenium. Sections 1 and 2 are on technetium and rhenium, respectively, and Section 3 consists of a comparative review of their chemistry. SECTION 1 Technetium in oxidation states (IV) (III) and (II). New complexes of technetium, with some organic ligands containing group V elements, have been identified. The tetravalent complexes have been prepared by direct reaction between technetium tetrachloride (and tetrabromide) and the ligand. They are all basicall six-coordinate complexes in which technetium has three unpaired electrons. Electronic spectra of these compounds, and the potassium hexahalogenotechnetates (IV), have been studied in detail. The value of Dq for technetium (IV) in a chloride field is ~2400 cm -¹, if the band assignments are correct. The reduction of technetium (IV) to technetium (III) can be brought about be relatively mild reducing agents, e.g. the reaction of technetium tetrachloride (or tetrabromide) with bis(diphenyl-phosphino)ethane, in ethanol, produces the complex [Tc(III)X₂(diphos)₂]X, where X = Cl,Br. This is further reduced by reaction in the cold with sodium borohydride to form [Tc(II)X₂(diphos)₂]. The properties of these compounds are consistent with those expected for six-coordinate d⁴ and d⁵ spin-paired complexes. Several attempts have been made to synthesise technetium trichloride, using a variety of methods; the high stability of the tetrachloride is a dominant factor in the non-formation of the trichloride. SECTION 2 Rhenium(III) “cluster” compounds. Trimeric rhenium trichloride, Re₃Cl₉, has been reacted with several neutral polydentate ligands containing group V elements. From the reaction products (often several), new trimeric complexes have been isolated in which the ligand is attached to one or more metal atoms. For example, in complexes such as [Re₃Cl₈(diarsine)₂]Cl, and [Re₃Cl₈(terp)]Cl, the organic ligand is probably bonded to one rhenium atom; however, in a complex such as Re₃Cl₉(diphos)1.5 (empirical formula), at least some of the ligand groups must be bridged across two metal atoms adjacent trimeric units. The effect of groups attached to the rhenium atom, within the complex anion, has been studied further by the preparation of compounds of types M (x+y-9)[Re₃Clxyy], (where Y is a singly-charged anion e.g. bromide), and M(x+2y-9)[Re₃Clxyy’], (where Y’ is a doubly-charged anion e.g. oxalate); M is a univalent cation and x+y = 10, 11 or 12. A study of the properties of these complexes indicates that the basic unit Re₃Cl₃, is still present in each. The influence of “external” groups in the trimeric anion causes minor shifts in the visible absorption spectra. An interesting compound, which has been formulated as Cs₅Re₄Cl₆Br₁₂, was isolated during the investigations. The physical and chemical properties of this complex indicates that it is a “lattice compound”, consisting of the complex halide, Cs₂Re(IV)Br₆, and the trimeric compound, Cs₃Re₃(III)Cl₆Br₆. The reaction between thionyl chloride and rhenium dioxide (described by R. Colton as a means of preparing Re₃(IV)Cl₁₂) was studied in detail. The main products are usually the monomeric compounds, Re(IV)Cl₃(OH). H₂O, and Re(IV)Cl₃(OH).2H₂O; small amounts of other compounds, e.g. rhenium trichloride, are sometimes formed. The analogous reaction for technetium gives similar results.

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  • Pseudo-conjunction in the cyclopropane ring

    Miller, Ian James (1966)

    Doctoral thesis
    University of Canterbury Library

    A survey of the available data on the properties of cyclopropane systems shows that the common assumption that cyclopropane can conjugate with unsaturated systems is questionable. A series of phenylcyclopropanecarboxylic acids, and a series of phenylcyclopropylamines were prepared, and a study was made of the basicity and nucleophilicity of the latter, and reactivity of the former, and the spectral properties of both. It was shown that the lone pair of the nitrogen of a phenylcyclopropylamine does not appear to conjugate with the cyclpropane ring, that the cyclopropane ring cannot transmit mesomeric effects, and that the cyclopro-pane ring electrons are not appreciably more polarizable than is expected classically. A general explanation of the properties of cyclopropane systems is offered in terms of strain, and it is pointed out that in certain cases, particularly in consideration of polarizability, the effects of ring closure cannot be neglected. It is concluded that the cyclopropane ring does not conjugate with unsaturated centres.

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  • The Ladenburg rearrangement

    Creamer, L. K. (1963)

    Doctoral thesis
    University of Canterbury Library

    Ladenburg found that thermal decomposition of pyridine ethiodide led to both 2- and 4-ethylpyridine. Because no systematic study of this reaction had ever been reported, the present work was undertaken to explore the reaction as a synthetic method, and also, to elucidate the reaction mechanism. To this end a number of alkylpyridine alkiodides have been decomposed and the products identified and analysed quantitatively, Gas chromatography and ion-exchange chromatography were used extensively in the analyses. It was found that the alkyl group entered the pyridine nucleus preferentially at the 2- and the 4- positions. It was also found that alkylpyridine alkiodides rearranged to give, in addition to the nuclear substituted products, substituted in 2- or 4-alkyl sidechains. In the case of the 4-ethylpyridine methiodide rearrangement, 4-iso-propylpyridine is the most important substitution product. Both nuclear and sidechain substitution appear to be intermolecular but while nuclear substitution seems most likely to involve a free radical intermediate, sidechain alkylation appears to involve carbonium ion attack on the deprotonated sidechain of an N-methylalkylpyridinium ion.

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  • Structure and reactivity relationships in organic molecules

    Blackwell, L. F. (1965)

    Doctoral thesis
    University of Canterbury Library

    As a test of Taft's δ° hypothesis the rates of solvolysis of benzyldimethylcarbinyl chloride, and twelve m- and p-substituted derivatives, have been measured in methanol at 66.5°C [FORMULA] The results, analysed by means, of the Hammett equation show that the effect of the aryl substituents on the reactivity is essentially inductive, any Ar-Y resonance interactions being effectively inhibited by the interposed methylene group. The substituent constants derived from this reaction series agreed with Taft's δ° values, within the precision of the latter, with the exception of the meta-methoxyphenyl substituent. This deviation is explained in terms of a dipole-dipole interaction which is possible as a result of the geometry of the system. Also studied were the rates of elimination of the compounds, in sodium methoxide solutions, to give olefins II and III. A Hammett analysis of the rates enabled conclusions regarding the nature of the transition states leading to the two olefins, to be drawn.

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  • The rearrangement of disubstituted diamines

    Russell, G. B. (1963)

    Doctoral thesis
    University of Canterbury Library

    The scope, mechanism and synthetic value of the acid-catalysed thermal decomposition of N,N'-diphenyl-1,3-propanadiamine has been investigated. This diamine has been decomposed under a variety of acid conditions and the products have been analysed by gas chromatography. Using the optimum conditions found in these experiments, a number of other N;N'-diaryl-1,3-propanediaminas have been decomposed with hydrogen bromide at elevated temperatures. The volatile products have been analysed by gas chromatography and have bean separated chemically to give the expected anilines and 1,2,3,4-tetrahydroquinolines and also significant quantities of julolidines in many cases where the formation of such tricyclic products is allowed. As well as these major components, a number of N-alkylanilines have also been isolated and some N-alkyltetrahydroquinolines have been provisionally identified. N,N’-Diphenyl-cis-1,3-cyclohexanediamine and sym-dianilino-dimethylether have been prepared and decomposed; examination of the reaction products has shown that 1,3-endoimino cyclohexane is probably produced in the first case while aniline and an intractable tar are obtained in the second case. A number of N-(3-bromopropyl)-arylarmines have been prepared and decomposed by heat. A comparison of the product ratios with those of the corresponding diamine decompositions has been made and the possibility that these compounds are intermediates in the diamine decomposition has been discussed. Comments have also been made of other mechanistic aspects of the decomposition, in the light of the experimental data. During the course of this work, it was noted that no reports could be found in the literature, of the application of the Hofmann-Martius reaction to N-alkylnaphthylamines. Consequently, N-methylnaphthylamine hydrohalides have been prepared and decomposed. With the hydrochlorides only dibenzacridines were isolated, but with the hydrobromides, normal Hofmann-Martius products were obtained as well. The influence of the halogen on the course of such break-down has been discussed.

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  • Military Settlement in the Middle Waikato Basin

    Allen, Peter D. H. (1969)

    Doctoral thesis
    University of Waikato

    Military settlement formed a brief but distinctive phase in the European occupation of the Middle Waikato Basin. Prior to the 1863 - 1864 Waikato War, few Europeans, other than a small number of missionaries and traders, were settled in the region. The setting of the Middle Waikato Basin was largely unmodified by Man, except along the major rivers where a dense Maori population was settled. During the 1850's, the encroachment of European settlers upon Maori tribal lands in many North Island regions, including the Waikato, led to an increase in tension between the two populations and open conflict. This conflict slowed down the progress of colonization in the North Island. To enable colonization to continue in those regions disturbed by Maori unrest, a scheme of military settlement was devised. The aim of this scheme was the formation of compact, self-sufficient defensive settlements to act as a deterrent to Maori unrest. These settlements would also provide an assurance to settlers of security for their life and property. Military settlement in the Middle Waikato Basin consisted of two phases. In the first phase, the nodal points of the military settlements, the townships, were established and occupied by the military settlers. In the second phase, farm districts were surveyed around the nodal points and the military settlers moved out from the townships to occupy and develop the land they were allocated. A number of factors, relating to deficiencies in the scheme of military settlement and to the particular problems of settlement in the region, contributed to the failure of the military settlers to successfully establish farms on the land they were allocated. The scheme of military settlement largely failed as a method of colonization in the Middle Waikato Basin. However, the pattern of human occupation, established in the initial phase of military settlement, remained when the need for defensive settlements had gone, and forms the basis of the present pattern of settlement.

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  • Studies in the solid state : optical spectra of IrCl62- and PtCl62- complexes

    Douglas, I.N. (1969)

    Doctoral thesis
    University of Canterbury Library

    The optical absorption spectra of the complexes IrCl62- and PtCl62- in single crystals of Cs2ZrCl6, Cs2HfCl6 and K2SnCl6, and PdCl62- in Cs2ZrCl6 have been studied at liquid helium temperature. Both molecular orbital theory and ligand field theory are used to interpret the results. The rich vibrational structure observed in many of the bands is analysed in terms of the vibrational modes of the complexes. Several long progressions involving up to twelve quanta of the totally symmetric vibration, ylg, were observed throughout the spectra, indicating that the transitions are to states in which the bond length has changed. Luminescent bands due to transitions from the triplet states of the 5d6 configuration of Pt4+ in crystals of the type K2PtCl6 have been found in the red and green regions of the spectrum. A study of the temperature dependence of the band width of the red luminescence in K2PtCl6 powder has been made and fitted to a coth function. At liquid helium temperature both bands showed vibrational progressions, involving several quanta of the totally symmetric vibration.

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  • Transformations of hecogenin acetate

    Coxon, J. M. (1965)

    Doctoral thesis
    University of Canterbury Library

    The Δ13,17a-C-nor-D-homo-spirostan olefin has been characterised. The epoxides derived from this olfin, and from the isomeric Δ17a,18-olefin have been made and their configurations determined, by the study of the tert-alcohols derived by reduction with lithium aluminium hydride. The boron trifluoride and perchloric acid catalysed reactions of these four epoxides have been studied. An attempt was made to synthesise and study the boron trifluoride catalysed rearrangements of the analogous C-nor-D-homo pregnene epoxides. The epoxides of 12-methylene tigogenin acetate have been made and their configurations determined by the study of the dehydration reactions of the tert-alcohols formed by reduction of the epoxides with lithium aluminium hydride. The Grignard reaction of the C12-ketone of hecogenin acetate was shown to proceed from the β-face. Dehydration of this alcohol gave the Δ11,12 olefin from which the 12β-methyl-11#945;,12#945;-epoxide was made. The boron trifluoride and perchloric acid catalysed rearrangements of this epoxide, along with the two 12,12'-epoxides, was studied.

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  • Low frequency infrared and other studies of coordination complexes

    Brodie, A. M. (1968)

    Doctoral thesis
    University of Canterbury Library

    This thesis is divided into two main sections. Section I is concerned with oxygen and sulphur ligand complexes of the divalent first row transition metals, and oxygen and nitrogen ligand complexes of the Group VB trihalides are described in Section II. Section I. (1). The preparation of new tertiary phosphine sulphide and arsine sulphide complexes of cobalt (II) is reported. Comparative spectral and magnetic data are presented for the tetrahedral oxo- and thio-ligand complexes of the types [CoL₄](ClO₄)₂ and CoL₂x₂ (X = Cl, Br and I). (L = Me₃PO and Me₃PS; Me₃As O and Me₃As S). In the perchlorate complexes corresponding oxo- and thio-ligands produce similar ligand field splitting energies, but lower β values of the sulphides and higher intensities of their spectral bands point to their greater covalent character. The considerably lower magnetic moments of [CoL₄](ClO₄)₂ thio-complexes as compared with their oxo-analogues is further evidence for differences in metal-oxygen and metal-sulphur bonding. Electronic spectra for the [CoL₄](ClO₄)₂ complexes have been compared with the spectra of related tetrahedral cobalt (II) complexes. The ⁴A₂→’⁴T₁(P) transition band shapes and intensity distributions are virtually identical for both the phosphine and arsine sulphides. In contrast the characteristic profiles produced by phosphine oxides are different from those produced by arsine oxides. Metal-ligand vibrations have been assigned for cobalt and corresponding zinc complexes. (2). Spectral and magnetic results show that trimethylarsine sulphide continues to give tetrahedral [M(Me₃AsS)₄] (ClO₄)₂ and M(Me₃AsS) ₂ x₂ (X= Cl, Br) complexes with iron (II) and nickel (II). The low β value and magnetic moment of [Ni(Me₃AS S)₄] (ClO₄)₂ again demonstrates the high metal-ligand covalency produced by thio-ligands. Metal-ligand vibrations fall in the same frequency range as observed for cobalt (II) complexes. By contrast trimethylarsine oxide reacts with the dihalides of iron, cobalt and nickel to give bridged octahedral M(Me₃As O)₂x₂ (X = Cl, Br) complexes thus providing an example of tetrahedral bridged octahedral isomerism involving oxo-ligands. Their structures have been elucidated using infra-red and electronic spectral, and magnetic data. The low As- O stretching frequencies suggest that polymerisation is being achieved via oxo- rather than halogen bridges. Further evidence is obtained from the infra-red spectra of the analogous M(Me₃As O)₂ (NCS)₂ thiocyanate complexes. (3). The preparation of high-spin five-co-ordinate [ML₅]²⁺ and [ML₄(ClO₄)]⁺ complexes with trimethylarsine oxide is described for a number of first-row, divalent, transition metal ions. The electronic spectra of these complexes more closely resemble the spectra obtained for other complexes known, from X-ray analysis, to have a basically square pyramidal structure rather than those of the trigonal bipyramidal class. Five co-ordination is considered to be stabilised by the steric requirements of the ligande Metal-ligand stretching vibrations are assigned and their frequencies compared with values for related tetrahedral complexes. Section II. Metal-ligand stretching frequencies have been assigned for MX₃ dipy and MX₃L₂ ( L = py, pyO and Ph₃As O) complexes of arsenic, antimony and bismuth. For the arsenic and antimony MX₃L₂ compounds υ(M - L) values fall in the same region as for the corresponding germanium and tiny MX₄L₂ compounds. However, υ(Sb -X) values are significantly lower than υ(Sn - X). Terpyridyl complexes are varied. Their compositions and constitutions were elucidated by spectral and conductivity studies. Antimony complexes are formulated as [SbX₂terpy] 2⁺ SbX² ²- and arsenic complexes as [As Cl₂ terpy]⁺ AsCl₄- and [As Br₂ terpy] ⁺ Br - . The bismuth complex [Bi Cl₃ terpy] is non-ionic.

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  • The effect of substituents on the coordination of nitrogen-containing ligands

    Bryant, Gillian M. (1969)

    Doctoral thesis
    University of Canterbury Library

    A wide range of complexes of divalent and trivalent iron, ruthenium and osmium containing coordinated 2.2'-bipyridine have been prepared. These are all six coordinate and are of general formulae (M(bipy)₃)N+, (M(bipy) ₂x₂)N+, (M(bipy)₂XY)N+ (M(bipy)X₄)N+, (M(htpy)X ₂Y₂)N+, where X and Y include a wide range of monodentate and bidentate ligands including cyanide, oxalate, ammonia, pyridine and the halogens. Several complexes containing 4,4'-dimethylbipyridine have also been prepared. The electronic absorption spectra of these complexes in solution have been measured, and a number of assignments made for the observed transitions. Both the divalent and the trivalent complexes show intense intraligand transitions of hipyridyl in the ultraviolet region. In the visible region, the divalent complexes show intense metal to ligand charge transfer transitions, while the trivalent complexes exhibit ligand to metal charge transfer transitions of different types. The effects of such factors as the metal ion, the charge on the metal ion, substituents in the bipyridyl ligand and the presence of coordinated ligands other than bipyridyl have been discussed, and the results of this work related to earlier studies. Proton magnetic resonance spectra of some divalent complexes containing 4,4'-dimethylbipyridine have been measured and these are correlated with the electronic absorption spectra where possible.

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  • The effects of solvent and substituents upon the ionization of phenols

    Leary, G. J. (1964)

    Doctoral thesis
    University of Canterbury Library

    The “dissociation constants” of a series of 4-substituted-phenols, 4-substituted-2,6-dichlorophenols, and 4-substituted-2,6-dimethylphenols have been measured potentiometrically in a variety of solvents. Excellent linear Hammett plots are obtained for each series in all solvents. The effects of changing solvent upon the Hammett ρ values for each of these three series are deduced from these measurements. As the “solvating power” of the solvent is reduced ρ for each series increases because of the increased demand placed on the 4-substituent for dispersal of the anionic charge. Within each solvent ρ is greater for the 2,6-disubstituted-phenols than for the unhindered phenols. The 2,6-substituents hinder solvation and tis increases the demand for anionic charge dispersal by the 4-substituent. 2,6-Dichloro- or 2,6-Dimethyl-substitution is found to hinder solvation of the phenoxide ion even in water. The solvent-dependence of the Hammett σρ values is discussed and some attempt is made to interpret the shape of the potentiometric titration curves in different solvents.

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  • Some reactions of oxygen atoms in flames

    McEwan, M. J. (1965)

    Doctoral thesis
    University of Canterbury Library

    A flame can be regarded as a flowing reaction system in which the time scale in the usual reaction rate expressions is replaced by a scale of distance along the flame. Flames provide a convenient system in which to study the kinetics of high temperature gas reactions because wall reactions are absent and the relatively high linear velocities enables quite rapid reactions to be followed; e.g. radical recombination reactions at atmospheric pressure. The reactions to be discussed in this thesis have been studied using the techniques of flame photometry. From measurements of light emission or absorption as a function of flame temperature, composition and time from primary combustion, it is possible to make important deductions concerning the rates of elementary reactions in the burnt gas and the nature of the equilibria set-up among the components of the burnt gas.

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  • Structure and reactivity in the naphthalene series: monobromo - peri-alkylnaphthalene isomer distributions

    Lewis, I. K. (1965)

    Doctoral thesis
    University of Canterbury Library

    1,8-Dimethylnaphthalene, perinaphthane and pleiadene were synthesized to form, with acenaphthene, a group of structurally analogous hydrocarbons. Acenaphthene was brominated under a variety of conditions and the distributions of the product isomers were measured by vapor phase chromatography. A selection of the brominating conditions was then tried on the group of hydrocarbons in an endeavour to relate the isomer distributions to the structural differences between the hydrocarbons. Finally, pairs of the hydrocarbons were brominated to determine their order of reactivity. The inferences that may be drawn from the results are discussed together with their reproducibility and reliability.

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  • The acid catalysed reactions of 3β-fluoro-6β-substituted-5α-cholestan-5-ols

    Lewis, A. J. (1967)

    Doctoral thesis
    University of Canterbury Library

    The effect of variation of the 6β-substituent in the sulphuric acid catalysed rearrangements of 3β-fluoro-6β-substituted-5α-choleatan-5-ols in acetic anhydride-acetic acid was studied. The relative rates of reaction and the variation in products were determined.

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  • Fluvial sediment transport at a large bed shear stress

    Hill, Ian Kennedy (1967)

    Doctoral thesis
    University of Canterbury Library

    The mechanics of a layer, many particle diameters thick, of a particle fluid system where the particles are large and exist at high concentrations is examined. Two distinct matters are examined, the first being the development of equations describing the overall characteristics of the system if the "local" equations governing the system at a point are known, and the second being the development of these local equations for large particles. It is shown that, if the local equations describing the dispersive stress - shear stress relationship and the stress - rate of strain relationship are single valued functions of the concentration, then the concentration profile in the bed of an open channel can be obtained by integrating a first order differential equation and the velocity profile obtained by carrying out a further integration. A method of obtaining the local equations is developed using previous results from a theory of a gas of rigid elastic spheres. Using these results and an equation derived from the calculated energy dissipation, local equations are developed. Results obtained theoretically are compared with previous experimental results and also with the results obtained using an open channel with a bed of gravel particles. A significant discrepancy between the results predicted by the theory developed and the results found by experiment was observed at high concentrations.

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  • Experimental and theoretical study of shallow doubly curved shells

    Croll, J. G. A. (1967)

    Doctoral thesis
    University of Canterbury Library

    This investigation is concerned with the application of finite difference methods to the solution of thin elastic shallow shells. In particular, the ruled surface hyperbolic paraboloid is systematically studied to determine the influences of boundary conditions, geometric shape and material properties. The method developed for representing and solving the discretised system is suitable for use on digital computers of limited storage capacity and arithmetic speed. For all boundary types considered, solutions upon successively finer difference grids have demonstrated convergence to the analytic solution. A number of methods for accelerating this convergence were found to result .in an increase of total computational labour for a given numerical accuracy. The considerable differences in the behaviour of the degenerate clamped and free edged shells demonstrate the necessity of theoretical solutions embodying the influence of edge members. A number of numerical - physical analogues for the shell-edge member interaction are studied to ensure compatibility with the degenerate boundary conditions upon choice of suitable beam dimensions. The construction and testing of a "perspex" model with varied boundary and corner support conditions is described. Results from these tests are used as a basis for comparison with theoretical solutions and to provide additional information concerning the critical influence of the corner diagonal thrust. Conclusions from the theoretical and experimental investigations are in close agreement, and also verify solutions obtained in past research

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