Browsing by Author "Irving, H M N H"

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    Complexes of iron (III) with derivatives of 8-quinolinol
    (1981) Golden, Corinne Ellen; Irving, H M N H
    The organic ligands 5- and 7- methyl-8-hydroxyquinoline have been synthesised and shown to form green, water soluble, 1:1 complexes with iron(III) and thus to possess the same composition as the complexes with 8-hydroxyquinoline and 2-methyl-8-hydroxyquinoline previously reported. Thermodynamic formation constants for the 1:1 complexes of 2-, 5- ,and 7-methyl-8-hydroxyquinoline with iron(III) have been determined -1 3 spectrophotometrically as 5.5. x 10¹⠴, 2.9 X 10¹⠵ and 3.6 x 10¹⠵ mole-¹ dm³ respectively at 25.0°C and I = 0.1M. When compared with the value 8.5 x lO¹⠴ for 8-hydroxyquinoline itself the results support the theory that methyl substitution affects the stability of these complexes by increasing the basicity of the nitrogen atom. The lesser stability of the 2-methyl complex, however, indicates an opposing steric effect of a bulky substituent in the 2-position.
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    Flux of cadmium through a laboratory food chain (media-algae-mussel) and its effects
    (1981) Hennig, Helmke F-K O; Irving, H M N H
    The increasing pollution of the aquatic environment by cadmium is a potentially severe problem and techniques are needed to document the effect of the metal. To investigate the flux of this metal through a laboratory food chain, algae were grown in various cadmium concentrations for subsequent use as contaminated food for mussels. The results showed that in order to make valid deductions, more information about chemical mechanisms and background ecophysiological data is needed, otherwise accumulation reports may become misleading. It was found that the best growth and accumulation results were achieved by harvesting algae from a zinc deficient media containing 7 μmole dm-3 cadmium and at a particular life cycle phase. Two uptake mechanisms are proposed. These "contaminated" algae were fed to mussels under different accumulation regimes. The metal gain and loss were determined and compared to a "baseline" dry body weight which had been calculated from a shell length-body weight relationship. Cadmium accumulation took place in the mussels and after some initial delay, could be correlated to weight loss. Such a weight loss was due to pathological and biochemical changes in the mussels. It was shown that the toxic effect of cadmium could be determined much earlier by the presence of special proteins. The elutant profiles of the gel chromatography study showed the production of metal binding protein as well as a spill over of cadmium into the enzyme pool, caused by a higher uptake than elimination rate. Cadmium on metal binding protein and in the enzyme pool could be related to the poisoning effect of the metal and a pollution history for the mussels identified. The characteristics of the metal binding protein were found to be very similar to those reported for metallothionein and had an approximate molecular weight of 10 600 daltons.
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    Gas-solid chromatographic studies of two well-known catalysts
    (1983) Mason, Robert Peter; Irving, H M N H; Koch, Klaus R
    This work was initiated to explore the scope and feasibility of using a gas chromatograph to study catalytic reactions. Various methods have been proposed in the literature and it was decided to investigate various possible systems. Two catalysts were chosen for study. The dehydration of alcohols over alumina catalysts has been extensively studied and found to be ideally suited to studies by gas chromatography. The effect of modification of the catalyst by inorganic ions and by water was investigated. The dehydration of ethanol and pentanol were studied. Results indicated that alumina has two types of active sites responsible for the dehydration of alcohols. Zeolite catalysts are well-known and in this work the catalytic cracking of alkanes over zeolite Y was studied. The reaction mechanism was found to be complex and catalyst deactivation due to build-up of highly carbonaceous deposits occurred. All components of the reaction products were produced at similar rates to the overall reaction rate indicating that desorption of alkane product species was not the rate determining step. Between 150° and 300°C propane was the smallest product formed. Only alkanes were found in the product spectrum which was temperature dependent. Addition of hydrogen gas greatly increased the amount of detectable products. Heptane was found to react significantly above 200 °C, hexane about above 225°C and pentane above 250°C. Hexane and cyclohexane reacted at similar temperatures.
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    Oxygen and sulphur heterocycles derived from chloroaldehydes
    (1984) Archer, Steven James; Irving, H M N H
    Chloral may be trimerised, tetramised and polymerised, to form parachloral, metachloral and polychloral, respectively. Parachloral has two isomers: the cis-isomer and the trans-isomer. An analysis of the conformational equilibria occuring in solution, was carried out for trans-parachloral, using the techniques of dipole moment measurement and infrared and nmr spectroscopy Both isomers exist in cis-chair conformations, but differ in the chirality of the β-carbon atoms in the side chains. A comparison of the mass spectral fragmentations of parachloral and parabutylchloral is included. The structure of a related five-membered heterocycle, trans-chloralide was also investigated by x-ray crystallography. The cis-isomer of chloralide is reported for the first time. The unusual mechanism, in which carbon monoxide acts as nucleophile, by which chloralide is formed from chloral and fuming sulphuric acid, has been elucidated using 13C-labelling. The dehydrochlorination of chloralide under unexpected conditions, is also discussed. The isomerism in a series sulphur-containing analogues of parachloral was investigated. 2-Trans-dithioparachloral and its dehydrochlorination product, were shown by x-ray crystallography. A comparative study of the effects on the 1H and 13Cnmr spectra, of structural changes in these six-membered heterocycles, is discussed at length. Some introductory preparative work was done, regarding the potential use of 1,3,5-trithiane 1,3,5-trioxides with three axial sulphoxide groups, as terdentate ligands.
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    Structural and spectroscopic studies with dithizone and its derivatives
    (1980) Hutton, Alan T; Irving, H M N H
    An X-ray crystal structure detennination of 3-nitro-l,5-di(2,6-dimethylphenyl) fonnazan, ArN:N•C(N02):N•NHAr (Ar= 2,6-dimethylphenyl), has shown that the N-N-C-N-N chain is stabilized by an unusual hydrogen bond in the closed-ring syn,s-cis configuration relative to the formal double C=N and single C-N bonds. The bond lengths reveal complete n-electron delocalization along the chain which results in a mesomeric structure; the possibility of such a mesomeric structure existing in solution rather than a rapid tautomeric equilibrium between two limiting forms of the resonance hybrid has been considered in the light of i.r. and n.m.r. spectroscopic measurements. The temporal changes in the visible absorption spectrum of S-methyldithizone, PhN:N•C(SCH3):N•NHPh, have been shown to arise from syn-anti isomerization about the fonnal C=N double bond and rotation about the C-N single bond by considering the evidence provided by i. r. and n.m.r. spectroscopic studies combined with the X-ray crystal structure of the di(o-tolyl) homologue. The parent compound dithizone, PhN:N•C(SH):N•NHPh, previously thought to exist as an equilibritim of thiol and thione forms in solution has now been shown to consist of a single species in solution mainly by consideration of its n.m.r. spectroscopic properties. Organomercury(II) complexes of dithizone have been shown to be photochromic in solution; X-ray crystal structure detenninations of phenyland methylmercury(II) dithizonate, besides revealing rare three-coordination of mercury, have been combined with spectroscopic measurements on the normal and activated fonns to reveal the structure of the labile photo-isomers.
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    Structures of lanthanide-edta complexes
    (1983) Mullins, Jennifer Mary; Irving, H M N H; Nassimbeni, Luigi R
    The structures of six lanthanide-edta complexes were elucidated by X-ray diffraction, so as to ascertain exactly at which point the change from the nine-coordinate [Ln(edta)(H₂O)₃ ]- complex to the eight-coordinate [Ln(edta)(H₂O)₂]-complex occurs. The transition was found to occur at Erbium. The structures of the complexes K⁺[Ln(edta)(H₂O)₃ ].5H₂O for Ln=Praseodymium, Europium, Gadolinium and Holmium were elucidated and found to be isomorphous crystallizing in the orthorhombic space group Fdd1 with Z = 16. In each case , the central metal ion has a coordination mnnber of nine, being bonded to the hexadentate edta ligand and three water molecules. For each structure, anomalous dispersion corrections were applied since Fdd2 is a polar space group. The molecules of water of crystallization were seen to be partially disordered. The structures of the complexes K⁺[Ln(edta)(H₂O)₂ ].4H₂O for Ln =Erbium and Ytterbium were elucidated and found to be isomorphous. A space group problem arose with these two structures as there was a problem of pseudo-synunetry, in that the oolecules were arranged in a P2₁/n pattern, but the motif in fact resembled that of C2/c or Cc. The structures were finally refined in the centrosynnnetric, oonoclinic space group C2/c with Z = 4, but were found to be disordered. In fact, in each case, two independent structures were identified, one 'good' and one 'lesser' structure. A study of the 'good' structure in each case showed that the central metal ion has a coordination number of eight, being bonded to the hexadentate edta ligand and two water molecules. The technique of thermogravirretric analysis was employed in the study of the molecules of water of crystallization.
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    Studies with dithizone : the extraction of thallium (III)
    (1985) Sacht, Cheryl; Irving, H M N H; Koch, Klaus R
    Thallium(III) reacts with dithizone(I) in a complicated way through a number of intermediate products which depend on the relative proportions of reactants, the pH of the aqueous phase, the order of mixing of reactants, the time of phase equilibrium and the nature of the organic solvent used. The reaction between thallium(III) and dithizone is essentially oxidative in character. In the present work the complete reaction scheme is proposed: Thallium(III) reacts with dithizone to give a thallic-dithizonate complex, [TlIII(HDz)₃], which spontaneously and oxidatively disproportionates to the disulphide (III) and a thallium(I)-dithizonate complex, [Tl(HDz)]. The disulphide(III) decomposes by first-order heterolytic fission to give equimolar amounts of dithizone and the mesoionic compound (IV) . The Tl(HDz) complex undergoes reversion to give Tl+ in the aqueous phase and dithizone in the organic phase. In the presence of excess thallium(III) the regenerated dithizone is oxidized to the mesoionic compound (IV): the mesoionic compound (IV), partitions between the two phases and appears to react with excess thallium(III) to give possibly a mesoionic compound (IV)-thallium(III) complex and an unspecified oxidation product. The molecular structure of the 1 : 1 adduct formed between diphenylthallium( III) and dithizone has been shown by single crystal X-ray diffraction, to be a five co-ordinate diphenylthallium(III) complex: the dithizone acts as a bidentate chelating ligand co-ordinating through the nitrogen and sulphur atoms. Ethanol (solvent of recrystallisation) co-ordinates in the fifth position.
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    The viscosity of aqueous electrolytes and viscometric titrations
    (1984) Crouse, Philippus Lodewyk; Irving, H M N H; Torrington, R G
    The thesis attempts to find the most appropriate equation from which to calculate the viscosities of mixtures of aqueous electrolytes so as to predict the course of viscometric titration curves for new systems, to interpret viscometric data already published, and to use in the possible determination of equilibrium constants where other methods are not applicable. An extensive literature survey is included in the introduction (section 1), including not only material directly related to the main objective of the thesis, but material published on the subject of the viscosity of electrolytes in general.