Thesis (Ph.D.)--Kent State University, 2007. / Title from PDF t.p. (viewed Nov. 21, 2007). Advisor: Robert J Twieg. Keywords: phenylpyridine LCs, thiophene-pyridine LCs, pyridinyl stannanes, selective Negishi coupling, liquid crystal semiconductors, smectic liquid crystals. Includes bibliographical references (p. 356-363).

Thesis (Ph. D.)--University of Massachusetts Amherst, 2009. / Includes bibliographical references (p. 126-135). Print copy also available.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 187-190). Also available in print.

Thesis (Ph. D.)--Columbia University, 1939. / Vita. Bibliography: p. [22-23].

Disertation (Ph.D.)--Worcester Polytechnic Institute. / Keywords: cyanopyridine; methylpyridine; pyridine; phototransposition; azaprefulvene Includes bibliographical references (317-321 ).

Aim: to characterise the surface sites present on unrefined and ball milled Cornish kaolin, with a view to ultimately determining the mode of interaction between the mineral and industrially significant organic molecules. Milling and temperature were found to affect the structure of kaolin and types of surface sites present. These changes were monitored primarily by variable temperature diffuse reflectance infrared Fourier transform spectroscopy (VT DRIFTS) and other complementary techniques including XRD and TGA. Curve fitting of the VT DRIFT spectra was used to aid characterisation of the types of water present on the mineral surface. The diagnostic probe molecule pyridine was used to identify the changes in reactive acid sites present as temperature increased both before and after milling, and oleic acid was used as a representative adsorbate to analyse the effects of carboxylic acid treatment. As ball milling time increased, so did the kaolin agglomerate size and the amount of surface sorbed water. The types of water present on the surface of unrefined and ball milled Cornish kaolin have been characterised, and grouped into four main types -strongly hydrogen bonded, moderately strongly hydrogen bonded, weakly hydrogen bonded and very weakly hydrogen bonded. The different water environments were observed using DRIFTS in the bending and stretching regions of the spectrum. Changes in the stretching region were generally less distinct, since the bands were broader than in the bending region. However, changes in both regions were elucidated by curve fitting of the VT DRIFT spectra, and certain bands appeared to have similar thermal behaviour. Freshly milled samples had a greater proportion of strongly hydrogen bonded water compared with the other, more weakly bonded types. Aged samples had less total surface sorbed water, and relatively less strongly hydrogen bonded water compared with the more weakly bonded species. Pyridine displaced the more strongly hydrogen bonded water (an effect similar to ageing). A dehydrated halloysite impurity was found which intercalated pyridine. VT XRD showed that deintercalation occurred at c 100 °C. The hydrogen bonding nature of the halloysite-pyridine interactions became less pronounced as milling increased. Pyridine adsorption to kaolin was via Bronsted sites in the unmilled kaolin. As milling time increased the mineral surface took on Lewis acid character and less hydrogen bonding occurred. Bronsted associations were present in all the milled (and unmilled) samples and became more significant as milling time increased (as more surface water was present). In addition to the intercalation reaction between halloysite and pyridine, this probe molecule is likely to bind to exposed (broken) edge sites on kaolin and/or halloysite, or to sorb between the slightly expanded mineral layers at the edges of the mineral stacks. Oleic acid adsorption onto kaolin at pH 3, was via surface adsorption of monodentate. Acid precipitate was loosely associated with the surface via hydrocarbon chain interactions with the adsorbed salt. At pH 9, total surface adsorption was low. Adsorbed species were monodentate in character. Mono- and dioleate were present as loosely bound surface precipitates. At pH 12 the salt was associated with the surface in the bridged bidentate form. Adsorption was high due to hydrocarbon chain associations with micelles, containing some trapped acid species. The precipitate at pH 12 was strongly held, and there was no significant reduction in intensity after washing.

xxi, 294 p. ill. (some col.) A print copy of this title is available through the UO Libraries under the call number: SCIENCE QD403.O23 2008 / Highly conjugated carbon-rich systems have demonstrated many attractive applications for fundamental and materials science applications, including--but not limited to--probes for aromaticity, charge-transfer complexes, conducting/semi-conducting materials, linear/nonlinear optical materials, and solar cells. The bulk of this research has focused on carbon-rich fullerenes, conjugated polymers, or polycyclic aromatic hydrocarbons; however, with recent developments in cross-coupling chemistry, carbon rich chemistry, particularly dehydrobenzo[ n ]annulenes (DBAs), has grown to yield molecules of great diversity and utility. Concurrently, materials based on conjugated heterocycles have been developed and display similar and often enhanced properties to the aforementioned carbon rich systems. The lone pair of the heterocycle often adds additional stability and polarizablity, creating novel and tunable molecules. Assimilating techniques used to produce DBAs with heteroaromatic molecules, our work has afforded a novel class of conjugated macrocycles with the highly tunable optical-electronic properties of a DBA system. That in turn has led to the systematic study of the diverse structure-property relationships of the thiophene/DBA hybrids reported herein. Chapter I details the synthetic advances in the field of DBA chemistry. The first section discusses the methods of synthesis, inter- vs. intra- molecular approaches, while the remaining sections provide current examples of the DBAs reported. Chapter II briefly discuses conjugated thiophene chemistry, then describes the advantages of utilizing planarized thiophenes. Several examples of thiophene macrocycles are reviewed: both planar and nonplanar. Particular attention in the review focuses on synthesis, optical properties, and some redox properties. Chapters III and IV detail the synthesis and analysis of thiophenes locked into [14]- and [15]annulene scaffolds, respectively. The dehydrothieno[14]annulenes (DTAs) and DTA/DBA hybrids of chapter III serve as aromatic probes and show significant tunabilty with respect to the number and orientation of the thiophenes. Chapter IV's dehydrobenzo[15]annulenes, which are comprised of a cross-conjugated system, also display a structure-property relationship where the optical properties encompass a wider dispersion of wavelengths. Chapter IV also explores the incorporation of pyridines and the affects on conjugation. The electronic properties of the macrocycles were explored using NMR, UV-Vis absorption and fluorescence spectroscopy, and electrochemically (cyclic voltammetry). Chapter V is devoted to further functionalization of DTAs through alkylation and further cycliziation to yield planarized terthiophene units. This dissertation includes my previously published and co-authored material. / Adviser: Michael M. Haley

Magneto-structural correlations have been made for a number of pyridine and pyrazine complexes of iron(II) and copper(Il), involving anions of a range of coordinating abilities, for example, sulfonate, RS0₃⁻ (where R is CF₃, CH₃ or p-CH₃C₆H₄); halide, Cl⁻ Br⁻ or I⁻; pseudohalide, NCO⁻ or NCS⁻; perchlorate and hexafluoroarsenate. Structure was determined by infrared, electronic and Mössbauer spectroscopy and differential scanning calorimetry, and, in some instances, by single-crystal X-ray diffraction. Spectroscopic results were used to investigate the nature of both anion and neutral ligand coordination. In complexes of stoichiometry ML₄ (RS0₃)₂ (where M is Fe or Cu, L is pyridine, pyrazine or 2-methylpyrazine and R is CF₃, CH₃ or p-CH₃C₆H₄), the neutral ligands were found to adopt a unidentate mode of coordination. For several of these complexes, X-ray crystallography revealed a square-planar array of pyridine ligands around the central metal, with anions coordinated in a unidentate mode above and below this plane. A monomeric molecular structure results in which the paramagnetic centres are well isolated from each other giving rise to magnetically-dilute species. In complexes of stoichiometry M(pyz)₂X₂ (where M is Fe or Cu and X⁻ is CF₃S0₃⁻, CH₃S0₃⁻, Cl⁻, Br⁻, I⁻, C10₄⁻ or NCS⁻), pyrazine was found to coordinate through both nitrogen donor atoms and inorganic coordination polymers were produced. X-ray crystallography revealed a two-dimensional lattice in Cu(pyz)₂(CH₃S0₃)₂ with two distinct kinds of bridging pyrazine groups and monodentate sulfonate anions. For the remaining bis(pyrazine) complexes, spectroscopic evidence supports similar structures with unidentate anion coordination and bidentate bridging pyrazine ligands leading to sheet-like polymers. Cu(pyz)₂(CH₃S0₃)₂ and Fe(pyz)₂(NCS)₂ exhibit magnetic susceptibilities which reveal the antiferromagnetic nature of these materials (ˣmax at temperatures of 7.0 and 8.0 K respectively); the data were analysed in terms of a two-dimensional Heisenberg model. For the copper complex, in which the structure shows stronger pyrazine coordination along one dimension, the data were also analysed in terms of a linear chain model. Mössbauer spectroscopy showed Fe(pyz)₂(NCS)₂ to undergo a transition to a magnetically-ordered state at 9.2 K. The magnitude of the exchange coupling through bridging pyrazine in Fe(pyz)₂X₂ complexes (where X⁻ is CF₃S0₃⁻, CH₃S0₃⁻, Cl⁻, Br⁻, I⁻ or C10₄⁻) is considerably less than that present in either Cu(pyz)₂(CH₃SO₃)₂ or Fe(pyz)₂(NCS)₂. Spectroscopic evidence indicates that for Fe(py)₂(CF₃S0₃)₂ and complexes of stoichiometry M(pyz)X₂ (where M is Fe or Cu and X⁻ is CF₃S0₃⁻, p-CH₃C₆H₄S0₃⁻, Cl⁻ or NCO⁻) bridging anionic ligands are present and for the mono(pyrazine) complexes the neutral ligand also coordinates in a bridging mode. Fe(pyz)(CF₃S0₃)₂, Fe(pyz)(NCO)₂ and Cu(pyz)(CF₃SO₃)₂ all exhibit magnetic susceptibility data characteristic of antiferromagnetic materials (ˣmax at temperatures of 4.4, 38 and 7.0 K respectively). The magnetic susceptibilities for these materials were analysed in terms of the two-dimensional Heisenberg model and a linear chain model. Mössbauer spectroscopy shows both Fe(pyz)(CF₃S0₃)₂ and Fe(pyz)(NCO)₂ to undergo a transition to long-range magnetic ordering at temperatures of 3.9 and 27.0 K respectively. Low-temperature (4.2-130 K) magnetic susceptibility measurements for the iron(II) sulfonate compounds, Fe(RS0₃)₂ (where R is F, CF₃, CH₃ or p-CH₃C₆H₄) are reported. For the compounds where R is F, CF₃ or p-CH₃C₆H₄ the magnetic moment data were assessed in terms of crystal-field splitting effects. The magnetic moment data for ɑ and β forms of Fe(CH₃S0₃)₂ are indicative of antiferromagnetic exchange interactions and the characteristics of the susceptibility curve for the β isomer are explained on the basis of a transition from short-range to long range three-dimensional magnetic ordering at 22 K. / Science, Faculty of / Chemistry, Department of / Graduate

Includes bibliographical references. / X-ray crystallographic studies have been used to elucidate the structures of two new Werner clathrates. ... The chloroform molecule is disordered, lying on a two-fold axis. Stoicheiometric characterization of the clathrates was determined using various chemical techniques, including mass spectroscopy, proton nuclear magnetic resonance and complex iometric titration. The clathrating phase of the second clathrate was investigated by guest-loss studies on a McBain balance followed by X-ray powder photography. Host-quest non-bonded interactions of both clathrate compounds were studied using atom-pair potentials.

MSc Thesis / A dissertation submitted in partial fulfilment of the requirements for the degree Master of Science in Engineering to the Faculty of Engineering and the Built Environment, School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Johannesburg, 2018 / This work aims at designing and simulating on Aspen Plus process simulator a process that can recover valuable chemicals from a High Organic Waste (HOW) stream produced at Sasol Secunda plant, South Africa. The waste is made up of low boiling point organic components such as pyridine, acetonitrile and Methyl Ethyl Ketone and water. Currently, the waste is incinerated without energy recovery. This practice serves to exacerbate the already high greenhouse gases emissions from the plant, but more importantly, it results in the missed opportunity to maximize revenues through resale of recycled valuable chemicals. The recovery of valuable chemicals from the HOW is made difficult by the formations of azeotrope between organic components and water; at least 6 azeotropes exist in the HOW stream. In this work the emphasis is on pyridine because of its established market value and demand. Pyridine market size is about 400 million USD in 2017 and is expected to increase to over 600 million USD by 2021 mainly due to increased usage in the agrochemical industry. Water integration strategy was also assessed demand because of the reported need to improve water utilization efficiency at Sasol Secunda plant. The recovery was achieved in 2 separate steps: 1) water-pyridine mixture was separated from the rest of the HOW stream using fractional distillation and 2) pyridine enrichment section which was designed using thermodynamic tools such as residue curve maps and isovolatility curves. The rest of the HOW stream (light fractions) was sent to the currently used incinerator. Liquid-liquid extraction and azeotropic distillation were considered for the pyridine enrichment step. Results showed that the combination of liquid-liquid extraction and distillation offered the benefit of a lower entrainer to azeotropic mixture ratio (EA) compared to azeotropic distillation. This gave the lowest recorded EA at 0.320:1. The comparison between the proposed process and the incineration of the whole HOW stream showed that the implementation of the process proposed reduced the incineration load by 60wt% and CO and CO2 emissions by 50%. Dividing Wall column process integration technique was implemented to reduce the number of distillation columns in the proposed process and 10% reduction in the reboiler and condenser duties was observed. Implementation of DWC further improved the purity of the recovered pyridine from 96mol% to over 99.9mol%. Preliminary economic evaluation carried out on Aspen Plus showed that the proposed recovery process was profitable with an Internal Rate of Return (IRR) of 20% and a payback period of 4.5 years. / MT 2018