<p>The interaction of carboxylic acids with copper is a phenomenon found both outdoors and, more commonly, indoors. The influence on copper of some carboxylic acids (formic, acetic, propionic, and butyric) have so far been studied at concentrations levels at least three or four orders of magnitude higher than actual indoor conditions (< 20 ppb, volume parts per billion), and with only limited emphasis on any mechanistic approach. In this licentiate study a unique analytical setup has been successfully applied for <i>in situ </i>characterization and quantification of corrosion products formed during initial atmospheric corrosion of copper in the presence of acetic, formic or propionic acid. The setup is based on monitoring mass changes by the quartz crystal microbalance (QCM) and simultaneously identifying the chemical species by infrared reflection-absorption spectroscopy (IRAS). Post-analysis of corrosion products was performed by coulometric reduction (mass of copper (I) oxide formed), grazing incidence x-ray diffraction (phase identification) and atomic force microscopy (surface topography).</p><p>The absolute amounts of mass of individual constituents in the corrosion products, mainly copper (I) oxide or cuprite, copper (II) carboxylate and water or hydroxyl groups, have been deduced<i> in situ</i> during exposure in 120 ppb of carboxylic acid concentration, 95% relative humidity and 20ºC. An overall result is the consistency of analytical information obtained. For copper (I) oxide the quantified data estimated from IRAS, QCM or coulomeric reduction agrees with a relative accuracy of 12 % or better.</p><p>The interaction of copper with the carboxylic acids seems to follow two spatially separated main pathways. A proton-induced dissolution of cuprous ions followed by the formation of copper (I) oxide, and a carboxylate-induced dissolution followed by the formation of copper (II) carboxylate. The first pathway is initially very fast but levels off with a more uniform growth over the surface. This pathway dominates in acetic acid. The second pathway exhibits a more constant growth rate and localized growth, and dominates in formic acid. Propionic acid exhibits low rates for both pathways. The difference between the carboxylic acids with respect to both total corrosion rate and carboxylate-induced dissolution can be attributed to differences in acid dissociation constant and deposition velocity.</p>

Title from title page of PDF (University of Missouri--St. Louis, viewed Mar. 3, 2010). Includes bibliographical references.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1964. / Includes bibliographical references (p. 64-66).

Determining the presence of an analyte of interest, and finding the enantiomeric purity of chiral molecules are challenging tasks. This work in molecular recognition is carried out routinely by many different researchers, including both academic as well as industrial research groups. The following dissertation presents original research directed toward two different areas of interest to the molecular recognition community: enantioselective sensing in solution, and sensing at a defined interfacial environment. This work begins with a review of the non-chromatographic ways that the enantiomeric purity of chiral carboxylic acids is determined, presented in Chapter 1. Carboxylic acids are important functional groups, both for organic synthesis as well as pharmaceutical drug development. Chapter 2 presents efforts that have been made to rapidly assess both the enantiomeric purity and identity of chiral carboxylic acids, utilizing the technique of exciton-coupled circular dichroism (ECCD). A twist is imparted on a complex, and can be correlated with the absolute configuration of the stereocenter. The enantiomeric composition can be rapidly determined. After creating the assay, the focus of the work shifted toward applying this system to new classes of analytes. Chapter 3 covers chemo- and enantioselective differentiation of [mathematical symbol]-amino acids, and continues to discuss the expansion to [mathematical symbol]-homoamino acids. Then a synthetic substrates was tested, and a series of reactions screened to determine if any enantioselectivity had been imparted by a Baeyer-Villiger oxidation. Finally, the enantiomeric composition of a biaryl atropisomer, a compound lacking a stereocenter, was determined. The signal produced from this assay is at a relatively short wavelength, and efforts were undertaken to push this signal to longer wavelength. Chapter 4 is a compendium of the lessons that were learned upon attempting to create a self-assembled sensing system. The final chapter details work that was done in collaboration with Professor Katsuhiko Ariga at the National Institute of Materials Science in Tsukuba, Japan. In this chapter, an indicator displacement assay was carried out for the first time at the air-water interface. This contribution opens the door for sensing to be carried out at defined regions, rather than free in bulk solution. / text

published_or_final_version / abstract / toc / Chemistry / Master / Master of Philosophy

xv, 116 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / Aqueous solutes next to hydrophobic interfaces arc prevalent in a multitude of chemical and biological systems throughout the world. Their presence ranges from environmental processes such as soil and water remediation to biological processes such as ion transport, membrane formation, and enzyme activity. In these and other examples, the interface is an integral part of the system. Understanding these chemically complex systems requires that a molecular level picture be built as a starting basis. In this dissertation, vibrational sum-frequency spectroscopy (VSFS), a surface selective non-linear optical technique, is used to obtain a fundamental understanding of the interfacial properties of carboxylic acid based surfactants and polymers at the oil-water interface. Interfacial studies of the solvating environment around a carboxylate headgroup surfactant are presented first. By utilizing different VSFS polarization schemes, the carboxylate vibrational stretching region was used to monitor the headgroup environment. Results showed the oil-water interface provides a unique environment for adsorption and structuring, and distinct differences exist from the air-water and solid-water interface. With the information gained in the first study, the binding of metal ions to carboxylate headgroups is investigated using VSFS. Mg 2+ , Ca 2+ , Mn 2+ , Ni 2+ , Cu 2+ , and Zn 2+ were used to perturb the headgroup vibrations to further our understanding of the types of interactions and the binding strength between the ion and headgroup. The results show each ion to have a different interaction characteristics with the strongest being bi-dentate in nature and the weakest having ionic character. The final work presented involves moving VSFS studies towards macromolccular assemblies at the oil-water interface to model inherently complex biomolecular systems. These studies present adsorption structure and dynamics of poly(acrylic-acid) as a function of pH, molecular weight, concentration, and the presence of mono and divalent salts. Poly(acrylic-acid) was found to have ordered adsorption characteristics that were highly dependent on the pH and the presence of aqueous salts. This dissertation includes unpublished co-authored materials. / Committee in charge: Thomas Dyke, Chairperson, Chemistry; Geraldine Richmond, Advisor, Chemistry; John Hardwick, Member, Chemistry; Jeffrey Cina, Member, Chemistry; 1. Andrew Berglund, Member, Chemistry; John Conery, Outside Member, Computer & Information Science

abstract: Carboxylic acids are an abundant and reactive species present throughout our solar system. The reactions of carboxylic acids can shape the organic abundances within oil field brines, carbonaceous chondrites, and different ranks of coal. I have performed hydrothermal experiments with model aromatic carboxylic acids in the presences of different oxide minerals to investigate the reactions available to carboxylic acids in the presence of mineral surfaces. By performing experiments containing one organic compound and one mineral surface, I can begin to unravel the different reactions that can occur in the presence of different minerals. I performed experiments with phenylacetic acid (PAA), hydrocinnamic acid (HCA) and benzoic acid (BA) in the presence of spinel (MgAl2O4), magnetite (Fe3O4), hematite (Fe2O3), and corundum (Al2O3). The focus of this work was metal oxide minerals, with and without transition metal atoms, and with different crystal structures. I found that all four oxide minerals facilitated ketonic decarboxylation reactions of carboxylic acids to form ketone structures. The two minerals containing transition metals (magnetite and hematite) also opened a reaction path involving electrochemical oxidation of one carboxylic acid, PAA, to the shorter chain version of a second carboxylic acid, BA, in experiments starting with PAA. Fundamental studies like these can help to shape our knowledge of the breadth of organic reactions that are possible in geologic systems and the mechanisms of those reactions. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2017

Orientador: Nelson Ramos Stradiotto / Banca: Hideko Yamanaka / Banca: Rodrigo Alejandro Abarza Muñoz / Resumo: O etanol é um importante componente da matriz energética brasileira, sendo produz ido a partir da cana - de - açúcar. Nesse processo de produção, é produzida vinhaça como subproduto, a qual pa ra cada 1 L de etanol gera - se de 12 L a 18 L . A vinhaça é constituída principalmente de sais de potássio, cálcio e magnésio e compostos orgânicos . Dentre estes, os ácidos carboxílicos tornam - se importantes por estarem presentes em concentrações significativas na vinhaça de cana - de - açúcar e por apresentarem expressiva importância industrial. Sendo assim, n esse trabalho foi dese nvolvi do um detector eletroquímico baseado em eletrodo s de diamante dopado com boro quimicamente modificado s com nanopartículas de níquel ( NiNPs - BDD ) e de cobre ( CuNPs - BDD ) para determinação dos ácidos lático, málico e tartárico em vinhaça de cana - de - açúca r utilizando a técnica de cromatografia líquida de alta eficiência (CLAE) de troca iônica. Imagens de microscopia eletrônica de varredura e espectros de raios X por dispersão em energia, em conjunto com os experimentos eletroquímicos, mostraram que o s elet rodo s de BDD fo ram efetivamente modificado s com nanopartículas de óxido - hidróxido de níquel e óxido de cobre com diâmetro s médio s de 89 nm e 91 nm, respectivamente . Os estudos voltamétricos mostraram que as oxidações dos ácidos lático, málico e tartárico, em meio básico, se dão em potenciais em torno de 0,50 V ( vs. Ag/AgCl) e 0,73 V ( vs. Ag/AgCl), nos eletrodos NiNPs - BDD e CuNPs - BDD, respectivamente, e são mediadas pelas espécies Ni 3+ e Cu 3 + . O eletrodo de NiNPs - BDD foi utilizado em CL AE com detecção amperométric a pulsada. A coluna de troca aniônica CarboPac PA 1 foi utilizada para separação dos ácidos carboxílicos em vinhaça . E mpreg ou - se como fase móvel água deionizada e 0,10 mol L - 1 de NaOH em 0,25 mol L - 1... / Abstract: Ethanol is an important component of the Brazilian energy ma trix, being produced from sugar cane. In this producing procedure, vinasse is produced as by - product, which for every 1 L of ethanol is generated from 12 L to 18 L . The vinasse is basically composed by salts of p otassium, calcium and magnesium and organic compounds . Among these, carboxylic acids are important because they are present in significant concentrations in the sugar cane vinasse and show sig nificant industrial importance. Thus, in this work it was developed an electrochemical detector based on boron - doped diamond electrodes chemically modified with nickel nanoparticles (NiNPs - BDD) and copper nanoparticles (CuNPs - BDD) for the determination of lactic ac id, malic acid and tartaric acid in vinasse from sugarcane using high - performance liquid chromatography (HPLC) by ion exchange. Image s of scanning electron microscopy and spectra of e nergy - dispersive X - ray in conjuction with electrochemical experiments showed the electrodes of BDD were effectively modified with nickel oxide - hydroxide nanoparticles and copper oxide nanoparticles with diameter s of 89 nm and 91 nm, respectively . The voltammetric studies showed the oxidation s of lactic acid, malic acid and tartaric acid, in basic medium, tooke place at potential s around 0.50 V ( vs. Ag/AgCl) and 0.73 V ( vs. Ag / AgCl) at NiNPs - BDD and CuNPs - BDD electrodes, respectively, and they are mediated by Ni 3 + and Cu 3 + species. NiNPs - BDD electrode was used in HPLC with pulsed amperometr ic detection. The anion exchange column Carbo Pac PA1 was used for separation of carboxylic acids in vinasse. It w as employed as mobile phase deion ized water and 0.10 mol L - 1 NaOH in 0.25 mol L - 1 CH3COONa und er flow of 1.0 m L min - 1 . The detect ion potential was 0.48 V vs . Pd. The NiNPs - BDD electrode showed good stability under chromatographic conditions... / Mestre

La formation argileuse du Callovo-Oxfordien (COx) est étudiée comme possible roche-hôte d’un stockage profond de déchets radioactifs (projet Cigéo). En effet, en plus d’être très faiblement perméable, elle présente une forte teneur en minéraux argileux, capables de retenir les radionucléides sous forme cationique et d’en retarder ainsi fortement leur transport. Néanmoins, certains colis de déchets sont susceptibles de relarguer d’importante quantité de molécules organiques, capables de complexer ces radionucléides et d’augmenter leur mobilité. Aussi, l’objectif de ce travail a été de mieux comprendre le comportement diffusif de plusieurs molécules organiques d’intérêt vis à vis de cette roche argileuse, en investiguant dans un premier temps leur affinité avec la roche hôte. La rétention de molécules organiques sous forme anionique (acétate, phtalate, adipate, benzoate, citrate) a été quantifiée sur la roche argileuse du COx dispersée à l’aide d’expériences d’adsorption/désorption en batch. Des expériences sur roche décarbonatée et fraction de faible granulométrie ont également été réalisées afin de mettre en évidence les phases de la roche et les fonctions chimiques responsables de la rétention. L’intensité de la rétention, Rd, a pu être corrélée avec le moment dipolaire, µ(Orga.), pour fournir une estimation qualitative de la rétention de molécules organiques polaires hydrophiles. Ainsi, le phtalate, légèrement polaire, présente une rétention réversible (Rd ~1,6 L.kg 1), majoritairement sur les phases argileuses. Le citrate, très polaire et fortement adsorbé (Rd ~ 40 L.kg-1), présente une hystérèse de désorption persistante et une affinité avec différentes phases de la roche (minéraux argileux et oxydes minoritaires). Enfin, l’acétate, l’adipate et le benzoate, peu polaires, présentent une affinité moindre avec la roche (Rd < 0,2 L.kg-1). Le comportement diffusif sur roche compacte de ces anions organiques a alors été étudié. Les valeurs de coefficient de diffusion effectif, De, et facteur de retard ont été quantifiées. La faible diffusivité, [De/D0]ANIONS ORGANIQUES ~ 0,1 à 0,25 × [De/D0]EAU, indique un effet d’exclusion anionique, de même intensité que celui observé pour les anions inorganiques. De plus, les coefficients d’adsorption, Kd, estimés à partir des retards à la diffusion sont environ 2 à 5 fois inférieurs aux coefficients de distribution Rd mesurés sur roche dispersée. Cette différence de comportement n’a pas pu être imputée, ni à des effets de cinétique, ni à des effets de porosité accessible aux anions. Quoiqu’il en soit, les espèces complexantes présentent un retard significatif à la diffusion (Kd > 0,2 L.kg-1), ce qui conforte les capacités de confinement de la roche vis-à-vis de ces espèces. / The Callovo-Oxfordian mudstone (COx) is studied as a possible host rock for a deep disposal of radioactive waste (Cigéo project). Indeed, besides being very weakly permeable, it presents a high content of clayey minerals, capable of retaining radionuclides under cationic form and to delay strongly their transport. Nevertheless, some waste packages may release a significant amount of organic molecules, capable of complexing these radionuclides and drastically increase their mobility. So, the objective of this work was to better understand the diffusive behavior of several organic molecules of interest in this mudstone, by investigating at first their affinity with the host rock. The retention of organic molecules under anionic form (acetate, phthalate, adipate, benzoate, and citrate) was quantified on to the dispersed COx mudstone using adsorption/desorption batch experiments. Experiments on decarbonated rock and clay fraction only (< 2µm) were also performed to identify solid phases and chemical functions responsible for the retention. A correlation of the intensity of retention, Rd, was pointed out whit the dipole moment µ(Orga.), providing a qualitative estimate of retention capacity for polar hydrophilic organic molecules. So, phthalate, slightly polar, displays a reversible retention (Rd ~1,6 L.kg-1), mainly on clayey phases. Citrate, very polar and strongly adsorbed (Rd ~ 40 L.kg 1), displays a persistent desorption hysteresis and an affinity to different solid phases (clayey minerals and minor oxides). Lastly, acetate, adipate and benzoate, weakly polar, display a lower affinity with rock (Rd < 0,2 L.kg-1). The diffusive behavior in compact rock of these organic anions was then studied. The effective diffusion coefficient and retardation factor values were quantified. The low diffusivity, [De/D0]ORGANIC ANIONS ~ 0,1 à 0,25 × [De/D0]WATER evidences an effect of anionic exclusion, with a same intensity as that observed for inorganic anions. Furthermore, the Kd adsorption coefficient, estimated from retarded diffusion are approximately 2 to 5 times lower than the Rd distribution coefficient measured on dispersed rock. This difference of behavior was not able to be attributed, or to kinetic effects, nor to accessible porosity to anions effects. Anyway, the complexing species display a significant diffusive retardation (Kd > 0,2 L.kg-1) consolidating the contain properties of the COx mudstone toward this species.

Proprietary mixtures of amines and carboxylic acids are used as volatile corrosion inhibitors (VCIs) for the protection of steel and iron components against atmospheric corrosion during storage and transportation. Interactions between amines and carboxylic acids have been comprehensively reported in the literature. However, little is known about the nature of the vapours these mixtures emit. The present study focused on the development of the evolved gas analysis method which will help in the characterisation of the vapours released by VCIs. In the method, the evaporation of various amine-carboxylic acid binary mixtures was monitored by thermogravimetric analysis (TGA). The nature and the composition of the released vapours was followed by Fourier transform infrared (FTIR) spectroscopy. Mixtures consisting of triethylamine (TEA) and acetic acid were studied as a model compound using TGA-FTIR at 50 °C to validate the TGA-FTIR method. As vaporisation progressed, the composition of the remaining liquid and the emitted vapour converged to a fixed amine content of ca. 27 mol %. This is just above the composition expected for the 1:3 amine: carboxylic acid complex. Mixtures close to this composition also featured the lowest volatility. TGA-FTIR proved to be a convenient method for studying the evaporation of TEA-acetic acid mixtures, and the nature and composition of the released vapours. Amine addition leads to the dissociation of carboxylic acid dimers in favour salt formation. The formation of an ion pair between the amine and carboxylic acid was confirmed by the FTIR spectra of the liquid phase. The resulting amine-carboxylic acid mixtures showed a slow mass loss rate on TGA when compared with the pure amines and pure carboxylic acids. This indicated that the mixtures have low volatility, hence low vapour pressure compared with the pure components. The low vapour pressure of the mixtures was confirmed by the calculated gas permeability values. These values were much higher for the pure amines and the pure carboxylic acids. However, they dropped significantly on amine addition. The strong amine-carboxylic acid interaction is responsible for the suppressed volatility of the mixtures. No interaction is observed between amine and carboxylic acid molecules in the vapour phase at 230 °C. The method developed was applied to characterise the model compounds simulating the amine-carboxylic acid-based volatile corrosion inhibitors. These model systems contained the primary, secondary and tertiary amines (hexylamine, morpholine and triethylamine), as well as carboxylic acids with different chain lengths (acetic, propanoic, hexanoic and octanoic). These systems are usually employed as equimolar mixtures to protect ferrous metals against atmospheric corrosion. The key finding of the study was that the vapours released by such equimolar mixtures initially contain almost exclusively free amine. After prolonged vaporisation, a steady-state “azeotrope”-like composition is approached. It contains excess acid and features impaired corrosion-inhibition efficiencies according to the Skinner test. In part, this behaviour can be attributed to the mismatch between the volatilities of the amine and carboxylic acid constituents. / Thesis (PhD)--University of Pretoria, 2013. / gm2013 / Chemical Engineering / unrestricted