Thesis (Ph. D.)--University of Chicago, 1946. / Includes bibliographical references.

No description available.

The preparation of a number of 2-substituted homophthalimides through the condensation of homophthalic anhydride with different arylalkyl arnines is reported. The prepared compounds were alkylated at the 4-position to generate 4-mono-, 4,4-disubstituted and 4-spirocyclic homphthalimides, the analogues of which were reported to have interesting biological activity. Regioselective reduction of the 4-substituted derivatives generated the corresponding carbinolamides. Treating the carbinolamides with mineral or Lewis acids generated N-acyliminiurn ions, which were trapped in situ by one of the following: ( 1) aromatic neucleophiles to generate analogues of the natural product berberine, (2) alkyl chain migration to generate tetrahydrophenanthridones and functionalised isoquinolones, (3) cyclopropane ring-opening to generate 4-alkylisoquinolones, (4) addition to double bond to generate cyclopentaisoquinolones and (5) benzyl or allyl elimination. The oxidation of 4-monosubstituted homophthalimides with triplet dioxygen in alkaline media was investigated, and it generated 4-hydroxyhomophthalimides and isobenzofurancarboxamides. Treating isobenzofurancarboxamides with POCI3 provided a concise route to analogues of the neuroactive naturally-occurring phthalideisoquinolines.

On-board hydrogen storage presents a challenging barrier to the use of hydrogen as an energy source because the performance of current storage materials falls short of platform requirements. Because boron is one of the lightest chemical elements that can form strong covalent bonds with hydrogen, it provides an excellent opportunity to design new lightweight materials on the basis of novel boron hydride building blocks. Realizing this potential requires an understanding of the electronic structure, chemical bonding, and stability of neutral and anionic BxHy clusters with variable stoichiometry. While a large number of boron hydride compounds are known, there are still entire classes of yet unknown neutral and anionic BxHy clusters and molecules with various new x/y ratios which may be good candidates for hydrogen storage or as intermediates of borane de-hydrogenation. The primary aim of this dissertation was to search for neutral and anionic BxHy clusters that are thermochemically stable towards hydrogen release and to understand the chemical bonding in these novel clusters. These goals were accomplished by performing an unbiased search for neutral and anionic global minimum BxHy clusters using ab initio methods. In addition to finding a rich variety of new neutral and anionic BxHy (x = 3 – 6 and y = 4 – 7) clusters that could be building blocks for novel hydrogen-boron materials during the course of conducting this research, optical isomerism was discovered in select neutral and anionic boron-hydride clusters. Furthermore, the transition from planar to 3- dimensional geometries in global minimum B6Hx - clusters was discovered using ab initio techniques during this study. Chemical bonding analysis using the AdNDP method was performed for all global minimum structures and low-lying isomers. The chemical bonding pattern recovered by the AdNDP method in all cases is consistent with the geometric structure. The theoretical vertical detachment energies presented in this dissertation may help interpret future photoelectron spectroscopic studies of the anions presented here.

Orientador: Antonio Claudio Herrera Braga / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-12T16:47:01Z (GMT). No. of bitstreams: 1 Rocha_DanieleFernandadeOliveira_M.pdf: 3918609 bytes, checksum: ca79955ba1bba5d8eb4ed332338d0115 (MD5) Previous issue date: 2008 / Resumo: Neste trabalho foi estudado o comportamento de uma série de iminas estruturalmente análogas quando submetidas à biocatálise com fermento de pão e cenoura. Também foi testado NaBH4 em conjunto com alguns aminoálcoois de diferentes tamanhos, como 1-amino-2-propanol, prolinol e 2-a-hidroxibenzil-benzimidazol ou ácido tartárico. A utilização da biocatálise já é consolidada para a redução assimétrica de carbonilas, mas para a ligação C=N há poucos relatos na literatura, devido à facilidade com que esta ligação sofre hidrólise em meios aquosos. Os resultados foram negativos para biocatálise, apresentando hidrólise do substrato em diversas condições e solventes testados, mesmo com a utilização de 18-C-6 como aditivo e com a imobilização do substrato ou do fermento. As causas destes resultados podem ser tanto a falta de afinidade das enzimas com os substratos testados quanto a instabilidade dos mesmos nos meios utilizados. Foi aplicada uma metodologia bastante simples, com mistura manual de ambos em um almofariz. Testadas várias condições e diferentes solventes, nenhuma delas proporcionou um bom excesso enantiomérico. Uma provável causa para estes resultados pode ser a não eficiência da complexação entre o NaBH4 e os reagentes quirais. Testes de EM e RMN de B e H mostram a formação de um boroidreto quiral, mas não em quantidade suficiente para gerar maior assimetria na redução. Uma grande contribuição deste trabalho é a caracterização de um boroidreto quiral formado a partir de NaBH4 e S-(+)-2- a-hidroxibenzil-benzimidazol já reportado na literatura, mas sem um conjunto de dados conciso acerca de sua estrutura. Este composto gerou o maior excesso enantiomérico 27%, para a redução de N-benzil-(1-feniletilideno)amina / Abstract: This project studies the behavior of a series of imines structurally analogues in bioreductions with baker yeast and carrots, and also with NaBH4 using alternative chiral reagents like 1-amine-2-propanol, prolinol and 2-a- hidroxybenzyl-benzimidazole or tartaric acid. For biocatalysis we investigated different temperatures, solvents and proportions of reagents, but all conditions resulted in hydrolysis of the substrate. The instability of the imines or the lack of affinity can be the cause for these results, even using 18-C-6 as additive and immobilized yeast or substrate. By the chemical imine reduction we tried a simple method of induction, mixing manually NaBH4 and the chiral reagent in a mortar, using different solvents and temperatures, but none of them gave a good enantiomeric excess. Probably there was no coupling between NaBH4 and the chiral reagents, and consequently no preference in for one face in the reduction transition state. MS and NMR analysis have shown the formation of a chiral borohydride, but not an enough amount to give asymmetry in the reduction. A great contribution of this project is the characterization of a chiral borohydride obtained from NaBH4 and S-(+)-2-a-hydroxybenzyl-benzimidazole. It was previously reported, but with no confirmation of its structure. This compound reduced Nbenzyl-(1-phenyletilidene)amine with 27% enantiomeric excess / Mestrado / Quimica Organica / Mestre em Química

As células a combustível de borohidreto direto apresentam uma alta voltagem teórica (1,64 V) e alto número de elétrons por íon do combustível. Além disso, a utilização de eletrólitos alcalinos abre a possibilidade do uso de metais eletrocatalisadores não nobres e, por conseqüência, economicamente viáveis para aplicação prática. Entretanto, a falta de um eletrocatalisador altamente eficiente para a reação de oxidação de borohidreto limita o desempenho desses dispositivos, pois a oxidação total do borohidreto, envolvendo 8 elétrons por espécie BH4-, compete com vias paralelas de reação, com menor número de elétrons trocados por cada ânion BH4-. Recentemente, simulações e cálculos teóricos foram feitos para determinar os passos elementares da cinética da reação e, também, para guiar a confecção de eletrocatalisadores metálicos para a oxidação de borohidreto. Baseado nos resultados dos estudos teóricos, este trabalho teve como objetivo a investigação da eletrocatálise desta reação em nanopartículas, suportadas sobre pó de carbono, de metais puros, Au/C, Ag/C, Pt/C e Pd/C e em nanopartículas bimetálicas, formadas pela combinação entre estes metais. Os eletrocatalisadores foram sintetizados por métodos de redução química e/ou de impregnação e foram caracterizados por Difratometria de Raios X, Microscopia Eletrônica de Transmissão de Alta Resolução e Espectroscopia de Energia Dispersiva de Raios X. As atividades eletrocatalíticas foram medidas através de curvas de polarização usando eletrodo de disco rotatório. A hidrólise, com a consequente formação de H2, foi monitorada em função do potencial do eletrodo por meio de medidas de espectrometria de massas eletroquímica diferencial on-line. Os experimentos eletroquímicos, para os eletrocatalisadores de metais puros, mostraram maior atividade para Pd/C, o que foi atribuído à usa alta atividade para a eletro-oxidação do intermediário BH3OH-. O estudo do efeito da concentração de BH4-, de BH3OH- mostrou que os potenciais de onset tenderam a menores valores com o aumento da concentração, indicando que as correntes Faradaicas de eletro-oxidação direta do borohidreto e de hidroxiborano foram muito maiores que as correntes de oxidação e de desprendimento de H2. O aumento da carga de Pd/C no eletrodo levou a um aumento da corrente global de reação em baixos potenciais, o que se traduz em um efeito do aumento de área total. Dentre os materiais bimetálicos investigados, a combinação entre Pt2Pd/C apresentou a maior corrente Faradaica. O material de AgPd/C apresentou o menor potencial de onset de reação. Apesar dos resultados teóricos indicarem o aumento da atividade do Pd/C com a inserção de Ag, os resultados eletroquímicos e de espectrometria de massas indicaram maior atividade para o Pd/C puro e baixo efeito sinérgico entre os átomos de Ag e Pd. Isso foi associado ao baixo grau de interação entre os átomos de Ag e Pd nas composições atômicas investigadas. / The direct borohydride fuel cells (DBFC) display a high theoretical cell voltage (1.64) and a high electron number per borohydride ion. Furthermore, the DBFC also presents the advantages of alkaline fuel cells, in which it is possible to use non-noble metal electrocatalysts and, hence, it is economically feasible for practical applications. However the lack of highly efficient electrocatalysts for the borohydride oxidation reaction (BOR) limits the performance of these devices, since its total oxidation, involving the transfer of eight electrons per BH4- ion, competes with parallel reaction pathways with a lower number of exchanged electrons. Recently, theoretical calculations were applied to determine the elementary steps of the reaction kinetics and also to guide metallic electrocatalyst design for borohydride oxidation. Based on the theoretical results, this work aimed at the BOR electrocatalysis investigation on carbon supported nanoparticles, of pure metals, Au/C, Ag/C, Pt/C and Pd/C, and on bimetallic nanoparticles, composed by the combination of these metals. The electrocatalysts were synthesized by chemical and/or impregnation reduction methods, and X-Ray Diffraction, High Resolution Transmission Electron Microscopy and X-Ray Energy Dispersive Spectroscopy techniques were used for their physical characterization. The electrocatalytic activities were studied by steady state polarization curves using rotating disc electrodes. The borohydride hydrolysis, with the production of H2, was monitored in function of the electrode potential by on-line differential electrochemical mass spectrometry. The electrochemical experiments for the pure metal electrocatalysts showed higher electrocatalytic activity for Pd/C, and this was attributed to its high activity for BH3OH- electro-oxidation. The study of BH4- and BH3OH- concentration effect showed that with the increase of concentration, the onset potential shifted to lower values, indicating that the Faradaic currents of borohydride and hydroxyborane electro-oxidation were much higher than the current for the H2 evolution. The increase in the Pd/C load on the electrode led to an increase of the global current reaction at low potentials, which was associated to an increase in total surface area. Among the investigated bimetallic materials, the Pt2Pd/C electrocatalyst presented the higher Faradaic current. The Ag2Pd/C material showed the lower reaction potential onset. Although theoretical calculations pointed out to an increased activity of the Ag-modified Pd/C electrocatalysts in relation to that of pure Pd/C, the electrochemical and mass spectrometry results of this work indicated higher activity for pure Pd/C, and low synergic effect between the Ag and Pd atoms. This was associated to the low degree of interaction between Ag and Pd for the present investigated atomic composition.

The main objective of this research was to develop a protocol in which pyridoxal phosphate (PLP) would act as a tag to identify PLP-dependent enzymes from complex mixtures or cell lysates. Following the purification of a PLP-dependent enzyme (CysM), a method was developed to reduce the PLP-lysine Schiff base to form a chemically stable bond between the PLP and the protein. The reduced protein was enzymatically digested resulting in multiple peptide fragments with one or more containing PLP (bound to the active site lysine). These fragments were analyzed by monitoring the absorbance or fluorescence using High Performance Liquid Chromatography. Immobilized Metal Ion Affinity Chromatography (IMAC) was then used to enrich the PLP-peptide(s) from the peptide mixture. The PLP-bound peptide(s) was then analyzed using Liquid Chromatography-Mass Spectrometry (LC-MS). More specifically, sodium borohydride (NaBH4) was used to reduce the Lysine-PLP bond in CysM. This reaction was monitored by either UV-vis spectroscopy or mass spectrometry. Trypsin was used to enzymatically digest the reduced CysM before it was enriched with IMAC and analyzed with LC-MS. Since the objective of this project was to develop a method which could be applied to a cell lysate, IMAC was used as an enrichment method to separate the PLP-peptide(s) from other peptides within the mixture. The PLP-peptide(s) was then located in the peptide mixture by monitoring the absorbance at 325 nm. The LC-MS results of the full reaction before IMAC treatment versus the final column, when monitoring the mass spectrum, showed that the treatment using the IMAC column separated the PLP-peptides from all other peptides within the sample. Using IMAC to enrich specifically the PLP-peptides, followed by analysis with LC-MS, may be a useful method for studying PLP-dependent enzymes within the proteome or the "PLP-ome."

L’hydrogène en tant que vecteur énergétique reste tributaire, pour un développement à grande échelle, de son stockage et de la facilité de dégagement du combustible stocké. Pour les applications embarquées, portables et stationnaires, aucune technologie de stockage (H2 comprimé, H2 liquide, hydrures métalliques ou chimiques) ne répond aujourd’hui au cahier des charges d’un système de stockage. De nombreuses études se penchent donc à la fois sur l'optimisation des composants et le développement de sources d'énergie miniatures. Dans cette optique, la production d'hydrogène par l'hydrolyse des borohydrures est une technologie prometteuse pour les piles à combustible portables. En particulier, le borohydrure de sodium (NaBH4) présente de multiples avantages. Par exemple, les solutions aqueuses de NaBH4 sont non inflammables assurant ainsi la sécurité des procédés, le taux de génération d’hydrogène est facilement contrôlé par un catalyseur, les produits de réaction sont respectueux de l'environnement et peuvent être recyclés. La réaction d’hydrolyse du borohydrure alcalin peut être décrite de la façon suivante : MBH4 + (2+x) H2O → 4 H2 + MBO2.xH2O L’optimisation de la réaction d’hydrolyse et plus globalement l’optimisation du fonctionnement de la cartouche et de ces performances nécessite d’améliorer les connaissances sur les propriétés physico-chimiques du borohydrure et des métaborates en milieu aqueux plus ou moins complexe. L’un des principaux défis consiste à augmenter la concentration en NaBH4 de la solution de la cartouche, tout en évitant les inconvénients induits par la cristallisation des sous-produits (NaBO2.xH2O). Mais il est alors nécessaire de contrôler la stabillité de cette solution, par ajout d'hydroxyde de sodium qui limitera l'auto–décomposition NaBH4. Ce travail montre les deux aspects de l'analyse de la durée de vie de la cartouche génératrice d’hydrogène : – La cinétique d'hydrolyse spontanée des solutions alcalines aqueuses NaBH4 en fonction de la concentration de NaOH (élément stabilisant) et de la plage de température de fonctionnement de la cartouche,– La compréhension sans équivoque de l'opération de cristallisation NaBO2 et plus particulièrement la délimitation du domaine de la phase liquide homogène dans le système quaternaire NaBH4–NaBO2–NaOH–H2O, qui représente l’évolution du mélange lors du fonctionnement de la cartouche d'hydrogène / Numerous investigations are addressing both component optimization and development of miniature energy sources. The rise of portable eletronic devices, brings to the fore the crucial issues of power supply. The foresceable evolution in functionalities and utilizations, as regards portable eletronic devices, together with the introduction of novel electronic components, entail considerable changes in requirements, in terms of power consumption and autonomy. Hydrogen generation by means of the hydrolysis of borohydrides is a promising technology for portable fuel cells. Particularly, sodium borohydride (NaBH4) presents many advantages for that purpose. For example, NaBH4 solutions are non–flammable thus yielding safe processes; the rate of H2 generation is easily controlled by a catalyst; reaction products are environmentally benign and finally the reaction by–product can be recycled. The hydrolysis of NaBH4 in water to produce H2 gives by–products, NaBO2.yH2O, hydrated sodium borate according to MBH4 + (2+x) H2O → 4 H2 + MBO2.xH2O The interesting point of this work is to increase the amount of produced H2 in order to improve the energy density of the H2 generator system. For this, one of the main challenges is to increase the NaBH4 concentration of the cartridge solution thus avoiding the drawbacks induced by NaBO2 crystallization, but also to control the stabillity of this solution, it means add sodium hydroxyde to limit the NaBH4 self–decomposition, thus stabilizing the system. This work shows the two aspects of the analysis of the cartridge timelife : – The kinetic of spontaneous hydrolysis of alkaline aqueous NaBH4 solutions as function of NaOH concentration and the operation temperature range of the cartridge, – An unequivocal understanding of the NaBO2 crystallization process and more specifically the delimitation of the homogeneous liquid phase domain in the quaternary system NaBH4– NaBO2–NaOH–H2O, which represents the mixture present during the hydrogen cartridge operation

As células a combustível de borohidreto direto apresentam uma alta voltagem teórica (1,64 V) e alto número de elétrons por íon do combustível. Além disso, a utilização de eletrólitos alcalinos abre a possibilidade do uso de metais eletrocatalisadores não nobres e, por conseqüência, economicamente viáveis para aplicação prática. Entretanto, a falta de um eletrocatalisador altamente eficiente para a reação de oxidação de borohidreto limita o desempenho desses dispositivos, pois a oxidação total do borohidreto, envolvendo 8 elétrons por espécie BH4-, compete com vias paralelas de reação, com menor número de elétrons trocados por cada ânion BH4-. Recentemente, simulações e cálculos teóricos foram feitos para determinar os passos elementares da cinética da reação e, também, para guiar a confecção de eletrocatalisadores metálicos para a oxidação de borohidreto. Baseado nos resultados dos estudos teóricos, este trabalho teve como objetivo a investigação da eletrocatálise desta reação em nanopartículas, suportadas sobre pó de carbono, de metais puros, Au/C, Ag/C, Pt/C e Pd/C e em nanopartículas bimetálicas, formadas pela combinação entre estes metais. Os eletrocatalisadores foram sintetizados por métodos de redução química e/ou de impregnação e foram caracterizados por Difratometria de Raios X, Microscopia Eletrônica de Transmissão de Alta Resolução e Espectroscopia de Energia Dispersiva de Raios X. As atividades eletrocatalíticas foram medidas através de curvas de polarização usando eletrodo de disco rotatório. A hidrólise, com a consequente formação de H2, foi monitorada em função do potencial do eletrodo por meio de medidas de espectrometria de massas eletroquímica diferencial on-line. Os experimentos eletroquímicos, para os eletrocatalisadores de metais puros, mostraram maior atividade para Pd/C, o que foi atribuído à usa alta atividade para a eletro-oxidação do intermediário BH3OH-. O estudo do efeito da concentração de BH4-, de BH3OH- mostrou que os potenciais de onset tenderam a menores valores com o aumento da concentração, indicando que as correntes Faradaicas de eletro-oxidação direta do borohidreto e de hidroxiborano foram muito maiores que as correntes de oxidação e de desprendimento de H2. O aumento da carga de Pd/C no eletrodo levou a um aumento da corrente global de reação em baixos potenciais, o que se traduz em um efeito do aumento de área total. Dentre os materiais bimetálicos investigados, a combinação entre Pt2Pd/C apresentou a maior corrente Faradaica. O material de AgPd/C apresentou o menor potencial de onset de reação. Apesar dos resultados teóricos indicarem o aumento da atividade do Pd/C com a inserção de Ag, os resultados eletroquímicos e de espectrometria de massas indicaram maior atividade para o Pd/C puro e baixo efeito sinérgico entre os átomos de Ag e Pd. Isso foi associado ao baixo grau de interação entre os átomos de Ag e Pd nas composições atômicas investigadas. / The direct borohydride fuel cells (DBFC) display a high theoretical cell voltage (1.64) and a high electron number per borohydride ion. Furthermore, the DBFC also presents the advantages of alkaline fuel cells, in which it is possible to use non-noble metal electrocatalysts and, hence, it is economically feasible for practical applications. However the lack of highly efficient electrocatalysts for the borohydride oxidation reaction (BOR) limits the performance of these devices, since its total oxidation, involving the transfer of eight electrons per BH4- ion, competes with parallel reaction pathways with a lower number of exchanged electrons. Recently, theoretical calculations were applied to determine the elementary steps of the reaction kinetics and also to guide metallic electrocatalyst design for borohydride oxidation. Based on the theoretical results, this work aimed at the BOR electrocatalysis investigation on carbon supported nanoparticles, of pure metals, Au/C, Ag/C, Pt/C and Pd/C, and on bimetallic nanoparticles, composed by the combination of these metals. The electrocatalysts were synthesized by chemical and/or impregnation reduction methods, and X-Ray Diffraction, High Resolution Transmission Electron Microscopy and X-Ray Energy Dispersive Spectroscopy techniques were used for their physical characterization. The electrocatalytic activities were studied by steady state polarization curves using rotating disc electrodes. The borohydride hydrolysis, with the production of H2, was monitored in function of the electrode potential by on-line differential electrochemical mass spectrometry. The electrochemical experiments for the pure metal electrocatalysts showed higher electrocatalytic activity for Pd/C, and this was attributed to its high activity for BH3OH- electro-oxidation. The study of BH4- and BH3OH- concentration effect showed that with the increase of concentration, the onset potential shifted to lower values, indicating that the Faradaic currents of borohydride and hydroxyborane electro-oxidation were much higher than the current for the H2 evolution. The increase in the Pd/C load on the electrode led to an increase of the global current reaction at low potentials, which was associated to an increase in total surface area. Among the investigated bimetallic materials, the Pt2Pd/C electrocatalyst presented the higher Faradaic current. The Ag2Pd/C material showed the lower reaction potential onset. Although theoretical calculations pointed out to an increased activity of the Ag-modified Pd/C electrocatalysts in relation to that of pure Pd/C, the electrochemical and mass spectrometry results of this work indicated higher activity for pure Pd/C, and low synergic effect between the Ag and Pd atoms. This was associated to the low degree of interaction between Ag and Pd for the present investigated atomic composition.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22461号 / 工博第4722号 / 新制||工||1737(附属図書館) / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 SIVANIAH Easan, 教授 田中 庸裕, 教授 陰山 洋 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM