Thesis(M.S.)--Case Western Reserve University, 2009 / Title from PDF (viewed on 2009-11-23) Department of EMC - Aerospace Engineering Includes abstract Includes bibliographical references and appendices Available online via the OhioLINK ETD Center

Orientadores: Elizabete Jordão, Wagner Alves Carvalho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-04T22:19:56Z (GMT). No. of bitstreams: 1 Figueiredo_FlaviaCamargoAlves_M.pdf: 2792481 bytes, checksum: 30096a0a78d59802544c5d197d9aa7ea (MD5) Previous issue date: 2005 / Resumo: A hidrogenação do adipato de dimetila catalisada por Pt e por Pd foi avaliada. Os catalisadores foram suportados em alumina, titânia e carvão. Os parâmetros investigados foram: a influência do suporte, a influência do metal ativo Pd quando comparado com Pt e a influência dos promotores Sn e K em alguns catalisadores. A caracterização físico-química dos sistemas catalíticos foi feita por Fisissorção de 'N IND. 2¿ ¿ BET, Quimissorção de 'H IND. 2¿, Microscopia Eletrônica de Varredura ¿ MEV, Redução a Temperatura Programada ¿ TPR e Espectrometria de Emissão Ótica em Plasma Indutivamente Acoplado ¿ ICP OES. A dispersão dos metais nos catalisadores mostrou-se diretamente relacionada à área superficial dos suportes, sendo que partículas bimetálicas ou parcialmente cobertas (no caso da titânia) podem estar presentes. O suporte altera o comportamento dos metais presentes na sua superfície por diferentes maneiras: efeito SMSI (titânia), acidez (aluminia) e presença de grupos funcionais oxidados (carvão). A conversão de adipato de dimetila á reduzida na presença do suporte titânia e aumenta quando o suporte é alumina, o que está relacionado à acidez deste, com a formação de uma elevada quantidade de produtos indesejáveis. Maiores valores de seletividade para a produção de 1,6 ¿ hexanodiol são observados com o uso de titânia, uma vez que espécies parcialmente reduzidas do suporte favorecem a ativação da carbonila do substrato ...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: The hidrogenation of dimethyl adipate catalyzed by Pt and Pd was evaluated. The catalysts were supported in 'Al IND. 2¿¿O IND. 3¿, 'TiO IND. 2¿ and coal. The investigated parameters were: the influence of the support, the influence of the active metal Pd when compared to Pt and the influence of Sn and K as promoters in some catalysts. The physical-chemistry characterization of the catalytic system was made by 'N IND. 2¿ sorption ¿ BET, 'H IND. 2¿ soption, Scanning Electron Microscopy ¿ SEM, Temperature Programmed Reduction ¿ TPR and Inductively coupled Plasma Optics Emission superficial area of the supports, and bimetallic particles or partially covered (in the case of the 'TiO IND. 2¿) can be present. Support modifies the behavior of metals in the surface for different ways: SMSI effect ('TiO IND. 2¿), acidity ('Al IND. 2¿¿O IND. 3¿) and presence of oxidized functional groups (coal). The conversion of dimethyl adipate is reduced in the presence of 'TiO IND. 2¿ and increases when the support is 'Al IND. 2¿¿O IND. 3¿. This is related to the 'Al IND. 2¿¿O IND. 3¿ acidity, with the formation of many undersirable products. Higher selectivity values for the production of 1,6-hexaodiol are observed with 'TiO IND. 2¿, due to the partially reduced species of the support that favor the activation of the carbonyl...Note: The complete abstract is available with the full electronic digital thesis or dissertations / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestre em Engenharia Química

Thesis advisor: James Morken / This dissertation will present two main projects focusing on the construction of enantiomerically enriched α-boryl organometallic reagents by transition metal catalysis. The first project describes the development of a platinum-catalyzed enantioselective hydrosilylation reaction of alkenyl boronic esters, which provides a general and efficient route to α-borylsilane species. Such species are configurationally stable and exhibit significant synthetic utilities. The second project depicts a nickel-catalyzed enantioselective carbozincation reaction of vinyl boronic esters, which for the first time giving approach to enantioenriched α-borylzinc reagents. These reagents possess good configurational stability at low temperatures and can participate in copper-catalyzed allylation, palladium-catalyzed Negishi cross-coupling and electrophilic halogenation reactions in stereospecific fashion to furnish a broad array of chiral boronic esters. These compounds are important and versatile building blocks in organic synthesis and utilized in the synthesis of (–)-aphanorphine and (–)-enterolactone. Detailed mechanistic studies were carried out, which revealed a nickel(I)-based redox neutral catalytic cycle. The properties of α-borylzinc compounds were also studied by 1H NMR and enabled the development of a stereoconvergent cross-coupling of racemic α-borylzinc reagents. Such catalytic system is also effective for an enantioselective silylzincation of vinyl boronic esters. / Thesis (PhD) — Boston College, 2021. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

No description available.

Le fluor a gagné un intérêt croissant dans de nombreux domaines de la chimie organique. De nombreuses méthodes de fluoration ont vu le jour afin de répondre à une demande croissante en molécules fluorées les plus diverses. Cependant certains synthons restent difficiles à obtenir par des moyens efficaces. Une réaction de fluoration électrophile d’allylsilanes a été développé afin d’accéder à des motifs α-fluroénamides hautement fonctionnalisés. Ces α-fluroénamides peuvent être de types variés : benzylamines, anilines, ou alkyles… Un accent particulier a été mis sur des dérivés d’acides aminés pouvant ainsi servir de peptido-mimétiques. Dans un souci d’accéder à une plus grande variété moléculaire, la réactivité de ces motifs fluorés allyliques vis-à-vis des réactions de métathèses croisées, très peu étudiée, a été investiguée. La faisabilité de ces deux méthodologies a été démontrée par la synthèse d’une molécule cible originale. Le fluor, principalement utilisé pour ses propriétés physico-chimiques et pharmacocinétiques a ici pu être exploité pour sa réactivité. Une réaction d’amination catalytiques sur les dérivés α-fluroénamides fonctionnalisés a été développée, permettant l’incorporation de nucléophiles aminés variés. Cette réaction permet de produire des motifs γ-aminomides-α,β-insaturés, mis à profit dans la synthèse d’alcaloïdes bicycliques. / Fluor has gained popularity in various fields of organic chemistry. Numerous fluorination reactions have been developed to answer increasing demand in diverse Fluor-containing molecules. Nevertheless, the syntheses of some structures are still unanswered. In this work, the electrophilic fluorination of allylsilanes has been developed allowing access to highly functionalised fluoroenamides. Said α-fluroenamides can be of various types such as benzylamines, anilines or alkyls. Focus has been brought on amino acids derivatives which could be used as peptidomimetics. Reactivity of those allylic fluorides towards cross-metathesis reactions has been investigated which has been very rarely reported yet. Validation of those two methodologies has been made in a form of the synthesis of a novel active molecule. Fluorine has been mainly used for the properties it brings in molecules it is incorporated in. In this case, fluorine has been exploited for its reactivity. A catalytic amination reaction has been developed on functionalised α-fluroénamides giving access to α,β-insatured-γ-aminomides.

Sol-gel-based silica monoliths with hierarchical mesopores/macropores are promising catalyst support and flow reactors. Here, we report the successful preparation of cylindrically shaped Pt-loaded silica monoliths (length: 2 cm, diameter: 0.5 cm) with a variable mean macropore width of 1, 6, 10, or 27 μm at a fixed mean mesopore width of 17 nm. The Pt-loaded monolithic catalysts were housed in a robust cladding made of borosilicate glass for use as a flow reactor. The monolithic reactors exhibit a permeability as high as 2 μm2 with a pressure drop below 9 bars over a flow rate range of 2–20 cm3 min−1 (solvent: water). The aqueous-phase hydrogenation of p-nitrophenol to p-aminophenol with NaBH4 as a reducing agent was used as a test reaction to study the influence of mass transfer on catalytic activity in continuous flow. No influence of flow rate on conversion at a fixed contact time of 2.6 s was observed for monolithic catalysts with mean macropore widths of 1, 10, or 27 µm. As opposed to earlier studies conducted at much lower flow velocities, this strongly indicates the absence of external mass-transfer limitations or stagnant layer formation in the macropores of the monolithic catalysts.