Photodegradation of 4-nitrophenol (4-Np) in the presence of water-soluble zinc phthalocyanines and water-insoluble metallophthalocyanines is reported. The water-soluble phthalocyanines employed include zinc tetrasulphophthalocyanine (ZnPcS[subscript 4]), zinc octacarboxyphthalocyanine (ZnPc(COOH)[subscript 8]) and a sulphonated ZnPc containing a mixture of differently sulphonated derivatives (ZnPcS[subscript mix]), while the water-insoluble phthalocyanines used include unsubstituted magnesium (MgPc), zinc (ZnPc) and chloroaluminium (ClAlPc) phthalocyanine complexes and the ring-substituted zinc tetranitro (ZnPc(NO[subscript 2])[subscript 4]), zinc tetraamino (ZnPc(NH[subscript 2])[subscript 4]), zinc hexadecafluoro (ZnPcF[subscript 16]) and zinc hexadecachloro (ZnPcCl[subscript 16]) phthalocyanines. The most effective water-soluble photocatalyst is ZnPcS[subscript mix] in terms of the high quantum yield obtained for 4-Np degradation (Φ[subscript 4-Np]) as well as its photostability. While ZnPc(COOH)[subscript 8] has the highest Φ[subscript 4-Np] value relative to the other water-soluble complexes, it degrades readily during photocatalysis. The Φ[subscript 4-Np] values were closely related to the singlet oxygen quantum yields Φ[subscript Δ] and hence aggregation. The rate constants for the reaction with 4-Np were kr = 0.67 x 10[superscript 6] mol[superscript -1] dm[superscript 3] s[superscript -1] for ZnPcS[subscript mix] and 7.7 x 10[superscript 6] mol[superscript -1] dm[superscript 3] s[superscript -1] for ZnPc(COOH)[subscript 8]. ClAlPc is the most effective photocatalyst relative to the other heterogeneous photocatalysts for the phototransformation of 4-Np, with 89 ± 8.4 % degradation of 4-Np achieved after 100 min. The least effective catalysts were ZnPcCl[subscript 16] and MgPc. The final products of the photocatalysis of 4-Np in the presence of the homogeneous photocatalysts include 4-nitrocatechol and hydroquinone, while degradation of 4-Np in the presence of the heterogeneous photocatalysts resulted in fumaric acid and 4-nitrocatechol. ClAlPc was employed for the heterogeneous photocatalysis of the non-systemic insecticide, methyl paraoxon. Complete degradation of the pesticide was confirmed by the disappearance of the HPLC trace for methyl paraoxon after 100 min of irradiation with visible light. The removal of 4-Np from an aqueous medium using commercially available Amberlite[superscript ®] IRA-900 modified with metal phthalocyanines was also investigated. The metallophthalocyanines immobilised onto the surface of Amberlite[superscript ®] IRA-900 include Fe (FePcS[subscript 4]), Co (CoPcS[subscript 4]) and Ni (NiPcS[subscript 4]) tetrasulphophthalocyanines, and differently sulphonated phthalocyanine mixtures of Fe (FePcS[subscript mix]), Co (CoPcS[subscript mix]) and Ni (NiPcS[subscript mix]). Adsorption rates were fastest for the modified adsorbents at pH 9. Using the Langmuir-Hinshelwood kinetic model, the complexes showed the following order of 4-Np adsorption: CoPcS[subscript mix] > NiPcS[subscript 4] > NiPcS[subscript mix] > FePcS[subscript 4] > FePcS[subscript mix] > CoPcS[subscript 4]. The adsorbents were regenerated using dilute HNO[subscript 3], with 76 % (7.6 x 10[superscript -5] mol) of 4-Np recovered within 150 min.

The development of abundant and economical first-row transition metal-based catalysts is an appealing area of research for efficient and selective chemical transformations. In this context, iron complexes are highly desirable as they feature a range of accessible oxidation states allowing for transfer of one or two electrons to or from a substrate. Therefore, over the past two decades, many iron-based catalysts have been developed, extensively studied, and exploited for catalysis ranging from oxidation and reduction to C-C bond forming reactions. In homogeneous transition metal catalysis, the ligand plays a vital role in determining activity and selectivity of the above stated catalytic reactions. Some key features of ligands that support both stoichiometric and catalytic reactions of metal complexes include: 1) strong chelation ability to metals, 2) tunability of donor atoms, 3) strong field ligands such as phosphine, phosphite, CO, and hydride favoring low-spin complexes, 4) hemilability allowing substrate activation via reversible dissociation of one donor atom, and 5) redox-activity enabling donation or accepting of electrons, thus avoiding a change of metal oxidation state. To this end, bifunctional ligands containing the above described properties have emerged as important elements in chemical synthesis and in catalysis. Iron and other transition metal complexes containing multidentate bifunctional ligands have recently been shown to activate small molecules and catalyze a number of chemical transformations with activity and selectivity typical of more well-studied precious metals. The objective of this thesis is to further advance the field of bifunctional ligands by preparing new sterically svelte tridentate ligands with a mixture of hard nitrogen and soft sulfur donors and to investigate their iron chemistry. The overall goal is to then explore the utility of these iron complexes as potential bifunctional catalysts. Chapter 2 describes a one-step synthesis of a new SMeNHS ligand in excellent yield that undergoes ring-opening on treatment with Fe(OTf)2 affording a thiolate-bridged, trinuclear iron complex, [Fe3(µ2-SMeNS−)4](OTf)2. The structure, spectroscopic, magnetic, and computational studies of this iron complex are provided along with its solvent-dependent reactivity towards monodentate donor ligands that yields both dinuclear and mononuclear derivatives. Chapter 3 describes the formation of an electron-rich Fe(II) thiolate complex, [Fe(SMeNS)(PMe3)3](OTf) and its substitution reactivity with both mono- and bidentate donor ligands. On heating this complex, an oxidative thioether Caryl-S bond cleavage is observed, leading to a cationic Fe(III)-CNS thiolate analog. Reduction of this Fe(III) species with cobaltocene yielded a neutral Fe(II)-CNS thiolate complex. To investigate the bifunctional activity of these Fe(II) complexes, both Fe(II)-SNS and -CNS species were assessed as precatalysts for amine-borane dehydrogenation. Chapter 4 employs the SMeNHS ligand in formation of a neutral, imine-coupled Fe-N2S2 complex that serves as an efficient and selective aldehyde hydroboration catalyst using pinacolborane. A reaction profile kinetic analysis implicates the hemilability and redox-active properties of this complex. Chapter 5 introduces the new unsymmetrical amine ligand, SMeNHSMe, and details its iron chemistry with formation of a pseudooctahedral Fe(II) bis(amido) complex. The Mössbauer spectra, MCD study, and DFT calculations support formation of a minor five-coordinate isomer in solution due to the hemilability of the six-membered ring thioether group. Reactivity studies of this Fe(II) species with a variety of donor ligands confirmed this lability and protonation at nitrogen yielded a cationic Fe(II) amine-amido complex. Reaction of the latter with the tridentate phosphine, triphos, gave a 16e-, low-spin, square-pyramidal Fe(II) complex that proved to be a robust precatalyst that is more active for dehydrogenation of dimethylamine-borane vs. ammonia-borane. Formation of a monohydride catalyst resting state under these reaction conditions is suggestive of a bifunctional activation pathway. Finally, Chapter 6 concludes the outcomes of the iron chemistry of hemilabile SNS ligands and discusses future directions and opportunities to extend these ligand systems to other transition metals. The knowledge gained by the stoichiometric and catalytic reactivity of iron-SNS complexes presented herein contributes to our understanding of bifunctional catalysis. With the increasing demand for base metal catalysts in chemical industry for efficient and selective synthesis of value-added chemicals, iron SNS complexes could offer economical, active, and selective catalyst precursors.

Made available in DSpace on 2014-10-09T12:31:23Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:03Z (GMT). No. of bitstreams: 1 01399.pdf: 1423391 bytes, checksum: 08febe2724da4dfe4af1b47ac4c334b1 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

No description available.

Orientador: Eduardo J. S. Vichi / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-06T15:46:01Z (GMT). No. of bitstreams: 1 BernardiJunior_Ernesto_D.pdf: 5488181 bytes, checksum: 9191e2a8912ede9a6844335070db1c20 (MD5) Previous issue date: 2005 / Resumo: Foram preparados aproximadamente quarenta materiais entre cromiossilicatos zeolíticos tipo MFI e sílica com superfície modificada por zircônio e depois servindo de suporte ao metal crômio. Estes materiais foram denominados Cr-ZSM-5 e Cr-SSM e foram devidamente caracterizados, visando processos de conversão catalítica de monóxido de carbono a dióxido de carbono. As caracterizações envolveram técnicas de: Difração de Raios-X de Pó, Espectrometria de Infravermelho do Estado Sólido, Análises Elementares por Fluorescência de Raios-X, Ressonância Paramagnética Eletrônica, Espectroscopia Fotoacústica, Análise de Área Superficial BET. As reações de conversão foram realizadas através de um reator de vidro microcatalítico, inserido num forno tubular microprocessado. Os efluentes gasosos foram analisados por Espectrometria de Infravermelho com Transformada de Fourier, Cromatografia Gasosa e Análise de Gases com Célula Eletroquímica. Dos zeólitos obtidos por planejamento estatístico, três amostras foram testadas nas conversões, denominadas, ZS-1, ZF-2 e ZP-3. Quanto ao material de sílica, duas amostras foram preparadas e utilizadas nas conversões, denominadas, SF-1 e SF-2. Destes materiais, somente uma amostra de cromiossilicato revelou-se mais ativa para a reação e ambas as amostras de sílica. As conversões foram muito eficientes e revelaram turnover elevados. Os zeólitos desativados foram regenerados com sucesso e a conversão continuou com gradual perda de eficiência. Os materiais de sílica não desativaram após 49 horas de operação. Reações tipo: CO+NOCO2+1/2N2, foram investigadas sem alimentação de ar, com relativo êxito. Existem perspectivas de aplicação do material de sílica em processos de catálise automotiva. Está sendo estudado o registro de propriedade intelectual para estes materiais. / Abstract: About forty catalyst materials were prepared among MFI zeolitic chromiumsilicates type and silica grafted by zirconium oxides, and after serve as anchoring cromium species. These materials were named Cr-ZSM-5 and Cr-SSM and were characterized to drive at catalytic process to change carbon monoxide to carbon dioxide. The characterizations involved, Powder X-Ray Diffraction, Infrared Spectroscopy (MID-IR), Elemental Analysis by X-Ray Fluorescence, Electron Paramagnetic Resonance, Photoacoustic Spectroscopy, BET Superficial Area. The catalytic reactions were carried out on a microcatalytic glass reactor, inserted in a microprocessed cilindrical owen. The gaseous products were analyzed by a Fourier Transformed Infrared Spectroscopy, Gas Chromatography and a Gas Analyzer with Electrochemistry Cell. Synthesis applying statistical planning for zeolites, resulted in three catalysts to be tested in reactions. In respect to silica catalyst, two samples were prepared and applied in reactions. From these materials only a sample of chromiumsilicate revealed active to reaction and more two samples of a silica type. The reactions were most efficacious and revealed high turnover number. The zeolitic catalysts switches off and were renewed with sucessfull process and the reaction extends with gradual loss of efficacious. The silica catalysts did not switches off after 49 hours in action. Class of reactions like: CO + NO CO2 + 1/2N2 were experimented without feed of air, with restrained results. There are applicative perspectives of silica catalysts in automotive catalytic process. This work will generate a patent request for these materials. / Doutorado / Quimica Inorganica / Doutor em Ciências

Made available in DSpace on 2014-10-09T12:31:23Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:03Z (GMT). No. of bitstreams: 1 01399.pdf: 1423391 bytes, checksum: 08febe2724da4dfe4af1b47ac4c334b1 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Orientador: Gustavo Paim Valença / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-19T15:00:40Z (GMT). No. of bitstreams: 1 Anjos_WilliamLimados_M.pdf: 3114140 bytes, checksum: 2d5b6af4d6d95550df4f2b5f509c8353 (MD5) Previous issue date: 2011 / Resumo: A peneira molecular SAPO-34 foi sintetizada pelo método de cristalização hidrotérmica com razões molares de 'SiO IND. 2/Al IND. 2 O IND. 3' (SAR) de 0,3, 0,5 e 0,7. As amostras foram secas e calcinadas para serem utilizadas na reação catalítica de conversão de metanol para olefinas leves (eteno e propeno). Os sólidos foram caracterizados e foi observado através da técnica de difração de raios-X que a fase chabasita (CHA) correspondente à peneira molecular SAPO-34 foi formada. A fase AlPO-5 (AFI) também foi observada como fase contaminante deste zeólito. As medidas de área superficial (BET) obtidas através da adsorção de N2 apresentaram valores para a SAPO-34 com SAR de 0,3, 05 e 0,7 de 549, 337 e 122 m2 g-1, respectivamente, sugerindo que ocorrem reduções significativas das áreas superficiais quando o teor de Si é aumentado. Com os resultados de microscopia eletrônica de varredura foram observados estruturas uniformes cúbicas e romboédricas típicas da morfologia da SAPO-34. Os testes catalíticos foram realizados em fase gasosa em reator de leito fixo construído em quartzo nas temperaturas de 600, 625, 650, 675, 700, 725 e 750 K para a SAPO-34 com SAR de 0,3 e 700 e 750 K para SAPO-34 com SAR de 0,5 e 0,7. A massa de catalisador utilizada foi de 0,020 g com pressão de vapor de metanol de 0,04 bar e fluxo de nitrogênio de 160 mL 'min POT.-1', fornecendo um WHSV (Weight Hourly Space Velocity) de 1,47 x10-1 s-1 e um tempo de contato (razão W/F) de 0,05 g h mol-1. Os produtos identificados por cromatografia gasosa com a coluna empacotada Porapak - Q foram água, metano, eteno e propeno, quantificados a partir de curvas de calibração obtidas pela injeção de padrões de alta pureza cromatográfica. O dimetiléter foi quantificado a partir do balanço de massa obtido a partir dos coeficientes estequiométricos da reação em função da água. O catalisador que apresentou maior rendimento inicial a propeno e eteno foi a SAPO-34 com SAR de 0,3 nas temperaturas de 675, 725 e 750 K que foram superiores a 80%, enquanto os outros dois catalisadores (SAR de 0,5 e 0,7) apresentaram rendimentos inferiores a 70%. Foram realizados também estudos de atividade catalítica para determinação das constantes de desativação da equação de Voorhies e determinação da ordem de desativação catalítica / Abstract: The molecular sieve SAPO-34 was synthesized by hydrothermal crystallization with molar ratios of 'SiO IND. 2/Al IND. 2 O IND. 3' (SAR) of 0.3, 0.5 and 0.7. The samples were dried, calcined and characterized in order to be used in the catalytic conversion of methanol to light olefins (ethylene and propylene). The formation of the chabazite (CHA) phase, corresponding to SAPO-34, was proved by X-Ray diffraction analysis, as well as the contamination of the zeolite with the AlPO-5 (AFI) phase. Nitrogen adsorption showed BET surface areas for the SAPO-34 with SAR of 0.3, 0.5 and 0.7 of 549, 337 and 122 m2 g-1, respectively, suggesting that the surface area decreases significantly with a rising Si content. Uniform cubic and rhombohedral structures, typical for the SAPO-34 morphology, were observed by scanning electron microscopy. Catalytic tests were carried out in gas phase in a fixed bed quartz reactor at various temperatures between 600 and 750 K for SAPO-34 with a SAR of 0.3 and at 700 and 750 K for SAPO-34 with SARs of 0.5 and 0.7. The utilized catalyst mass was 0.020 g, the methanol vapor pressure was 0.04 bar and the total flux of methanol and nitrogen added up to 160 mL min-1, resulting in a weight hourly space velocity (WHSV) of 1,47 × 10-1 s-1 and a mass/flow ratio (W/F) of 0.05 g h mol-1. The reaction products, identified by gas chromatography employing a packed Porapak - Q column and quantified with calibration curves obtained by injection of highly pure standard samples, were water, methane, ethylene and propylene. The quantification of dimethyl ether was based on the mass balance and the reaction stoichiometry as a function of water. The catalyst exhibiting the highest initial ethylene and propylene yield was a SAPO-34 with a SAR of 0.3 at temperatures of 675, 725 and 750 K, reaching more than 80% yield, while the other catalysts (SARs of 0.5 and 0.7) showed yields of less than 70%. Studies of catalytic activity also were carried out in order to determine the deactivation constants of the Voorhies' equation and the order of catalytic deactivation / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

This thesis contains the preparation of a new design of ligand for the palladium catalysed allylic substitution reaction. The phosphine oxazoline ligands detailed in the thesis give high levels of enantiocontrol when used in conjunction with symmetrical allyl systems in the palladium catalysed allylic substitution reaction. For unsymmetrical allyl systems the palladium catalysed allylic substitution process proceeds with complete regiocontrol and high levels of stereocontrol are again observed. The products from the palladium catalysed allylic substitution reaction can be readily converted to succinic acids, γ-lactones and aryl propanoic acids.

Palladium catalysed asymmetric hydroxy- and alkoxycarbonylation reactions of alkenes have the potential to deliver valuable chiral carboxylic acid and ester building blocks from cheap feedstocks: alkenes, carbon monoxide and water (alcohols in the case of alkoxycarbonylation). Despite the attractive nature of these reactions, extensive research has so far been unable to produce effective catalysts which are capable of controlling both regio- and enantioselectivity. Building on exciting recent results involving the use of highly enantioselective palladium catalysts derived from Phanephos-type ligands, this research focuses on paracyclophane-diphosphines and their use in asymmetric hydroxy- and alkoxycarbonylation reactions. An investigation into reaction conditions analysed several factors, including solvents, CO-pressure, acidic additives and halide sources, to provide optimal activity and selectivities. Two novel electron-poor paracyclophane-diphosphines and their mono- and di-palladium complexes were synthesised and shown to provide exceptional levels of regioselectivity while maintaining high levels of asymmetric induction. These are the first such examples of hydroxy- or alkoxycarbonylation catalysts to facilitate simultaneous control over both regio- and enantioselectivity. The most effective catalyst was used to promote the reactions of a selection of aryl alkenes and was shown to be tolerant of several different functional groups. A selection of non-symmetric paracyclophane-diphosphine ligands and their palladium complexes were also synthesised and assessed for their performance in hydroxy- and alkoxycarbonylation. We also report the use of Phanephos-type ligands to promote the highly enantioselective hydroxycarbonylation of N-(p-toluenesulfonyl)-3-pyrroline to deliver a chiral proline derivative in high ee.

Ph.D. (Chemistry) / This study discusses the preparation of various sized dendrimer encapsulated ruthenium nanoparticles (RuDEN) with the use of the generation 4 (G4), generation 5 (G5) and generation 6 (G6) hydroxyl-terminated poly(amidoamine) (PAMAM-OH) dendrimers as templating agents. The size of the nanoparticles ranges from 1.1-2.2 nm. The RuDENs were used as nanoparticle solutions in catalytic reactions or immobilised on amorphous silica 60 and silica 100 and subsequently referred to as RuSil catalysts. These catalysts were evaluated in the reduction of 4-nitrophenol, toluene hydrogenation, citral hydrogenation, cinnamaldehyde hydrogenation and styrene oxidation...