Neste trabalho foram estudadas a atividade e a estabilidade de lacases dos fungos Coriolus hirsutus e Trametes versicolor em meio aquoso contendo líquidos iônicos (LI) como co-solventes, com o objetivo de se obter informações sobre os efeitos desses solventes na atividade enzimática. Foi avaliado o efeito de onze LI (cátions: tetrabutilamônio, 1-butil-3-metilpiperidina e 1-alquil-3-metilimidazólios; combinados com ânions: brometo, cloreto, metilsulfato, metanossulfonato e tetrafluorborato) em diferentes frações molares em meio aquoso tamponado com ácido acético (0,1 mol L-1, pH 4,7 e 25 &#176;C). De um modo geral, a atividade inicial das lacases nos diferentes líquidos iônicos foi inferior à obtida em solução aquosa somente tamponada. O aumento da concentração dos LI também resultou no decréscimo da atividade enzimática. Tanto os resultados obtidos para atividade, como para estabilidade enzimática, se correlacionaram bem com a série de Hofmeister, que ordena os íons de acordo com suas propriedades cosmotrópicas/caotrópicas. Ânions cosmotrópicos e cátions caotrópicos estabilizam proteínas, enquanto ânions caotrópicos e cátions cosmotrópicos as desestabilizam. As lacases estudadas foram fortemente inibidas na presença dos ânions caotrópicos Br- e BF4-. Entre os LI utilizados neste trabalho, o metanossulfonato de 1-etil-3-metilimidazólio foi co-solvente mais promissor para lacase. Os dados cinéticos das reações enzimáticas em metanossulfonato de 1-etil-3-metilimidazólio e metanossulfonato de 1-butil-3-metilimidazólio, utilizando os substratos catecol e siringaldazina, revelaram que o decréscimo da atividade enzimática é resultado do aumento da constante michaeliana. Os resultados obtidos da estabilidade e temperatura de transição de desnaturação térmica da lacase em LI formado por MeSO3-, cosmotrópico, foram comparáveis aos obtidos em tampão. A ordem crescente de atividade e estabilidade da lacase em líquidos iônicos para cátions foi BuN+&#8776;BMPP+&#8776;BMIM+&#60;EMIM+, enquanto para ânions foi Br-&#8776;BF4- < MeSO4- < MeSO3-. A diminuição da eficiência catalítica da reação (Kcat/Km) em meio contendo líquido iônico foi proporcionada principalmente pelo aumento da Km. Líquidos iônicos têm se apresentado como potenciais solventes para utilização em biocatálise. As propriedades físico-químicas dos LI podem ser moduladas pela combinação de diferentes cátions e ânions, visando características diferenciais para atividade enzimática. O estudo do mecanismo catalítico e dos efeitos específicos dos íons é de fundamental importância para a utilização vantajosa desses solventes em reações enzimáticas. / In this study, the activity and stability of laccase of T. versioclor and C. hirsutus were studied in ionic liquid (IL)-containing aqueous systems to provide valuable information with regard to the effect of IL on the enzyme activity. The effect of IL on the laccase performance was investigated by comparing the activity, stability, kinetic (such as Km, Vmax) and thermal denaturation. An excessive amount of these ILs in the reaction systems resulted in decline in enzymatic activity. Both activity and stability of the enzyme correlate well with the Hofmeister series in terms of the salt\'s kosmotropic/chaotropic properties. Proteins are usually found to be stabilized by a kosmotropic anion and a chaotropic cation and destabilized by a chaotropic anion and a kosmotropic cation. Laccases strong had been inhibited presence of chaotropic anions Br- and BF4-. Among the IL used here, 1-etyl-3-methylimidazoliun methanesulfonate was the most promising IL for laccase. A detailed analysis of kinetic data in the presence of catecol and syrigadalzine as substrate revealed that the decrease in the laccase activity was a result of increase in Km. Equal stability the transition temperature for the thermal denaturation of laccase of T. versioclor in ionic liquids based in MeSO3- (kosmotropic) was comparable to that of the control sample. It was observed an ion effect on the laccase activity and stability, for cations this parameters values increased in the order BMIM+&#8776;BuN+&#8776;BMPP+ < EMIM+; while for anions the order is Br-&#8776;BF4- < MeSO4- < MeSO3-. Also an increase in Km is correlated with the decrease in the catalytic reaction efficiency (Kcat/Km) in medium containing ionic liquid. Design and use of water-mimicking IL composed of chaotropic cations and kosmotropic anions may facilitate the applications of IL in biotransformations.

Cubosomes are nanostructures formed by the self-assembly of a lipid an aqueous solution, under certain experimental circumstances. Nanoparticles have been widely used as carriers of hydrophobic drugs, acting as a drug delivery method, with the potential to solve problems related to the drug, such as low solubility and instability. Theses facts are specially related to the cubic crystalline structure of these particles, in particular their large usable hydrophobic volume. The production of cubosomes relies on the self-assembly of lipids in excess of water, aided by the presence of a polymer acting as a emulsifier. The physicochemical properties of such particles can be characterized mainly by scattering techniques, namely small angle x-ray scattering (SAXS), dynamic light scattering (DLS), conventional and cryogenic transmission electron microscopy (TEM) and &#950; (zeta) potential. This project aims the investigation of cubosomes production in the absence and presence of ionic liquids functionalized with alkyl chains, in order to produce cationic nanoparticles suitable for gene therapy, as in the case of DNA transfection. Cubosomes were prepared with two different lipid/polymer/water systems: phytantriol or monoolein stabilized with Puronic F127 in excess of water or buffer. Ionic liquid [C14mim][Cl] and cationic surfactant TTAB was added to these formulations and it was verified that the final dispersions contained cationic cubosomes. Particles positively charged with sizes between 300 nm and 350 nm and cubic crystalline internal structure were obtained and characterized. / Cubossomos não nanopartículas formas pela fase de auto-associação de um lipídio em solução aquosa, sob certas condições experimentais. Nanopartículas tem sido amplamente utilizadas como carreadores de fármacos hidrofóbicos, atuado como um método de entrega controlada, como potencial de resolver problemas relacionados ao fármaco, como baixa solubilidade e instabilidade. Esses benefícios estão especialmente relacionados com a estrutura interna cristalina dessas partículas, em particular, seu grande volume hidrofóbico. A produção de cubossomos baseia-se na auto-associação de lipídios em excesso de água, auxiliada pela presença de um polímero como estabilizador. As propriedades físico-químicas dessas partículas podem ser caracterizadas principalmente por técnicas de espalhamento, nomeadamente espalhamento de raios-X a baixos ângulos (SAXS), espalhamento de luz dinâmico (DLS), microscopia eletrônica de transmissão (TEM), criogênica ou por contrastação negativa, e potencial &#950; (zeta). Este projeto tem como objetivo investigar a produção de cubossomos na ausência e presença de líquidos iônicos funcionalizados com cadeias alquílicas, objetivando a produção de nanopartículas catiônicas compatíveis com uso em terapia gênica, como no caso de transfecção de DNA. Cubossomos foram preparados com dois sistemas diferentes: monoleína e phytantriol estabilizados com Pluronic F127 em excesso de água ou tampão. O líquido iônico [C14mim][Cl] e o surfactante catiônico TTAB foram adicionados a essas formulações e foi verificado que as soluções finais eram compostas por cubossomos catiônicos. Partículas carregadas positivamente com tamanhos entre 300 nm e 350 nm foram obtidas e caracterizadas.

Experimentalmente, a transição entre as fases gel e gel-líquida de bicamadas fosfolipídicas pode ser mensurada por técnicas de anisotropia de fluorescência. A partir de uma sonda interna à membrana, a diferença entre as radiações absorvida e emitida, causada pela rotação da sonda no intervalo de fluorescência, relaciona-se com a fluidez da membrana. Com esta técnica aplicada à sondas DPH, foi encontrada influência do líquido iônico (LI) C14MImCl na temperatura de transição de fase de fosfolipídios carregados (DPPG), mas não nos casos neutros (DPPC e DMPC). A temperatura de transição para DPPG apresenta queda de 45oC, em estado puro, para 26oC com concentração de 30%mol de LI. Neste estudo, simulações de dinâmica molecular foram conduzidas de forma a descrever as interações de LI com os fosfolipídios de bicamadas em dois casos, DPPC e DPPG, e de analisar o comportamento dinâmico da sonda. Diferentes condições iniciais de mistura entre lipídios e LI foram consideradas nas simulações. Os resultados indicam que, quando misturadas aleatoriamente, ambos os lipídios apresentam agregação espontânea, evoluindo para forma lamelar com LI distribuído uniformemente. Quando uniformemente distribuído, o LI diminuí a interação entre lipídios e outras moléculas do sistema nos dois casos, porém com maior intensidade em DPPG devido à repulsão dos contra íons catiônicos (Na+) do lipídio, enquanto que em DPPC os contra íons aniônicos provenientes do LI (Cl-) mantém-se perto da interface. O comportamento da sonda foi qualitativamente reproduzido e visto ser altamente correlacionado com a fluidez das caudas, medida por meio do parâmetro de ordem deutérica. Por conta da equivalência das caudas entre DPPC e DPPG, encontrou-se omportamento similar nos dois sistemas. / The gel-liquid phase transition of phospholipid bilayers can be experimentally measured via fluorescence anisotropy techniques. Using a fluorescent probe within the membrane, the difference between absorbed and emitted radiation due to rotational movement can be related to the bilayer fluidity. The use of the fluorescent probe DPH shows the influence of the ionic liquid (IL) C14MImCl on the phase transition temperature of charged lipids (DPPG) but not neutral ones (DPPC and DMPC). The phase transition temperature for DPPG bilayers dropped from 45oC, in pure state, to 26oC, with 30%mol concentration of IL. In this study, molecular dynamics (MD) simulations were performed in order to describe the IL interactions with the phospholipids in the membranes for two cases, DPPG and DPPC, and to analyze the dynamical behavior of the probe. Different initial conditions of the mixture between IL and lipids were considered in the simulations. The results indicate that in random initial conditions, both lipids spontaneously aggregates with the IL into a bilayer shape with IL uniformly distributed across it. The uniform distribution of IL in the membranes decreased the total interaction of the lipids and the other molecules in the system for both cases, but with higher influence in DPPG due to repulsion of cationic counter ions from the lipids (Na+), whereas in DPPC the anionic counter ions from IL (Cl-) remained closer to the bilayer interface. The probe behavior was qualitatively verified and found to be highly correlated with the lipid tails fluidity, through the calculated Deuter order parameter. Because of tails equivalence between the DPPG and DPPC, it was found a similar behavior of the probe in both systems.

<div>Liquid desiccant air dehumidification (LDAD) is a promising substitute for the conventional dehumidification systems that use mechanical cooling. However, the LDAD system shares a little market because of its high installation cost, carryover problem, and severe corrosion problem caused by the conventional liquid desiccant. The research reported in this thesis aimed to address these challenges by applying membrane technology and ionic liquid desiccants (ILDs) in LDAD. The membrane technology uses semi-permeable materials to separate the air and liquid desiccants, therefore, the solution droplets cannot enter into the air stream to corrode the metal piping and degrade the air quality. The ILDs are synthesized salts in the liquid phase, with a large dehumidification capacity but no corrosion problems. In order to study the applicability and performance of these two technologies, both experimental and modeling investigations were made as follows.</div><div>In the study, experimental researches and existing models on the membrane-based LDAD (MLDAD) was extensively reviewed with respects of the characteristics of liquid desiccants and membranes, the module design, the performance assessment and comparison, as well as the modeling methods for MLDAD.</div><div>A small-scale prototype of the MLDAD was tested by using ILD in controlled conditions to characterize its performance in Oak Ridge National Lab. The preliminary experimental results indicated that the MLDAD was able to dehumidify the air and the ILD could be regenerated at 40 ºC temperature. However, the latent effectiveness is relatively lower compared with conventional LDAD systems, and the current design was prone to leakage, especially under the conditions of high air and solution flow rates.</div><div>To improve the dehumidification performance of our MLDAD prototype, the two-dimensional numerical heat and mass transfer models were developed for both porous and nonporous membranes based on the microstructure of the membrane material. The finite element method was used to solve the equations in MATLAB. The models for porous and nonporous membranes were validated by the experimental data available from literature and our performance test, respectively. The validated models were able to predict the performance of the MLDAD module and conduct parametric studies to identify the optimal material selection, design, and operation of the MLDAD.</div><div><br></div>

Esta tese tem como objetivo a derivatização da celulose sob condições homogêneas de reação, através de um método simples, reprodutível e eficiente. As três etapas de derivatização da celulose (ativação, dissolução, e reação) foram estudadas com ênfase na relação entre a estrutura do biopolímero, as condições da reação e as propriedades dos derivados obtidos. Foi realizado estudo do intumescimento de celuloses (microcristalina, algodão, eucalipto, algodão mercerizado e eucalipto mercerizado) em solventes próticos e apróticos. O intumescimento foi correlacionado com as propriedades dos solventes. Nos próticos, as celuloses nativas e mercerizadas foram sensíveis aos mesmos quatro descritores (acidez, basicidade, dipolaridade/polarizabilidade e volume molar), porém, a contribuição relativa dessas propriedades foi diferente, sendo que no caso da celulose MC e das nativas a dipolaridade/polarizabilidade foi mais significativo e para as celuloses mercerizadas o volume molar foi o descritor mais importante. Para o intumescimento em solventes apróticos, para as celuloses mercerizadas, boas correlações foram obtidas empregando apenas um descritor (dipolaridade/polarizabilidade). No intumescimento intracristalino, investigamos as mudanças nas propriedades físico-químicas após a mercerização. Este tratamento resultou em: ocorreu aumento no teor de &#945;-celulose; diminuição da cristalinidade; redução da espessura da fibra; remoção de fragmentos da superfície; aumento na área superficial. Salientamos que não ocorre uma diminuição significativa no grau de polimerização das celuloses. Empregamos uma nova classe de solvente (líquidos iônicos) para a dissolução e subsequente funcionalização da celulose. Tanto na dissolução por aquecimento térmico ou por micro-ondas a integridade física da celulose foi mantida. Alem disto, observamos que a dissolução facilita a acessibilidade/reatividade da celulose, pois ocorre a diminuição do índice de cristalinidade e o aumento da área superficial. O uso de aquecimento por micro-ondas mostrou-se mais rápido e eficiente do que aquecimento térmico, sendo que tempo necessário para a dissolução e acilação da celulose foi de 25 a 30% menor daquele com aquecimento térmico. O líquido iônico (AlBuImCl) mostrouse um excelente solvente em termos de controle do GS e reprodutibilidade do mesmo. Realizou-se um estudo da dependência das propriedades dos acetatos de celulose e seus filmes com o grau de substituição do biopolímero. Foram empregadas sondas solvatocrômicas e medidas térmicas para investigar as propriedades de filmes de acetatos de celulose. Os resultados obtidos mostraram que a dependência de tais propriedades sobre o grau de substituição dos acetatos de celulose pode ser descrita por equações simples. Por fim, desenvolveu-se um método simples, rápido, e preciso para a determinação do GS de ésteres de celulose (acetato, butirato e hexanoato), através do uso de sondas solvatocrômicas / The objective of this thesis is to study some aspects of the derivatization of cellulose under homogeneous reaction conditions. The three steps of this reaction scheme (activation, dissolution and derivatization) were studied, with emphasis on the relationship between the biopolymer structure, the conditions of the reaction and the properties of the products. Swelling of different celluloses (microcrystalline (MC), cotton linter, eucalyptus, cotton linter mercerized, eucalyptus mercerized) by protic and aprotic solvents was determined. The results were correlated with a series of solvent descriptors. For protics solvents, although native and mercerized celluloses are sensitive to the same set of four solvent properties (acidity, basicity, dipolarity/polarizability, and molar volume), the relative contributions are different; &#960;* is most important for MC and native celluloses, VS is most important for mercerized celluloses. Because of absence of hydrogen-bon donation by aprotics solvents, a smaller number of solvent descriptors is required in order to describe cellulose swelling. For example, the swelling of mercerized cellulose can be reasonably described by a single descriptor (dipolarity/polarizability). The effect of mercerization on cellulose properties was investigated; it leads to: increase of &#945;-cellulose content; decrease of Ic; decrease of fiber cross section, smoothing of its surface, and increase of its surface area. The ionic liquid 1-allyl-3-(1-butyl)imidazolium chloride showed to be a convenient reaction medium for the dissolution and derivatization of cellulose, with reproducible easily controlled degree of substitution, DS. The physical integrity of the cellulose is maintained during dissolution by using either \"conventional\" or convection-, or microwave heating. Compared with the former, MW irradiation has resulted in considerable decrease in dissolution- and reaction times. The value DS was found to be DSethanoate > DSpropanoate > DSbutanoate. The values of DSpentanoate and DShexanoate were found to be slightly higher than DSethanoate. The dependence of the properties of cellulose acetates and their films on the degree of biopolymer substitution was investigated. Solvatochromic probes and thermal analysis have been employed. The results showed that the dependence of the properties (solvatochromic parameters and thermal properties) of CAs on their DS can be described by simple equations; a consequence of the substitution of the OH by the ester group. Finally, an expedient, accurate method for the determination of the degree of substitution of cellulose carboxylic esters (ethanoate, butanoate and hexanoate) was developed, using Uv-vis spectroscopy (dye perichromism)

Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-06-21T17:33:49Z No. of bitstreams: 1 AngelaSantos.pdf: 3784731 bytes, checksum: 4f751c6199d9097c62df463675bc5301 (MD5) / Made available in DSpace on 2017-06-21T17:33:49Z (GMT). No. of bitstreams: 1 AngelaSantos.pdf: 3784731 bytes, checksum: 4f751c6199d9097c62df463675bc5301 (MD5) Previous issue date: 2016-06-30 / Fundação de Amparo à Pesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhão (FAPEMA) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPQ) / The use of ionic liquids and pyridine complex catalysts are an interesting alternative for use in organic synthesis processes especially in the transesterification reaction for producing biodiesel. They may come to replace homogeneous basic catalysts (NaOH and KOH) because of saponification of the reaction medium and the purification step difficulty catalyst recovery. These compounds have advantages that improve the reaction process and can be used as both solvents and catalysts, it being possible reuse. The objective of this study was to syntetize and characterizes the LI and other catalysts pyridine base and pyridine alkyl with Brønsted acids and Lewis and evaluate the catalytic efficiency of the transesterification of vegetable oil babassu oil and soybean with methanol and ethanol, as well as optimize the reaction conditions for obtaining biodiesel using the technique of Delineation Composite Central Rotational (CCRD) and Response Surface Methodology (RSM) and characterize biodiesel by the standards of the National Petroleum, Natural Gas and Biofuels - RDC 14/2012. The structural composition of the catalysts was identified by spectroscopy in the infrared (FTIR) and 1H NMR. The yields mass of the catalysts were above 65%. The results obtained in catalytic testing of transesteriifcação reaction with babassu oil and soybean via methyl ethyl route were satisfactory for conversion to esters with average yield above 70%. It was observed by Thin Layer Chromatography (TLC) separation of the compounds of biodiesel and the observed FTIR the functional groups present in the ester oil conversion. Quantitative analysis by Gas Chromatography with Flame Ionization Detector (GC-FID) showed that the compounds chlorobis (pyridine)tin(II) dihydrate [Sn(Py)2Cl2] .2H2O (71.6%); chlorobis(collidine)Zinc(II) [Zn(TPy)2Cl2] (86.5%); chlorine(collidine) aluminum (III) [Al(TPy)Cl3] (89.2%); pyridinium p-toluenesulfonate [TPy+][p-TSA-] (79.2%); pyridinium p-toluenesulfonate [Py+][p-TSA-] (89.1%), dihydrogeno phosphate p-aminotoluene-m-sulfonic [p-ATS-] [H2PO4-] (85.3%) used in the transesterification of vegetable oils obtained satisfactory performance in biodiesel synthesis. In the factorial design and the MSR observed efficiency of dihydrogeno phosphate p-aminotoluene-m-sulfonic for biodiesel synthesis. For biodiesel methyl babassu (BMB) the most significant variable was the molar ratio. However, the methyl soybean biodiesel (BMS), soybean biodiesel ethyl (BES) and ethyl biodiesel babassu (BEB), all variables affecting the process and were statistically significant. ANOVA (Analysis of Variance) provides a model with good concordance and predictive results in conversion to esters. The better reaction conditions in the optimization process for the production of biodiesel employing the [p-ATS-] [H2PO4-] was BMB (91.7%) molar ratio (MR) methanol: oil 17.5: 1, LI 3 5%, temperature 185 ° C, BMS (97.3%) RM methanol: oil 10: 1, LI 2.0%, temperature 200 ° C, BEB (92.2%) MR ethanol: oil 25: 1, LI 5.0%, temperature 200 °C and BES (98.3%) MR ethanol: oil 30.1: 1, 3.5% LI, 185 ° C temperature. At the maximum point calculated for BMB, ANOVA was statistically significant with R2 = 93.0%. Optimum conditions for achieve maximum point were: RM alcohol: oil 30.5: 1, LI 4.68% and temperature of 171 ° C to yield 92.2% to esters. Therefore, the catalysts used in the production of biodiesel obtained high to performance and methyl and ethyl esters can be studied in future work for other types of organic reactions. / O uso de líquidos iônicos e catalisadores complexos de piridina são uma alternativa interessante para utilizar em processos de síntese orgânica, principalmente na reação de transesterificação para produção de biodiesel. Eles podem vir a substituir os catalisadores básicos homogêneos (NaOH e KOH) devido a saponificação do meio reacional e na etapa de purificação dificuldade de recuperação do catalisador. Estes compostos possuem vantagens que melhora o processo reacional e podem ser usados tanto como solventes ou catalisadores, sendo possível a sua reutilização. O objetivo deste trabalho foi sintetizar e caracterizar os LI e outros catalisadores a base de piridina e piridina alquílica com ácidos de Brønsted e Lewis e avaliar a eficiência catalítica destes na reação de transesterificação do óleo vegetal de babaçu e soja com metanol e etanol, assim como otimizar as condições reacionais para obtenção do biodiesel utilizando a técnica de Delineamento Composto Central Rotacional (DCCR) e a Metodologia de Superfície de Resposta (MSR) e caracterizar o biodiesel pela normas da Agência Nacional de Petróleo, Gás Natural e Biocombustíveis – RDC Nº14/2012. A composição estrutural dos catalisadores foi identificada por espectroscopia na região do infravermelho (FTIR) e RMN de 1H. Os rendimentos em massa dos catalisadores foram acima de 65%. Os resultados obtidos nos ensaios catalíticos da reação de transesteriifcação com óleo de babaçu e soja via rota metílica e etílica foram satisfatórios para conversão a ésteres com rendimento médio acima de 70%. Foi observada pela Cromatografia de Camada Fina (CCF) a separação dos compostos no biodiesel e pelo FTIR observaram-se os grupos funcionais presente na conversão do óleo a ésteres. A análise quantitativa por Cromatografia Gasosa com Detector de Ionização em Chama (CG-DIC) revelou que os compostos clorobis(piridina)estanho(II) diidratado [Sn(Py)2Cl2].2H2O (71,6%); clorobis(colidina)zinco(II) [Zn(TPy)2Cl2] (86,5%); cloro(colidina)alumínio(III) [Al(TPy)Cl3] (89,2%); p-toluenosulfonato de piridínio [TPy+][p-TSA-] (79,2%); p-toluenosulfonato de piridínio [Py+][p-TSA-] (89,1%), diidrogeno fosfato de p-aminotolueno-m-sulfônico [p-ATS-][H2PO4-] (85,3%) empregados na transesterificação do óleos vegetais obtiveram desempenho satisfatório na síntese de biodiesel. No planejamento fatorial e a MSR observou-se a eficiência do diidrogeno fosfato p-aminotolueno-m-sulfônico na síntese de biodiesel. Para o biodiesel metílico de babaçu (BMB) a variável mais significativa foi à razão molar. No entanto, o biodiesel metílico de soja (BMS), o biodiesel etílico de soja (BES) e o biodiesel etílico de babaçu (BEB), todas as variáveis influenciaram no processo e foram estatisticamente significativas. A ANOVA (Análise de Variância) prevê um modelo com boa concordância e preditivo nos resultados da conversão a ésteres. As melhores condições reacionais no processo de otimização para a produção de biodiesel empregando o [p-ATS-][H2PO4-] foram para o BMB (91,7%) razão molar (RM) álcool: óleo 17,5:1, LI 3,5%, temperatura 185 °C, BMS (97,3%) RM álcool: óleo 10:1, LI 2,0%, temperatura 200 °C, BEB (92,2%) RM álcool: óleo 25:1, LI 5,0%, temperatura 200 °C e BES (98,3%) RM álcool: óleo 30,1:1, LI 3,5%, temperatura 185 °C. No ponto máximo calculado para o BMB, a ANOVA foi estatisticamente significativa com o R2 = 93,0%. As melhores condições para alcançar o ponto máximo foram: RM álcool: óleo 30,5:1, LI 4,68% e temperatura de 171 °C com rendimento de 92,2% a ésteres. Portanto, os catalisadores utilizados na produção de biodiesel obtiveram elevados desempenho a ésteres metílicos e etílicos e podem ser estudados em trabalhos futuros para outros tipos de reações orgânicas.

<p>This thesis deals with the development of catalytic oxidation reactions utilizing hydrogen peroxide as terminal oxidant. The main focus has been to find flavin catalysts that are easy to handle and stable to store but still able to perform the desired reaction. A variety of dihydroflavins were prepared and the electrochemical oxidation potentials were measured and compared with their catalytic activity.</p><p>A flavin catalyst was applied in the sulfoxidation of allylic and vinylic sulfides by H₂O₂. This transformation was highly chemoselective and the sulfoxides were obtained without formation of other oxidation products. The scope of the reaction was demonstrated by applying the method on substrates with a wide range of functional groups such as a tertiary amine. Another flavin catalyst was immobilized in the ionic liquid [BMIm]PF₆ and used for sulfoxidations by H₂O₂. The chemoselectivity was maintained in this system and the catalyst-ionic liquid system could be recycled several times.</p><p>Finally two bimetallic catalyst systems for the dihydroxylation of alkenes by H₂O₂ were immobilized in the ionic liquid. These systems employed either vanadium acetylacetonate VO(acac)₂or methyl trioxorhenium (MTO) as co-catalysts together with the substrate-selective osmium catalyst. Good to excellent yields of the diols were obtained.</p>

Injection of a mixture of HAuCl4 and cellulose dissolved in the ionic liquid (IL) 1-butyl-3-methylimidazolium chloride [Bmim]Cl into aqueous NaBH4 leads to colloidal gold nanoparticle/cellulose hybrid precipitates. This process is a model example for a very simple and generic approach towards (noble) metal/cellulose hybrids, which could find applications in sensing, sterile filtration, or as biomaterials.

With the aim of finding alternative reaction media for the synthesis of subvalent main group and transition metal cluster compounds, traditionally made through solid state reactions or in superacidic media, different alternative reaction media have been explored in this work. Room-temperature ionic liquids are amongst the more unconventional reaction media used. The syntheses performed have been aimed at both anionic and cationic cluster and the main tools used for characterization have been different X-ray diffraction and spectroscopic techniques. Selected ionic liquids have along with dichloromethane been shown to work as alternative reaction media for room temperature synthesis of the Bi5[GaCl4]3 salt. The salt containing the subvalent naked bismuth polycation Bi5 3+ was isolated from reduction reactions of BiCl3 in Ga/GaCl3-dichloromethane respectively Ga/GaCl3-ioinc liquid media. Three different classes of ionic liquids based on phosphonium-, imidazolium- and pyrrolidinium- salts have been used in synthesis. Homopolyatomic clusters from the lighter Group 15 element arsenic have also been studied. Solutions from the oxidative and reductive reaction routes of arsenic and AsCl3 in Lewis acidic toluene media were studied by EXAFS spectroscopy. The results were evaluated using molecular dynamics simulations of arsenic clusters. A discussion on how the calculated As4 cluster model relates to the experimental data resulted from this study. In terms of homopolyatomic anionic clusters the [K+(2,2,2-crypt)]2Ge9 2- compound containing the naked Ge9 2- anionic cluster has been isolated. The crystallographic investigation of [K+(2,2,2-crypt)]2Ge9 2- shows Zintl cluster anion Ge9 2- to be tricapped trigonal-prismatic with a symmetry very close to D3h. A chemical bonding analysis reveals two local minima of D3h symmetry and the cluster interaction scheme to be based on highly delocalised bonding. Ligand supported transition metal clusters from tungsten and palladium have also been prepared. Reduction of WCl6 in a reaction mixture of ionic liquid and co-solvent toluene resulted in tritungsten decachloride; W3Cl10(MeCN)3, being formed. Furthermore, palladium sandwich compounds; [Pd2(Ga2Cl7)(C7H8)2], [Pd2(GaCl4)(C9H12)2]∙C9H12 and [Pd2(Ga2Cl7)(C6H5Cl)2] have been prepared using GaCl3-arene reaction media. / <p>QC 20121212</p>

This thesis deals with the development of catalytic oxidation reactions utilizing hydrogen peroxide as terminal oxidant. The main focus has been to find flavin catalysts that are easy to handle and stable to store but still able to perform the desired reaction. A variety of dihydroflavins were prepared and the electrochemical oxidation potentials were measured and compared with their catalytic activity. A flavin catalyst was applied in the sulfoxidation of allylic and vinylic sulfides by H2O2. This transformation was highly chemoselective and the sulfoxides were obtained without formation of other oxidation products. The scope of the reaction was demonstrated by applying the method on substrates with a wide range of functional groups such as a tertiary amine. Another flavin catalyst was immobilized in the ionic liquid [BMIm]PF6 and used for sulfoxidations by H2O2. The chemoselectivity was maintained in this system and the catalyst-ionic liquid system could be recycled several times. Finally two bimetallic catalyst systems for the dihydroxylation of alkenes by H2O2 were immobilized in the ionic liquid. These systems employed either vanadium acetylacetonate VO(acac)2 or methyl trioxorhenium (MTO) as co-catalysts together with the substrate-selective osmium catalyst. Good to excellent yields of the diols were obtained.