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Orientador: Luiz Carlos Dias / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-06T03:43:39Z (GMT). No. of bitstreams: 1 Goncalves_CarolinedaCostaSilva_M.pdf: 2686591 bytes, checksum: c80dce86656a36dd72ca46fac32d08d0 (MD5) Previous issue date: 2005 / Resumo: As ebelactonas A e B são inibidores enzimáticos isoladas pelo grupo de Umezawa em 1980, a partir de uma cepa de cultura de solos actinomicetos (MG7-G1 referente a Streptomyces aburaviensis). Neste trabalho descrevemos a síntese dos fragmentos C1-C5 e C7-C13 da (-)-ebelactona A. Os fragmentos C1-C5 e C7-C13 da (-)-ebelactona A são oriundos de um intermediário comum, o álcool 72. As etapas chave incluem uma reação do tipo aldol anti e uma hidroboração diastereosseletiva. O fragmento C1-C5 foi obtido em 6 etapas a partir da N-propioniloxazolidinona com rendimento global de 32%. Alternativamente, sintetizamos o anel b-lactona, uma segunda versão do fragmento C1-C5, sendo o mesmo obtido em 13 etapas com um rendimento global de 2,8%. O fragmento C7-C13 foi obtido em 14 etapas a partir da N-propioniloxazolidinona com rendimento global de 5,5%. As etapas principais incluem uma reação de Horner-Wadsworth-Emmons, uma epoxidação diastereosseletiva de um álcool alílico com m-CPBA seguida de abertura do epóxido com Me2CuCNLi2. / Abstract: The ebelactones A and B are enzime inhibitors isolated by Umezawa and cowokers in 1980, from a culture strain of soil actinomycetes (MG7-G1 related to Streptomyces aburaviensis). This work describes the synthesis of C1-C5 and C7-C13 fragments of (-)-ebelactone A. The C1-C5 and C7-C13 fragments of (-)-ebelactone A were prepared from a common intermediate, alcohol 72. Notable features of this approach include an anti-aldol reation and a diastereoselective hydroboration. Fragment C1-C5 was prepared in 6 steps and 32% overall yield from N-propionyloxazolidinone. A second version of C1-C5 fragment, corresponding to the b-lactone ring, was prepared in 13 steps and 2.8% overall yield. Fragment C7-C13 was prepared in 14 steps and 5.5% overall yield from N-propionyloxazolidinone. Notable features include a Horner-Wadsworth-Emmons, a diastereoselective epoxidation of an allylic alcohol with m-CPBA followed by epoxide opening with Me2CuLi2. / Mestrado / Quimica Organica / Mestre em Química

Orientador: Rubens Maciel Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-20T08:38:40Z (GMT). No. of bitstreams: 1 Bonon_AndersonDeJesus_M.pdf: 18231652 bytes, checksum: 5f90aa98f05330f8a92f9b1163036e84 (MD5) Previous issue date: 2012 / Resumo: Uma das olefinas de fontes renováveis de maior importância no Brasil é o Limoneno, terpeno que compõe cerca de 90% do óleo da casca da laranja. O Brasil é o maior produtor mundial de laranja, com uma produção, entre 2010-2011, de cerca de 15,33 milhões de toneladas do fruto, dos quais 89% da produção são destinadas à produção de suco, sendo a casca e o óleo fixo, resíduos do processo. A parte volátil do óleo é constituída majoritariamente de (R)-limoneno (90 %). Terpenos como o limoneno, podem ser submetidos a reações de oxidação catalítica nos quais os epóxidos são os principais produtos, e podem ser utilizados como precursores para uma ampla variedade de produtos como fármacos, fragrâncias e na fabricação de biopolímeros e resinas. Mediante ao exposto, este trabalho tem por objetivo o estudo da epoxidação de limoneno para a obtenção de epóxidos que possam ser utilizados como monômeros para a síntese de biomateriais para a construção de dispositivos médicos, sendo que avaliou-se sistemas epoxidativos contenho metiltrioxorênio, montmorilonita e alumina. O sistema mais promissor, utilizando H2O2 como oxidante, ?-Al2O3 como catalisador em acetato de etila, foi avaliado em condições reacionais brandas, a 80 °C em pressão atmosférica, caracterizando um sistema verde. As variações na concentração inicial de reagentes a fim de entender o sistema foram estudadas, o que direcionou o estudo para sua otimização via planejamento de experimentos, sendo atingida uma conversão de 100 % em 10 h de reação. A obtenção de limoneno por evaporação de passo curto do óleo de laranja também foi estudada e otimizada, chegando-se à pureza de 99,6 %. O ensaio nas condições ótimas de reação com o limoneno obtido do óleo de laranja mostrou-se idêntico ao limoneno comercial. Os resultados obtidos demonstram a eficácia tanto do processo de obtenção do limoneno, como do sistema reacional com uma produção limpa, uma característica imprescindível para biofabricação / Abstract: One of the most important olefins from a renewable source of in Brazil is limonene. The orange peel oil is about 90% limonene. Brazil is the largest producer of orange in the world wild, with a 2010-2011 production about 15.33 million tons of fruit. About 89% of the fruits are intended for the production of juice, which peel and fixed oil are residue from the process. The volatile oil portion is composed predominantly of (R)-limonene. Terpenes such as limonene, may be subjected to catalytic oxidation reactions where the epoxides are the main products, and can be used as precursors for a wide variety of products such as pharmaceuticals, fragrances and the manufacture of biopolymers and resins. By the above, this work is dedicated to study the epoxidation of limonene in order to obtaining epoxides that may be used as monomers for the synthesis of biomaterials with chemical quality to medical devices manufacturing. Thus, some systems like methyltrioxorhenium, montmorillonite and alumina were tested. The most promissory system, using H2O2 as oxidant, ?-Al2O3 as catalyst and ethyl acetate as solvent, was evaluated in mild reaction conditions, at 80 °C at atmospheric pressure, featuring a green system. It was carried out the initial concentration of the substrate, oxidant and catalyst variation studies in order to understand the system, which directed for the optimization by experimental design. It was achieved a 100% of conversion in 10 hours of reaction. It was also studied the limonene purification by short path evaporation of the orange oil. It was achieved a limonene with 99.6 % of purity. The optimum reaction conditions were performed with limonene obtained from orange oil, the comparative result showed and an identical behavior between the commercial and the distillated limonene. These results demonstrate the effectiveness of both the process, the limonene obtainment and the reaction system with a clean and no toxic production, an essential feature for biofabrication / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Abstract The first part of this monograph discusses the asymmetric, ylide based, reagent controlled epoxidations. Both different chiral ylides and epoxidation processes, stoichiometric and catalytic, are reviewed. In the following part, new chiral sulfide catalysts were discovered as enantioselective catalysts for the Corey-Chaykovsky reaction (epoxidation of aldehydes via sulfonium ylides). Using a crystal structure of an oxazolidine derivative as a starting point, a thiazolidine ligand family was designed, synthesized and finally employed as catalysts in the asymmetric epoxidation of benzaldehyde. The ligands were prepared starting from L-valine, L-tert-leucine, D-penicillamine and L-cysteine. The differently tuned thiazolidine ligands were demonstrated to catalyze the formation of trans-stilbene oxide with varying enantioselectivities. On the basis of these results, a mechanistic rationale for the asymmetric induction was presented. The results heavily demonstrated the importance of ring rigidity as an affecting factor in the enantioselectivity of the tested thiazolidines.

This thesis studies the interaction between free radical species and supported noble metal nanoparticles (silver and gold) in the context of oxidation reactions. The peroxidation of cumene is the first reaction to be discussed and the difference in peroxidation product distribution using silver nanoparticles (AgNP) versus gold nanoparticles (AuNP) is examined. Specifically, cumyl alcohol is obtained as the major product obtained when using supported AuNP, whereas cumene hydroperoxide is favoured for AgNP. Such variations in product distribution are partially explained by the differences in the nanoparticle Fenton activity, where the TiO2 support was proposed to enhance such activity due to possible electron shuttling capabilities with the nanoparticle surface. Use of hydrotalcite as a support was found to minimize this characteristic, due to its insulator properties. The stability of hydroperoxide was tested in the presence of various others supports (activated carbon, Al2O3, ZnO, SiO2 and clays) with little success, with hydroperoxide exhibiting stability in the presence of HT. Using an oxygen uptake apparatus, the interaction of the cumyl peroxyl radical with the AuNP surface was demonstrated. Furthermore, this interaction promotes decomposition leading to the corresponding alkoxyl radical and subsequent hydrogen abstraction to form the observed cumyl alcohol product. The radical interaction with supported nanoparticles, and its reversibility appear different for gold and silver and accounts for a large part of the product distribution differences observed between AuNP and AgNP, as illustrated below. The peroxidation of ethylbenzene and propylbenzene was studied and revealed the participation of a reactive surface oxygen species due to the decomposition of peroxyl radicals on the nanoparticle surface. The reactive oxygen species was found to be transient in nature in the case of AuNP . Furthermore, this surface species was found to be an important participant in hydrogen abstraction leading to peroxide product formation. Finally, supported nanoparticle catalyzed tetralin peroxidation was investigated to determine the influence of temperature on the peroxidation product distribution and how changes in the reaction temperature can effect the radical-nanoparticle surface interactions.

Orientador: Ulf Friedrich Schuchardt / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-07T20:41:43Z (GMT). No. of bitstreams: 1 RinaldiSobrinho_Roberto_D.pdf: 13717889 bytes, checksum: 44d71665f771669d5a379b692f3356c0 (MD5) Previous issue date: 2006 / Doutorado / Quimica Inorganica / Mestre em Química

Reaction of the thiosemicarbazone ligands, [4-(p-bromophenyl)thiosemicarbazone of salicylaldehyde (H2L1), 4-(p-X-phenyl)thiosemicarbazone of o-vanillin {X = F (H2L2), X = Cl (H2L3) and X = OMe (H2L4)}, 4-(p-bromophenyl)thiosemicarbazone of 5-bromosalicylaldehyde (H2L5), and 4-(p-chlorophenyl)thiosemicarbazone of o-hydroxynaphthaldehyde (H2L6)] with [MoO2(acac)2] afforded a series of new oxidomolybdenum(VI) complexes [Mo(VI)O2L1–6(solv)] (1–6) {where solv (solvent) = DMSO (1, 3, 5 & 6) and H2O (2 & 4)}. The molecular structures of 2 and 3 were determined by X-ray crystallography, demonstrating the dibasic tridentate behavior of ligands. The cyclic voltammogram pattern is similar for 1–6, which includes two irreversible reduction processes within the potential window −0.71 to −0.66 V and −0.92 to −0.85 V corresponding to the metal centered reduction from Mo(VI)/Mo(V) and Mo(V)/Mo(IV) respectively. Catalytic potential of 1–6 was tested for the oxidation of styrene and cyclohexene. The effect of various parameters such as the amount of catalyst, oxidant, NaHCO3, and solvent was checked to optimize the conditions for the best performance of the catalyst. 100% product selectivity for the formation of cyclohexene oxide from cyclohexene and ∼98–99% product selectivity for the oxidation of styrene to styrene oxide was observed.