Made available in DSpace on 2017-06-01T18:20:47Z (GMT). No. of bitstreams: 1 gustavo_henrique_raposo_macedo.pdf: 1336452 bytes, checksum: 232f7e45a1f0c8329324f707c77f0d1e (MD5) Previous issue date: 2016-09-30 / Concern for the environment, linked to economic growth becomes increasingly competitive energy challenge in the world. It is this backdrop that the used frying oil and other oil begin to appear as a strong source of biodiesel in the generation sector of the national production. The production of biofuel from waste this brings many benefits to society, with significant reduction of problems related to disposal. With the implementation of this fuel in the Brazilian energy matrix will result in a positive environmental impact because, in addition to providing a suitable target for waste oil, its use in fleet vehicles will drastically reduce the emission of greenhouse gases such as carbon dioxide, responsible for the effect emissions, and completely eliminate the sulfur, one of the worst culprits of acid rain. In this sense, the objective of this work was to study the feasibility of producing biodiesel by transesterification of used frying oil in the generation of carbon credits. The methodology used to assess the economic viability of the process was the cost of fuel level, prepared using the Cost Index - Benefit (ICB), where it was possible to assess the sensitivity to variations in key parameters (investment and operation cost) . We used the spreadsheet Microsoft Excel ® that formed the basis for calculations of the platform of the process and results in carbon credits. The study showed the feasibility of biodiesel production process, where the great advantage is in the environmental sector, for reducing emissions of particulate matter and sulfur in the atmosphere, brings benefits to public health and the foreign country through the generation of credits carbon. / A preocupação com o meio ambiente, atrelada ao crescimento econômico torna cada vez mais competitivo o desafio energético no mundo. É neste panorama que o óleo de fritura usado, bem como as demais oleaginosas, começa a aparecer como forte fonte de geração de biodiesel no setor da produção nacional. A produção de um biocombustível a partir deste resíduo trás inúmeros benefícios para a sociedade, com significativa diminuição de problemas relacionados ao seu descarte. Com a implantação deste combustível na matriz energética brasileira resultará em um impacto ambiental positivo porque, além de dar um destino adequado aos óleos residuais, sua utilização na frota de veículos reduzirá drasticamente a emissão de gases poluentes, como o dióxido de carbono, responsável pelo efeito estufa, além de eliminar completamente o enxofre, um dos principais vilões da chuva ácida. Neste sentido, o objetivo do presente trabalho foi estudar a viabilidade da produção de biodiesel através da transesterificação de óleo de fritura usado na geração de créditos de carbono. A metodologia utilizada para avaliar a viabilidade econômica do processo foi a de custo nivelado de combustível, elaborada utilizando-se o Índice de Custo Benefício (ICB), onde foi possível avaliar a sensibilidade à variação de parâmetros centrais (investimento e custeio da operação). Utilizou-se a planilha eletrônica Excel da Microsoft® que serviu de base para a plataforma de cálculos do processo e dos resultados em créditos de carbono. O estudo mostrou a viabilidade do processo de produção de biodiesel, onde a grande vantagem é no setor ambiental, pois a redução das emissões de material particulado e de enxofre na atmosfera, trás benefícios a saúde pública e divisas ao país através da geração de créditos de carbono.

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Due to a number of factors, the biodiesel industry in the United States is surging in growth. Traditionally, oil seed crops such as soybean are used as the feedstock to create biodiesel. However, the crop production can no longer safely keep up with the demand for the growing biodiesel industry. Using algae as a feedstock has been considered for a number of years, but it has always had limitations. These limitations were mainly due to the production methods used to grow and harvest the algae, rather than the reaction methods of creating the biodiesel, which are the same as when using traditional crops. Algae is a promising alternative to other crops for a number of reasons: it can be grown on non arable land, is not a food crop, and produces much more oil than other crops. In this project, we propose a novel attached growth method to produce the algae while recycling dairy farm wastewater using the microalga Chlorella sp. The first part of the study provided a feasibility study as the attachment of the alga onto the supporting substrate as well as determining the pretreatment options necessary for the alga to grow on wastewater. The results showed that wastewater filtered through cheesecloth to remove large particles was feasible for production of Chlorella sp, with pure wastewater producing the highest biomass yield. Most importantly, the attached culture system largely exceeded suspended culture systems as a potentially feasible and practical method to produce microalgae. The algae grew quickly and were able to produce more than 3.2 g/m2-day with lipid contents of about 9% dry weight, while treating dairy farm wastewater and removing upwards of 90% of the total phosphorus and 79% of the nitrogen contained within the wastewater. Once the "proof-of-concept" work was completed, we investigated the effects of repeat harvests and intervals on the biomass and lipid production of the microalgae. The alga, once established, was harvested every 6, 10, or 15 days, with the remaining algae on the substrate material functioning as inoculums for repeated growth. Using this method, a single alga colony produced biomass and lipids for well over six months time in a laboratory setting. The second part of this study investigated another aspect of biodiesel production from algae. Rather than focus solely on biomass production, we looked into biodiesel creation methods as well. Biodiesel is created through a chemical reaction known as transesterification, alcoholysis, or commonly, methylation, when methanol is the alcohol used. There are several different transesterification methods. By simplifying the reaction conditions and examining the effects in terms of maximum fatty acid methyl esters (FAME) produced, we were able to determine that a direct transesterification with chloroform solvent was more effective than the traditional extraction-transesterification method first popularized by Bligh & Dyer in 1959 and widely used. This synergistic research helps to create a more complete picture of where algal biodiesel research and development is going in the future. / Master of Science

This study focuses on the development of novel two-stage esterification-transesterification synthesis of biodiesel from used cooking oil (UCO) using novel heterogeneous catalysts. The esterification of the UCO was investigated using three types of ion exchange resins catalysts including Purolite D5081, Purolite D5082 and Amberlyst 15. Of all the catalysts investigated, Purolite D5081 resin showed the best catalytic performance and was selected for further optimisation studies. From the optimisation study, it was found that the external and internal mass transfer resistance has negligible effect on the esterification reaction. At the optimum reaction conditions, Purolite D5081 achieved 92% conversion of FFA. During reusability study, the conversion of FFA dropped by 10% after each cycle and it was found that progressive pore blockage and sulphur leaching were dominant factors that decreased the catalytic performance of the Purolite D5081 catalyst. A kinetic modelling for FFA esterification was carried out using Purolite D5081 as a catalyst. Three types of kinetic models were investigated i.e. pseudo homogeneous (PH), Eley-Rideal (ER) and Langmuir-Hinshelwood-Hougen-Watson (LHHW). Experimental data obtained from the batch kinetic studies was successfully represented by the PH model and a good agreement between experimental and calculated values was obtained. The activation energy for esterification and hydrolysis reaction was found to be 53 and 107 kJ/moL. The transesterification of pre-treated cooking oil (P-UCO) was investigated using various types of heterogeneous catalysts including Purolite CT-122, Purolite CT-169, Purolite CT-175, Purolite CT-275, Purolite D5081, Diaion PA306s and Cs-supported heteropolyacids catalysts. Of all the catalysts investigated, Diaion PA306s catalyst showed the highest conversion of triglycerides and was selected for further optimisation studies. At the optimum reaction conditions, Diaion PA306s achieved ca. 75% of triglycerides conversion. During the reusability study, Diaion PA306s catalyst gave a similar conversion of triglycerides after being reused once. Therefore, it was concluded that the resin can be used several times without losing catalytic activity. Several purification methods have been investigated and dry washing method was chosen as the best alternative for biodiesel purification.

Le présent travail de thèse porte sur l’étude de l’impact de la texturation par DIC (Détente Instantanée Contrôlée) sur les deux opérations d’extraction d’huile et de transestérification in-situ appliquées aux graines de colza et fèves de Jatropha Curcas. Une analyse fondamentale a prouvé l’importance de la diffusion du solvant ou réactif dans la matrice solide, et permis d’identifier les processus d’intensification au travers des trois caractéristiques physiques de diffusivité effective, d’accessibilité initiale et de rendement d’extraction ; ainsi que la cinétique de transestérification in-situ et le rendement d’ester méthylique d’acides gras. Une étude phénoménologique a permis de déterminer les diverses valeurs de ces caractéristiques en fonction des paramètres opératoires DIC (pression de vapeur d’eau saturée P et temps de traitement t).Dans le cas d’extraction, la diffusivité effective (Deff) de produits traités par DIC peut atteindre 8,01 10-12 m2/s contre 0,715 10-12 m2/s pour le colza non traité et 5,90 10-12 m2/s contre 2,42 10-12 m2/s pour le jatropha non traité. Le taux d’accessibilité initiale de produits traités par DIC peut atteindre 80,53% contre 26,71% pour le colza non traité et 92,58% contre 75,91% pour le jatropha non traité. Au plan du rendement, la DIC a pu impliquer un rendement de 153% pour le colza et 112% pour le jatropha.Dans le cas de la transestérification in-situ, les rendements d’esters méthyliques d’acides gras totaux (FAME total) obtenus pour les produits traités par DIC sont systématiquement supérieurs à ceux de la matière première non traitée par DIC pour les deux cas de colza et de jatropha. Le temps de réaction a été réduit à 30 - 45 minutes contre 120 minutes pour le produit non traité par DIC (cas de colza) et à 15 minutes au lieu de 60 minutes pour le produit non traité par DIC (cas de fèves de jatropha). / The present work has concerned the impact of Instant - Controlled Pressure Drop (DIC) texturing on both operations of oil extraction and in-situ transesterification, carried out with the rapeseed and the kernels of Jatropha Curcas. A fundamental analysis proved the importance of the reactive or solvent diffusion within the solid matrix. By texturing the natural product, the whole operation can be intensified. The process is revealed through three characteristics, which are the effective diffusivity, the starting accessibility, and the yields of extraction. Also, the kinetics and yield of fatty acid methyl ester of in-situ transesterification are discovered. A phenomenological study allowed determining the value of these characteristics versus DIC operating parameters (saturated steam pressure P and treatment time t).A 2 h solvent extraction of DIC treated material allowed the total oil yields to be improved by 153% for colza and 112% for jatropha, the effective diffusivity (Deff) can reach up to 8.014*10-12 m2/s as against 0.715*10-12 m2/s for colza untreated by DIC, and up to 5.90*10-12 m2/s as against 2.42*10-12 m2/s for the untreated jatropha. The rate of initial accessibility of products treated by DIC can reach up to 80.53% as against 26.71% for untreated colza and can reach up to 92.58% as against 75.91% for the product untreated jatropha. In the case of in situ transesterification, the total yield of fatty acid methyl esters (FAME total) obtained from the DIC treated products is systematically higher than that of untreated colza and jatropha raw material. The reaction time was decreased to 30 - 45 min instead of 120 min in the case of colza, and to 15 min instead of 60 min in the case of jatropha kernel.

Des nouvelles voies de synthèse sont proposées pour la préparation des hydroxyuréthanes et polyhydroxyuréthanes glycériliques, sans isocyanate, à partir de composés biosourcés fournisseurs de groupements cyclocarbonates hautement réactifs vis-à-vis des amines, diamines, polyamines. Les fournisseurs de groupement cyclocarbonate sont le carbonate de glycérol et le nouveau synthoon bifonctionnel l’acrylate de carbonate de glycérol. Des hydroxyuréthanes ou polyhydroxyuréthanes glycéryliques polyoxygénés et polyazotés ont été ainsi élaborés via ces nouveaux intermédiaires cyclocarbonates glycériliques en substitution des carbonates cycliques d’origine fossile comme les carbonates d’alkylènes. La stratégie d’élaboration des polyhydroxyuréthanes glycériliques à haut poids moléculaire s’appuie sur la réactivité séquencée de l’acrylate de carbonate de glycérol : réaction d’Aza-Michaël sur le groupement éthylénique de l’acrylate et réaction d’aminolyse par ouverture de cycles carbonates à 5- chaînons. Selon la nature des polyamines, on prépare des polymères de poids moléculaire supérieur à 40000 g/mol, d’aspects gel, mousse ou résine selon que les pontages linéaires ou interchaînes prédominent. Des réseaux chimiques intramoléculaires sont constitués par l’établissement des liaisons hydrogène entre les sites O-H ou N-H et l’oxygène du groupement carbamoyle du squelette glycérilique avec comme conséquence la réduction de la susceptibilité du groupe carbamoyle à l’hydrolyse et l’amélioration des propriétés de résistance chimique et mécanique des polyhydroxyuréthanes glycériliques. / New synthesis routes have been developed for the preparation of glycerilic hydroxyurethanes and polyhydroxyurethanes without the use of isocyanates. They were prepared from biosourced cyclocarbonates, highly reactive towards amines, diamines and polyamines. The providers of cyclocarbonate function are glycerol carbonate and glycerol acrylate carbonate which is a bifunctional reactive. Glycerilic hydroxyurethanes and polyhydroxyurethanes with high oxygenated and nitrogenated potential were then designed via these new glycerilic cyclocarbonates’ intermediates, substitutes of fossil cyclic carbonates such as ethylene or propylene carbonates. The strategy development of high molecular weights glycerilic polyhydroxyurethanes is based on the sequenced reactivity of the glycerol acrylate carbonate: Aza-Michaël reaction on the ethylenic function of the acrylate and aminolysis reaction of the 5-membered cyclic carbonate function. According to the nature of the amine, polyhydroxyurethanes up to 40,000 g/mol were obtained. They can be obtained as foams, gels, resins, depending on the predominance of linear or cross-linked bridges. Intramolecular chemical networks were elaborated by hydrogen bonding between O-H or N-H sites with the oxygen atom of the carbamoyl function of the glycerilic skeleton. That is the reason why carbamoyle functions are less susceptible to hydrolysis and why the chemical and mechanical resistance properties of the glycerilic polyhydroxyurethanes are increased.

O presente trabalho teve como objetivo o aprimoramento da transesterificação do óleo de palmiste por rota etílica, por meio da atuação simultânea de lipases de diferentes fontes microbianas, visando a produção de biodiesel com teores residuais de monoacilglicerol (MAG) e diacilglicerol (DAG) dentro dos limites exigidos pela legislação ANP no 45/2014 para biocombustíveis. Para tal propósito, as lipases foram imobilizadas em suporte híbrido sílica-hidroxietilcelulose (SiO2- HEC) e os ensaios foram iniciados em regime descontínuo em reator de tanque agitado, temperatura fixa de 45 °C e razão molar óleo:álcool de 1:8. As lipases de Burkholderia cepacia, Pseudomonas fluorescens e Thermomyces lanuginosus, foram utilizadas de maneira isolada e em associação, com base no conhecimento prévio do bom desempenho destas enzimas para a produção de biodiesel. Conforme a capacidade de atuar em diferentes posições da molécula de triacilglicerol, as associações formaram combi-lipases de mesma especificidade (B. cepacia e P. fluorescens) e de diferente especificidade (B. cepacia e T. lanuginosus), com proporções de cada lipase variando de 75, 50 e 25% em relação ao seu par enzimático. Os melhores resultados foram observados quando utilizadas ambas as combinações em proporções equivalentes. Nestas condições, foram obtidas conversões similares (?98%) e ausência de DAG, com redução da viscosidade cinemática do óleo de palmiste de 30,35 para aproximadamente 4,00 mm2/s. Embora as conversões tenham sido próximas, a combi-lipase de diferente especificidade apresentou menor teor de MAG (1,68%, m/m), sendo escolhida como biocatalisador para o estudo em reatores de leito fixo em regime contínuo. Nesta etapa, foram realizados ensaios para testar os efeitos da razão molar óleo:álcool (1:12, 1:10 e 1:8) e do tempo espacial (16 e 14 h) na conversão, qualidade e produtividade do biodiesel. O melhor desempenho foi apresentado pela razão molar de 1:8 com tempo espacial de 16 h, proporcionando teor em MAG residual de 0,62% (m/m), conversão de 98% e produtividade de 30,9 mmolésteres.gcatalisador -1.h-1. Com relação à qualidade do biodiesel formado em termos de viscosidade cinemática (4,22 mm2/s), massa específica (870 kg/m3) e teor residual de MAG (0,62%, m/m), foi verificada adequação aos parâmetros exigidos pela ANP (3-6 mm2/s, 850-900 kg/m3 e <= 0,7%, m/m, respectivamente). / The objective of the present work was to improve the transesterification of palm kernel oil by ethanolic route through simultaneous action of lipases from different microbial sources, aiming to produce biodiesel with residual levels of monoacylglycerol (MAG) and diacylglycerol (DAG) within the limits required by ANP regulation 45/2014 for biofuels. For this purpose, lipases were immobilized on silica-hydroxyethylcellulose hybrid support (SiO2-HEC) and the assays were first carried out in a stirred tank batch reactor, at fixed temperature of 45 oC and oil -to-alcohol molar ratio of 1:8. The lipases from Burkholderia cepacia, Pseudomonas fluorescens and Thermomyces lanuginosus isolated and in association were used, based on the previous knowledge of the good performance of these enzymes for the biodiesel production. According to the ability to act at different positions of the triacylglycerol molecule, the associations formed combilipases of the same specificity (B. cepacia and P. fluorescens) and different specificities (B. cepacia and T. lanuginosus) at proportion of each lipase ranging from 75, 50 and 25% relative to their enzymatic pair. The best results were attained when both combinations were used at equivalent proportions. Under these conditions, similar conversions (?98%) and absence of DAG were obtained, which was consistent with the kinematic viscosity reduction of the palm kernel oil from 30.35 to 4.00 mm2/ s, approximately. Although similar conversions were attained, the combi-lipase of different specificities provided lower MAG contentes (1.68 wt%), being chosen as a biocatalyst for performing continuous runs in packed-bed reactor. In this step, the effects of the molar ratios oil-to-alcohol (1:12, 1:10 and 1:8) and space-times (16 and 14 h) on biodiesel production, quality and productivity were evaluated. The best performance was achieved by using molar ratio of 1:8 and space-time of 16 h, yielding residual MAG contents of 0.62 wt%, conversion of 98% and productivity of 30.9 mmolester.gcatalyst-1.h-1. The quality of biodiesel produced in terms of kinematic viscosity (4.22 mm2/s), specific mass (870 kg/m3) and residual MAG content (0.62 wt%) was found in accordance of ANP resolution (3-6 mm/ s, 850-900 kg/m3 and <= 0.7 wt%, respectively).

O objetivo do presente trabalho foi propor e estabelecer um novo método de preparação de peptídeos protegidos &#945;-esterificados. Para tal, investigamos inicialmente o efeito da presença de HAc, Ca(OAc)2 e mistura de ambos na eficiência de metanólise de Ac-Ala-Gly-X-KOR (onde, X= Gly, Ala ou Phe) em DCM. Surpreendemente, as reações assistidas por Ca2+ forneceram os produtos esterificados desejados com os mais altos rendimentos. Com base nestes dados comparamos as eficiências das reações de metanólise de Ac-Ala-Gly-X-KOR [onde, X= Lys(2-Cl-Z), Phe, Ala ou Gly] asssistidas pelo íon cálcio. Estas se mostraram dependentes da natureza do resíduo C-terminal ligado à resina, pois os rendimentos de desligamento peptídeo da KOR obtidos para as reações de 6 horas apresentaram a seguinte ordem: Lys(2-Cl-Z)< Phe <Ala < Gly. Após 48 h, os rendimentos foram superiores a 68%. A possibilidade de preparar Ac-Ala-Gly-X-OEt [onde, X= Lys(2-Cl-Z) ou Ala] usando o mesmo procedimento foi também investigada. Ac-Ala-Gly-Ala-OEt e Ac-Ala-Gly-Lys(2-Cl-Z)-OEt foram produzidos com 69 e 24% de rendimento em 72h a 37ºC, respectivamente. Quando DCM foi substituído por DMSO ou 25%DMSO/tolueno a 55ºC, houve um aumento significativo nos rendimentos de etanólise da Ala-Gly-Lys(2-Cl-Z)-KOR. Benzólise e tiólise de Ac-Ala-Gly-X-OEt (onde, X= Lys(2-Cl-Z)ou Ala] foram testadas. As análises de aminoácidos das peptidil-KOR residuais mostraram que o desligamento do peptídeo da KOR ocorreu em certa extensão, mas infelizmente nas condições de análise por RP-HPLC empregadas não fomos capazes de detectar os produtos formados. Metanólises adicionais foram realizadas em presença de Ca(OAc)2 empregando peptidil-KOR relacionados ao hormônio colecistocinina: Ac-lle-Ser(Bzl)-Asp(OBzl)-KOR(1), Ac-lle-Ser(Bzl)-Asp(OcHex)-KOR (2) e Ac-lle-Ser(Bzl)-Asp(OBzl)-Arg(Mtr)-KOR (3). Os rendimentos de desligamento dos peptídeos 1, 2 e 3 foram 54, 68 e 84%, respectivamente. Não foram detectadas nos meios reacionais quantidades significativas de produtos secundários resultantes de rearranjos ou de transesterificação simultânea do éster presente na cadeia lateral do resíduo de ácido aspártico. Estes resultados evidenciaram que a assistência do Ca2+ é seletiva e o método aplicável a peptídeos contendo arginina e ácido aspártico protegidos ligados à resina de Kaiser. O efeito do solvente foi investigado realizando-se metanólises de Ac-lle-Ser(Bzl)-Asp(OcHex)-KOR em DCM, DMSO e CHCl3 em presença de Ca(OAc)2. Em 72 horas as metanólises realizadas em DMSO foram quantitativas, enquanto que em DCM ou CHCl3 estas apresentaram rendimentos de ~63%. Em seguida, examinamos a capacidade do Eu3+ em assistir a reação de metanólise de peptidil-KOR em DCM. Os rendimentos de desligamento do peptídeo foram semelhantes ou ligeiramente superiores aos obtidos em presença de Ca2+. Estudos adicionais demonstraram que não é necessário excesso molar de Ca2+ ou Eu3+ para o aumento da eficiência das metanólises. Metanólise e etanólise de Ac-lle-Ser(Bzl)-Asp(OcHex)-KOR em DCM e DMSO em presença de Ca(OAc)2, EuCl3 e TbCl3 também foram realizadas. As metanólises em DCM em presença de Ca2+, Eu3+ ou Tb3+ forneceram o produto desejado com 62, 95 ou 95% de rendimento, respectivamente. Em DMSO, a reação assistida por Ca2+ foi quantitativa, mas nenhum produto foi obtido em presença de Eu3+ ou Tb3+. As etanólises em DCM assistidas por estes ións lantanídicos foram também mais eficientes do que as mediadas por Ca2+ (28, 17 e 5%, respectivamente). Em DMSO, observou-se a formação do éster etílico apenas para a reação assistida por Ca2+. O rendimento de desligamento do peptídeo da KOR foi de 80%, mas observou-se a presença de um produto secundário no peptídeo &#945;-esterificado bruto. Novamente, nenhum produto foi obtido nas reações assistidas por Eu3+ ou Tb3+ em DMSO. Estudos adicionais demonstraram que Ca(OAc)2 pode também assistir a aminólise de Ac-lle-Ser(Bzl)-Asp(OcHex)-KOR por Arg(HCl)OMe ou Arg(HCl)OEt em DMF. Os rendimentos de desligamento do peptídeo da KOR foram superiores a 70%, sendo os ésteres desejados os produtos majoritários formados nos meios reacionais (47 e 68% do total, respectivamente). Na ausência do íon metálico, os rendimentos foram de apenas 10-13%. Reações comparativas evidenciaram que a aminólise assistida por Ca2+ é equivalente (ou ligeiramente inferior em termos de seletividade) àquelas descritas na literatura catalisadas pelo ácido acético. Tentativas de aminólise em DMSO, NMP e DMSO/tolueno (1:1, v:v) na presença de Ca2+, Eu3+ e Tb3+ também foram feitas. Os resultados demonstraram que apenas o Ca2+ foi capaz de assistir a maioria delas. Isto ocorreu provavelmente devido a interações entre o DMSO e os lantanídeos. Uma análise preliminar de Ac-Ala-Gly-Lys(2-Cl-Z)-KOR e de Ac-lle-Ser(Bzl)-Asp(OcHex)-KOR através de HR-MAS na presença e ausência de Ca2+ foi feita com o intuito de investigar as interações estabelecidas entre o íon metálico e os peptídeos sob o ponto de vista estrutural. Os resultados obtidos sugeriram que a presença do Ca2+ diminue a mobilidade da cadeia peptídica, o que sugere complexação. Uma complexação tomaria a ligação peptídeo-KOR mais susceptível ao ataque nucleofílico do álcool ou aminoácido esterificado. Medidas de inchamento de peptidil-KOR em diferentes solventes puros e nas misturas utilizadas nos estudos descritos acima demonstraram que a solvatação da peptidil-KOR não é o fator determinante na eficiência destas reações. Por outro lado, estudos qualitativos sugeriram, que a solubilidade dos sais de cálcio, európio e térbio seja crucial. Concluindo, os dados obtidos até o momento indicam que a metanólise, etanólise e aminólise de peptidil-KOR assistidas pelos íons Ca2+ consistem em uma alternativa nova e atraente para preparar ésteres &#945;-metílicos e &#945;-etílicos de N&#945;-acil-peptídeos totalmente protegidos ou desprotegidos. As reações foram realizadas em pH aparente neutro e se mostraram muito seletivas à ligação oxima. / The ultimate goal of the present work was to propose and stablish a new method to prepare a-esterified protected peptides. At first, we examined the effect of HAc, Ca(OAc)2 and mixtures of both on the efficiency of methanolysis of Ac-Ala-Gly-X-KOR (where, X= Gly, Ala or Phe) in DCM. Surprisingly, the reactions carried-out in the presence of Ca(OAc)2 gave the corresponding esterified peptides with the highest yields. Based on these data, we compared the efficiencies of methanolysis of Ac-Ala-Gly-X-KOR [where, X= Lys(2-Cl-Z), Phe, Ala or Gly] assisted by the calcium ion. They showed to be dependent on the nature of the C-terminal residue linked to the solid support since the yields found for 6-hour reactions were: Lys(2-Cl-Z)< Phe <Ala < Gly. After 48 h of reaction, yields were all higher than 68%. The possibility of obtaining Ac-Ala-Gly-X-OEt [where, X= Lys(2-Cl-Z) or Ala] using the same procedure was then investigated. In 72 hours at 37°C Ac-Ala-Gly-Ala-OEt and Ac-Ala-Gly-Lys(2-Cl-Z)-OEt were produced with yields of 69% and 24%, respectively. When DCM was replaced by DMSO or 25%DMSO/toluene at 55°C, the percentages of peptide release from Ala-Gly-Lys(2-Cl-Z)-KOR were 44% in 72h and 66% in 36h, respectively. Benzolysis and thiolysis of Ac-Ala-Gly-X-OEt [where, X= Lys(2-C-Z) or Ala] were tested as well. Despite the fact that amino acid analysis of the remaining peptidyl-KOR showed that the peptide detachment from the resin had occurred to some extent, we were not able to detect by analytical RP-HPLC the products formed in the reaction media. We also studied the methanolyses of some peptidyl-resins related to the peptide hormone cholecystokinin: Ac-lle-Ser(Bzl)-Asp(OBzl)-KOR (1), Ac-lle-Ser(Bzl)-Asp(OcHex)-KOR (2) and Ac-lle-Ser(Bzl)-Asp(OBzl)-Arg(Mtr)-KOR (3). The yields of peptide detachment from 1, 2 or 3 were 54, 68 and 84%, respectively. No significant amounts of byproducts resulting from possible rearrangements or simultaneous transesterification of the ester present at the lateral side chain of aspartic acid were detected in the reaction media. Such results allowed us to conclude that the procedure proposed was quite selective and applicable to peptides containing protected arginine or aspartic acid attached to Kaiser oxime resin. The effect of the solvent on the methanolysis efficiency was then investigated. For that, reactions containing Ac-lle-Ser(Bzl)-Asp(OcHex)-KOR and Ca(OAc)2 suspended in DCM, DMSO and CHCl3 were carried-out. That in DMSO was quantitative while those in DCM or CHCl3 yielded the esterified peptide with 63% in 72 h. The ability of Eu3+ to assist methanolysis of peptidyl-KOR in DCM was demonstrated since peptide detachment yields for some reactions were similar or slightly superior to those assisted by Ca2+. Additional studies showed that molar excess of Ca2+ or Eu3+ is not required for the enhancement of methanolysis efficiency. Comparative methanolyses and ethanolyses of Ac-lle-Ser(Bzl)Asp(OcHex)-KOR assisted by Ca2+, Eu3+ and Tb3+ in different solvents were also studied. Methanolysis in DCM in the presence of Ca2+, Eu3+ or Tb3+ supplied the desired product with yields of 62, 95 or 95%, respectively. In DMSO, the reaction assisted by Ca2+ was quantitative, but no product was formed in presence of Eu3+ or Tb3+. Ethanolysis in DCM assisted by Eu3+ or Tb3+ was also more efficient than that performed in presence of Ca2+ (28, 17 and 5%, respectively). However, in DMSO the desired &#945;-ethyl ester was formed only in the presence of Ca2+. We were able to show that Ca(OAc)2 can also assist the aminolysis of Ac-lle-Ser(Bzl)-Asp(OcHex)-KOR in DMF by Arg(HCl)OMe or Arg(HCl)-OEt. The peptide detachment yields were higher than 70%, being the desired esters the major products formed in the reaction medium. In the absence of the metal ion, yields were only 10-13%. Further studies evidenced that aminolysis assisted by Ca2+ is equivalent (or slightly inferior in terms of selectivity) to those described in the literature that uses HAc as catalyst. Attempts of aminolysis in DMSO, NMP, DMSO/toluene (1:1, v/v) containing Ca2+, Eu3+ and Tb3+ showed that only Ca2+ was able to assist the formation of the esterified peptide in all these solvents. This is probably due to DMSO interaction with the lanthanide ions. Preliminary analyses of two peptidyl-KOR by HR-MAS in the presence and absence of Ca2+ were performed in order to obtain structural information that could help us to determine the interactions established between the metal ion and peptides. The results found indicated that the presence of Ca2+ makes peptide chain less mobile, which suggests complexation. A complexation could make the peptide-resin oxime bond more susceptible to nucleophilic attacks, favoring solvolysis and aminolysis. Swelling measurements of Ac-Ala-Gly-Lys(2-Cl-Z)-KOR and Ac-lle-Ser(Bzl)-Asp(OcHex)-KOR in pure solvents and in the mixtures employed showed that the solvation of peptidyl-KOR is not the factor that determines the efficiency of these reactions. On the other hand, qualitative studies suggested that the solubility of the calcium, europium and terbium salts could be crucial. Hence, the data presented here indicate that methanolysis, ethanolysis and aminolysis of peptidyl-KOR assisted by Ca2+ provide a new alternative and attractive way to prepare fully protected or unprotected N&#945;-acyl-peptides &#945;-methyl and &#945;-ethyl esters. The reactions were performed at neutral pH and showed to be very selective to oxime bond.