EQA - Escola de Química e Alimentos
URI permanente desta comunidadehttps://rihomolog.furg.br/handle/1/1610
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37 resultados
Resultados da Pesquisa
- ItemThe addition of 2-tert-butyldimethylsilyloxyfuran to cyclic N-acyliminium ions containing cyclohexyl-based chiral auxiliaries(Elsevier, 2000) D'Oca, Marcelo Gonçalves Montes; Pilli, Ronaldo Aloise; Vencato, IvoThe vinylogous Mannich addition of silyloxyfuran 5 to chiral five- and six-membered N-acyliminium ions derived from 3/4a,b occurred exclusively through the addition to the N-acyliminium Si face to provide threo-6/7a,b as the major isomer (73–84% yield, 2:1–7:1 diastereoisomeric ratio) which were converted to the corresponding bicyclic lactams 10 and 11 with efficient recovery of the chiral auxiliary.
- ItemSynthesis and antimycobacterial activity of isoniazid derivatives from renewable fatty acids(Elsevier, 2013) Rodrigues, Marieli Oliveira; Cantos, Jéssica Borges; D'Oca, Caroline Da Ros Montes; Soares, Karina Lotz; Coelho, Tatiane Silveira; Piovesan, Luciana Almeida; Russowsky, Dennis; Silva, Pedro Eduardo Almeida da; D'Oca, Marcelo Gonçalves MontesThis work describes the synthesis of a series of fatty acid hydrazide derivatives of isoniazid (INH). The compounds were tested against Mycobacterium tuberculosis H37Rv (ATCC 27294) as well as INH-resistant (ATCC 35822 and 1896 HF) and rifampicin-resistant (ATCC 35338) M. tuberculosis strains. The fatty acid derivatives of INH showed high antimycobacterial potency against the studied strains, which is desirable for a pharmaceutical compound, suggesting that the increased lipophilicity of isoniazid plays an important role in its antimycobacterial activity.
- ItemDiesel/biodiesel proportion for by-compression ignition engines(Elsevier, 2007) Villarreyes, Joaquín Ariel Morón; Soldi, Cristian; Amorim, Alexandra Mara de; Pizzolatti, Moacir Geraldo; Mendonça Junior, Antônio Possidônio de; D'Oca, Marcelo Gonçalves MontesNowadays, computational combustion (CC) presents complex mathematical models where the fuel physical properties are important parameters. Most research on biodiesel aims at reducing pollutant emissions placing little emphasis on the relation between the fuel physical properties and its internal combustion. In this work it is presented a brief review on the importance of the physical properties and their relation to the internal combustion proposing a method to determine the volumetric proportion of biodiesel which will have efficient combustion in compression engines. The main injection and atomization properties related to the quality of ignition were measured, such as: density, viscosity and surface tension for mineral diesel (B0), biodiesel (B100) and other eleven mixtures BXX. With the proposed method, it was found that mixtures of diesel/soybean ethylic biodiesel from B2 to B30, present satisfactory internal combustion. The method may be used to predict the behavior of BXX proportions from other animal or vegetable sources and even be used as a preliminary or complementary criterion for the biodiesel certification.
- ItemThe Addition of Allyltrimethylsilane to Cyclic N-Acyliminium Ions Derived from (S)-(+)-Mandelic Acid and Cyclohexyl-Based Chiral Auxiliaries(2001) D'Oca, Marcelo Gonçalves Montes; Pilli, Ronaldo Aloise; Pardini, Vera Lúcia; Curi, Denise; Comninos, Francisco Carlos MikulaA adição de aliltrimetilsilano, promovida por TiCl4, a íons N-aciliminios cíclicos de 5- e 6-membros derivados do ácido (S)-(+)-mandélico, (1R,2S)-trans-2-fenil-1-cicloexanol e (1R,2S,5R)-8-fenilmentol ocorreu com baixas a moderadas razões diastereoisoméricas (1:1-6:1) e forneceu as respectivas amidas e carbamatos em bons rendimentos. A melhor diastereosseleção facial foi observada com o uso de (1R,2S,5R)-8-fenilmentol como auxiliar quiral. As amidas e carbamatos 2-substituídos foram convertidos nos alcalóides (S)- e (R)-propil pirrolidina e coniina com eficiente recuperação dos auxiliares quirais.
- ItemIntrinsic gas-phase electrophilic reactivity of Ccclic N-alkyl- and N-acyliminium ions(2001) D'Oca, Marcelo Gonçalves Montes; Moraes, Luiz Alberto Beraldo; Pilli, Ronaldo Aloise; Eberlin, Marcos Nogueirahe intrinsic gas-phase reactivity of cyclic N-alkyl- and N-acyliminium ions toward addition of allyltrimethylsilane (ATMS) has been compared using MS2 and MS3 pentaquadrupole mass spectrometric experiments. An order of electrophilic reactivity has been derived and found to agree with orders of overall reactivity in solution. The prototype five-membered ring N-alkyliminium ion 1a and its N-CH3 analogue 1b, as well as their six-membered ring analogues 1c and 1d, lack N-acyl activation and they are, accordingly, inert toward ATMS addition. The five- and six-membered ring N-acyliminium ions with N-COCH3 exocycclic groups, 3a and 3b, respectively, are also not very reactive. The N-acyliminium ions 2a and 2c, with s-trans locked endocyclic N-carbonyl groups, are the most reactive followed closely by 3c and 3d with exocyclic (and unlocked) N-CO2CH3 groups. The five-membered ring N-acyliminium ions are more reactive than their six-membered ring analogues, that is: 2a > 2c and 3c > 3d. In contrast with the high reactivity of 2a, its N-CH3 analogue 2b is inert toward ATMS addition. For the first time, the transient intermediates of a Mannich-type condensation reaction were isolatedthe β-silyl cations formed by ATMS addition to N-acyliminium ionsand their intrinsic gas-phase behavior toward dissociation and reaction with a nucleophile investigated. When collisionally activated, the β-silyl cations dissociate preferentially by Grob fragmentation, that is, by retro-addition. With pyridine, they react competitively and to variable extents by proton transfer and by trimethylsilylium ion abstractionthe final and key step postulated for α-amidoalkylation. Becke3LYP/6-311G(d,p) reaction energetics, charge densities on the electrophilic C-2 site, and AM1 LUMO energies have been used to rationalize the order of intrinsic gas-phase electrophilic reactivity of cyclic iminium and N-acyliminium ions.
- ItemElectrochemical Oxidation of N - p -Toluenesulfinamides(2002) D'Oca, Marcelo Gonçalves Montes; Russowsky, Dennis; Canto, Karen Fabiano Santos do; Gressler, Tanara; Gonçalves, Reinaldo SimõesContrasting and interesting electrochemical behavior is observed in anodic oxidation of N-substituted p-toluenesulfinamides under controlled current conditions. For sulfinamides derived from secondary alkylamines and primary arylamines, the N-sulfinyl group is removed and the corresponding amines are formed; for sulfinamides derived from primary alkylamines, sulfur oxidation yields the corresponding sulfonamides in good yields.
- ItemMulticomponent biginelli's synthesis of 3,4-dihydropyrimidin-2(1H)-ones promoted by SnCl2.2H2O(Communication, 2004) Russowsky, Dennis; Lopes, Fabricio Abella; Silva, Victor da; Canto, Karen Fabiano Santos do; D'Oca, Marcelo Gonçalves Montes; Godoi, Marla Narciso BiajoliThe ability of SnCl2.2H2O as catalyst to promote the Biginelli three-component condensation reaction from a diversity of aromatic aldehydes, ethyl acetoacetate and urea or thiourea is described. The reaction was carried out in acetonitrile or ethanol as solvents in neutral media and represents an improvement of the classical Biginelli protocol and an advantage in comparison with FeCl3.6H2O, NiCl2.6H2O and CoCl2.6H2O which were used with HCl as co-catalyst. The synthesis of 3,4-dihydropyrimidinones was achieved in good to excelent yields.
- ItemMulticomponent Biginelli’s Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones Promoted by SnCl2.2H2O(Sociedade Brasileira de Química, 2004) Russowsky, Dennis; Lopes, Fabricio Abella; Silva, Victor da; Canto, Karen Fabiano Santos do; D'Oca, Marcelo Gonçalves Montes; Godoi, Marla Narciso BiajoliThe ability of SnCl2.2H2O as catalyst to promote the Biginelli three-component condensation reaction from a diversity of aromatic aldehydes, ethyl acetoacetate and urea or thiourea is described. The reaction was carried out in acetonitrile or ethanol as solvents in neutral media and represents an improvement of the classical Biginelli protocol and an advantage in comparison with FeCl3.6H2O, NiCl2.6H2O and CoCl2.6H2O which were used with HCl as co-catalyst. The synthesis of 3,4- dihydropyrimidinones was achieved in good to excelent yields.
- ItemAnti-MDR and antitumoral action of acetylsalicylic acid on leukaemic cells(Biochemical Society, 2011) Garcia, Michele Carrett Dias; Votto, Ana Paula de Souza; Filgueira, Daza de Moraes Vaz Batista; Almeida, Daniela Volcan; Vallochi, Adriana Lima; D'Oca, Marcelo Gonçalves Montes; Marins, Luis Fernando Fernandes; Trindade, Gilma SantosASA (acetylsalicylic acid) is an NSAID (non-steroidal anti-inflammatory drug). ASA has gained attention as a potential chemopreventive and chemotherapeutic agent for several neoplasms. The aim of this study was to analyse the possible antitumoural effects of ASA in two erythroleukaemic cell lines, with or without the MDR (multidrug resistance) phenotype. The mechanism of action of different concentrations of ASA were compared in K562 (non-MDR) and Lucena (MDR) cells by analysing cell viability, apoptosis and necrosis, intracellular ROS (reactive oxygen species) formation and bcl-2, p53 and cox-2 gene expression. ASA inhibited the cellular proliferation or induced toxicity in K562 and Lucena cell lines, irrespective of the MDR phenotype. The ASA treatment provoked death by apoptosis and necrosis in K562 cells and only by necrosis in Lucena cells. ASA also showed antioxidant activity in both cell lines. The bcl-2, p53 and cox-2 genes in both cell lines treated with ASA seem to exhibit different patterns of expression. However, normal lymphocytes treated with the same ASA concentrations were more resistant than tumoral cells. The results of this work show that both cell lines responded to treatment with ASA, demonstrating a possible antitumoral and anti-MDR role for this drug.
- ItemExposure Assessment for Formaldehyde and Acetaldehyde in the Workplace(Sage, 2005) Cavalcante, Rivelino Martins; Seyffert, Bianca Hartwig; D'Oca, Marcelo Gonçalves Montes; Nascimento, Ronaldo Ferreira do; Campelo, Clayton Souza; Pinto, Isis Saraiva; Anjos, Frederico Barroggi dos; Costa, Ana Hilda RomeroPersonal exposure and possible cancer risk to formaldehyde and acetaldehyde were appraised in 8 work places at a university in Brazil. Levels of formaldehyde measured ranged from 22.5 to 161.5 g·m 3 and from 18.3 to 91.2 g·m 3 for acetaldehyde. The personal exposure, expressed as the potential dose in indoor air, was calculated to range from 129.8 to 930.4 g·day 1 (low exposure) and 183.9 to 1318.1 g·day 1 (medium exposure) for formaldehyde and 105.5 to 525.3 g·day 1 (low exposure) and 149.5 to 744.2 g·day 1 (medium exposure) for acetaldehyde. The indoor/outdoor ratio showed the existence of indoor sources of the compounds which were mainly in practical classes and research laboratories. The highest formaldehyde and acetaldehyde levels were found where chemical reagents were manipulated. Relating the levels found to the permissible limit given by the US OSHA showed there was no particular risk although some formaldehyde levels did exceed the lower exposure limit of the US agency NIOSH. Any cancer risk would be highest for female technicians and teaching researchers.