Biodiesel a partir de óleos de alta acidez: desenvolvimento de um processo catalítico homogêneo

O presente trabalho visa o desenvolvimento de um processo para a produção de biodiesel partindo de óleos de alta acidez, aplicando um processo em duas etapas de catálise homogênea. A primeira é a reação de esterificação etílica dos ácidos graxos livres, catalisada por H2SO4, ocorrendo no meio de triglicerídeos e a segunda é a transesterificação dos triglicerídeos remanescentes, ocorrendo no meio dos ésteres alquílicos da primeira etapa e catalisada com álcali (NaOH) e álcool etílico ou metílico. A reação de esterificação foi estudada com uma mistura modelo consistindo de óleo de soja neutro acidificado artificialmente com 15%p de ácido oleico PA. Este valor foi adotado, como referência, devido a certas gorduras regionais (óleo de mamona advinda de agricultura familiar, sebos de matadouro e óleo de farelo de arroz, etc.) apresentarem teores entre 10-20%p de ácidos graxos livres. Nas duas etapas o etanol é reagente e também solvente, sendo a razão molar mistura:álcool um dos parâmetros pesquisados nas relações 1:3, 1:6 e 1:9. Outros foram a temperatura 60 e 80ºC e a concentração percentual do catalisador, 0,5, 1,0 e 1,5%p, (em relação à massa de óleo). A combinatória destes parâmetros resultou em 18 reações. Dentre as condições reacionais estudadas, oito atingiram acidez aceitável inferior a 1,5%p possibilitando a definição das condições para aplicação ótima da segunda etapa. A melhor condição nesta etapa ocorreu quando a reação foi conduzida a 60°C com 1%p de H2SO4 e razão molar 1:6. No final da primeira etapa foram realizados tratamentos pertinentes como a retirada do catalisador e estudada sua influência sobre a acidez final, utilizando-se de lavagens com e sem adição de hexano, seguidas de evaporação ou adição de agente secante. Na segunda etapa estudaram-se as razões molares de óleo:álcool de 1:6 e 1:9 com álcool metílico e etílico, com 0,5 e 1%p de NaOH assim como o tratamento da reação (lavagem ou neutralização do catalisador) a 60°C, resultando em 16 experimentos. A melhor condição nesta segunda etapa ocorreu com 0,5%p de NaOH, razão molar óleo:etanol de 1:6 e somente as reações em que se aplicaram lavagens apresentaram índices de acidez adequados (<1,0%p) coerentes com os parâmetros da ANP.

Refolding of omega conotoxin peptide derived from marine snail, Conus magus, to evaluate its analgesic effects

Oxidative refolding is one of the key challenges hampering the development of peptide based compounds as therapeutics. The correct refolding for three disulfide peptide like w-Conotoxi n MVIIA is difficult and crucial for biological activity. This work advanced knowledge of chemical and biological for improve oxidative refolding of synthetic w-Conotoxi n MVIIA in base of Conus magus venom. The present study aimed to set up an appropriate and effective protocols for refolding of disulfide-rich w-Conotoxin MVIIA. In this study, the crude peptide was protected with Acm group, according to the right amino acid sequences (Synthesized by Australian Company). The crude peptide was purified by H PLC. To prepare the peptide to refolding, innovative deprotection applied molar ratio (AMR) method was performed based on mercury. Accuracy of deprotection was approved by reverse phase chromatography. The deprotected target peptide (omega-conotoxin) was determined by SDS-PAGE. Then the Oxidative refolding of target peptide was performed in six protocol based on Guanidinium chloride and oxidized and reduced Glutathione. Analgesic effect of refolded peptide was surveyed with formalin test in mice Balb/c. Non neurotoxic effects of target peptides were survey with ICV injection in mice model (C57/BL6). The innovative deprotection protocol performed based on the best ratio of mercury/2-mercaptoethanol adjusted to 1mg/10p1 in 90 minute. The results showed the yield and purity of omega-conotoxin MVIIA as 93 and 95%, respectively. Refolding of 40 mg omega Conotoxin with GSSG and GSH on ratio of 10:1 and 20 mM ammonium acetate showed the best analgesic effect compared with the other methods. The result showed 95.5% yield and 98% purity of omega-conotoxin MVIIA in this refolding method. Related refolding method reduced 85% pain in experimented mice using 7 ng of the peptide. That was 71.5 fold stronger than morphine and 2 times than standard Prialt®. And it was not neurotoxic in mice. In this study, refolding method for omega-conotoxin MVIIA was optimized in the fourth factor including: reducing the time, amount and number of reagent and increase the efficiency. We introduced new method for deprotection of omega-conotoxin MVIIA. Effective, economic and applied refolding and deprotecti on method was performed in this research may al so be applied to similar omega conotoxin peptides.

Exploring coordination-driven self-assembly with autonomous chemical robots

The work presented herein focused on the automation of coordination-driven self assembly, exploring methods that allow syntheses to be followed more closely while forming new ligands, as part of the fundamental study of the digitization of chemical synthesis and discovery. Whilst the control and understanding of the principle of pre-organization and self-sorting under non-equilibrium conditions remains a key goal, a clear gap has been identified in the absence of approaches that can permit fast screening and real-time observation of the reaction process under different conditions. A firm emphasis was thus placed on the realization of an autonomous chemical robot, which can not only monitor and manipulate coordination chemistry in real-time, but can also allow the exploration of a large chemical parameter space defined by the ligand building blocks and the metal to coordinate. The self-assembly of imine ligands with copper and nickel cations has been studied in a multi-step approach using a self-built flow system capable of automatically controlling the liquid-handling and collecting data in real-time using a benchtop MS and NMR spectrometer. This study led to the identification of a transient Cu(I) species in situ which allows for the formation of dimeric and trimeric carbonato bridged Cu(II) assemblies. Furthermore, new Ni(II) complexes and more remarkably also a new binuclear Cu(I) complex, which usually requires long and laborious inert conditions, could be isolated. The study was then expanded to the autonomous optimization of the ligand synthesis by enabling feedback control on the chemical system via benchtop NMR. The synthesis of new polydentate ligands has emerged as a result of the study aiming to enhance the complexity of the chemical system to accelerate the discovery of new complexes. This type of ligand consists of 1-pyridinyl-4-imino-1,2,3-triazole units, which can coordinate with different metal salts. The studies to test for the CuAAC synthesis via microwave lead to the discovery of four new Cu complexes, one of them being a coordination polymer obtained from a solvent dependent crystallization technique. With the goal of easier integration into an automated system, copper tubing has been exploited as the chemical reactor for the synthesis of this ligand, as it efficiently enhances the rate of the triazole formation and consequently promotes the formation of the full ligand in high yields within two hours. Lastly, the digitization of coordination-driven self-assembly has been realized for the first time using an in-house autonomous chemical robot, herein named the ‘Finder’. The chemical parameter space to explore was defined by the selection of six variables, which consist of the ligand precursors necessary to form complex ligands (aldehydes, alkineamines and azides), of the metal salt solutions and of other reaction parameters – duration, temperature and reagent volumes. The platform was assembled using rounded bottom flasks, flow syringe pumps, copper tubing, as an active reactor, and in-line analytics – a pH meter probe, a UV-vis flow cell and a benchtop MS. The control over the system was then obtained with an algorithm capable of autonomously focusing the experiments on the most reactive region (by avoiding areas of low interest) of the chemical parameter space to explore. This study led to interesting observations, such as metal exchange phenomena, and also to the autonomous discovery of self assembled structures in solution and solid state – such as 1-pyridinyl-4-imino-1,2,3-triazole based Fe complexes and two helicates based on the same ligand coordination motif.

Hydroalumination of Thioacetylenes: A Versatile Generation and Reactions of -Aluminate Sulfides Intermediates

Hydroalumination of thioacetylenes using DIBAL-H and lithium di-(isobutyl)-n-(butyl)-aluminate hydride (Zweifel's reagent), followed by addition of water, furnished exclusively the (Z)- and (E)-vinyl sulfides, respectively. The regio- and stereochemistry of the intermediates generated, (Z)- and (E)-phenylthio vinyl alanates, were determined by capture with iodine, which afforded the corresponding (E)- and (Z)-1-iodo-1-phenylthio-2-organoyl ethenes. Reactions of the (E)-iodo(thio)ketene acetals with n-BuLi followed by addition of hexanal afforded the (Z)-phenylthio allylic alcohol, while the (Z)-iodo(thio)ketene acetals under similar reactions conditions gave the (E)-phenylthio allylic alcohol exclusively.

Antioxidant and antimicrobial activities of solvent fractions of Vernonia cinerea (L.) Less leaf extract.

Background: Vernonia cinerea (L.) Less is used in folk medicine as a remedy for various diseases. Objectives: The present study reports antioxidant and antimicrobial activities of solvent fractions of Vernonia cinerea. Methods: The antioxidant properties of solvent fractions of V. cinerea were evaluated by determining radicals scavenging activity, total flavonoid and phenolic contents measured with the 2,2-diphenyl-1-picryl hydrazyl (DPPH) test, the aluminum chloride and the Folin-ciocalteau methods, respectively. Antimicrobial activities were tested against human pathogenic microorganisms using agar diffusion method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of each active extract were determined. Results: The ethyl acetate fraction having the IC50 value of 6.50 μg/mL demonstrated comparable DPPH radical-scavenging activity with standard antioxidants, gallic acid and quercetin included in the study. All fractions displayed moderate antimicrobial potential against the tested pathogens with the zone of inhibition that ranged from 9.0 to 13.5 mm. The MIC (1.56 mg/mL) and MBC (3.13 mg/mL) indicated highest susceptibility of Candida albicans in all fractions. Conclusion: The results of this study showed that the solvent fractions of V. cinerea possess antioxidant and antimicrobial activities, hence justifying the folkloric use of the plant for the treatment of various ailments in traditional medicine.

Hydroalumination of seleno acetylenes: a versatile generation and reactions of alpha-aluminate vinyl selenide intermediates in the highly regio and stereoselective synthesis of telluro(seleno)ketene acetals

The hydroalumination of butylseleno acetylenes with DIBAL-H followed by addition of n-butyllithium generated in situ the (Z)-butylseleno vinyl alanates intermediates which were captured with C(4)H(9)TeBr furnishing the (E)-telluro(seleno)ketene acetals exclusively. The isomers with opposite stereochemistry (Z)-telluro(seleno)ketene acetals were obtained by the reduction of phenylseleno acetylenes with lithium di-(isobutyl)-n-butyl aluminate hydride (Zweifel's reagent) followed by reaction of (E)-phenylseleno vinyl alanates intermediates with C(4)H(9)TeBr. (c) 2008 Elsevier Ltd. All rights reserved.

Synthèse de sulfilimines et de sulfoximines catalysée par les métaux de transition

Les sulfilimines et les sulfoximines sont des motifs structuraux dont l’intérêt synthétique est grandissant, notamment du fait de leurs applications en chimie médicinale et en agrochimie. Les travaux rapportés dans cet ouvrage décrivent le développement de nouvelles méthodes de synthèse efficaces pour la production de ces unités atypiques. Ces méthodes sont basées sur la réactivité d’une source d’azote électrophile, vis-à-vis de thioéthers et de sulfoxydes. L’utilisation d’un complexe métallique introduit en quantité catalytique a permis de favoriser le processus réactionnel. En tirant bénéfice de l’expertise de notre groupe de recherche sur le développement de réactions d’amination stéréosélectives de liaisons C-H et d’aziridination de styrènes, nous avons d’abord étudié la réactivité des N-mésyloxycarbamates comme source d’azote électrophile. Après avoir optimisé sa synthèse sur grande échelle, ce réactif chiral a été utilisé dans des réactions d’amination de thioéthers et de sulfoxydes, catalysées par un dimère de rhodium (II) chiral. Un processus diastéréosélectif efficace a été mis au point, permettant de produire des sulfilimines et des sulfoximines chirales avec d’excellents rendements et sélectivités. Au cours de l’optimisation de cette méthode de synthèse, nous avons pu constater l’effet déterminant de certains additifs sur la réactivité et la sélectivité de la réaction. Une étude mécanistique a été entreprise afin de comprendre leur mode d’action. Il a été observé qu’une base de Lewis telle que le 4-diméthylaminopyridine (DMAP) pouvait se coordiner au dimère de rhodium(II) et modifier ses propriétés structurales et redox. Les résultats que nous avons obtenus suggèrent que l’espèce catalytique active est un dimère de rhodium de valence mixte Rh(II)/Rh(III). Nous avons également découvert que l’incorporation de sels de bispyridinium avait une influence cruciale sur la diastéréosélectivité de la réaction. D’autres expériences sur la nature du groupe partant du réactif N-sulfonyloxycarbamate nous ont permis de postuler qu’une espèce nitrénoïde de rhodium était l’intermédiaire clé du processus d’amination. De plus, l’exploitation des techniques de chimie en débit continu nous a permis de développer une méthode d’amination de thioéthers et de sulfoxydes très performante, en utilisant les azotures comme source d’azote électrophile. Basée sur la décompositon photochimique d’azotures en présence d’un complexe de fer (III) simple et commercialement disponible, nous avons été en mesure de produire des sulfilimines et des sulfoximines avec d’excellents rendements. Le temps de résidence du procédé d’amination a pu être sensiblement réduit par la conception d’un nouveau type de réacteur photochimique capillaire. Ces améliorations techniques ont permis de rendre la synthèse plus productive, ce qui constitue un élément important d’un point de vue industriel.

Unexpected seasonality in quantity and composition of Amazon rainforest air reactivity.

The hydroxyl radical (OH) removes most atmospheric pollutants from air. The loss frequency of OH radicals due to the combined effect of all gas-phase OH reactive species is a measureable quantity termed total OH reactivity. Here we present total OH reactivity observations in pristine Amazon rainforest air, as a function of season, time-of-day and height (0?80 m). Total OH reactivity is low during wet (10 s1) and high during dry season (62 s1). Comparison to individually measured trace gases reveals strong variation in unaccounted for OH reactivity, from 5 to 15% missing in wet-season afternoons to mostly unknown (average 79%) during dry season. During dry-season afternoons isoprene, considered the dominant reagent with OH in rainforests, only accounts for B20% of the total OH reactivity. Vertical profiles of OH reactivity are shaped by biogenic emissions, photochemistry and turbulent mixing. The rainforest floor was identified as a significant but poorly characterized source of OH reactivity.

Estudo da síntese e propriedade magnética de ferritas de manganês/cobalto dopadas com níquel

For the chemical method of synthesis of co-precipitation were produced ferrite powders manganese-cobalt equal stoichiometric formula Mn (1-x) Co (x) Fe2O4, for 0 < x < 1, first reagent element using as the hydroxide ammonium and second time using sodium hydroxide. The obtained powders were calcined at 400 ° C, 650 ° C, 900 ° C and 1150 ° C in a conventional oven type furnace with an air atmosphere for a period of 240 minutes. Other samples were calcined at a temperature of 900 ° C in a controlled atmosphere of argon, to evaluate the possible influence of the atmosphere on the final results the structure and morphology. The samples were also calcined in a microwave oven at 400 ° C and 650 ° C for a period of 45 minutes possible to evaluate the performance of this type of heat treatment furnace. It was successfully tested the ability of this group include isomorphic ferrite with the inclusion of nickel cations in order to evaluate the occurrence of disorder in the crystalline structures and their changes in magnetic characteristics.To identify the structural, morphological, chemical composition and proportions, as well as their magnetic characteristics were performed characterization tests of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDX), thermogravimetric (TG), vibrating sample magnetometry (MAV) and Mössbauer spectroscopy. These tests revealed the occurrence of distortion in the crystal lattice, changes in magnetic response, occurrence of nanosized particles and superparamagnetism

Estudo de reatores eletroquímicos para remoção de Cu2+ , Zn2+, Fenol e BTEX em água produzida

The production of water has become one of the most important wastes in the petroleum industry, specifically in the up stream segment. The treatment of this kind of effluents is complex and normally requires high costs. In this context, the electrochemical treatment emerges as an alternative methodology for treating the wastewaters. It employs electrochemical reactions to increase the capability and efficiency of the traditional chemical treatments for associated produced water. The use of electrochemical reactors can be effective with small changes in traditional treatments, generally not representing a significant additional surface area for new equipments (due to the high cost of square meter on offshore platforms) and also it can use almost the same equipments, in continuous or batch flow, without others high costs investments. Electrochemical treatment causes low environmental impact, because the process uses electrons as reagent and generates small amount of wastes. In this work, it was studied two types of electrochemical reactors: eletroflocculation and eletroflotation, with the aim of removing of Cu2+, Zn2+, phenol and BTEX mixture of produced water. In eletroflocculation, an electrical potential was applied to an aqueous solution containing NaCl. For this, it was used iron electrodes, which promote the dissolution of metal ions, generating Fe2+ and gases which, in appropriate pH, promote also clotting-flocculation reactions, removing Cu2+ and Zn2+. In eletroflotation, a carbon steel cathode and a DSA type anode (Ti/TiO2-RuO2-SnO2) were used in a NaCl solution. It was applied an electrical current, producing strong oxidant agents as Cl2 and HOCl, increasing the degradation rate of BTEX and phenol. Under different flow rates, the Zn2+ was removed by electrodeposition or by ZnOH formation, due the increasing of pH during the reaction. To better understand the electrochemical process, a statistical protocol factor (22) with central point was conducted to analyze the sensitivity of operating parameters on removing Zn2+ by eletroflotation, confirming that the current density affected the process negatively and the flow rate positively. For economical viability of these two electrochemical treatments, the energy consumption was calculated, taking in account the kWh given by ANEEL. The treatment cost obtained were quite attractive in comparison with the current treatments used in Rio Grande do Norte state. In addition, it could still be reduced for the case of using other alternative energy source such as solar, wind or gas generated directly from the Petrochemical Plant or offshore platforms

Cytotoxic, anti-inflammatory and antioxidant activities of four different extracts of Galega officinalis L (Goat’s rue)

Purpose: To evaluate the cytotoxic, anti-inflammatory and antioxidant activities of four different solvent extracts obtained from the aerial parts of Galega officinalis L Methods: The hexane, DCM, methanol and water extracts of G. officinalis were successively obtained by soxhlet extraction method. The cytotoxic activity of the extracts was assessed against human lung carcinoma (A-549), human colorectal adenocarcinoma (HT-29), human brain glioblastoma (U-87), and colon adenocarcinoma (DLD-1) by Resazurine test. The antioxidant activity of extracts were determined by Folin-Ciocalteau, oxygen radical absorbing capacity (ORAC), and 2’.7’-dichlorofluorescin-diacetate (DCFH-DA) cell-based assay while their anti-inflammatory activity was determined by nitric oxide (NO) assay. Results: DCM extract showed strong cytotoxic activity against lung adenocarcinoma and brain glioblastoma cell lines, with IC50 (concentration inhibiting 50 % of cell growth) values of 11 ± 0.4 and 16 ± 3 μg/mL, respectively. The hexane extract showed moderate anticancer activity against the same cell lines (59 ± 13 and 63 ± 16 μg/mL, respectively). DCM extract also showed significant anti-inflammatory activity, inhibiting NO release by 86.7 % at 40 μg/mL in lipopolysaccharide (LPS) - stimulated murine RAW 264.7 macrophages. Of all test extracts, the methanol extract of G. officinalis showed the highest antioxidant activity with 2.33 ± 0.09 μmol Trolox/mg , 7.10 ± 0.9 g tannic acid equivalent (TAE), and IC50 of 44 ± 4 μg/mL. Conclusion: The findings of this study suggest that DCM extract may possess anticancer effect against lung adenocarcinoma and brain glioblastoma, as well as serve as an anti-inflammatory agent.

A Study of the Microwave Carbothermic Reduction of Chromite Ore

Microwave reduction testing using activated charcoal as a reducing agent was performed on a sample of Black Thor chromite ore from the Ring of Fire deposit in Northern Ontario. First, a thermodynamic model was constructed for the system. Activity coefficients for several species were found in the literature. The model predicted chromium grades of 61.60% and recoveries of 93.43% for a 15% carbon addition. Next, reduction testing on the chromite ore was performed. Tests were performed at increasing power levels and reduction times. Testing atmospheres used were air, argon, and vacuum. The reduced product had maximum grades of 72.89% and recoveries of 80.37%. These maximum values were obtained in the same test where an argon atmosphere was used, with a carbon addition of 15%, optimal power level of 1200 W (actual 1171 W), and a time of 400 seconds. During this test, 17.53% of the initial mass was lost as gas, a carbon grade of 1.95% was found for the sintered core product. Additional work is recommended to try and purify the sintered core product as well as reduce more of the initial sample. Changing reagent schemes or a two step reduction / separation process could be implemented.

Heterogeneous Catalysts: Design, Applications and Research Insights

The cyclization of pseudoionone yields a mixture of alpha-ionone, beta-ionone and gamma-ionone. By careful control of reagent and reaction conditions, either the alpha- and beta- isomer can be favoured. The alpha-ionone has violet odour and is widely used in perfumery and flavours. beta-Ionone is the main precursor of Vitamin A and beta-carotene. Traditionally, strong homogeneous catalysts, like sulphuric acid and phosphoric acid have been used. These problems can be overcome by the use of solid acid catalysts. This work reports the cyclization of pseudoionone over USY zeolites, at 80ºC. USY It is observed that the initial activity increases with the Si/Al ratio of zeolite until a maximum, which is obtained with USY3. With higher Si/Al ratio, a decrease in the catalytic activity is observed. Selectivity to ionone isomers is around 42 %, at 75% of pseudoionone conversion, after 24 h of reaction. USY3 zeolite was reused four times with the same catalyst sample in the same condicions. It was observed a stabilization of the catalytic activity, after the second use.

THERMOGRAVIMETRIC ALTERATIONS OF CASSAVA STARCH GRANULES INDUCED BY HYDROGEN PEROXIDE, UV RAYS AND MICROWAVE

Starches are applied in several fields of industry. Amylose and amylopectin (natural polymers) constitute the starch in vegetable cells. In some processes native starches cannot support high stress conditions (high temperatures/acidity). Then, modification methods are developed aiming the improving of starch technological utilization. Oxidative modification with H2O2 has been the subject of many researches. UV rays as well microwave irradiation can be used. The aim was to confirm possible thermogravimetric alterations in native cassava starch (A) granules due to a double starch modification: 1st step) H2O2 standard solutions 0.1 mol L-1 (B), 0.2 mol L-1 (C) and 0.3 mol L-1 (D) and UV rays exposure for 1h; 2nd step) microwave irradiation for 5 min. The results of thermogravimetric curves (TG-DTA) show that the behaviors of the starch proprieties were modified. Highlighting, the modified samples C and D showed a decrease on the thermal stability step. This alteration turned them suitable to many field of industry like the paper one.