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The objective of this work was to evaluate the effect of the addition of cagaita leaf ethanolic extract (EFC) on soybean methyl biodiesel samples and to compare the effect of oxidative degradation during the storage period of 120 days. The quercetin, a natural antioxidante, was added to biodiesel samples for comparison purposes. All samples, after addition, were stored at room temperature and protected from light. Oxidative stability was monitored by the induction period through the Rancimat ® method during the storage period of 120 days. It was also evaluated the antioxidant activity of the extract, by the DPPH (2,2-diphenyl-1-picrylhydrazyl) method and the phenolic compounds content, by the method of Folin Cicateou. The phytochemical prospection of the extract indicated the presence of flavonoids, tannins and steroids/triterpenoids, and FT-IR spectrum analysis showed bands of phenolic compounds. The 50 ppm solution of the extract showed the percentage of antioxidant activity of 96.52% and the content of phenolic compounds was 876.46 mg gallic acid equivalent (EAG)/g EFC. The EFC showed to be efficient in retarding the oxidation of biodiesel, since the induction period increased from 4.53 h to 6.04 h. After 120 days of storage, the samples with 800 ppm or more had the induction period higher than that recommended by EN 14214 and samples added with the extract were more effective in retarding the oxidation of biodiesel than quercetin, which is a known antioxidant and widely used, thus confirming the potential use of EFC to retard biodiesel oxidation.

In biodiesel, long chain methyl esters crystallize at very low temperatures, forming paraffin crystals that clump together and clog fuel filters, preventing engine operation. When the fuel is at high temperatures and in the presence of oxygen from the air, chemical changes may occur, forming insoluble compounds in the fuel itself. This work followed the evolution of deposits and enhancers formation in biodiesel samples and their mixtures with diesel. Thus, samples of pure biodiesel mixed with diesel were stored under two temperature conditions, 30 °C and 4 °C–10 °C, for a period of 12 months. The results indicate that the residue formation in soybean biodiesel was intensified by the low temperature, time and presence of dissolved water, being the monoglycerides the main inducers.

The objective of the present work was to obtain methyl biodiesel from soybean oil (BMS) using immobilized Porcine pancreas lipase (PPL) on the support of p-nitrobenzyl cellulose xanthate (NBXCel). The influence of the parameters immobilized enzyme quantity, reaction time and buffered reaction medium were studied. As the reaction time increased, the conversion rate increased because using 5.16% mPPL/mNBXCel with 24 h reaction, the conversion rate achieved was 50.35%, and after 48 h the conversion increased to 71.19% conversion using the same amount. The pH 7.0 buffered reaction medium also contributed to decrease the required amount of immobilized lipase to achieve satisfactory conversion, because in the experiment using 4.27% mPPL/mNBXCel over 36 h of reaction, there was an increase in the OSjC conversion rate. for BMS ranging from 50.54% in bufferless reaction medium to 89.94% in buffered reaction medium. After the 40 experiments performed, the conditions of six experiments allowed a conversion higher than 96.5%, as required by the regulators, and under these conditions the reuse of the support was performed by evaluating the conversion obtained in 10 reuse cycles.

The objective of the present work was to evaluate the effect of the addition of dichloromethane extract obtained from Ginger rhizomes (Zingiber officinale Roscoe) in biodiesel, as well as to compare the results obtained with the synthetic antioxidants BHT and TBHQ. The soybean methyl biodiesel (BMS) used was produced in our laboratory. The thermal behavior of the extract, synthetic antioxidants and biodiesel produced were evaluated using TG/DTG techniques. The additions of EDG and BHT and TBHQ were performed in increasing proportions relative to the mass of the extract: mass of the methyl biodiesel and the samples were stored under the same conditions and studied for storage time of up to ninety days using TG/DTG and method to evaluate the action of the addition of these antioxidants in inhibiting and/or retarding the oxidative stability of the biodiesel samples. After 90 days of storage, the BAN-4 sample had the highest initial decomposition temperature. Regarding the oxidative stability, the samples with EDG additions also presented values higher than the minimum regulated by the ANP, confirming the action of the antioxidants present in the EDG in the control of the oxidation reactions of BMS.

This study identified the effects of dietary supplementation with ractopamine, chromium picolinate, chromium yeast, or an energetic feed restriction on the growth performance and lipid profile of subcutaneous fat, in late finishing gilts. Twenty genetically similar gilts with initial body weight of 105.35 ± 4.77 kg and a final body weight of 131.37 ± 5.58 kg were distributed in a completely randomized block design with five treatments (control; ractopamine: 20 ppm; chromium picolinate: 0.48 ppm; chromium yeast: 0.80 ppm; and energetic feed restriction: -150 kcal kg-1 of metabolizable energy), with four replicates of one animal each. The experimental diets were isonutritives, except for the metabolizable energy level of the diet fed to the group subjected to energy restriction. There were no effects on the growth performance and carcass characteristics. Ractopamine and organic chromium (picolinate and yeast) supplementation increased the concentration of total polyunsaturated fatty acid. The proportion of α-linolenic fatty acids were higher when the diets were supplemented with ractopamine or chromium yeast. The energy restriction increased the n-6:n-3 ratio and reduced α-linolenic acid concentration. Therefore, ractopamine, chromium picolinate, chromium yeast supplementation, and energetic feed restriction did not affect the growth performance or carcass characteristics but altered the lipid profile of subcutaneous fat in finishing gilts. Ractopamine and organic chromium supplementation increased PUFA in the fat of finishing female pigs. RESUMO: Este estudo foi conduzido com o objetivo de identificar os efeitos da suplementação com ractopamina, cromo picolinato, cromo levedura, ou da restrição alimentar energética, sobre o desempenho e o perfil de ácidos graxos da gordura subcutânea de fêmeas suínas em fase final de terminação. Foram utilizadas 20 fêmeas suínas, geneticamente similares, com peso inicial de 105,35 ± 4,77 kg e peso final de 131,37 ± 5,58 kg, distribuídas em delineamento experimental de blocos ao acaso em cinco tratamentos (controle; ractopamina: 20 ppm; picolinato de cromo: 0,48 ppm; cromo levedura: 0,80 ppm; e restrição energética: -150 kcal kg-1 de energia metabolizável) com quatro repetições de um animal cada. As dietas experimentais foram isonutritivas, exceto para o nível de energia metabolizável da dieta fornecida ao grupo submetido à restrição energética. Não houve efeito dos tratamentos sobre o desempenho e as características de carcaça. As suplementações com ractopamina e cromo orgânico (picolinato ou levedura) aumentaram a concentração de ácidos graxos poli-insaturados. A proporção do ácido α-linolênico foi maior com a inclusão da ractopamina ou do cromo levedura na dieta. A restrição energética aumentou a proporção n-6:n-3 e reduziu a concentração do ácido α-linolênico. As suplementações com ractopamina, picolinato de cromo, cromo levedura, ou restrição alimentar energética, não influenciaram o desempenho e as características de carcaça, mas alteraram o perfil lipídico da gordura subcutânea de fêmeas suínas. As suplementações com ractopamina e cromo orgânico aumentaram a proporção de AGPI.

This study was conducted to evaluate the impact of soybean oil level on performance and fatty acid profile of backfat and longissimus lumborum muscle of gilts. Forty-eight gilts with an initial weight of 21.75 ± 0.138 kg and final weight of 98.65 ± 2.106 kg were subjected to one of the following six dietary soybean oil inclusions (0.00, 1.086, 2.173, 3.259, 4.345, and 5.432%). Experimental design was completely randomized block with six treatments and four replicates of two animals each. Lipid profile of backfat and longissimus lumborum muscle was analyzed by gas chromatography. Increasing dietary soybean oil levels did not influence final weight, daily weight gain, and feed intake (P > 0.05) but improved feed to gain ratio (P

This work studied the obtaining of methyl biodiesel and ethyl biodiesel using alkaline transesterification from macroalgae Fucus vesiculosos oil (FVO). FVO has 86.59% of its composition in unsaturated fatty acids, with a greater quantity of linoleic acid and oleic acid, a chemical composition near the soybean oil, the most used raw material for the production of biodiesel. Linoleic acid (47.88%), and oleic acid (34.66%) are the fatty acids present in the greatest amount in FVO, and unsaturated fatty acids correspond to 86.59% the composition of FVO, a composition of fatty acids close to that of soybean oil, which is the oil most produced and used for the production of biodiesel. To obtain methyl biodiesel (MBFVO) and ethyl biodiesel (EBFVO) the molar ratio oil: alcohol 1: 3 and 1% alkaline catalyst, NaOH, was used. The yield of the transesterification reaction was evaluated by varying the reaction time between 30 and 60 minutes and the highest yields were obtained after 60 minutes of reaction. In order to check the quality of the obtained biodiesel, the properties acidity index, iodine value, water content, specific mass at 20 o C, oxidative stability, cold filter lugging point and kinematic viscosity were evaluated. The oxidative stability had an induction period below the recommended, but it can be corrected with the addition of antioxidants to the biodiesel. All other physical and chemical properties had values within the stipulated by the regulatory agencies, indicating that the macroalgae Fucus vesiculosus can be a raw material in potential for production of biodiesel

Objetivou-se compreender o papel das práticas integrativas na promoção da saúde mental e no cuidado aos usuários de álcool e outras drogas. Revisão integrativa nas bases do Portal da CAPES e Biblioteca Virtual em Saúde. Selecionaram-se 18 artigos em português, disponíveis gratuitamente. As práticas contribuíram para a redução da ansiedade e sentimentos negativos; aumento do humor, prazer, estímulo para atividades laborais e interação usuário-profissional. Surgiram como estratégias que promovem melhor enfrentamento no uso abusivo de álcool e outras drogas; apoio nas recaídas; permitindo sentimentos que levem à diminuição da ansiedade e à redução do uso de drogas. Torna-se essencial a oficialização das discussões sobre as práticas integrativas, estimulando os profissionais a desconstruírem o velho conceito de que saúde só é feita a partir de práticas convencionais e socialmente aceitas, instituindo um pensamento novo e integral, indo de encontro aos preceitos do Sistema Único de Saúde.

This paper describes the synthesis and characterization of methylic and ethylic esters from tucuma ( A. huaimi Mart.) seeds oil. Thermal properties of these biofuels were evaluated by thermogravimetric and differential-thermogravimetric analyses (TG/DTG) as well as differential scanning calorimetry (DSC). Chemical analysis indicated that tucuma seeds oil content was around 21% (w/w). The oil was rich in low molecular weight fatty acids, with lauric acid being the major constituent (38%), followed by oleic (24.8%) and myristic (17.9%) acids. The 1 H NMR spectra of the biodiesel produced revealed that all samples were free from contamination of triacylglycerol oil, indicating the efficiency of the transesterification process. The TG/DTG and DSC analyses indicated similar thermal behavior for both biofuels, but the ethylic biodiesel exhibited exothermals at lower temperatures, in the cooling cycles, which suggested better cold properties. The predicted CFPP value was −8.8 °C for ethylic biodiesel.

This study was conducted to evaluate the effect of ractopamine concentrations on swine fat and meat lipid profiles. Ninety finishing barrows, initially weighing 71.9±4.4kg, were distributed in a randomized block design in three ractopamine concentrations (0, 10 and 20ppm) with fifteen replicates of two animals in each. Gas chromatography was used to analyze the lipid profiles of backfat and meat. The inclusion of ractopamine in the diet changed (P0.05) any of the other fatty acids or indexes evaluated. In the meat, a significant effect (P0,05) nenhum dos outros ácidos graxos ou índices avaliados. Em relação à gordura da carne, houve efeito (P

We report herein the design and synthesis via click chemistry of twelve novel triazole retinoid analogues of tamibarotene (AM80) and the evaluation of their anticancer activities against six cancer cell lines: HL60, K562, 786, HT29, MCF7 and PC3. Among the synthesized compounds, two were more potent than tamibarotene against solid tumor cells, and one of them had similar potency to tamibarotene against HL60 cells. The bioisosteric exchange between the amide group and the 1,2,3-triazole core in the retinoid agent tamibarotene (AM80) reported in this work is a valid strategy for the generation of useful compounds against cancer.

The development of electroanalytical methods for determining three or more analytes simultaneously in a complex sample is highly desirable. Unfortunately, this is not an easy task in electrochemical studies of organic compounds, and alternative methods to achieve this goal have been increasingly sought in recent years. To this end, the present investigation employed a combination of screen-printed electrodes (SPEs), cetyltrimethylammonium bromide (CTAB), and a peak deconvolution procedure as an alternative approach to improve the sensitivity and selectivity in the simultaneous determination of three antioxidants in samples of biodiesel and cosmetic oils. The use of CTAB also prevents the occurrence of SPE fouling by matrix constituents, being essential in the simultaneous detection of the antioxidants tert-butylhydroquinone (TBHQ), propyl gallate (PG), and butylhydroxyanisole (BHA). Under optimized conditions, the limit of detection proved satisfactory, with relative standard deviations of 0.99% for TBHQ, 2.1% for PG, and 0.61% for BHA, indicating that the method has satisfactory repeatability. The approach was successfully applied to determine the target antioxidants in biodiesel samples at different concentrations after simple, rapid dilution, yielding recovery rates of 98–106% for TBHQ, 98–103% for PG, and 92–101% for BHA. In the analysis of cosmetic oils, a deconvolution procedure was applied to achieve separation of the oxidation peak potentials, with recovery rates of 94% for PG and 101% for BHA using the standard addition method. The results were satisfactory compared with those obtained using high-performance liquid chromatography.

This study was conducted to evaluate the effects of net energy levels on the lipid profile of adipose tissue and muscle of swines. A total of 90 animals, with initial weight of 71.94±4.43kg, were used, and distributed in a randomized block design in five net energy levels (2,300, 2,425, 2,550, 2,675, and 2,800Kcal kg-1 feed), with nine replicates and two animals per experimental unit. Lipid profiles of adipose tissue and muscle were analyzed using gas chromatography. Increasing the levels of net energy using soybean oil, improved the lipid profile of adipose tissue and muscle, increased linearly (P

A simple synthesis of 3-iodothiophenes was demonstrated using a wide range of (Z)-thioenynes. The key step in the iodocyclofunctionalization was the selective reduction of the triple bond in (Z)-thioenynes by the addition of iodine as an electrophilic agent. The 3-iodothiophenes were obtained in good to excellent yields of 61–92%. The 3-iodothiophenes were used as substrates in Sonogashira cross-coupling reactions to obtain thiophene acetylenes.

The objective of the present work was to study the oxidative stability (OS) estimated from the induction period (IP) and the cold filter plugging point (CFPP) of blends made with different proportions of soybean methyl biodiesel (BOS) and bovine tallow methyl biodiesel (BSB). BOS is poorly resistant to oxidation because its composition is predominantly unsaturated esters, but it has a satisfactory cold filter plugging point. The BSB is composed of saturated esters and of the lower carbon chain and thus has good oxidation stability values, but has poor CFPP values. Thus, BOS / BSB mixtures in different proportions were made to evaluate the ideal amount of the mixture in which it was possible to obtain IP and CFPP properties in satisfactory values by the legislation. The mixtures started at 10% BSB and 90% BOS and was increased 5% up to the 50% percentage of each biodiesel in each blend. Samples with 45% and 50% BSB had oxidative stability above the minimum required by law, and all blends had the CFPP value within the legal values.

An electroanalytical method for the simultaneous detection and quantification of tert -butylhydroquinone (TBHQ) and butyl hydroxyanisole (BHA) in biodiesel was developed using a voltammetric technique and screen-printed electrodes. The supporting electrolyte solution was composed of Britton–Robinson buffer (0.04 mol L −1 ) containing methanol (2.0%) and the cationic surfactant cetyltrimethylammonium bromide (CTAB). In the presence of CTAB, the peak current intensity and voltammetric resolution increased significantly for both studied antioxidants. Using the optimized conditions, the method presented a linear response in the concentration range of 5.0 × 10 −7 –1.0 × 10 −5 mol L −1 for TBHQ ( r = 0.999) and BHA ( r = 0.999) with detection limits of 3.40 × 10 −7 mol L −1 and 1.76 × 10 −7 mol L −1 , respectively. The proposed method was successfully applied for the quantification of TBHQ and BHA in biodiesel samples after a simple and rapid dilution with recoveries from 97.90% to 110.0% and 91.90% to 101.0%, respectively. The obtained results were satisfactory when compared with those obtained using high-performance liquid chromatography (HPLC). Additionally, the proposed method can be easily adapted for on-site analysis.

Hydrothiolation of symmetrical and unsymmetrical buta-1,3-diynes with sodium organylthiolate anions in reflux, generated in situ by reacting C 4 H 9 SH with NaOH, afforded ( Z )-organylthioenynes in low to good yields (25–80%). By using tetrabutylammonium hydroxide (TBAOH) as base instead of NaOH, the hydrothiolation of buta-1,3-diynes was more rapid and efficient, providing ( Z )-organylthioenynes in good to excellent yields (70–95%).

Os óleos de frutos estão sendo estudados por seu potencial na indústria de alimentos e também para aumento do consumo de ácidos graxos monos e poli-insaturados. Este estudo objetivou determinar as constantes físico-químicas, composição centesimal, identificar e quantificar os principais ácidos graxos presentes na fração lipídica da polpa e da amêndoa dos frutos de guarirova, espécie Syagrus oleracea (Mart.) Becc. Foi realizada a caracterização físico-química dos óleos, composição de ácidos graxos e índices de qualidade nutricional. O óleo da amêndoa possui maior concentração de ácidos graxos saturados (89,2%), sendo representado principalmente pelo ácido láurico (48,34%). A polpa apresentou ácidos graxos monoinsaturados (24,84%) e poli-insaturados (33,25%), com maior percentual de ômega-6 (31,94%) e ômega-9 (19,15%); e menor de ômega-3 (1,31%). The oils of fruits are being studied for its potential in the food industry and also to increase the consumption of mono and polyunsaturated fatty acids. This study aimed to determine the physio-chemical constants, chemical composition and identify and quantify the major fatty acids present in the lipid fraction of pulp and kernel of the fruits of guarirova, species Syagrus oleracea (Mart.) Becc. It was performed the physicochemical characterization of oils, fatty acid composition and nutritional quality indexes. Almond oil has the highest concentration of saturated fatty acids (89,2%), represented mainly by lauric acid (48,34%). The pulp showed monounsaturated (24,84%) and polyunsaturated fatty acids (33,25%), with higher percentage of omega-6 (31,94%) and omega-9 (19,15%) and lower omega-3 (1,31%).

The hydroalumination of silylacetylenes with DIBAL-H followed by the addition of n-butyllithium generated in situ the (Z)-β-vinylorganosilane alanates intermediates, which were trapped with butyltellurenyl bromide (C4H9TeBr), furnishing exclusively the (E)-1-butyltelluro-1-tri(organyl)silyl-2-organyl-1-alkenes in 45–70% yields. These telluro(silyl)ketene acetals were utilized as substrates in Sonogashira cross-coupling Pd-catalyzed reactions, furnishing the (Z)-1,4-diorganyl-2-tri(organyl)silyl-1-buten-3-ynes with total control of regio- and stereochemistry in 62–80% yield.

Sonogashira cross-coupling reactions involving ( E )-iodo vinyl stannanes and terminal acetylenes were carried out in the presence of Pd(PPh 3 ) 4 , CuI and several amines, affording ( Z )-tributylstannyl enynes in moderate to good yields (62–91%). Utilizing the catalytic system containing Pd(PPh 3 ) 4 (5%), CuI (10%), and TBAOH (40% in aqueous media) as activator, better yields (72–91%) and lower reaction times were achieved.

This paper reports an electroanalytical method developed for tert-butylhydroquinone (TBHQ) determination in biodiesel in the presence of surfactant Triton X-100 (T-100). T-100 was shown to improve the electroanalytical signal and its use was decisive for direct analysis of TBHQ in biodiesel, only requiring previous dilution of biodiesel samples in methanol. Several parameters were studied and optimized for the development of this methodology. Under optimal conditions, oxidation peak current was proportional to TBHQ concentration in the range of 1.05–10.10 × 10−6 mol L−1, with limits of detection and quantification of 3.43 × 10−8 mol L−1 and 1.14 × 10−7 mol L−1, respectively, by square wave voltammetry (SWV). The results achieved with the proposed method were satisfactory, relative to those obtained using high-performance liquid chromatography (HPLC).

Hydrothiolation of 1-organylbuta-1,3-diynes and 1,4-di-organylbuta-1,3-diynes with the sodium organylthiolate anions,which were generated in situ by reacting diphenyl and dibutyl di-sulfide with NaBH 4 in ethanol, results in the regio-, stereo-, andchemoselective formation of ( Z )-1-organylthio-4-organylbut-1-en-3-ynes and ( Z )-1-organylthio-1,4-diorganylbut-1-en-3-ynes, re-spectively. Key words: hydrothiolation, organylthiolate anion, vinyl sulfides,1,3-diacetylenes, ( Z )-1-organylthiobut-1-en-3-ynes Vinyl sulfides are present in naturally occurring com-pounds with important biological activity. 1 Griseoviridin,for example, is a type A streptogramin antibiotic, first iso-lated from Streptomyces graminofaciens , 1a,b and benzyl-thiocrellidone is a yellow pigment isolated from thebright-red sponge Crella spinulata . 1c These compounds are versatile and useful intermediatesin organic synthesis. 2–13 They can be converted into thecorresponding aldehyde, ketone, 2 carboxylic acid, orester

Forty four samples of type C gasoline, obtained from service stations of five different distributors, and samples of type A gasoline were analyzed by gas chromatography–flame ionization detection (GC–FID) using a low-polarity capillary column. Linear retention indices (LRI) were calculated, and individual components of the gasoline samples were characterized using a detailed hydrocarbon analysis software (StarDHA™). The quantitative data obtained by the chromatographic method were compared with data obtained by official standard methods. Hierarchical cluster analysis was used to determine the degree of similarity between the samples. Detailed hydrocarbon analysis revealed that some of the samples from service stations were probably adulterated with organic solvents.

In this work, different procedures were compared for the extraction of synthetic antioxidants such as propyl gallate (PG), tert-Butylhydroquinone (TBHQ), 3-tert-butyl-4-hydroxyanisole (BHA) and 3,5-di-tert-butyl-4 hydroxytoluene (BHT) from biodiesel samples. The efficiency of target procedures was tested using liquid-liquid extraction and solid phase extraction containing different stationary phase. To accomplish this efficiency and determine the antioxidants, a method based on high performance liquid chromatography coupled with diode array detector (HPLC / DAD) was optimized. In liquid-liquid extraction was used acetonitrile and n-hexane, however, only acetonitrile presented selectivity, able to extract just PG and BHA, with recovery between 78.3 and 96.0%. Using solid phase extraction cartridges containing C-18 as stationary phase, only the PG and BHA were extracted, which the recovery was between 52.4 and 99.7%. Moreover, the macroporous poly(divinylbenzene-co-N-vinylpyrrolidone) polymer presented satisfactory results for the extraction of PG and BHA with recovery between 77.3 and 103 %. All these procedures provided elimination of the sample interferences, allowing recovery with coefficients of variation always lower than 1.00%. However, the comparison of liquid-liquid extraction and solid phase extraction techniques proved that there are many difficulties in extracting, with precision and accuracy, the PG, TBHQ, BHA and BHT antioxidants contained simultaneously in complex samples such as biodiesel. These difficulties are increased when the interest is to reduce the costs of analysis by reducing organic solvent extractors and propose extraction techniques with considerable environmental benefits. DOI: http://dx.doi.org/10.17807/orbital.v7i2.672

Topical administration of powdered shells of the land snailMegalobulimus lopesiwas evaluated in Wistar rats for their healing activity in an excision wound model. The animals were distributed into three groups—G1 (control): no therapeutic intervention; G2 (vehicle controls): Lanette cream once daily; G3 (experimental animals): treated with powdered shells. Variables investigated were: wound area contraction, angiogenic activity, morphometric data, leukocytic inflammatory infiltrate, and total leukocyte count in peripheral blood. Thermogravimetric analysis and quantification and characterization of powdered shell proteins were also performed. Wound area on days 3, 7, and 14 was smaller in G3, besides presenting wound closure on day 21 for all these animals. Topical administration of the powdered shells also led to an increased number of vessels at the wound site, higher leukocyte counts in peripheral blood, and increased leukocytic inflammatory infiltrate. The results lend support to the southern Brazilian folk use ofM. lopesipowdered shells, as shown by the enhanced secondary-intention healing achieved with their topical administration to wounds in rats. Topical administration caused inflammatory response modulation, crucial to accelerating the healing process, the chronification of which increases the risks of wound contamination by opportunistic pathogens.

The search for new biologically active compounds and, consequently, with possible use in the treatment of various diseases has been increasing in recent decades. In this study we used the bioisosterism as molecular modification strategy of the neoliganans grandisin and veraguensina what are the natural compounds with biological activity against neglected diseases. The isoxazolic heterocyclic ring was chosen as substituent of the tetrahidrofuranic rings found in these neolignans. In order to obtain more potent compounds with fewer side effects and better physicochemical characteristics, in this study were synthesized 12 isoxazolic analogues, these were sent for antileishmania and anti-trypanosomal biological activity testing, which provided us important informations about the structure-activity relationship.

Organochalcogene compounds (S, Se and Te) have been investigated in recent decades because of their many applications in synthetic organic chemistry, preparation of new materials, and medicinal chemistry. Among them, the thiophene group has emerged in recent years as one of the most-studied compounds by synthetic organic chemists, due to being found in various chemical compounds, with a broad range of applications in the electronics industry to produce electroluminescent diodes (OLED), organic field effect transistors (OFET), photovoltaic cells, sensors, semiconductors, liquid crystals and "displays". 1 Because of the strong interest in the synthesis of new thiophene compounds and its applications, in this communication we show our results in the synthesis of thiophene acetylenes through Sonogashira cross coupling reactions. 2

A new, short total synthesis of dihydroactinidiolide 1 is described using selenium carbenium ion-promoted carbon–carbon bond formation as the key step. Our synthetic strategy starts with a lactonization reaction between 1,3,3-trimethylcyclohexene 13 and α-chloro-α-phenylseleno ethyl acetate 14, affording the key intermediate, α-phenylseleno-γ-butyro lactone 15, which reacted via a selenoxide elimination to the target compound 1.

The hydrothiolation reaction in the presence of TBAOH and NaOH have proved to be highly region-, stereo-, and chemoselective. However, the five examples of (Z)-thiobutenynes synthesized by new approach were obtained in better yields and shorter reaction time than ones prepared only using NaOH (Table 1). Table 1. (Z)-thiobutenynes synthesized (Z)-thiobutenynes Time (Yield %) NaOH Time (Yield %) TBAOH

This paper reports an electroanalytical method developed for determining the antioxidant tert-butylhydroquinone (TBHQ) in biodiesel, based on the enhancement effect of cetyltrimethylammonium bromide (CTAB). In pH 6.5 Britton–Robinson buffer, a poorly defined oxidation peak was observed for TBHQ at a carbon paste electrode (CPE). In the presence of low concentrations of CTAB, however, the oxidation peak current was markedly increased. Several parameters were studied and optimized for the development of this methodology, and under optimal conditions the oxidation peak current was proportional to TBHQ concentration in the range of (1.05–10.15) × 10 −6 mol L −1 , with limits of detection and quantification of 7.11 × 10 −8 mol L −1 and 2.37 × 10 −7 mol L −1 , respectively, by linear sweep voltammetry (LSV). The method was applied to TBHQ determination in soybean biodiesel samples. The results were satisfactory in comparison with those obtained using high-performance liquid chromatography (HPLC).

Hydrothiolation of 1-organylbuta-1,3-diynes and 1,4-di-organylbuta-1,3-diynes with the sodium organylthiolate anions,which were generated in situ by reacting diphenyl and dibutyl di-sulfide with NaBH 4 in ethanol, results in the regio-, stereo-, andchemoselective formation of ( Z )-1-organylthio-4-organylbut-1-en-3-ynes and ( Z )-1-organylthio-1,4-diorganylbut-1-en-3-ynes, re-spectively. Key words: hydrothiolation, organylthiolate anion, vinyl sulfides,1,3-diacetylenes, ( Z )-1-organylthiobut-1-en-3-ynes Vinyl sulfides are present in naturally occurring com-pounds with important biological activity. 1 Griseoviridin,for example, is a type A streptogramin antibiotic, first iso-lated from Streptomyces graminofaciens , 1a,b and benzyl-thiocrellidone is a yellow pigment isolated from thebright-red sponge Crella spinulata . 1c These compounds are versatile and useful intermediatesin organic synthesis. 2–13 They can be converted into thecorresponding aldehyde, ketone, 2 carboxylic acid, orester

In this study we describe an experimental procedure based on a chemical industrial process of soya-bean oil extraction applied in general chemistry for undergraduate students. The experiment was planned according to the Science, Technology and Society (STS) approach to teach basic chemical concepts and provide grounding in the management of environmental care. The use of real life chemistry problems seems to salient the relevance of chemistry to our students and enhances their motivation to learn both the practical and theoretical components of the discipline.