Accessibility / Report Error
Journal of the Brazilian Chemical Society, Volume: 31, Issue: 8, Published: 2020
  • Dreaming is a Must, Despite the Current Crisis Editorial

    Rocha-Filho, Romeu C.
  • Tenofovir Disoproxil Fumarate: New Chemical Developments and Encouraging in vitro Biological Results for SARS-CoV-2 Communication

    Clososki, Giuliano C.; Soldi, Rafael A.; Silva, Rodrigo M. da; Guaratini, Thais; Lopes, José N. C.; Pereira, Pâmela R. R.; Lopes, João L. C.; Santos, Thiago dos; Martins, Ronaldo B.; Costa, Cristina S.; Carvalho, Andréia N. de; da Silva, Luis L. P.; Arruda, Eurico; Lopes, Norberto P.

    Abstract in English:

    The recent emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led society to live with a serious public health problem. In this sense, repositioning of antiretrovirals has captured the attention of the scientific community. Tenofovir disoproxil fumarate (TDF) is an antiretroviral compound that is used to treat acquired immune deficiency syndrome (AIDS) and hepatitis B. In this short report, we present a scale-up investigation of TDF by in situ infrared spectroscopy monitoring and a forced degradation study to describe a new degradation product. Finally, we have evaluated TDF in vitro for SARS-CoV-2 for the first time foreseeing the using of this medicine in pre-clinical and clinical investigations for the COVID-19 (coronavirus disease 2019) treatment.
  • Chemoenzymatic Synthesis and Anti-Inflammatory Activity of Fatty Acid Amides Prepared from Bertholletia excelsa (Brazil Nut) Triglycerides Articles

    Barata, Pedro H. S.; Sarquis, Ícaro R.; Carvalho, Helison O.; Barros, Albenise S.; Rodrigues, Alex B.; Galue-Parra, Adan J.; Silva, Edilene O.; Carvalho, José Carlos T.; Ferreira, Irlon M.

    Abstract in English:

    This study reports the synthesis of fatty acid amides (FAA), analogous to anandamide, prepared from Brazil nut oil (BNO), using Amano lipase from Pseudomonas fluorescens as a catalyst of direct aminolysis, with a good yield (95-68%). The anti-inflammatory effects of BNO and FAA were evaluated by the carrageenan-induced paw edema method. Analysis of the formation of edema showed that these FAA, at all dose used, significantly reduced the development of edema.
  • Antimicrobial High-Density Polyethylene (HDPE)/ZnO Nanocomposites Obtained by in situ Polymerization Articles

    Pavoski, Giovani; Kalikoski, Renan; Souza, Gustavo; Baldisserotto, Daniel; Brum, Luiz Fernando W.; Santos, Cristiane dos; Bergmann, Carlos; Brandelli, Adriano; Jacobi, Marly; Galland, Griselda B.

    Abstract in English:

    Nanostructured zinc oxide (ZnO) prepared by combustion in solution was used to obtain nanocomposites. The ZnO particles were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), and scanning electron microscopy (SEM), showing crystallite size of 32 nm and a superficial area of 32.6 m2 g-1. Nanocomposites with 1, 3, and 5 wt.% of ZnO in the polymeric matrix were obtained using the in situ polymerization of ethylene with catalytic activities between 1500-1700 kg (molZr h PE)-1. The high-density polyethylene nanocomposites (PEZnO) were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), SEM, and transmission electron microscopy (TEM). The nanocomposites with 1 wt.% ZnO gave excellent mechanical properties, and all were active against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria.
  • A Simple and Effective Liquid-Liquid-Liquid Microextraction Method with Ultraviolet Spectrophotometric Detection for the Determination of Bisphenol A in Aqueous Matrices and Plastic Leachates Articles

    Huelsmann, Ricardo D.; Martendal, Edmar

    Abstract in English:

    This study shows the development and application of an analytical method for the determination of bisphenol A (BPA) in aqueous samples such as tap, river and mineral water and plastic leachates, based on an extensive literature search to understand the gaps for the determination of BPA in aqueous samples. We found that most of the methods in the literature employ some chromatographic strategy, and, to a much lesser extent, non-chromatographic instrumentation. In this scenario, we show an ultraviolet spectrophotometric-based method that can be used for routine analysis. Sample preparation was conducted by means of solvent extraction followed by back-extraction into an alkaline aqueous solution (liquid-liquid-liquid microextraction) and the detection was performed by UV spectrophotometry at 294 nm. Optimization of variables affecting both extraction and back-extraction was conducted, and the optimal extraction conditions were obtained: 85 mL aqueous sample buffered at pH 10, ionic strength adjusted with NaCl to a 2 mol L-1 final concentration, extraction with 6 mL of ethyl ether for 10 min and back-extraction into 0.5 mL of 2 mol L-1 aqueous NaOH. The following quality parameters were obtained: determination coefficient (R2) > 0.999, intra and inter-day repeatability better than 7.8% and 300 enhancement factor. The method was applied in different aqueous samples with excellent recovery and precision results, and no BPA was detected in natural water, even with the excellent limit of detection (3.5 μg L-1) and limit of quantification obtained. Limitations of this method involve analysis of samples with humic acid concentrations higher than 2 mg L-1 or high concentration of phenols and/or phthalate esters.
  • Preparation and Characterization of the β-Cyclodextrin Inclusion Complex with Benzbromarone Articles

    Sousa, Iran L.; Porto, Caio M.; Bassani, Kátia C.; Martins, Milene H.; Pessine, Francisco B. T.; Morgon, Nelson H.

    Abstract in English:

    Benzbromarone (BZB) is a drug that has diuretic activity and is used in the gout treatment. Its therapeutic efficiency is decreased by its low water solubility (11.8 mg L-1) and highly hydrophobic aspect (logP 2.7), which are responsible for affecting its intestinal absorption and bioavailability. BZB inclusion complex (IC) aims at increasing the drug solubility in water and reduce adverse effects resulting in more efficient formulations. The coprecipitation encapsulating method was used to obtain the IC of BZB in β-cyclodextrin (β-CD) and the complex (BZB@β-CD) was characterized via physical-chemical analysis. A comparative study of time-dependent density functional theory (TD-DFT) and configuration interaction singles (CIS), along with “our own N-layered integrated molecular orbital and molecular mechanics” (ONIOM) method, has been carried out on the UV-Vis absorption of BZB and BZB@β-CD. The qualitative description of the simulated spectrum, given by ONIOM(CIS:PM6), is in accord with the formation of BZB@β-CD. It only became possible when phosphate buffer (pH 7.4) was used to prepare the solutions, since the complex formation did not occur in deionized water or buffered acid. Furthermore, by using the Job plot, the Scatchard method and fluorescence, it was possible to conclude that the complex molecular stoichiometry was 1:1 (1 BZB to 1 β-CD).
  • Catalytic Dehydration of Glycerol to Acrolein over Aluminum Phosphate Catalysts Articles

    Ma, Tianlin; Ding, Jianfei; Liu, Xueli; Zheng, Jiandong; Yun, Zhi

    Abstract in English:

    Gas phase conversion of glycerol to acrolein over a variety of aluminum phosphate (AlP) catalysts synthesized by a simple replacement reaction method with a variation in calcination temperature (300-700 ºC, AlP-300, AlP-400, AlP-500, AlP-600, and AlP-700, respectively) has been investigated. The textural properties, acidities and coke contents of the samples were also determined. The catalysts were presented in an amorphous state when the AlP sample was calcined below 500 ºC. Further increasing the calcination temperature promoted the formation of orthorhombic α-AlPO4 crystal. The weak acid sites increased when the calcination temperature was raised from 300 to 500 ºC. However, the weak acid sites decreased when the AlP was calcined above 500 ºC. The acidity of the catalyst played a crucial role in the glycerol dehydration reaction. The maximum acrolein selectivity of 66% at 98% glycerol conversion was obtained over AlP-500 catalyst, due to the largest number of acid sites and appropriate textural properties. AlP-700 exhibited the lowest glycerol conversion, owing to the formation of orthorhombic α-AlPO4 crystalline phase and the lowest amount of acid sites under high calcination temperature. The significant reduction in the acidity of the used sample led to a decrease of glycerol conversion.
  • New Synthetic Quinolines as Cathepsin K Inhibitors Articles

    Silva, Taynara L.; Bartolomeu, Aloisio de A.; Jesus, Hugo C. R. de; Oliveira, Kleber T. de; Fernandes, João B.; Brömme, Dieter; Vieira, Paulo C.

    Abstract in English:

    Cathepsin K is a papain-like cysteine protease and is responsible for collagen degradation in bone tissue and thus represents an important target for the development of new therapies for treating diseases such as osteoporosis. Quinolines are an important class of heterocyclic molecular leads with a great pharmacological potential and represent a relevant scaffold to explore the chemical space of cathepsin K (CatK) inhibitors. This study presents the synthesis of nine 2,4-diphenylquinolines, including five phthalonitrile quinolines dyads, and the evaluation of their CatK inhibitory activity. Among the evaluated compounds, 4b was the most potent inhibitor with an IC50 (half-maximal inhibitory concentration) value of 1.55 µM (against Z-Phe-Arg-MCA substrate) acting in an uncompetitive inhibition mode. Molecular docking studies provided important information on the interaction of the inhibitor with the enzyme showing that these quinoline derivatives can play an important role as CatK inhibitors.
  • Chitosan Nanoparticles Loaded with Carvacrol and Carvacryl Acetate for Improved Anthelmintic Activity Articles

    André, Weibson P. P.; Paiva Jr., José R.; Cavalcante, Géssica S.; Ribeiro, Wesley L. C.; Araújo Filho, José V. de; Cavalcanti, Bruno C.; Morais, Selene M. de; Oliveira, Lorena M. B. de; Bevilaqua, Claudia M. L.; Abreu, Flávia O. M. S.

    Abstract in English:

    Carvacrol (CV) and carvacryl acetate (CVA) are bioactive compounds that have anthelmintic action and the nanoencapsulation may be an alternative to potentialize their efficacy. The aim of this work was to nanoencapsulate CV and CVA using chitosan/gums and evaluate cytotoxicity and the anthelmintic activity. A 24 factorial experimental design was performed to determine the influence of gum type (arabic or chichá), amount of surfactant and the number of layers in the nanoencapsulation degree. CVA and CV presented encapsulation efficiency (EE) optimum values of 90 and 20% (experiments 8 and 9), respectively. The monolayer and bilayer formulations presented maximum size of 479 and 811 nm, respectively. Nanoencapsulated CVA (nCVA) with bilayer coating and higher surfactant levels showed good thermal stability and no toxicity. In vitro kinetics for nCVA with chitosan/chichá gum showed slower release profiles than nCVA with chitosan/gum arabic, with 50% release after 30 and 20 h, respectively. CVA and nCVA at a concentration of 150 µg mL−1 reduced the motility of H. contortus adult nematodes by 100 and 91.7%, respectively. In summary, nCVA chitosan/chichá gum showed high encapsulation efficiency, favorable release rate and anthelmintic activity against H. contortus.
  • Chemical and Spectroscopic Characteristics of Anthrosol (Amazonian Dark Earth) and Surrounding Soil from the Brazilian Amazon Forest: Evaluation of Mineral and Organic Matter Content by Depth Articles

    Bento, Lucas R.; Constantino, Isabela C.; Tadini, Amanda M.; Melo, Camila A.; Ferreira, Odair P.; Moreira, Altair B.; Bisinoti, Márcia C.

    Abstract in English:

    The chemical and spectroscopic characteristics of soil organic matter (SOM) isolated from Amazonian dark earth (ADE) and surrounding soil (SR) were evaluated according to the soil depth. The results showed opposite trends for the soils. While ADE featured SOM with a greater aromatic condensation degree and greater hydrophobicity in the top layer, the SR showed more aliphatic and polar SOM. The SOM arrangement from ADE was less hydrophobic, aromatic, and more polar in depth. In contrast, the SOM from SR showed an increase in molecular weight and hydrophobicity. Besides the aromatic protection in the SOM from ADE, there was organo-mineral protection through binding to soil minerals. This suggested that the SOM from ADE was protected by its hydrophobicity and interaction with minerals compared with that from the SR, thereby showing that the combination of both characteristics is important to create new technologies for soil carbon storage.
  • A Simple Fluorescent Chemosensor for Detection of Zinc Ions in Some Real Samples and Intracellular Imaging in Living Cells Articles

    Aziz, Ayman A. A.; Aboelhasan, Amir E.; Sayed, Mostafa A.

    Abstract in English:

    A new designed fluorescent chemosensor TYMN ((E)-1-((thiazol-2-ylimino)methyl)naphthalen-2-ol) for highly sensitive and selective tracing of trace amount of Zn2+ ions in some real samples was synthesized and characterized. The sensor TYMN can detect Zn2+ ions via fluorescence enhancement with a high selectivity over a wide range of metal ions, especially Cd2+. The sensor showed large fluorescence enhancement upon complexation with Zn2+ and simultaneous color change from yellow to orange. The limit of detection was analyzed to be 0.0311 μM with a linear dynamic range 0.1-1.0 μM. The sensor could work in a pH span of 5.0-8.0. Based on the physicochemical and analytical methods like electrospray ionization (ESI)-mass, Job plot, 1H nuclear magnetic resonance (NMR) and theoretical calculations, the detection mechanism for Zn2+ was explained based on restriction of internal charge transfer (ICT) mechanism. TYMN sensor was potentially utilized for Zn2+ ions concentration evaluation in some real samples. Fluorescence microscopy experiments revealed that probe TYMN may have application as a fluorophore to detect the Zn2+ in living cells.
  • Synthesis of ZnO Nanoparticles by the Sol-Gel Protein Route: A Viable and Efficient Method for Photocatalytic Degradation of Methylene Blue and Ibuprofen Articles

    Silva, Emilly C. da; Moraes, Maria O. S. de; Brito, Walter R.; Passos, Raimundo R.; Brambilla, Rodrigo F.; Costa, Luiz P. da; Pocrifka, Leandro A.

    Abstract in English:

    The photocatalytic degradation of methylene blue dye and ibuprofen drug was studied in the presence of zinc oxide, synthetized by the protein sol-gel route. The catalyst, calcined at 1000 ºC, presented a tendentious morphology to filaments characteristic of ZnO crystalline, characterized by X-ray diffraction (XRD) and confirmed by the presence of Zn energy band in X-ray photoelectron spectrometer (XPS). The result of ultraviolet (UV) light photodegradation of this work is comparable to others that made use of more complex routes, considering the degradation of 97% of methylene blue dye solution and the solution of the ibuprofen drug reached 60% of degradation after 1 h of light incidence. In this research, it is possible to report good degradation results, and the research differential is a material made with a simple and less aggressive route, capable of generating a stable and efficient material.
  • Biodegradation of the Pyrethroid Pesticide Esfenvalerate by a Bacterial Consortium Isolated from Brazilian Savannah Articles

    Anjos, Charlene S. dos; Birolli, Willian G.; Porto, André L. M.

    Abstract in English:

    New biocatalysts for bioremediation techniques are necessary nowadays. Therefore, a bacterial consortium isolated from Brazilian Savannah was employed for biodegradation of 100 mg L-1 esfenvalerate in liquid culture medium. The bacterial consortium (Lysinibacillus xylanilyticus CBMAI2085, Bacillus cereus CBMAI2067, Lysinibacillus sp. CBMAI2051 and Bacillus sp. CBMAI2052) biodegraded this pyrethroid efficiently. The assays were conducted in triplicate, and after 12 days, 90% of the pesticide was degraded producing 3-phenoxybenzoic acid (35.0 ± 3.1 mg L-1) and 2-(4-chlorophenyl)-3-methylbutanoic acid (34.0 ± 2.8 mg L-1). The bacterial consortium (52 ± 5% biodegradation) was more efficient in the biodegradation than the average of the same strains solely employed (40 ± 7% biodegradation), showing that the use of consortia is an interesting approach. However, the strain Bacillus cereus CBMAI2067 (67 ± 3% biodegradation) was more efficient than the bacterial consortium, showing its potential as source of carboxylesterases and proving that, in this case, the use of a unique efficient strain is more adequate.
  • Evaluation of the Oxidation Degradation Process of Biodiesel via 1H NMR Spectroscopy Articles

    Mantovani, Ana Carolina G.; Chendynski, Letícia Thaís; Galvan, Diego; Borsato, Dionísio; Mauro, Eduardo Di

    Abstract in English:

    Biodiesel is a suitable alternative to replace the petro-diesel. The biodiesel is formed by unsaturated esters easily degraded by interferences of oxygen, temperature, contact with metals or contaminants. The aim of this research was to investigate the biodiesel degradation process via 1H nuclear magnetic resonance (NMR) spectroscopy, observing the olefinic, bis-allylic and allylic protons signals of the chemical bonds, and by the induction period of the Rancimat. Biodiesel samples with metallic ions (Fe and Cu) and with rosemary natural extract were analyzed. The metal compounds showed a catalytic effect in the samples and the rosemary natural extract showed to be efficient by retarding the degradation process. The extract was ineffective in the presence of iron. Through the 1H NMR spectra was possible to observe changes in the signal intensities of the olefinic, bis-allylic and allylic protons as well as the formation of oxidation products in the biodiesel in the degradation process.
  • New Diesters Derived from Piperine: in silico Study and Evaluation of Their Antimicrobial Potential Articles

    Trindade, Emmely O.; Souza, Helivaldo D. S.; Brandão, Maria Cláudia R.; Neto, Hermes D.; Lima, Edeltrudes O.; Lira, Bruno F.; Athayde-Filho, Petrônio F. de; Barbosa-Filho, José M.

    Abstract in English:

    Piperine, previously extracted from black pepper (Piper nigrum L.), was used as a precursor for the synthesis of twelve new diester derivatives. The final products were obtained through the bimolecular nucleophilic substitution reaction (SN2) of the alkyl 2-chloroacetates and the salt of piperic acid, obtained from the basic hydrolysis of piperine. The compounds were synthesized with yields of 55-84% and characterized by infrared spectroscopy and 1H and 13C nuclear magnetic resonance. The evaluation of the compounds’ potential as new drug candidates was done through an in silico study of ADME properties (absorption, distribution, metabolization and excretion) and evaluation of antimicrobial activity against bacterial strains (Staphylococcus aureus and Pseudomonas aeruginosa), yeasts (Candida albicans and Candida tropicalis) and filamentous fungi (Aspergillus fumigatus, Aspergillus flavus and Aspergillus niger). The in silico study showed that the compounds were good drug candidates and antimicrobial evaluation demonstrated that 9 of the 12 compounds exhibited a minimum inhibitory concentration (MIC) ranging 1024-256 μg mL-1.
  • Copaifera multijuga, Copaifera pubiflora and Copaifera trapezifolia Oleoresins: Chemical Characterization and in vitro Cytotoxic Potential against Tumoral Cell Lines Articles

    Carneiro, Luiza J.; Tasso, Thercius O.; Santos, Mario F. C.; Goulart, Mirian O.; Santos, Raquel A. dos; Bastos, Jairo K.; Silva, Jonas J. M da; Crotti, Antônio E. M.; Parreira, Renato L. T.; Orenha, Renato P.; Veneziani, Rodrigo C. S.; Ambrósio, Sérgio R.

    Abstract in English:

    Copaifera species (Fabaceae) comprises approximately 70 species of large trees, from which 16 can be found in Brazil. The oleoresins obtained from their trunk are widely used in Brazilian folk medicine, which display important antitumoral potential. Chemically, these oleoresins are mainly composed of a mixture of sesquiterpenes and diterpenes. In this paper we are describing the isolation and identification of 12 already known terpenes from oleoresins obtained from three different Copaifera species (C. multijuga, C. pubiflora and C. trapezifolia) and 2 novel diterpenes (ent-16-hidroxy-3,13 clerodadien-15,18-dioic acid and ent-labda-5,13-dien-15-oic acid) from C. trapezifolia. Both new compounds were identified by nuclear magnetic resonance (NMR) spectroscopic (1H and 13C NMR, correlation 1H-1H (COSY), heteronuclear multiple quantum coherence (HMQC) and heteronuclear multiple bond correlation (HMBC)) and by high-resolution electrospray ionization mass spectrometry (HR-ESIMS) analyses. The cytotoxic potential of these oleoresins, their main non-volatile compounds and their volatile compound fractions were evaluated against a panel of tumoral (MCF-7, ACP01, A549, HeLa) and normal cell lines (MCF-10A, GM07492-A) through XTT (tetrazolium salt) and SRB (sulforhodamine B) assays. The novel diterpene ent-labda-5,13-dien-15-oic acid displayed relevant cytotoxic effect against most of the cancer cell lines with mean inhibitory concentration (IC50) values ranging from 3.57 ± 1.12 to 22.56 ± 1.03 µg mL-1, and a high selectivity level in both assays.
  • 1H NMR and Chemometric Methods to Estimate the Octane Number in Brazilian C Gasolines Articles

    Pinto, Vinícius S.; Gambarra-Neto, Francisco F.; Flores, Igor S.; Monteiro, Marcos R.; Lião, Luciano M.

    Abstract in English:

    Brazilian gasoline type C can be purchased with octane number as the main difference. This quality parameter directly affects the price. Intermediate formulations may not be easily distinguished from conform samples due to similarity in visual appearance and physicochemical properties. The use of anhydrous ethanol as an additive also influences the octane values of the product. In this context, the present study describes the use of 1H nuclear magnetic resonance spectroscopy (1H NMR) associated with chemometrics in the characterization and distinction of gasolines by different octane number. Conform samples of common, premium and blends of common-premium were used. Models of NMR-PCA (principal component analysis) and NMR-SIMCA (soft independent modelling of class analogies) showed a good correlation with the values determined by the standard method. The octane values predicted by the NMR-PLS (partial least squares) model achieved a good correlation root mean square errors of prediction (RMSEP = 0.50), with the values determined by the standard method as well.
  • New Insights into the Partitioning of Phenothiazine Dyes in Aqueous Two-Phase Systems Articles

    Coelho, Yara L.; Agudelo, Álvaro J. P.; Ferreira, Guilherme M. D.; Ferreira, Gabriel M. D.; Castro, Alan S. B. de; Hudson, Eliara A.; Pires, Ana Clarissa S.; Silva, Luis H. M. da

    Abstract in English:

    Aqueous two-phase systems (ATPSs) have proven to be efficient and environmentally safe methods for extracting chemical species. However, the driving forces behind the partition of solutes in these systems are still little understood. A complete thermodynamic partitioning of phenothiazine dyes was investigated in poly(ethylene oxide) (PEO) + salt + water ATPSs. Standard transfer parameters (Gibbs free energy change (ΔtrGº), enthalpy change (ΔtrHº) and entropy change (TΔtrSº)) were evaluated, and their dependence on the dye structure, electrolyte nature and tie line length (TLL). All phenothiazine dyes are concentrated predominantly in the polymer enriched phase, with ΔtrGº values ranging from -4.1 up to -13.4 kJ mol-1. Due to the dye-PEO attractive interactions that occur mainly via benzene condensed ring present in the structures of phenothiazine dyes, the partitioning of these dyes was enthalpically driven, with -11.4 ≥ ΔtrHº ≥ -52 kJ mol-1 and -4.93 ≥ TΔtrSº ≥ -38 kJ mol-1.
  • New Magnetic Fe Oxide-Carbon Based Acid Catalyst Prepared from Bio-Oil for Esterification Reactions Articles

    Ballotin, Fabiane C.; Almeida, Vitor F.; Ardisson, José D.; Silva, Márcio J. da; Soares, Ricardo R.; Teixeira, Ana Paula C.; Lago, Rochel M.

    Abstract in English:

    In this work, bio-oil (an organic matrix rich in oxygen functionalities) was used to efficiently dissolve and disperse Fe3+ which upon thermal treatment produced a carbon containing dispersed and encapsulated Fe oxide magnetic nanoparticles. These materials were prepared by dissolution of 8, 16 and 24 wt.% Fe3+ salt in bio-oil followed by treatment at 400, 450, 500 or 600 ºC in N2 atmosphere. X-ray diffraction (XRD), scanning (SEM) and transmission electron microscopies (TEM), elemental analysis, thermogravimetric-mass spectrometry (TG-MS), potentiometric titration, Raman and Mössbauer spectroscopies showed that Fe3+ species in bio-oil is reduced to produce magnetic nanoparticles phases: magnetite Fe3O4 and maghemite γ-Fe2O3. At low temperatures, the iron phases were less protected, and the carbon matrix was more reactive, while in temperatures above 500 ºC, the iron phases were more stable, however, the carbon matrix was less reactive. Reaction of these magnetic carbon materials with concentrated H2SO4 produced surface sulfonic acidic sites (ca. 1 mmol g-1), especially for the materials obtained at 400 and 450 ºC. The materials were used as catalysts on esterification reaction of oleic acid with methanol at 100 ºC and conversions of 90% were reached, however, after 2 consecutive uses, the conversion decreased to 30%, being required more studies to improve the material stability.
  • Expeditious Syntheses to Pharmochemicals 1,3-Dihydroxyacetone, 1,3-Dichloro-, 1,3-Dibromo- and 1,3-Diiodoacetone from Glycerol 1,3-Dichlorohydrin Using Homogenous and Heterogenous Medium Articles

    Silva, Fernanda Priscila N. R. da; Santos, Priscila F. dos; Silva, Sara R. B. da; Pereira, Vera Lúcia P.

    Abstract in English:

    New efficient and reproductive routes to production of 1,3-dihydroxyacetone (1), 1,3-dichloroacetone (6), 1,3-dibromoacetone (7) and 1,3-diiodoacetone (8) from glycerol 1,3-dichlorohydrin (3) were developed. The synthesis of 1 was processed in three steps from glycerol 2 (1,3-selective chlorination of 2 to 3, oxidation of 3 to 6 and subsequent di-hydroxylation) in 51% overall yield. On the other hand, 7 and 8 were produced from3, via a trans-bromination and trans-iodination, respectively, followed by oxidation and hydroxylation steps, in 38-52% overall yield. It was used homogeneous media with different reagents (HCl/AcOH, pyridinium chlorochromate (PCC), PCC-HIO4) and heterogeneous media with reagents supported on polymer resins such as Amberlyst® A26-HCrO4– form, PV-PCC (polyvinyl-pyridinium chlorochromate) and Amberlyst® A26-OH- form or reagents supported on alumina such as KI/Al2O3, KBr/Al2O3, in solvent free conditions.
  • Imiquimod/β-Cyclodextrin Inclusion Complex: Experimental and Theoretical Studies Articles

    Guedes, Luciana S.; Morgon, Nelson H.; Martins, Milene H.; Pessine, Francisco B. T.

    Abstract in English:

    Imiquimod (IMQ), an immune response modifier, is used for topical treatment of basal cell carcinoma and actinic keratosis. The very poor aqueous solubility of imiquimod gives rise to difficulties in designing aqueous formulations with this drug. One approach that is widely used to enhance drug solubility is complexation with cyclodextrins. The formation of the inclusion complex between IMQ and β-cyclodextrin was investigated in solution and in solid state. IMQ aqueous solubility was improved in the presence of citric acid. The experimental results and molecular modeling indicated the formation of the inclusion complex in aqueous solution of citric acid pH 3.0; however, the low apparent stability constant suggested weak interaction between β-cyclodextrin and IMQ which hampered the use of this approach to improve imiquimod aqueous solubility and the development of an aqueous formulation containing IMQ in the same concentration as in the commercial product.
  • A New Energetic Complex: Synthesis, Structure, and Combustion Catalysis Performance Articles

    Qiao, Chengfang; Fu, Zhengyu; Wang, Runrun; Gao, Yulin; Chen, Fengying; Gao, Xia; Zhou, Chunsheng; Xia, Zhengqiang

    Abstract in English:

    The potential of tetrazole-based ligands for forming energetic complexes applied in pyrotechnics and propellants is demonstrated with the use of 5,5’-(1,3-phenylene)bis(1H-tetrazole) (H2BTB) to generate an energetic complex with high energy. A new energetic complex of PbII-tetrazolate, [Pb2(BTB)2(H2O)8]·5H2O (1), was synthesized and structurally characterized by single crystal X-ray diffraction. Structural analysis reveals that the central PbII ions present two distinct coordination environments in the asymmetric unit, including distorted pentagonal bipyramid and distorted tetragonal pyramid geometries, respectively. To identify potential combustion catalyst as additives in propellants, we employed differential scanning calorimetry technique to evaluate the influence of the complex on thermal decomposition of ammonium perchlorate (AP) and cyclotrimethylenetrinitramine (RDX). The kinetic parameters of an exothermic process for the catalytic system of RDX+1 were investigated by the Kissinger’s and Ozawa-Doyle’s methods. For both AP and RDX, the decomposition temperature decreased obviously in the presence of 1, and the released heat could effectively compensate the propellants. Our observations demonstrate that 1 shows good catalytic activity toward the thermal decomposition of AP and RDX.
  • A New Isoflavone and Other Constituents from Roots of Clitoria guianensis Short Report

    Cunha, Camila L.; Siebeneichler, Susana C.; Nascimento, Isabele R.; Holzbach, Juliana C.

    Abstract in English:

    A new isoflavone named pratensein-7-O-β-D-rutinoside [(-)-7-O-α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranosyl-5,3’-dihydroxy-4’-methoxyisoflavone] and the known compounds biochanin A-7-O-β-D-rutinoside, 6-deoxyclitoriacetal 11-O-β-D-glucopyranoside, 6-deoxyclitoriacetal, (2S)-naringenin-6-C-β-D-glucopyranoside, (2R)-naringenin-6-C-β-D-glucopyranoside, tachioside, and koaburaside were isolated from the roots of Clitoria guianensis (Aubl.) Benth var. guianensis (Fabaceae), a subshrub found in the Brazilian Cerrado biome. The structures of the compounds were identified by physical and spectroscopic data measurements (specific rotation ([α]D), circular dichroism (CD), ultraviolet (UV), infrared (IR), 1D and 2D nuclear magnetic resonance (NMR), and mass spectrometry (MS)). The EtOAc fraction of the roots exhibited high toxicity against Artemia salina with median lethal dose (LD50) value of 8.53 mg L-1.
Sociedade Brasileira de Química Instituto de Química - UNICAMP, Caixa Postal 6154, 13083-970 Campinas SP - Brazil, Tel./FAX.: +55 19 3521-3151 - São Paulo - SP - Brazil
E-mail: office@jbcs.sbq.org.br