Journal of the Brazilian Chemical Society This is an RSS file. You can use it to subscribe to this data in your favourite RSS reader or to display this data on your own website or blog.

Synthesis, Characterization and Exchange Reactions of Layered Double Hydroxides of Copper and Aluminum, Intercalated with Sulfate
Layered double hydroxides (LDHs) of Cu:Al in the molar ratio of 2:1, intercalated with sulfate, sulfate/(Li+, Na+, K+ or NH4+), NO3- and CO32-, were synthesized by co-precipitation with increasing pH. The materials were submitted to exchange reactions using B2SO4 (B = Li+, Na+, K+, NH4+) solutions in an attempt to replace previously intercalated cations or incorporated cations without removing intercalated sulfate. X-ray diffraction (XRD) patterns and Fourier transform infrared (FTIR) spectra were consistent with the expected intercalated species and scanning electron microscopy (SEM) images indicated submicrometric platel...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

An Efficient and Recyclable Sn-Based Phosphotungstic Acid with Tunable Brønsted/Lewis Acidity for Selective Oxidation of Benzyl Alcohol
A series of metal ion (M = Sn2+, Fe3+, Ni2+, Co2+, Ag+, Cu2+) exchanged tungstophosphoric acid (H3PW12O40; TPA) catalysts with tunable Br ønsted/Lewis acidity were synthesized and exploited for the oxidation of benzyl alcohol (BzOH) to benzaldehyde (BzH) using hydrogen peroxide (H2O2) as oxidant. The structure of these M-TPA composite salts was also characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (X RD), thermogravimetric analyses (TGA) and solid-state 31P nuclear magnetic resonance (NMR) probe molecule method. Among these M-TPAs, the Sn1/2H2PW12O40 catalyst, which presented strong Brøn...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Brazilian Mineral Clays: Classification, Acid Activation and Application as Catalysts for Methyl Esterification Reactions
In this study, three raw Brazilian clays from Jo ão Pessoa, Paraíba State (Aço AP, AVL and Verde Lodo) were characterized before and after purification and acid activation. Several instrumental techniques were used, and the raw clays were classified as dioctahedral smectites with different compositions, where the AVL sample had the highest cont ent of montmorillonite. In addition, analyses showed modification in clay mineral compositions, mainly due to removal of impurities and octahedral sheet cation leaching during acid activation, which resulted in specific areas ranging from 42 to 93 m2 g-1 and increase of the Brøn...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Interaction of Suspended Particulate Material with Cd2+ and Pb2+ in a Brazilian Lagoon Estuarine System
The suspended particulate material (SPM) present in waters has fundamental importance for a better understanding of environmental behaviors of aquatic pollutants. This work determined the physicochemical parameters (pH, temperature, conductivity, total organic carbon and metals concentration) in water samples from Munda ú-Manguaba estuarine-lagoon system, Alagoas, Brazil. This work extracted and characterized the organic matter present in SPM in this estuary and studied the interaction of this organic matter with potentially toxic metals (Cd2+ and Pb2+). The results of the physical-chemical parameters evaluated sh owed in...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Evaluation of the Metabolic Profile of Arabica Coffee via NMR in Relation to the Time and Temperature of the Roasting Procedure
Coffee is one of the most popular and consumed products in the world, with high nutritional value and economic importance. However, some factors can change the organoleptic properties of a coffee species, without causing significant damage such as loss of important components. The present study evaluated the chemical profile, via nuclear magnetic resonance (NMR), of the main biological properties and substances of the drink, verifying similarities in the composition of different types of arabica coffee made in different conditions, such as the roasting time and temperature. The main components were identified, using inform...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Automated Framework for Developing Predictive Machine Learning Models for Data-Driven Drug Discovery
The increasing availability of extensive collections of chemical compounds associated with experimental data provides an opportunity to build predictive quantitative structure-activity relationship (QSAR) models using machine learning (ML) algorithms. These models can promote data-driven decisions and have the potential to speed up the drug discovery process and reduce their failure rates. However, many essential aspects of data preparation and modeling are not available in any standalone program. Here, we developed an automated framework for the curation of chemogenomics data and to develop QSAR models for virtual screeni...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Blue Glow Sticks: Cinnamic Acids and Arylacrylonitriles with Liquid-Crystalline Properties and Highly Fluorescent
Five new π -conjugated chromophores derived from acrylic acid and acrylonitrile were synthesized and their thermal and photophysical behaviors were analyzed. They were designed and synthesized through Knoevenagel condensations between arylacetylenebenzaldehydes and a methylene group activated from cyanoacetic and malonic acids. The characterization of the target compounds was performed by Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (NMR), 13C NMR, thermogravimetric analysis (TGA), absorption and emission spectroscopy techniques. Arylcinnamic acids were obtained as pure E-isomers. On the o...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Molecular Modelling Study of Heteroarylamide/Sulfonamide Compounds with Antitrypanosomal Activity
In this study, the quantitative structure-activity relationship (QSAR) were built using partial least squares (PLS) regression, and the results were robust and adequate for predicting and proposing five new derivatives according to the statistical parameters. The docking results suggest that the best-scored HA/S derivatives showed hydrogen bonds with the residuals that comprise the catalytic region of the enzyme. The molecular dynamics (MD) simulations, performed with different methods, revealed the strong stability of the compound obtained by the QSAR model of this study, in addition to a better binding free energy value ...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

o-DGT Devices for the Determination of Emerging Contaminants in Aqueous Matrices
Samplers based on the diffusive gradients in thin films for organics (o-DGT) were developed and applied in Brazilian aqueous matrices for the determination of four emerging contaminants (EC): 4-octylphenol, 4-nonylphenol, triclosan, and bisphenol A. The OASIS HLB resin used as the binding phase presented a high sorption capacity and the extraction associated with sonication, using a mixture of acetonitrile and methanol (2:1, v v-1) as the solvent, provided a higher desorbed mass of the compounds. The diffusion coefficients determined experimentally were in the range of the values found in the literature and the pH and ioni...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Isotopic Analysis of Sugarcane/Petroleum Polyethylene Blends: A Perspective on the Application of Stable Isotope Method (δ13C)
In the present work, we propose the application of stable isotope analysis ( δ 13C) as an auxiliary tool for the inspection of sugarcane/petroleum polyethylene blends. Our results are supported from the analysis of selected samples by accelerator mass spectrometry (14C-AMS). From the results, it was concluded that the δ 13C method is suitable to discriminate samples derived from sugarcane, petroleum, or its blends. It was also noted that both regression models ( δ 13C method and the δ 13C vs 14C-AMS regression) presents potential to estimate the bio-based content; however, future work should focus on validating these m...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Study of Inorganic Profiles of Street Cocaine Samples Using ICP-MS and ICP OES
In this study, we analyzed 52 street cocaine samples, seized in three different regions of Esp írito Santo, state of Brazil. Inductively coupled plasma optical emission spectrometry was used to determine Al, Ca, Cu, Fe, Mn, Mg, Zn concentrations and inductively coupled plasma mass spectrometry to determine Mo, Co, Pb and P concentrations. From analyte recovery tests, the accuracy was conside red acceptable and the proposed method satisfactory. Most of the samples exhibited a relatively homogeneous inorganic profile with similar concentrations of investigated elements, however some samples had very discrepant concentration...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Synthesis of Antioxidant Additive from Safflower Seed Oil
Several published studies have evaluated the problems associated with the utilization of biodiesel obtained from safflower (Carthamus tinctorius L.) oil due to the low oxidative stability, caused by the high content of unsaturated fatty acids. Thus, this study aimed at the extraction of safflower seed oil and its use as an unsaturation source to obtain a synthetic antioxidant. The synthesis of this phenolic additive was done by modifying its structure through the addition of hydroquinone to the unsaturation of the oil, by electrophilic substitution. It was investigated and confirmed that this reaction is promising for obta...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Evaluation of Lignins of Trunk and Roots from Citrus sinensis L. Osbeck: A Large Available Brazilian Biomass
Citrus biomass is a source of biobased products and presents extensive chemical diversity. Among the structural macromolecules, lignins have been used in resins, bioplastics, and nanoencapsulation. Brazil has a large source of lignins, which are orange trees removed from groves that need to be renewed. However, the knowledge about these lignins is limited and little explored. Thus, this work aimed to evaluate the lignins from Citrus sinensis and to provide information on the interesting use of orange trees as a source of macromolecules. The lignins were isolated from the trunk, central and secondary roots from the orange t...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Optimization of the Reaction Conditions for the Synthesis of Dihydrobenzofuran Neolignans
We have optimized the experimental conditions for the silver(I)-promoted oxidative coupling of methyl p-coumarate (I) and methyl ferulate (II), which is the most frequently used methodology to synthesize the bioactive dihydrobenzofuran neolignans 1 (( ±)-trans-dehydrodicoumarate dimethyl ester) and 2 ((±)-trans-dehydrodiferulate dimethyl ester). Most of the tested conditions affected the conversion (i.e., the consumption of I and II) and the selectivity (i.e., the percentage of I and II that was converted into 1 and 2, respectively), so the opt imized conditions were the ones that afforded the best balance between conver...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research

Speciation of Antimony in Injectable Leishmanicidal Drugs by Lowering Citric Acid Concentration Used in Hydride Generation Atomic Absorption Spectrometry Analysis
This study proposes a procedure for speciation of antimony by hydride generation atomic absorption spectrometry in pentavalent antimony drugs. The SbIII content was determined by selective generation of SbH3 in medium with higher SbV concentration using 4 to 20-fold lower citric acid solutions than recommended in the available literature. The multivariate optimization of the methods was performed through factorial design followed by a central composite design (CCD). The limit of detection (LOD) and limit of quantification (LOQ) were calculated at 0.15 and 0.05 µg L-1 and 0.48 and 0.17 µg L-1, for total Sb and SbIII, resp...
Source: Journal of the Brazilian Chemical Society - January 20, 2021 Category: Chemistry Source Type: research