Scielo RSS <![CDATA[Journal of the Chilean Chemical Society]]> http://www.scielo.cl/rss.php?pid=0717-970720170001&lang=es vol. 62 num. 1 lang. es <![CDATA[SciELO Logo]]> http://www.scielo.cl/img/en/fbpelogp.gif http://www.scielo.cl <![CDATA[<strong>VOLATILE CONSTITUENTS OF THE AERIAL PARTS OF <i>TERATAENIUM LASIOPENTALUM</i> (BOISS.) MANDEN., STEMS AND LEAVES OF <i>DOREMA AMMONIACUM</i> D.DON. AND LEAVES, FRUITS AND STEMS OF <i>LEUTEA PETIOLARE </i>(<i>DC.</i>) M.PIMEN FROM IRAN</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100001&lng=es&nrm=iso&tlng=es The Composition of the essential oils from three Umbelliferae species of Iran, Tetrataenium lasiopetalum (Boiss.) Mandem ., Dorema ammoniacum D.Don., which is endemic to Iran, and Leutea petiolare (DC.) M.Pimen. obtained by hydrodistillation were analyzed by GC and GC/MS. Germacrene D (17.72%) and (E,Z) farnesol (12.58%) were the main components in the oil of aerial parts of T. lasiopetalum. The major compound in the stem oil of D. ammoniacum was α-muurolol (13.68%), whereas the leaf oil contained (E)-ß-ocimene (30.94%), γ-terpinene (11.09%), p-cymene (10.03%) and (Z)-ß-ocimene (7.11%). Terpinolene (13.93%, 8.28% and 10.27%), (E)-ß-ocimene (10.24%, 24.63% and 10.46%) and endo-fenchyl acetate (15.1%, 7.42% and 7.57%) were the main constituents in the leaf, fruit and stem oils of L. petiolare respectively. <![CDATA[<strong>ADVANCES IN TOTAL SYNTHESIS OF ALTERNARIC ACID</strong>: <strong>AN ANTI-FUNGAL AND PHYTOTOXIC NATURAL PRODUCT</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100002&lng=es&nrm=iso&tlng=es Alternaric acid is characterized as 1,4-diene, possessing (E)-1,2-disubstituted alkene known for nanomolar phytotoxic and antifungal activities. This article highlights the major synthetic approaches attempted towards the total synthesis of alternaric acid reported by three groups (Ichihara & coworkers, Trost & coworkers and Johnson and Slade) which involved novel pathways for the rapid construction of this functionalized natural molecule. <![CDATA[<strong>INCLUSION OF [H<sub>3</sub>PW<sub>12</sub>O<sub>40</sub>] AND [H<sub>4</sub>SiW<sub>12</sub>O<sub>40</sub>] INTO A SILICA GEL MATRIX VIA "SOL-GEL" METHODOLOGY</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100003&lng=es&nrm=iso&tlng=es Here we report the inclusion of two Keggin Polyoxometalates (POMs), [H3PW12O40] and [H4SiW12O40], into silica gels by integrating them during the preparation of the SiO2 matrix via "sol-gel" methods. Aerogels were produced by supercritical drying of the wet gels impregnated with the POMs, and lyogels were obtained by means of a lyophilization process. These materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed infrared (FT-IR) spectroscopy and thermoanalytical techniques (TGA-DSC). We found that a large fraction of POMs are lost during the aging time, and solvent exchange for lyophilization. However the thermal stability of the bare matrix is modified by the inclusion of POMs. Some aggregates with a high content of POMs were found via SEM-EDX. <![CDATA[<strong>A STABILITY INDICATING ION-PAIR LC METHOD FOR THE DETERMINATION OF ASENAPINE IN PHARMACEUTICALS</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100004&lng=es&nrm=iso&tlng=es In this study, a new, simple and specific stability indicating ion-pair LC method was developed and fully validated for the determination of asenapine in tablets. The analysis was performed on an Agilent Eclipse XDB-C8 column (4.6 x 150 mm, 3.5 μm particles) at 30°C. A mixture of phosphate buffer (pH 3, 20 mM) containing 10 mM 1-heptane sulfonic acid and acetonitrile, (60:40, v/v) at a flow rate of 1 mL min-1 was used as mobile phase. Detection was performed by a diode array detector at 220 nm. The developed method was validated according to related ICH guideline and US Pharmacopeia and it was suitable in terms of accuracy, precision, specificity, robustness and stability. The method was linear in the concentration range of 0.5-100 μg mL-1. Limit of detection and limit of quantification values were calculated as 0.0836 μg mL-1 and 0.2788 μg mL-1, respectively. This ion-pair LC method was applied successfully for the determination of asenapine in its sublingual tablets. <![CDATA[<strong>NANO-SIZED La<sub>0.5</sub>Ca<sub>0.5</sub>CoO<sub>3</sub>-MEDIATED REDUCTION BY NaBH<sub>4</sub> OF ARYL NITRILES TO BIS-(BENZYL) AMINES</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100005&lng=es&nrm=iso&tlng=es Nano-sized La0.5Ca0.5CoO3 perovskite, which was produced via the sol-gel method, was an efficient heterogeneous catalyst in combination with NaBH4 for the rapid chemoselective reduction of aryl nitriles to bis-(benzyl)amines at 40 °C in good to excellent yields. The physico-chemical properties of the catalyst were characterized by means of differential thermal analysis (DTA), thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and particle size distributions images. The results show that nanoparticles have regular shapes with well-defined crystal faces with an average size of 30 nm. <![CDATA[<strong>CHEMICAL COMPOSITION AND BIOLOGICAL ACTIVITIES OF THE ESSENTIAL OILS AND THE METHANOLIC EXTRACTS OF <i>BUNIUM INCRASSATUM</i> AND <i>BUNIUM ALPINUM</i> FROM ALGERIA</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100006&lng=es&nrm=iso&tlng=es In order to study the curing proprieties of endemic Algerian plants, it is evaluated the chemical composition and four biological activities of two Apiaceae species, which are Bunium incrassatum and Bunium alpinum. The essential oils (EO) obtained by hydro-distillation of dried aerial parts were analyzed by GC/ MS. The antibacterial activity was investigated using the disc diffusion assay against ten (10) Gram-positive and Gram-negative bacteria. Antioxidant activity was evaluated by DPPH technique. Methanolic extracts (Me EXTs) were used in studying in vitro anti-inflammatory activity using egg albumin technique and in vitro anti-hemolytic activity using HBRC technique. The EO yield based on dried plant material was 0.09 % for B. incrassatum and 0.10 % for B. alpinum. Thirty-one compounds (corresponding to 97.19%) were identified for B. incrassatum. The main component was palmitic acid (18.39%). While twenty-four compounds (coresponding 87.33%) were identified for B. alpinum. The main component was caryophyllene oxide (33.84%). The study of antibacterial activity demonstrated that the EOs showed a modest antibacterial activity compared to gentamicin. The antioxidant activity revealed that EOs and Me EXTs demonstrated a very important anti-radical activity compared to standards (BHT, BHA, tocopherol, quercitin and rutin). The Me EXTs demonstrated also, significant antihemolytic and anti-inflammatory activities to those of standard (sodium diclofenac). It was found that all these activities are much related to the chemical composition of EO and Met EXTs. These activities could be exploited in the food industry for food preservation or in pharmaceutical industry. <![CDATA[<strong>BENZAMIDE DERIVATIVES AS POTENTIAL CANDIDATES FOR ANTI-ALZHEIMER, ANTI-FATIGUE, ANTI-UREASE AND ANTI-OXIDANT ACTIVITY</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100007&lng=es&nrm=iso&tlng=es Benzamide derivatives were screened for their anti-alzheimer, anti-fatigue, anti-urease and anti-oxidant activity and their results were calculated in the form of %age inhibition and IC50 value. Compounds 3a and 3g exhibited the highest anti alzheimer activity. Group of mice's treated by compounds 3f and 3g showed significantly longer swimming times than those of the treated with caffeine. The prominent urease inhibitory activity was shown by only one compound among seven benzamide derivatives. Controlled experiments suggest that benzamide derivatives (3a-3g) can be serve as the therapeutic agents <![CDATA[<strong>SYNTHESIS, QUALITY CONTROL AND BIODISTRIBUTION OF TECHNEIUM-99M TRIAMCINOLONE ACETONIDE (<sup>99m</sup>Tc-TA) COMPLEX</strong>: <strong>AN INFLAMMATION TRACER AGENT</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100008&lng=es&nrm=iso&tlng=es In present study synthesis of 99mTc-triamcinolone acetonide (99mTc-TA) complex and its stability using set of quality control parameters such as ligand concentration, reducing agent concentration, pH, temperature and reaction time was assessed. 99mTc-TA complex was characterized in terms of percent (%) yield, stability in saline and serum using chromatographic procedures. Radiochemically the 99mTc-TA complex was found quite stable in saline and serum. After 30 min of reaction the complex showed maximum radiochemical yield of 96.32% which decreased to 96.25 % after 4 h incubation period. In serum, the % yield of radiochemical was remained same up to 2 h which decreased to 93.5% at 24 h time point. Normal biodistribution pattern in Sprague-Dawley rats revealed liver, stomach and kidneys as areas of high 99mTc-TA complex uptake (8.44 ± 1.32, 8.75 ± 1.03 and 12.67 ± 1.21%, respectively) at 1 h post injection time point. Scintigraphy of 99mTc-TA in rabbits showed similar eco as observed in biodistribution study. Based on the promising results obtained in context of in vitro and in vivo stability and biodistribution, 99mTc-TA complex could be further studied to identify the inflammation based diseases. <![CDATA[<strong>SYNTHESIS, CRYSTAL STRUCTURE ANALYSIS AND CHARACTERIZATION OF MERCURY(II) COMPLEX CONTAINING 2-(AMINOMETHYL)PYRIDINE AND BROMIDE</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100009&lng=es&nrm=iso&tlng=es The new complex of [Hg(2-AMPy)2Br]2.HgBr4 (1) was synthesized from the reaction of HgBr2 with 2-(aminomethyl)pyridine (2-AMPy) in methanolic solution. Suitable crystals of 1 for diffraction experiment was obtained by slow evaporation from DMSO. Resulted complex was characterized by IR, elemental analysis, thermal analysis and single crystal X-ray diffraction. In this compound, two five-coordinated mercury centers in the cationic parts have slightly and highly distorted square-based pyramidal geometries by the trigonal-indexes, τ5, of 0.18 and 0.49, respectively. According to four-coordinate geometry index, τ4, of 0.95, anionic part has perfect tetrahedral geometry. <![CDATA[<strong>EFFECTIVE MICROWAVE SYNTHESIS OF BIOACTIVE THIENO[2,3-</strong><em><b>d</b></em><strong>]PYRTMIDINES</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100010&lng=es&nrm=iso&tlng=es A series of novel 2-amino-3-cyanothiophenes (2a-2j) were synthesized using heterogeneous base (K2CO3) supported Gewald reaction. Cyclization of 2a-j with formamide and urea in conventional heating as well as microwave irradiation gave thieno[2,3-d]pyrimidines (3a-3j) and thieno[2,3-d]pyrimidin-2(1H)-ones(4a-4j) respectively. The reaction rates were faster and yields were higher in the microwave conditions. The structures of the compounds were confirmed with elemental analysis, mass spectral analysis, FTIR, ¹H NMR and 13C NMR techniques. All the synthesized compounds were subjected to antimicrobial activity (MIC) in vitro by broth dilution method and exhibited a moderate antimicrobial activity. <![CDATA[<strong>REMOVAL OF CRYSTAL VIOLET DYE FROM AQUEOUS SOLUTION BY GAMMA IRRADIATION</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100011&lng=es&nrm=iso&tlng=es In this study the radiation-induced degradation of crystal violet (CV) dye under various experimental conditions has been investigated. D0.5, D0.9 and D0.99 values suggests that lower doses are required for 50%, 90% and 99% removal of CV dye when the sample solution contains excessive amount of �OH radicals. The removal efficiency of CV dye in terms of G-values was also calculated under each reaction conditions. The results showed that �OH radicals are playing effective role in the degradation of CV dye as compared to e aq‒ and .H radicals. The gamma irradiation process effectively degraded CV dye at all pH values. The organic byproducts were examined and accordingly degradation pathway was proposed. <![CDATA[<strong>THE INFLUENCES OF POPLAR INNER AND OUTER BARK CONTENT ON MECHANICAL PROPERTIES OF WOOD/POLYPROPYLENE COMPOSITES</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100012&lng=es&nrm=iso&tlng=es This study evaluated the individual and interaction effects of inner bark flour (IBF), outer bark flour (OBF), wood flour (WF), and blending of IBF, OBF, and WF content of poplar tree on the morphology and mechanical properties of wood-plastic composites (WPCs). The IBF, OBF, and WF with 2 wt% maleic anhydride-grafted polypropylene (MAPP) and polypropylene were compounded into the pellets using a counter-rotating twin-screw extruder. Test specimens were prepared by injection molding machine. The results indicated that the WF alone significantly (P<0.05) increased the flexural strength, flexural modulus, and tensile strength. The composites made with IBF/WF exhibited higher tensile modulus compared to those made with WF alone and IBF/OBF alone. Moreover, the results showed that the IBF/OBF alone increased the notched impact strength compared to all of reinforced composites. The neat polypropylene had higher notched impact strength than the other reinforced composites (P<0.05). <![CDATA[<strong>SYNTHESIS, SPECTRAL ANALYSIS AND ANTIBACTERIAL EVALUATION OF 5-SUBSTITUTED-1,3,4-OXADIAZOL-2-YL 4-(4-METHYLPIPERIDIN-1-YLSULFONYL)BENZYL SULFIDES</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100013&lng=es&nrm=iso&tlng=es Owing to valuable biological activities of 1,3,4-oxadiazole, sulfamoyl and piperidine functionalities, some new 1-(4-{[(5-substituted-1,3,4-oxadiazol-2-yl) thio]methyl}benzene sulfonyl)-4-methylpiperidine (6a-o) derivatives have been introduced. The target molecules were synthesized from different aralkyl/aryl carboxylic acids, 1a-o, through a series of steps. First the compounds, 1a-o, were converted to heterocyclic 1,3,4-oxadiazole nucleophiles, 4a-o. Second an electrophile as 1-(4-bromomethylbenzenesulfonyl)-4-methylpiperidine (5) was synthesized from 4-methylpiperidine. Finally the target compounds, 6a-o, were prepared by reacting 4a-o with 5 in DMF and LiH. The final compounds were structurally elucidated by spectral data of IR, ¹H-NMR and EI-MS. All the compounds were screened for their antibacterial evaluation and found to exhibit valuable results. <![CDATA[<strong>EFFECTS OF PHYSICAL AND CHEMICAL MODIFICATION ON BIOLOGICAL ACTIVITIES OF CHITOSAN/ CARBOXYMETHYLCELLUSE BASED HYDROGELS</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100014&lng=es&nrm=iso&tlng=es Hydrogels network based on carboxymethylcellulose (CMC) and chitosan (CS), CCI and CC2, have been prepared respectively in the presence or without the crosslinking agents [(N-hydroxysuccinimide (NHS)/N,N'-dicyclohexylcarbodiimide (DCC)] and characterized by FT-IR. The swelling behavior in distilled water at 25°C and biological activities have been investigated. CC1 hydrogel revealed higher potential swelling than CC2. Hydrogels showed to possess an important antioxidant activity equal to 66.67% for CC1 and 57.27% for CC2, to scavenge hydroxyl radicals at 2mg/mL. And the values of their reducing power were approximately 53% and 57%. From the hemolytic potential test the obtained materials were hemo-compatible. The anti-inflammatory activity exhibited that hydrogels were able to protect albumin from denaturation. <![CDATA[<strong>TWO NOVEL TCPP PORPHYRINIC COMPOUNDS</strong>: <strong>IN SITU SYNTHESES, CHARACTERIZATION AND REACTION MECHANISM</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100015&lng=es&nrm=iso&tlng=es Two novel porphyrinic compounds, {Zn[TCPP(CH2CH3)2(CH3)2]}n (1) and TCPP(CH3)4 (2) (TCPP = meso-tetra(4-carboxyphenyl)porphyrin), with the TCPP(CH2CH3)2(CH3)2 and TCPP(CH3)4 generated in situ, have been synthesized via a solvothermal reaction and structurally characterized by single-crystal X-ray diffraction. Compound 1 is characteristic of a two-dimensional (2-D) coordination polymer, based on the zinc ion coordinating to four nitrogen atoms and two oxygen atoms. Compound 1 possesses a large void space (220 ³) corresponding to 4.6% of the unit-cell volume. Compound 2 is characterized by an isolated structure. The reaction mechanism of preparing both compounds was explored. The photoluminescence properties, FT-IR, UV-vis absorption spectra, fluorescence lifetime and fluorescence quantum yield of TCPP were also reported. <![CDATA[<strong>VISCOMETRIC BEHAVIOR OF CONCENTRTED PERCHLORIC ACID</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100016&lng=es&nrm=iso&tlng=es Viscosity q and density p of aqueous concentrated perchloric acid 1.0 moldm-3 to 9.0 moldm-3 were measured at 297.65K. The viscosity data were used to calculate the value of A and B-coefficient of Jones-Dole equation. The value of B-coefficient is positive which suggests the strong ion-solvent interaction in aqueous perchloric acid. The three concentration regions of perchloric acid having value of B-coefficient (measure of ion-solvent interaction or structure making capacity) in the order 1.0 to 4.0 moldm-3 < 4.0 to 6.0 moldm-3 < 6.0 to 9.0 moldm-3 has been proposed. <![CDATA[<strong>PREDICTION OF PHYSICAL AND THERMODYNAMIC PROPERTIES OF ALIPHATIC ETHERS FROM MOLECULAR STRUCTURES BY MULTIPLE LINEAR REGRESSION</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100017&lng=es&nrm=iso&tlng=es The interrelation of topological indices with enthalpy of vaporization at standard conditions (ΔH° vap), and normal temperature of boiling point (Tboil/K) for series of aliphatic ethers has been investigated. For obtaining model for predicted target properties we have used multiple linear regression (MLR) techniques and followed Back ward regression analysis. The results have shown that combining the four descriptors (J, Wp, ¹X, H) are included, with values of the correlation coefficient (r= 0.979), the standard error (s= 1.343 K),the Fisher-ratio (F= 304.992) could be used successfully for modeling and predicting the normal temperature of boiling points of 30 aliphatic ethers. The best model for estimating the enthalpy of vaporization of compounds are included two descriptors (WW, ¹X), with values of the correlation coefficient (r=0.994), the standard error (s= 5.900 kJ/mol) and the Fisher-ratio (F= 558.789) . <![CDATA[<strong>VISIBLE RANGE PHOTOCATALYSTS FOR SOLID PHASE PHOTOCATALYTIC DEGRADATION OF POLYETHYLENE AND POLYVINYL CHLORIDE</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100018&lng=es&nrm=iso&tlng=es Solid phase photocatalytic degradation of polyethylene (PE) and polyvinyl chloride (PVC) with various photocatalysts such as ceria annealed at 350°C and 850°C, zinc oxide annealed at 250°C, copper sulfide and titania particles was studied under different light sources. Except titania, all the other photocatalysts performed reasonably well both in the visible and ultra-violet (UV) radiations. Ceria annealed at 850°C showed degradation efficiencies higher than 70% for PVC in the fluorescent and solar radiation. Ceria annealed at 350°C showed degradation efficiencies higher than 75% for polyethylene in fluorescent, solar and UV radiation. The Fourier transform infrared spectroscopy studies show the presence of adsorbed carbon dioxide on the degraded polymer-photocatalyst composite films. The UV-visible spectroscopic studies show that the ceria, zinc oxide and copper sulfide photocatalysts are active in the visible spectrum resulting in enhanced degradation efficiency in fluorescent and solar radiation. <![CDATA[<strong>GRINDING SYNTHESIS OF 2-AMINO-4H-CHROMENES USING 3,3-(BUTANE-1,4-DIYL) BIS (1,2-DIMETHYL- 1H-IMIDAZOLE-3-IUM)Br-CAN AS A NOVEL REAGENT</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100019&lng=es&nrm=iso&tlng=es A clean and environmentally benign route to 2-amino-4H-chromenes has been developed via three-component condensation reaction of various benzyl alcohols, malononitrile and 1-naphthol, using a catalytical amount of CAN and a reusable ionic liquid 3,3-(Butane-1,4-diyl)bis(1,2-dimethyl-1H-imidazole-3-ium) bromide ([BDBDMIm]Br) as a catalyst at room temperature. The present methodology offers several advantages such as solvent-free conditions, excellent yields, simple procedure, mild conditions and reduced environmental consequences. The ionic liquid was recovered and reused. All of synthesized compounds were characterized by IR, NMR and elemental analyses. <![CDATA[<strong>SYNTHESIS, CRYSTAL STRUCTURE AND PHOTOLUMINESCENCE PROPERTIES OF A NEW RARE-EARTH CARBONATE Na<sub>3</sub>Eu(CO<sub>3</sub>)<sub>3</sub>6H<sub>2</sub>O</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100020&lng=es&nrm=iso&tlng=es A new sodium europium carbonate hydrate, Na3Eu(CO3)3•6H2O, has been prepared using the hydrothermal method, and its structure was determined by single crystal X-Ray diffraction analysis for the first time. It crystallizes in the polar hexagonal space group P6(3) with a = 11.382(9) Å, c = 5.989(5) Å, V = 672.06(9) ų, Z = 2, Mr = 509.06, Dc = 2.516 g/cm³, F(000) = 492, μ(MoKα) = 4.84 mm-1, R1 = 0.015 and wR = 0.038. The structure features a three-dimensional (3D) framework composed of planar (CO3)2- triangles, Eu3+ ions and Na+ ions, which delimits 1D infinite chains with a hexangular star appearance along the c-axis. The IR spectrum and the self-activated photoluminescence properties were studied. Under the excitation of near UV light (395nm), it shows strong red emission at 618 nm with a lifetime of 348.7 μs. Present research indicates that Na3Eu(CO3)3•6H2O is a promising red phosphor for white light-emitting diodes. <![CDATA[<strong>IMPROVE THE CATALYTIC ACTIVITY OF FEOOH/BENTONITE MATERIAL BY MECHANICAL ACTIVATION</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100021&lng=es&nrm=iso&tlng=es To improve the catalytic activity of FeOOH/bentonite material used in Fenton-like process, the activation of FeOOH/bentonite by mechanical activation was studied. The optimum conditions for activation of FeOOH/bentonite were as follows: filling ratio of grinding medium 30%, "15 mL of D06 balls plus 15 mL of D10 balls" as combination mode of grinding medium, rotation speed of planet carrier 600 rpm, milling time 40 min, and powder-to-ball ratio 0.5:30 (g•mL-1). The mechanical activation was an effective method to improve the catalytic activity of FeOOH/bentonite. Both the lattice distortion and crystal size decrease happened in α-FeOOH and the change of layer structure of bentonite were contributed to the increase of catalytic activity of activated FeOOH/bentonite. <![CDATA[<strong>ELECTROPHILIC AND NUCLEOPHILIC CHEMICAL REACTIVITY OF NEUTRAL AND ANIONIC FORMS OF 4-CPA, 24D-CPA, 34-CPA AND 245T-CPA THROUGH CONCEPTUAL DFT REACTIVITY DESCRIPTORS</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100022&lng=es&nrm=iso&tlng=es In the present work, we have analyzed the electrophilic and nucleophilic chemical reactivity of the neutral and anionic chlorophenoxyacetic acid herbicides, 4-CPA, 24D-CPA, 34-CPA and 245T-CPA at the X/6-311++G(2d,2p) level of theory (where X= wB97XD, MPW91B1K and MP2). Chemical reactivity was analyzed in the aqueous phase and employing global and local DFT reactivity descriptors. The structural parameters derived from DFT calculations are equivalent to those obtained at the MP2 level. The Fukui Function values suggest that nucleophilic attacks to the neutral and anionic forms would cause dechlorination on 24D-CPA, 34-CPA and 245T-CPA and hydrogen abstraction in 4-CPA. At pH values lower than 2.7, electrophilic attacks would cause the cleavage of the ether bond in 4-CPA, 24D-CPA and 34-CPA and dechlorination in 245T-CPA. But, at pH > 3.6, electrophiles may cleave the ether bond to start the degradation of the four CPAs. <![CDATA[<strong>MICROWAVE-ASSISTED LIQUID PHASE MICROEXTRACTION FOLLOWED WITH FLAME ATOMIC ABSORPTION SPECTROMETRY FOR TRACE DETERMINATION OF ZINC IN FOOD SAMPLES</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100023&lng=es&nrm=iso&tlng=es In this work, microwave-assisted liquid phase microextraction (MA-LPME) was followed by flame atomic absorption spectrometry for determination of zinc in food samples. Zinc was complexed with a chelating agent to form hydrophobic species.1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF6]) ionic liquid (IL) was used as environmentally-friendly extraction solvent. In order to disperse the extraction phase into the sample solution and improve the extraction efficiency, microwave irradiation was used as a disperser agent. The heating effect of microwave irradiation makes the ionic liquid dissolved and dispersed through the sample, which significantly improves the speed and efficiency of extraction. After extraction process, sample solution was centrifuged and the settled phase was diluted and introduced to flame atomic absorption spectrometry by conventional aspiration. Various parameters including amount of ionic liquid, microwave power, irradiation time, pH, amount of chelating agent and salt amount were studied and optimized. At optimized condition, a limit of detection (LOD) of 1.5 ng mL-1, a linear range of 5-32 ng mL-1 and a RSD of 4.3% were obtained. Finally, the developed protocol was utilized for determination of zinc in food samples. <![CDATA[<strong>EVALUATION OF MICROWAVE-ASSISTED EXTRACTION FOR ORGANOTIN DETERMINATION IN VEGETAL AND SOIL MATRICES</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000100024&lng=es&nrm=iso&tlng=es A new method for the extraction of methyl-, butyl-, phenyl- and octyltin compounds from soil and vegetal samples was proposed. The extraction procedure is based on an acidic solution in methanol for both matrices using a microwave system. The optimal conditions for each matrix were determined using the experimental design methodology and the respective figures of merit were evaluated. In optimal conditions, the analytes can be detected between 0.1-2.9 ng g-1 with repeatability lower than 6.5 % for both matrices. The extraction procedure was satisfactorily applied to spiked real samples, reaching recoveries ranged to 48.5-94.1% and 69-123 % for vegetal and soil samples, respectively. The proposed methodology is a promising alternative for control of organotin compounds in terrestrial ecosystems. Finally, the analytical performance of the proposed methodology was compared with published works in order to demonstrate its advantages and benefits.