Scielo RSS <![CDATA[Journal of the Chilean Chemical Society]]> vol. 60 num. 4 lang. es <![CDATA[SciELO Logo]]> <![CDATA[<b>DEGRADED PET FOR THE REMOVAL OF METAL IONS FROM AQUEOUS SOLUTION</b>]]> Poly(ethylene terephthalate) waste was degraded by glycolysis in order to obtain low molecular weight molecules for the batch removal of Cd(II), Cr(III), Cu(II), Ni(II), and Pb(II) from aqueous solution. The degradation product was characterized by IR, H¹NMR, DSC, and GPC, being identified as bis(2-hydroxy ethyl) terephthalate (BHET). The results show that metal absorption follows the order Pb(II)>Cd(II)>Ni(II)>Cu(II)>Cr(III). Degraded PET presented an affinity to remove over 75% of lead in solution at pH 4 and 5 and cadmium over 70% at pH 6. IR spectroscopy and DSC evidenced the presence of metal ions in the structure of the material. <![CDATA[<b>FLAME ATOMIC ABSORPTION SPECTROMETRIC DETERMINATION OF TRACE AMOUNTS OF SILVER IN RADIOLOGICAL WASTE SAMPLES AFTER SOLID PHASE EXTRACTION USING MULTI-WALLED CARBON NANO-TUBES MODIFIED BY SODIUM DODECYL SULFATE</b>]]> Multi-walled carbon nano-tubes was modified with sodium dodecyl sulfate and used as a solid phase extraction adsorbent for the determination of trace silver in radiological waste samples by flame absorption spectrometry. The effects of pH, initial silver ion concentration, sample flow rate and volume, elution conditions and the amount of adsorbent on the recovery of the analyte were investigated and optimized. The results showed that silver could be fully adsorbed at pH 7.0 and eluted by 5.0 mL 2% thiourea in HNO3 (0.1 mol.L-1). Under the optimized conditions, the adsorption capacity of modified multi-walled carbon nano-tubes was found to be 3.2 mg.g-1 of silver. The detection limit of the proposed method was 350 μg. L-1 for silver with an enrichment factor of 35. The relative standard deviation for ten replicate measurement of 0.5 ug of silver from 700 mL samples was 4.7%. The analytical procedure was successfully applied to the determination of trace silver in a few radiological waste samples with the recoveries between 94% and 105%. Graphite furnace atomic absorption spectrometric technique was also used for the comparison with the suggested method for the determination of the real samples. <![CDATA[<b>ADSORPTION STUDIES OF POMEGRANATE PEEL ACTIVATED CHARCOAL FOR NICKEL (II) ION</b>]]> Presence of toxic heavy metals in air, soil, and water are growing threats to the environment. In this study, removal of divalent nickel from aqueous solutions has been investigated by utilizing a low cost pomegranate peel activated charcoal (PPAC) adsorbent. Adsorption capacity of the prepared charcoal at various parameters such as pH, contact time, metal ion concentration and adsorbent dose has been studied. Batch equilibrium experiments showed that maximum nickel adsorption takes place at neutral pH, while the maximum adsorption capacity for PPAC was 10.82 mg g-1. It was also found that percentage removal of nickel is directly proportional to the adsorbent dose with maximum adsorption at an adsorbent dose of 0.5g/50 ml for various concentrations (10-150 ppm) and contact time of 50 minutes. Experimental equilibrium data was verified for Langmuir and Freundlich isotherm models to establish the adsorbate-adsorbent interaction phenomena. The values of regression coefficient for Langmuir and Freundlich isotherm are found to be 0.942 and 0.931 respectively which showed that data fitted well in both models. <![CDATA[<b>SYNTHESIS OF 2,3-UNSATURATED O-GLYCOSIDES FROM OPTICALLY ACTIVE ALCOHOLS VIA FERRIER REARRANGEMENT</b>: <b>CONFIGURATIONAL STUDIES</b>]]> 4-[3-(aryl)-1,2,4-oxadiazol-5-yl] butanones 4a-e have been reduced to optically active 4-[3-(aryl)-1,2,4-oxadiazol-5-yl] butanols 5a-e with baker's yeast. We subjected the alcohols possessing (S)-configuration to Ferrier' rearrangement with tri-O-acetyl-D-glucal 6 which furnished new unsaturated O-glycosides 7a-e. The crystallographic data of the glycosides 7b confirmed the (S)-configuration for the aglycone portion of the carbon atom. <![CDATA[<b>VALIDATED THIN-LAYER CHROMATOGRAPHY/DENSITOMETRY METHOD FOR THE ANALYSIS OF ANTI-ALZHEIMER DRUG IN BULK AND IN CAPSULE FORMULATION</b>]]> A simple, sensitive and precise Thin-Layer Chromatography (TLC)/ Densitometry method has been developed for estimation of Rivastigmine hydrogen tartrate [RVT] in bulk and in capsule formulation. The chromatographic separation was accomplished on aluminium backed precoated silica gel 60 F254 as the stationary phase using n- Hexane: Ethyl acetate: triethylamine (1.5: 8.5: 0.3 v/v) as mobile phase. The R F value was observed to be 0.46 ± 0.02 for RVT when the sports were analyzed densitometrically at 213 nm. The method was linear in the range of 1000 - 6000 ng band-1 with coefficient correlation value 0.9990. RVT was subjected to acid, alkali hydrolysis, oxidation, dry heat degradation and photo degradation. The degraded product peaks were well resolved from the pure drug peak with significant difference in their R F values. Analysis of drug was performed in the presence of degraded samples. The proposed method validated for linearity, accuracy, precision and robustness. The developed TLC-densitometric method can be used as an alternative method for the precise assay of rivastigmine hydrogen tartrate in capsules form because it fulfils the validation criteria of an analytical method designated for quantity control of pharmaceutical preparations. <![CDATA[<b>INSIGHTS INTO THE REACTION MECHANISM BETWEEN AZACYCLOPROPENYLIDENE AND AZACYCLOPROPANE</b>: <b>A THEORETICAL STUDY</b>]]> The reaction mechanism between azacyclopropenylidene and azacyclopropane has been systematically investigated employing the second-order Møller-Plesset perturbation theory (MP2) method to better understand the azacyclopropenylidene reactivity with three-membered ring compound azacyclopropane. Geometry optimization, vibrational analysis, and energy property for the involved stationary points on the potential energy surface have been calculated. For the first step of this reaction, azacyclopropenylidene can insert into azacyclopropane at its C-N bond to form a spiro intermediate IM. Through the ring-opened step at C-C bond of azacyclopropenylidene fragment, IM can transfer to product P1, which is named as pathway (1). On the other hand, through the H-transferred step and subsequent ring-opened step at C-N bond of azacyclopropenylidene fragment, IM can turn into product P2, which is named as pathway (2). From the thermodynamics viewpoint, the P2 is the dominating product. From the kinetic viewpoint, the pathway (1) of formation to P1 is primary. <![CDATA[<b>INVESTIGATED THE SUPRAMOLECULAR INTERACTION OF TRAMADOL HYDROCHLORIDE WITH P-SULFONATED CALIX[4,6,8]ARENE</b>]]> In this paper, the interaction behavior of p-sulfonated calix[n]arene (SCnA) with tramadol hydrochloride was investigated by fluorescence spectra, ¹H NMR spectra, and theoretical calculations in aqueous solution. At the optimized conditions, the fluorescence intensity of tramadol hydrochloride showed positive correlation to the concentration of SCnA, which led to a validated, simple, and sensitive fluorescence quenching method for the determination of tramadol hydrochloride was established for the first time. Moreover, the interaction based on SCnA superstructure provided has promising potential for therapeutic monitoring and pharmacokinetics and clinical application <![CDATA[<b>ARSENIC STATUS AND SPECIATION IN CHICKEN HEART TISSUES</b>]]> This study evaluated the total and main arsenic species in chicken heart tissues. The experimental study was carried out using two sets of samples. In the first one, 30-day-old chickens were exposed to sodium arsenate, using spiked drinking water. These chickens grew normally and were killed after fifty days of arsenic exposure. The second sets were edible chickens were nonexposed to sodium arsenate for a parallel study. The total arsenic and arsenic species content in the exposed samples were at least twice those in the normal edible chicken. One important aspect is the capability of the heart tissues to preconcentrate the most toxic species, arsenite, in the exposed chicken. Arsenobetaine was also detected in fat in the non exposed chicken. This study could be a way of establishing similarities and differences with humans exposed to the same As(V) species, to ascertain whether chickens can be used in arsenic metabolism evaluation and the results extrapolated to humans. <![CDATA[<b>STRUCTURAL FEATURES OF 2-(4,5-DIPHENYL-4H-1,2,4-TRIAZOL-3-YL)THIO)-1-(3-METHYL-3-PHENYLCYCLOBUTYL) ETHANONE</b>: <b>X-RAY DIFFRACTION AND DFT CALCULATIONS</b>]]> This paper reported that the combined X-ray diffraction and DFT computational study on molecular structure of the title compound, [C27H25N3O2S]. The compound contains a cyclobutane, a triazole and three phenyl rings. The molecular geometry of the compound was brought to light by X-ray single crystal structure determination. X-ray study shows that the title compound has a weak intermolecular C-O···π interaction as well as many D-H···A and D-H···π hydrogen bonds. The initial guess on the compound was first obtained from the X-ray coordinates which were optimized by Density Functional Theory (DFT)/B3LYP method with 6-31G(d, p) and 6-31G+(d, p) as basis sets. DFT electronic structures were compared to the experimentally determined molecular structure in the solid state. <![CDATA[<b>SYNTHESIS, CHARACTERIZATION AND CRYSTAL STRUCTURE OF A POLYMERIC SILVER(I) COMPLEX WITH CYTOTOXIC PROPERTY</b>]]> A new polymeric silver(I) complex, [Ag2(L¹)2(L²)(OH2)]n, was obtained by the reaction of 3-aminopyrazine-2-carboxylic acid (HL¹), 2-amino-5-methylpyridine (L²) and silver oxide in aqueous ammonia. The complex was characterized by elemental analysis, IR spectra and single crystal X-ray determination. The smallest repeat unit contains a [Ag2(L¹)2(L²)(OH2)] moiety. The Ag···Ag distance is 7.490(2) Å. One Ag atom is coordinated by three pyrazine N and two carboxylate O atoms from four L¹ ligands, forming a square pyramidal coordination, and the other one is coordinated by one pyrazine N and one carboxylate O atoms from a L¹ ligand, one pyridine N atom from a L² ligand, and one water O atom, forming a square planar geometry. In the crystal structure of the complex, the dinuclear silver moieties are linked through L¹ ligands, to form 1D chains along the x-axis direction. The chains are further linked through intermolecular hydrogen bonds in the y- and z-axis directions, forming a 3D network. In addition, there are π···π interactions among the chains. The complex showed effective cytotoxic property on human lung cancer cell line A549. <![CDATA[<b>PRODUCTION OF NON-ESTER RENEWABLE DIESEL BY THE HYDROGENATION OF VEGETABLE OIL ON THE 15Co5Ni-10Ce / Al<sub>2</sub>O<sub>3</sub> CATALYST</b>]]> The catalysts by incipient wetness impregnation method were prepared and characterized by XRD, BET, H2-TPD, NH3 -TPD and H2-TPR analysis, and the catalyst activity was detected by WFSM-3060 high-pressure reactor. Effective double metal catalysts were produced by using y-Al2O3 as carrier and Co and Ni as activity center, and more effectiveness by using Ce to modify. The results revealed that the 15Co5Ni-10Ce catalyst was the best in producing bio-fuels. The catalyst had good thermal stability, three kinds of adsorbed sites and three kinds of acidic sites. Compared with sintering, the catalyst deactivation was due to coke deposition. The results of FT - IR, SF-3, GC and GC-MS indicated that reaction temperature is the key factor and that oil velocity is a very important factor. The optimized condition was at reaction temperature of 450°C, reaction pressure of 3.0 MPa, oil velocity of 0.1 mL/min and the gas velocity of 35 mL/min, respectively. The alkanes and alkenes content of liquid products are 50.02% and 40.03% under the optimized condition. The main products are the hydrocarbon compounds under C18. The results of GC online and trace water determination showed that the main products of oxygen in the oil are CO and CO2, and that the minor product is H2O. The importance and the economical production of the Non-ester renewable diesel from vegetable oil are presented. From the results of FT-IR, SF-3 and GC-MS, the generating mechanism of Non- ester renewable diesel was deduced. <![CDATA[<b>ESSENTIAL AND FIXED OIL CHEMICAL COMPOSITIONS OF THE SEEDS FROM THE ENDEMIC SPECIES <i>Salvia Sharifii</i> RECH. F. & ESFAND</b>]]> The essential oil content in the seeds of Salvia sharifii growing wild in south of Iran was found to be 0.2% (v/w). The essential oil was analyzed by GC and GC-MS. Twenty eight constituents, representing 85.0 % of the seeds essential oil were identified. The major components of the S. sharifii seeds essential oil were identified as sclareol (21.9%) and n-decane (17.3%). The fixed oil content and fatty acid composition of the seeds were also analyzed in order to determine their potential for human or animal consumption. The oil content in these edible seeds was found to be 19.9 %. The oil was analyzed by GC and GC/MS and five fatty acids identified which constituted 88.0 % of the oil. The main fatty acids of the oil were characterized as linoleic acid (39.7%) and linolenic acid (36.7%). <![CDATA[<b>APPLICATION OF IONIC LIQUIDS IN THE ULTRASOUND-ASSISTED EXTRACTION OF ANTIMICROBIAL COMPOUNDS FROM THE BARK OF <i>CINNAMOMUM CASSIA</i></b>]]> This study compares the chemical constituents of extracts from the bark of Cinnamomum cassia obtained with the use of ionic liquids and organic solvents, as well as investigates their antifungal and yeasticidal activity. The type of ionic liquid was found to play a significant role in this process. We found that the ionic liquid tris (2-hydroxyethyl) methylammonium methylsulfate is a most efficient extracting agent, superior to classical solvents such as ethanol, ethyl acetate, hexane, dichloromethane. The obtained extract revealed high antimicrobial activity against yeasts, fungi pathogenic for plants and bees, dermatophytes, filamentous moulds with similar potencies as the standard fungicides. <![CDATA[<b>ANTIBACTERIAL AND ENZYME INHIBITION SCREENING OF SOME NEW ACETAMIDE AND AZOMETHINE DERIVATIVES</b>]]> The synthesis of poly-functional moieties as one unit has been under consideration by the synthetic chemists to search out new potent molecules. 2-Chlorobenzoic acid (1) was converted to 5-(2-chlorophenyl)-1,3,4-Oxadiazol-2-thiol (4) through a series of steps. This nucleophile was attached with different electrophiles, prepared by the reaction of aryl/alkyl amines with 2-bromoacetylbromide, in NaH/DMF to synthesize N-substituted-2-((5-(2-chlorophenyl)-1,3,4-Oxadiazol-2-yl)sulfanyl)acetamide, 7a-f. The molecule 4 was stepped to ethyl ester and carbohydrazide. The carbohydrazide was made to react with aryl carboxaldehydes in methanol to synthesize N'-substituted-2-(5-(2-chlorophenyl)-1,3,4-Oxadiazol-2-ylthio)acetohydrazide, 11a-i. The structures of all the molecules were corroborated through IR, ¹H-NMR and EI-MS spectral data. Both the series were screened for antibacterial and enzyme inhibition activity. <![CDATA[<b>RECOVERY OF HYDROCHLORIC ACID FROM ION EXCHANGE PROCESSES BY REACTIVE ELECTRODIALYSIS</b>]]> The purification process of electrolytes contaminated from electrorefining consists in placing them in contact with an ion exchange resin which can function continuously due to its reconditioning with hydrchloric acid. The treatment of the resultant solution, known as elution, consists in doing a fractional distillation releasing hydrochloric acid and gaseous chlorine. The release of these represents most of the operational problems in the electrolyte treatment plant. This paper proposes an alternative to this distillation process, using a reactive electrodialysis cell and cation and anion exchange membranes. <![CDATA[<b>SOLID STATE MORPHOLOGY AND SIZE TUNING OF NANOSTRUCTURED PLATINUM USING MACROMOLECULAR COMPLEXES</b>]]> The macromolecular complexes Chitosan●(PtCl2)n and PSP-co-4-PVP●(PtCl2)n, were prepared from the respective polymer and PtCl2 in metal:polymer molar ratios 1:1 and 1:5. Pyrolisis of the macromolecular complexes Chitosan●(PtCl2)n and PSP-co-4-PVP●(PtCl2)n at 800 °C under air affords cubic nanostructured Pt in the pure phase. The morphology of the pyrolityc products depends on the molar metal:polymer ratio; i.e. a "cotton" 3D shape for the 1:1 ratio and a 'foamy" 3D shape for the 1:5 ratio. On the other hand, the particle size depends on the polymer nature, obtaining Pt nanoparticles as small as 6 nm for the chitosan precursors in both molar ratio. <![CDATA[<b>CHEMICAL COMPOSITION AND BIOLOGICAL ACTIVITIES OF <i>DAUCUS AUREUS</i> ESSENTIAL OILS FROM EASTERN ALGERIA</b>]]> The aim of this study was to investigate the chemical composition of the essential oils of three populations of Daucus aureus from three sites in Eastern Algeria (Setif, Constantine and Oum Elbouaghi) and to test their antibacterial and antioxidant activities. The essential oils were obtained by hydrodistillation and analyzed by GC and GC/MS. The major components were sabinene (30.6% and 36.2%), n-nonane (8.0% and 7.9%), α-pinene (5.5% and 6.3%) and 4-terpineol (4.4% and 6.0%) in D. aureus from Setif and Constantine populations essential oils, respectively; whereas, α-pinene (19.4%), β-pinene (12.0%) and p-cymene (12.2%) were the major components in Oum Elbouaghi essential oil population. The chemical compositions of D. aureus from Eastern Algeria are markedly different from those from Western Algeria, and likely represent new chemotypes. The antimicrobial activity of the essential oils was evaluated against four bacteria and one fungus, using the disc-diffusion method and minimal inhibitory concentration (MIC), whereas, the antioxidant activity of the essential oils was evaluated using the DPPH test. The results showed that the oils have an antimicrobial activity against the microorganisms tested, with minimal inhibitory concentration (MIC) values between 0.97 and 3.23 mg/mL and weaker antioxidant and DPPH radical scavenging activities were found in comparison to butylated hydroxyl toluene (BHT). <![CDATA[<b>SIMULTANEOUS DETERMINATION OF LEVODROPROPIZINE, METHYLPARABEN, AND PROPYLPARABEN IN ORAL CO-FORMULATED SYRUP BY RP-HPLC METHOD</b>]]> A selective, rapid, isocratic RP-HPLC method has been developed and validated for the simultaneous determination of the cough suppressant drug levodropropizine and its two co-formulated preservatives methylparaben and propylparaben in Levopront® syrups. The chromatographic separation was achieved on Inertsil® C18, (250 mm x 4.6mm, 5um) column using a mixture of (acetonitrile: 0.1 % triethylamine in water, pH 3.0) 50:50: (v/v), as a mobile phase with a flow rate of 1.0 ml/min, at 30° C column temperature and detector wavelength of 240 nm. All peaks were symmetrical and well resolved in a short run time. Method validation demonstrated to be selective, accurate and precise with good linearity over the concentration range of (7.5-60 μg/ml), (1.625-13 μg/ml), and (0.25-2 μg/ ml) with limits of detection and quantification of 0.502 and 1.520 μg/ml, 0.071 and 0.215 μg/ml, and 0.040 and 0.122 μg/ml for Levodropropizine, Methylparaben, and Propylparaben, respectively. Robustness against small modifications of column temperature, flow rate and pH of the mobile phase was ascertained. The developed method was successfully applied for the separation and quantification of Levodropropizine in presence of its two co-formulated preservatives in drug substances and in Levopront® oral pharmaceutical formulation; therefore it's highly suitable for routine analysis in QC labs. <![CDATA[<b>A SINGLE HPLC-DAD METHOD FOR SIMULTANEOUS ANALYSIS OF PARACETAMOL, PHENYLEPHRINE, CAFFEINE AND LEVOCETIRIZINE IN BULK POWDER AND TABLET FORMULATION</b>: <b>APPLICATION TO IN-VITRO DISSOLUTION STUDIES</b>]]> Present work describes development and validation of HPLC-DAD method for the analysis of a complex mixture consisting phenylephrine hydrochloride (PHE), paracetamol (PAR), caffeine (CAF) and levocetirizine (LEV). Chromatographic separation was achieved using a Kinetex-C18 column involving gradient elution, the mobile phase composed of 10mM phosphate buffer (pH 3.3) and methanol. The three step gradient program started with step-1 initially with 2% (by volume) methanol and 98 % phosphate buffer (pH 3.3) for first 5 minutes. In step-2 methanol concentration changed linearly to 80% in next 12 minutes the analysis was concluded by step-3 changing methanol to 2% in next 8 minutes. The method was linear in concentration ranges of 50 to 200 % of labeled claims with r² near to 1. Developed method proved to be precise for inter and intra-day studies the %RSD values were < 2 , accuracy studies by standard addition at 80, 100 and 120% levels resulted in recoveries of standard near to 100%. The method was selective with no interferences from placebo; robustness of method was proved by no significant alteration in system suitability parameters. The LOD values for PHE, PAR, CAF and LEV were 0.13, 0.51, 0.05 and 0.05 and LOQ were 0.39, 1.53, 0.15 and 0.15 respectively. The study concluded a validated HPLC method for analysis of complex mixture consisting PHE, PAR, CAF and LEV in bulk, tablet and dissolution samples in simulated gastric fluid (SGF). <![CDATA[<b>UNDERSTANDING THE STRUCTURE, SUBSTITUENT EFFECT, NATURAL BOND ANALYSIS AND AROMATICITY OF OSMABENZYNE</b>: <b>A DFT STUDY</b>]]> The structures and properties of osmabenzyne and para-substituted osmabenzynes (X=F, Cl, Br, Me, NH2, OH, NO2, CHO, COOH) have been explored using theoretical methods. Frontier orbital analysis indicates the HOMO and LUMO are distributed on the ring carbon atoms, Os and Cl ligands. Time dependent density functional theory (TD-DFT) is used to calculate the energy, oscillatory strength and wavelength absorption maxima (λmax) of various electronic transitions and their nature within molecules. Non linear optical (NLO) behavior of title compounds is investigated by the computed value of first hyperpolarizability (βtotal). <![CDATA[<b>ESSENTIAL AND FIXED OIL CHEMICAL PROFILES OF <i>Salvia aegyptiaca</i> L. FLOWERS AND SEEDS</b>]]> The essential oil content in the flowers of Salvia aegyptiaca growing wild in south of Iran was found to be 0.1% (v/w). The essential oil was analyzed by GC and GC-MS. Ten constituents, representing 98.7 % of the flowers essential oil were identified. The major component of S. aegyptiaca flowers essential oil was identified as octane (60.7%). The fixed oil content and fatty acid composition of the seeds were also analyzed in order to determine their potential for human or animal consumption. The oil content in these edible seeds was found to be 16.2 %. The oil was analyzed by GC and GC/MS and twenty six components identified which constituted 84.6 % of the oil. The main compounds of the seeds oil were characterized as n-dodecane (23.9%), tetradecane (15.6%) and n-decane (10.5%). <![CDATA[<b>PREPARATION AND CHARACTERIZATION OF ZnO/CuO SEMICONDUCTOR AND PHOTOCATALYTIC ACTIVITY ON THE DECOLORIZATION OF DIRECT RED 80 AZODYE</b>]]> Zinc oxide, an n-type semiconductor, has been used as photocatalyst for contaminated water purification by organic compounds. The addition of a p-type semiconductor as copper oxide could increase the catalytic efficiency through the p-n junction in order to decrease the electron-hole recombination. In this work, zinc and copper oxides containing 1.0, 3.0, and 5.0 % of copper were prepared by manual grinding, followed by heat treatment at 300°C during 5 h. The zinc oxide and copper oxide mixture as well as their precursors were characterized by x-ray diffraction, diffuse reflectance, scanning electron microscopy, and x-ray fluorescence. The photocatalytic efficiency was verified by the direct red 80 tetraazodye decolorization using UV radiation under pseudo-first order conditions at natural pH (7.5-8.0) and 30 °C. The highest photocatalytic activity occurred to the semiconductor containing 1.0 % copper oxide, whose decolorization rate constant was equivalent to 6.40×10-2 min-1, that is, 17.4 % larger in comparison to ZnO, 5.45×10-2 min-1.