Ethyl Acetate (ethyl + acetate)

Distribution by Scientific Domains
Distribution within Chemistry

Terms modified by Ethyl Acetate

  • ethyl acetate extract
  • ethyl acetate fraction

  • Selected Abstracts

    Pinacol Coupling of Aromatic Aldehydes and Ketones Mediated by TiCl4,Zn in Ethyl Acetate under Ultrasound.

    CHEMINFORM, Issue 50 2007
    Ji-Tai Li
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

    Lipase-Mediate Epoxidation Utilizing Urea,Hydrogen Peroxide in Ethyl Acetate.

    CHEMINFORM, Issue 8 2007
    Emanuel G. Ankudey
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

    Acoustical Properties of Binary Mixtures of Heptane with Ethyl Acetate or Butyl Acetate

    Divya Shukla
    Abstract Mixed solvents rather than single pure liquids are of utmost practical importance in chemical and industrial processes as they provide an ample opportunity for the continuous adjustment of desired properties of the medium. Therefore, ultrasonic velocity (u) and density (,) were measured for the binary mixtures formed by heptane with ethyl acetate or butyl acetate at temperatures 293, 298 and 303 K over the entire composition range. Deviation in ultrasonic velocity (,u), deviation in isentropic compressibility (,,s), and excess intermolecular free length (LEf) have been evaluated using the ultrasonic velocity data and the computed results were fitted to the Redlich-Kister polynomial equation. The values of ,u, ,,s and LEf were plotted against the molar fraction of heptane. The observed positive and negative values of excess parameters were discussed in terms of molecular interaction between the components of the mixtures. Experimental values of ultrasonic velocity and density were compared with the results obtained by theoretical estimation procedures. The results were discussed in terms of average absolute deviation (AAD). [source]

    Nanostructure Copper-exchanged ZSM-5 Catalytic Activity for Conversion of Volatile Organic Compounds (Toluene and Ethyl Acetate)

    S. Ali Hosseini
    Abstract Gas phase catalytic oxidation of ethyl acetate and toluene was examined over copper modified ZSM-5 catalysts under atmospheric pressure. Nanostructure of ZSM-5 was characterized by XRD, SEM and TEM techniques. Elemental composition of ZSM-5 was determined using EDX, ICP-AES and XPS techniques. Results of catalytic studies showed better catalytic activity of Cu-ZSM-5 catalysts than those of parent ZSM-5 and HZSM-5, which revealed catalytic role of copper ions in the Cu-ZSM-5 catalysts. Effects of some parameters over catalytic conversion of these compounds were also studied. Ethyl acetate showed more reactivity than toluene over the Cu-ZSM-5 catalysts. Furthermore, the catalytic activity of Cu-ZSM-5 catalysts increased with increasing the copper loadings. The conversion behavior of a binary mixture of ethyl acetate and toluene was different from that of a single form. A promotive and inhibitive behavior was observed for conversion of ethyl acetate and toluene in the binary mixture, respectively. Water vapor as co-feed had an inhibitive effect on conversion of organic compounds over the Cu-ZSM-5 catalysts. [source]

    Catalytic Combustion of Ethyl Acetate over Nanostructure Cobalt Supported ZSM-5 Zeolite Catalysts

    Aligholi NIAEI
    Abstract Gas phase catalytic combustion of ethyl acetate, as one of volatile organic compounds (VOC), was studied on nanostructure ZSM-5, HZSM-5 and Co-ZSM-5 with different cobalt loadings. Nanostructure of ZSM-5 was determined by XRD, SEM and TEM. Catalytic studies were carried out under atmospheric pressure in a fixed bed reactor. Results showed that the Co-ZSM-5 catalysts had better activity than others and at temperatures below 350 °C, amount of Co loading was more effective on catalytic activity. The order of conversion of ethyl acetate over different Co loading is as follows: Co-ZSM-5 (0.75 wt%)ethyl acetate, the lower the conversion yield, and oxygen concentration in catalytic oxidation conditions has not so large influence on conversion. Furthermore, the presence of water vapor in inlet gaseous feed has an inhibitive effect on ethyl acetate conversion and at the temperatures above 400?C, the effect decreases. [source]

    Preferential extractability of ,-oryzanol from dried soapstock using different solvents

    Raj R Kumar
    Abstract BACKGROUND: ,-Oryzanol from rice bran has lately gained potential importance because of its proven health benefits. Thus the extractability of ,-oryzanol from the soapstock of crude rice bran oil is important from the perspective of future large-scale production, which would give value addition to this by-product obtained from the rice bran oil industry. The aim of the present study was to investigate the extraction of ,-oryzanol from the drum-dried soapstock of rice bran oil using various solvents. RESULTS: It was found that ,-oryzanol could be extracted most effectively using ethyl acetate, followed by dichloromethane and ethyl methyl ketone. All components of ,-oryzanol have an alcohol group in the ferulate portion giving rise to relatively high polarity, thereby increasing the extraction in more polar solvents efficiently. Ethyl acetate showed maximum extractability of ,-oryzanol by the Soxhlet method. To quantify ,-oryzanol, reverse phase high-performance liquid chromatography (RP-HPLC) was used for fingerprinting the ,-oryzanol analogues with respect to standard ,-oryzanol. CONCLUSION: A new RP-HPLC method for determining the individual components of ,-oryzanol has been reported that can be used for performing an online characterisation of ,-oryzanol analogues by liquid chromatography/mass spectrometry. Copyright © 2008 Society of Chemical Industry [source]

    Reactivity of ethyl acetate and its derivatives toward ammonolysis: ramifications for ammonolysis-based microencapsulation process

    Younglim Chung
    Abstract The reactivity of three ester organic solvents toward ammonolysis was examined in relation to the development of an ammonolysis-based microencapsulation process. Ethyl acetate, ethyl chloroacetate, and ethyl fluoroacetate were chosen as ester organic solvents. Progesterone was considered as a model drug to be encapsulated into poly- D, L -lactide- co -glycolide microspheres. A polymeric dispersed phase was emulsified in an aqueous phase, to which ammonia was added to initiate ammonolysis. The polarization status of a carbonyl group in the backbone of the ester was found to decide the magnitude of the ester reactivity. In fact, the simple ester ethyl acetate hardly reacted with ammonia, while ethyl chloroacetate and ethyl fluoroacetate showed greater reactivity toward ammonolysis. The rapid completion of ammonolysis led to the conversion of the water-immiscible solvents into water-soluble solvents, thereby providing an efficient tool for microsphere solidification. Among microencapsulation parameters, the type of dispersed solvent, the molar ratio of ammonia to a dispersed solvent, and the percentage of the progesterone payload decisively influenced the characteristics of the microspheres. Subsequently, variations in such parameters accompanied considerable influence on microsphere morphology, incorporation efficiency, thermal behavior, the degree of residual solvents, and the physical status of progesterone. Optimization of the process parameters would not only contribute to improving the ammonolysis-based microencapsulation process, but would also permit the tailoring of microsphere properties to specific demands. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Nanostructure Copper-exchanged ZSM-5 Catalytic Activity for Conversion of Volatile Organic Compounds (Toluene and Ethyl Acetate)

    S. Ali Hosseini
    Abstract Gas phase catalytic oxidation of ethyl acetate and toluene was examined over copper modified ZSM-5 catalysts under atmospheric pressure. Nanostructure of ZSM-5 was characterized by XRD, SEM and TEM techniques. Elemental composition of ZSM-5 was determined using EDX, ICP-AES and XPS techniques. Results of catalytic studies showed better catalytic activity of Cu-ZSM-5 catalysts than those of parent ZSM-5 and HZSM-5, which revealed catalytic role of copper ions in the Cu-ZSM-5 catalysts. Effects of some parameters over catalytic conversion of these compounds were also studied. Ethyl acetate showed more reactivity than toluene over the Cu-ZSM-5 catalysts. Furthermore, the catalytic activity of Cu-ZSM-5 catalysts increased with increasing the copper loadings. The conversion behavior of a binary mixture of ethyl acetate and toluene was different from that of a single form. A promotive and inhibitive behavior was observed for conversion of ethyl acetate and toluene in the binary mixture, respectively. Water vapor as co-feed had an inhibitive effect on conversion of organic compounds over the Cu-ZSM-5 catalysts. [source]

    Potential of combining of liquid membranes and molecularly imprinted polymers in extraction of 17,-estradiol from aqueous samples

    Olga Nemulenzi
    Abstract The potential of combination of liquid membranes (microporous membrane liquid,liquid extraction) and molecularly imprinted polymers (MIPs) was performed using 17,-estradiol (E2) as model compound. The model compound was extracted from aqueous sample through a hydrophobic porous membrane that was impregnated with hexane/ethyl acetate (3:2), which also formed part of the acceptor phase. In the acceptor phase, the compound was bound onto MIP particles that were also part of the organic phase. The potential of such combination was optimised for the type and amount of MIP particles in the organic acceptor phase, the extraction time, and the type of organic acceptor solvent. Ultrasound assisted binding of E2 onto MIP particles was also investigated. MIPs prepared by precipitation polymerization were found to be superior to those prepared by bulk polymerization. Increase in the extraction time and the amount of MIP particles in the acceptor phase led to more E2 binding onto the MIP particles. Hexane/ethyl acetate (3:2) as an organic acceptor was found to give higher E2 binding onto MIP particles compared to toluene, diethyl ether, and hexane. Ultrasound was furthermore found to increase the binding of E2 onto MIP particles. The selectivity of the technique was demonstrated by extracting wastewater and where clean chromatograms were obtained compared to liquid membrane extractions (SLMs) alone. [source]

    Synthesis and HPLC enantioseparation of the cyclopropane analogue of valine (c3Val)

    CHIRALITY, Issue 1 2005
    Ana I. Jiménez
    Abstract A new and efficient method is presented for the preparation of the N -Boc-protected cyclopropane analogue of valine, 1-(N-tert -butoxycarbonyl)amino-2,2-dimethylcyclopropanecarboxylic acid, both in racemic and enantiomerically pure forms. Cyclopropanation of the exocyclic double bond of 2-phenyl-4-isopropylidene-5(4H)-oxazolone with diazomethane followed by elaboration of the heterocyclic moiety provided multigram quantities of the racemic target compound. Subsequent HPLC resolution of a racemic precursor on a noncommercial chiral stationary phase has given access to enantiomerically pure products. Almost 1.5 g of the first-eluted enantiomer and 1.0 g of the second-eluted enantiomer have been isolated in optically pure form using a 150 × 20 mm ID column containing mixed 10-undecenoate/3,5-dimethylphenylcarbamate of cellulose covalently bonded to allylsilica gel with a mixture of hexanes/tert -butyl methyl ether/ethyl acetate as the mobile phase. Chirality 17:22,29, 2005. ©2004 Wiley-Liss, Inc. [source]

    Organic Phase PPO Biosensors Prepared by Multilayer Deposition of Enzyme and Alginate Through Avidin-Biotin Interactions

    ELECTROANALYSIS, Issue 24 2004
    S. Cosnier
    Abstract Films of electrogenerated polypyrrole and hydrophilic alginate, both functionalized with biotin moieties, were used to allow for the transfer of polyphenol oxidase activity in organic media. Enzyme electrodes, based on multilayered structures, were protected at the molecular level by the affinity binding of alginate as a hydrophilic additive, and were then transferred into chlorobenzene, dichloromethane, chloroform, ethyl acetate or acetonitrile. The biosensor performance for the detection of catechol at ,0.2,V was investigated, highlighting the main influence of the hydrophobicity of the solvent and, to a lesser extent, the dielectric constant. The effect of the substrate hydrophobicity on the biosensor response was examined in chlorobenzene. [source]

    Voltametric and Flow Injection Determination of Oxytetracycline Residues in Food Samples Using Carbon Fiber Microelectrodes

    ELECTROANALYSIS, Issue 7 2003
    L. Agüí
    Abstract A voltammetric method for the determination of the antibiotic oxytetracycline (OTC) in food samples is reported. Carbon fiber microelectrodes (CFMEs), which allow voltammetric measurements to be performed in a small volume (1,mL) of the analyte extract from the samples, are employed. Repeatable electroanalytical responses were obtained with no need of applying cleaning treatments to the CFME. Under the optimized square-wave conditions, a linear calibration plot for OTC was obtained in the 1.0×10,6,1.0×10,4,mol,L,1 range, with a detection limit of 2.9×10,7,mol,L,1 (150,ng,mL,1) OTC. The determination of OTC by a flow-injection method with amperometric detection using a homemade flow cell specially designed to work with CFMEs, was also evaluated using pure acetonitrile as the carrier. The SW voltammetric method was applied to the determination of OTC in spiked milk and eggs samples, at 100,ng,mL,1 and 200,ng g,1 levels, respectively. The procedure involved the extraction of the analyte in ethyl acetate, evaporation of the solvent and reconstitution of the residue in acetonitrile ,5.0×10,4,mol,L,1 tetrabutylammonium perchlorate medium. Recoveries of 96±8 and 91±8% were obtained for milk and eggs, respectively, by applying the standard additions method. [source]

    Simultaneous determination of memantine and amantadine in human plasma as fluorescein derivatives by micellar electrokinetic chromatography with laser-induced fluorescence detection and its clinical application

    ELECTROPHORESIS, Issue 11 2010
    Hsin-Hua Yeh
    Abstract A nonionic surfactant MEKC method with LIF detection was developed for the simultaneous determination of memantine, an anti-Alzheimer's disease agent, and amantadine, an anti-Parkinson's disease drug, in human plasma. Before analysis, the plasma samples were pretreated by liquid,liquid extraction with ethyl acetate, and derivatized with 6-carboxyfluorescein N -hydroxysuccinimide ester. The chemical derivatization is performed with 6-carboxyfluorescein N -hydroxysuccinimide ester in ACN , 5,mM pH 9.0 borate buffer (40:60, v/v) at 35°C for 3,h. After the derivatization reaction, hydrodynamic injection (0.5,psi, 8,s) was used to introduce the derivatized solution, and the separation was performed in borate buffer (30,mM, pH 9.5) with the nonionic surfactant Brij-35® (0.07%, w/v); the separation voltage was 6,kV. The linear ranges of the method for the determination of memantine and amantadine in human plasma were over a range of 2.0,60.0,ng/mL. The detection limit was 0.5,ng/mL (S/N=3). This method was applied successfully to monitor the concentration of memantine or amantadine in patients with Alzheimer's disease or Parkinson's disease. [source]

    Whole body extract of Mediterranean fruit fly males elicits high attraction in virgin females

    Vassilis G. Mavraganis
    Abstract The search for effective female attractants emanating from the host or body of fruit flies has been an area of intensive research for over three decades. In the present study, bodies of male Mediterranean fruit flies, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), were extracted with diethyl ether or methanol and subjected to gas chromatography,mass spectrometry. Analysis revealed substantial qualitative and quantitative differences between males from a laboratory culture and wild males captured alive in an orchard. Most notably, the hydrocarbon sesquiterpene (±)-,-copaene, which is known to be involved in the sexual behaviour of the species, was found in substantial amounts in wild males, but was not detected in laboratory males. In laboratory tests, 15 laboratory or wild male equivalents of diethyl ether extracts or combined diethyl ether and methanol extracts, or, to a lesser extent, methanol extracts alone, were found to attract virgin females. In a citrus orchard, traps baited with combined diethyl ether and methanol extracts of wild males attracted significantly more virgin females than traps baited with various doses of pyranone or blends of other compounds identified in the extracts or reported in the literature, such as ethyl acetate, ethyl-(E)-3-octenoate, and 1-pyrroline. Traps baited with blends of compounds, however, displayed substantial attractiveness compared to control (non-baited) traps. These results are important for better understanding the mating system of C. capitata as well as for further improving existing monitoring and control systems. [source]

    Toxicity testing using esterase inhibition as a biomarker in three species of the genus Lecane (Rotifera)

    Ignacio Alejandro Pérez-Legaspi
    Abstract We have developed an esterase inhibition test to investigate the effects of 10 toxicants, including six metals (cadmium, chromium, copper, lead, mercuric chloride, and titanium) and four organics (benzene, ethyl acetate, toluene, and vinyl acetate) in three species of the benthic rotifer genus Lecane (L. hamata, L. luna, and L. quadridentata). Metals affect esterase inhibition by an average value of 4,957-fold greater than the four organics tested for the three rotifer species. Most of the EC50 (effect concentration where a 50% reduction in esterase activity is observed) values correspond to environmentally realistic concentrations. Comparisons of acute-to-chronic ratios among these three species showed that in two species, L. luna and L. quadridentata, esterase inhibition is an outstanding biomarker for most of the toxicants tested. [source]

    Supercritical extraction of borage seed oil coupled to conventional solvent extraction of antioxidants

    Carmen Soto
    Abstract This paper describes the extraction of borage seed oil by supercritical carbon dioxide (SC-CO2) and the further extraction of antioxidants from the SC-CO2 -defatted borage meal with organic solvents (water, methanol, ethanol and ethyl acetate). The optimal conditions for oil extraction were obtained at 303 and 323,K at 200,bar, 2.5,h and a continuous flow of CO2 of 1.5,L/h introduced through the bottom when the operating pressure and temperature were reached, attaining a yield of 60%. Borage oil is rich in unsaturated fatty acids; oleic acid, linoleic acid and linolenic acid accounted for 74% of the total fatty acid content under the above conditions. The highest extraction yield was achieved using water or methanol as extracting solvent from the SC-CO2 -defatted borage meal at 303,K and pressures of 200 and 150,bar for water and methanol, respectively. The most potent extracts, according to all methods tested, were obtained with water and methanol. [source]

    Effects of the nature and concentration of substrates in aqueous solutions on the solubility of aroma compounds

    Marco Covarrubias-Cervantes
    Abstract The solubility of nine aroma compounds (acetone, 2-butanone, 2-hexanone, 2-octanone, ethyl acetate, ethyl butanoate, ethyl hexanoate, n -hexanal, and n -hexanol) in both water and various aqueous solutions was measured at 25 °C using the mutual solubility method. The aqueous solutions consisted of sucrose, glucose, sorbitol, glycerol, polyethylene glycol 200, or maltodextrins at different concentrations. Aroma solubility in water decreased with increased hydrophobicity. For aroma molecules which have the same number of carbon atoms in their structure, aqueous solubility decreased as follows: aldehyde > methyl ketone > alcohol > ethyl ester. When using a group contribution method, the estimated solubility of ethyl esters and methyl ketones in water was, respectively, underestimated and overestimated. Compared to water, the solubility of the volatile molecules in aqueous solutions was higher in the aqueous polyols solutions than in the carbohydrate solutions, although solubility decreased as substrate concentration increased. Aqueous solutions properties, such as water activity, also in,uenced aroma compound solubility. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    Synthesis of novel thiazole and pyrrolothiadiazine derivatives from aldehyde thiosemicarbazones

    Mohsen A.-M.
    Substituted thiosemicarbazones 7a,e reacted with ethenetetracarbonitrile (TCNE) in ethyl acetate with formation of 5-amino-3-(substituted ben-zylidene-amino)-2-phenylimino-2,3-dihydrothiazole-4-carbonitrile 8a,e 2-amino-6-phenyl-imino-1,6- dihydropyrrolo[1,3,4]thiadiazine-3-carbonitrile 9, and phenyl-(5-{substituted phenyl}-3H-[1,3,4]thiadiazole-2-ylidene)amines 10a,e. Rationales for the observed conversations are presented. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:261,266, 2006; Published online in Wiley InterScience ( DOI 10.1002/hc.20198 [source]

    The atmospheric oxidation of ethyl formate and ethyl acetate over a range of temperatures and oxygen partial pressures

    John J. Orlando
    The Cl-atom-initiated oxidation of two esters, ethyl formate [HC(O)OCH2CH3] and ethyl acetate [CH3C(O)OCH2CH3], has been studied at pressures close to 1 atm as a function of temperature (249,325 K) and O2 partial pressure (50,700 Torr), using an environmental chamber technique. In both cases, Cl-atom attack at the CH2 group is most important, leading in part to the formation of radicals of the type RC(O)OCH(O,)CH3 [R = H, CH3]. The atmospheric fate of these radicals involves competition between reaction with O2 to produce an anhydride compound, RC(O)OC(O)CH3, and the so-called ,-ester rearrangement that produces an organic acid, RC(O)OH, and an acetyl radical, CH3C(O). For both species studied, the ,-ester rearrangement is found to dominate in air at 1 atm and 298 K. Barriers to the rearrangement of 7.7 ± 1.5 and 8.4 ± 1.5 kcal/mole are estimated for CH3C(O)OCH(O,)CH3 and HC(O)OCH(O,)CH3, respectively, leading to increased occurrence of the O2 reaction at reduced temperature. The data are combined with those obtained from similar studies of other simple esters to provide a correlation between the rate of occurrence of the ,-ester rearrangement and the structure of the reacting radical. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 397,413, 2010 [source]

    Tyrosinase inhibitors isolated from the roots of Paeonia suffruticosa

    H. -Y.
    J. Cosmet. Sci., 60, 347,352 (May/June 2009) Accepted for publication November 6, 2008. Synopsis The inhibition of mushroom tyrosinase by Paeonia suffruticosa root-derived materials was evaluated. Six tyrosinase inhibitors were isolated by ethanol extraction, n -hexane, ethyl acetate, n -BuOH, and water partition, silica gel column chromatography, Sephadex LH-20, Lobar PR-8, and high-performance liquid chromatography methods, and they were identified as kaempferol (I), quercetin (II), mudanpioside B (III), benzoyloxypaeoniflorin (IV), mudanpioside H (V), and pentagalloyl-,-D-glucose (VI) on the basis of spectroscopic evidence. The inhibitory activities of compounds I to VI against mushroom tyrosinase were determined with IC50 values of 0.120, 0.108, 0.368, 0.453, 0.324, and 0.063 mM, respectively. The kinetic study indicated that all purified inhibitors acted competitively for the L-dopa binding site of the enzyme, with an exception of compound VI, which acted non-competitively. [source]

    An in vitro evaluation of various Rosa damascena flower extracts as a natural antisolar agent

    H. Tabrizi
    Synopsis The aim of this work was to evaluate ultraviolet (UV) absorption ability of various extracts of Rosa damascena flowers as an antisolar agent. Extracts were prepared using the following solvent mixtures: water:ethanol (50 : 50), ethyl acetate:ethanol (80 : 20) and ether. The hydroalcoholic and ethyl acetate:ethanol extracts were prepared by maceration, and ether extract was prepared by soxhletion. Preliminary studies on the extracts prepared confirmed the presence of flavonoids as the major components of all extracts. Next, the UV absorption spectra (in the range of 200,400 nm) of all extracts were obtained. Results show that all three extracts can effectively absorb UV radiation in the range of 200,400 nm. However, the range giving maximum absorption for the hydroalcoholic, ethyl acetate:ethanol and ether extracts were 200,320, 250,360 and 230,370 nm, respectively. In the next stage, extracts prepared were incorporated into an oil in water cream base (prepared based on preliminary studies), at two concentrations of 5 and 8%. The sun protection factor (SPF) of these creams were determined. Based on the findings, the hydroalcoholic extract seems to give the highest SPF among the three extracts evaluated, when incorporated to the cream base. On the other hand, by performing a few physicochemical tests on the prepared creams, cream containing 5% ether extract showed the most desirable appearance and stability among the creams investigated. The UV absorption ability of these extracts is suggested to be because of the presence of flavonoid compounds within the extracts. However, it should be noted that in order to obtain an effective suncare product with high SPF values, these extracts could be used along with other synthetic antisolar agents. Résumé Le but de ce travail était d'évaluer la capacité d'absorption des Ultraviolets (UV) de différents extraits de fleurs de Rosa damascena en tant qu'agents de protection solaire. Les extraits ont été préparés par utilization des mélanges de solvants suivants: Eau:ethanol (50 : 50), Acetate d'éthyle:ethanol (80 : 20) et l'Ether. Les extraits hydro-alcoolique et d'acétate d'ethyle:ethanol ont été réalisés par macération tandis que l'extrait d'éther était obtenu par l'utilization d'un soxhlet. Les études préliminaires des extraits ainsi préparés confirmaient la présence de flavonoïdes en tant que constituants majeurs de tous les extraits. Les spectres d'absorption UV (échelle 200,400 nm) furent ensuite obtenus. Les résultats montrent que tous les extarits peuvent absorber fortement les radiations UV dans l'échelle de 200 à 400 nm. Cependant, les domaines donnant le maximum d'absorption pour les extraits hydroalcoolique, acétate d'éthyle:ethanol et ether étaient respectivement de 200,320, 250,360 et 230,370 nm. Dans une étape ultérieure, les extraits ont été incorporés dans une base type crème huile dans l'eau (préparée selon des études préliminaires) aux deux concentrations de 5 et 8%. Les facteurs de protection solaire (SPF) de ces crèmes étaient ensuite déterminés. Les résultats ont montré que l'extrait hydroalcoolique semblait, parmi les trois, conduire au plus fort SPF, quand incorporé dans une base type crème. De plus, en conduisant quelques tests physioco chimiques sur les crèmes préparées, la crème contenant 5% de l'extrait par éther, comparé aux autres crèmes, offrait l'aspect le plus désirable et le plus stable. Il est suggéré que la capacité d'absorption UV de ces extraits est due à la présence des composés de type flavonoïdes en leur sein. On doit noter, cependant, qu'afin d'obtenir un produit solaire efficace à haut SPF, ces extraits pourraient être adjoints à d'autres filtres solaires synthétiques. [source]

    Chemical composition and inhibitory effect of essential oil and organic extracts of Cestrum nocturnum L. on food-borne pathogens

    Sharif M. Al-Reza
    Summary In this study, we examined the chemical compositions of essential oil and tested the efficacy of oil and organic extracts of Cestrum nocturnum L. against food-borne pathogens. The chemical compositions of the oil was analysed by gas chromatography-mass spectrometry (GC-MS). Forty-seven compounds representing 93.28% of the total oil were identified. The oil [5 ,L of 1:5 (v/v) dilution of oil with methanol] and organic extracts of hexane, chloroform, ethyl acetate and methanol (300 ,g per disc) of C. nocturnum displayed a great potential of antibacterial activity against Staphylococcus aureus (ATCC 6538 and KCTC 1916), Listeria monocytogenes (ATCC 19166 and ATCC 15313), Bacillus subtilis ATCC 6633, Pseudomonas aeruginosa KCTC 2004, Salmonella typhimurium KCTC 2515 and Escherichia coli ATCC 8739. Also the oil had strong detrimental effect on the viable count of the tested bacteria. The results obtained from this study may contribute to the development of new antimicrobial agents with potential applications in food industries as natural preservatives to control food-borne pathogens. [source]

    Analysis of key aroma components in cider from Shaanxi (China) Fuji apple

    Bangzhu Peng
    Summary Aroma components play an important role in the quality of cider. To understand the contribution of every component to cider aroma quality, major aroma components present in ten ciders processed with different technological methods with different yeasts and apple orchards were determined by Headspace-solid phase microextraction,gas chromatography,mass spectrometry and internal standard method. Experimental results by principal component analysis indicated that ethyl acetate, acetic acid isobutylester, isopentylacohol acetate, ethyl caprylate, ethyl 4-hydroxybutanoate, isopentylalcohol, 3,4,5-trimethyl-4-heptanol, nonyl alcohol, 3-methylthio-1-propanol serve as the key aroma components in cider from Shaanxi (China) fuji apple. A model was established and verified for evaluating aroma quality based on factor analysis by comparing with the sensory evaluation method. [source]

    Michael Reaction of Nitroalkanes with ,-Nitroacrylates under a Solid Promoter: Advanced Regio- and Diastereoselective Synthesis of Nitro-Functionalized ,,,-Unsaturated Esters and 1,3-Butadiene-2-carboxylates

    Alessandro Palmieri
    Abstract A new class of nitro-functionalized ,,,-unsaturated esters has been prepared by a regio- and diastereoselective Michael addition of nitroalkanes to ,-nitroacrylates, performed at room temperature, under carbonate on polymer as promoter, and in the presence of ethyl acetate as eco-friendly solvent. Moreover, by the modular choice of the reaction conditions the method allows the synthesis of 1,3-butadiene-2-carboxylates. [source]

    Laboratory and field evaluations of extracts from Rhododendron molle flowers as insect growth regulator to imported cabbage worm, Pieris rapae L. (Lepidoptera:Pieridae)

    G. H. Zhong
    The insect growth regulating properties of rhodojaponin-III (Abbr. R-III) and ethyl acetate (EtOAc) extract from Rhododendron molle G. Don flowers against imported cabbage worm, Pieris rapae L., were determined under laboratory and field conditions. The values of IC50 (the median of concentration for inhibiting weight increase) for R-III and EtOAc extract were 6.78 p.p.m. and 70.29 p.p.m. against 3rd instar larvae and 13.72 p.p.m. and 346.00 p.p.m. against 5th instar larvae, respectively. R-III and EtOAc extract also could reduce pupating rate, pupal weight, emergence rate and extend the duration of development. Thus development of insects was inhibited significantly and development index decreased. R-III would be superior to toosendanin as insect growth regulator. EtOAc extract 1000 p.p.m. mixture with molosultap 500 p.p.m. could achieve an effective control rate of 87.34% against P. rapae in field trials when adjusted cumulative insect-days were used as index. [source]

    Synthesis and characterization of Schiff-base-containing polyimides

    Mousa Ghaemy
    Abstract Benzyl bisthiosemicarbazone and its complexes with nickel (NiLH4) and copper (CuLH4) were used as diamine monomers for the synthesis of new Schiff-base polyimides. The solution polycondensation of these monomers with the aromatic dianhydrides afforded metal-containing Schiff-base polyimides with inherent viscosities of 0.98,1.33 dL/g (measured in N -methyl-2-pyrrolidone at 25°C). The polyimides were generally soluble in a wide range of solvents such as N,N -dimethylformamide, N,N -dimethylacetamide, tetrahydrofuran, dimethyl sulfoxide, tetrachloroethane, hexamethylene phosphoramide, N -methyl-2-pyrrolidone, ethyl acetate, and pyridine at room temperature. The initial degradation temperatures of the resultant polyimides fell in the range of 220,350°C in nitrogen with char yields ranging from 36 to 64% at 700°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    Perfluorosulfonic acid,Tetraethoxysilane/polyacrylonitrile (PFSA-TEOS/PAN) hollow fiber composite membranes prepared for pervaporation dehydration of ethyl acetate,water solutions

    Hai-Kuan Yuan
    Abstract Preparation of organic-inorganic composite membranes and their pervaporation (PV) permeation and separation characteristics for the aqueous solution of ethyl acetate were described. Polyacrylonitrile (PAN) hollow fiber ultrafiltration membrane as support membrane, the mixtures of perfluorosulfonic acid (PFSA) and tetraethoxysilane (TEOS) by the sol-gel reaction as the coating solution, the PFSA-TEOS/PAN hollow fiber composite membranes by the different annealing conditions were prepared. The swelling of PFSA in ethyl acetate aqueous solutions was inhibited with addition of TEOS. The PFSA-TEOS/PAN composite membranes containing up to 30 wt % TEOS in coating solution exhibited high selectivity towards water, then the selectivity decreased and permeation flux increased with increasing the TEOS concentration more than 30 wt %. When the PFSA-TEOS/PAN composite membranes were annealed, the separation factor increased with increasing annealing temperature and time. Higher annealing temperature and longer annealing time promoted the crosslinking reaction between PFSA and TEOS in PFSA-TEOS/PAN composite membranes, leading to the enhanced selectivity towards water. For the PFSA/PAN and PFSA-TEOS/PAN composite membrane with 5 and 30 wt % TEOS annealed at 90°C for 12 h, their PV performance of aqueous solution 98 wt % ethyl acetate were as follows: the separation factors were 30.8, 254 and 496, while their permeation flux were 1430, 513 and 205 g/m2 h at 40°C, respectively. In addition, the PV performance of PFSA-TEOS/PAN composite membranes was investigated at different feed solution temperature and concentration. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    HTPB-based polyurethaneurea membranes for recovery of aroma compounds from aqueous solution by pervaporation

    Yunxiang Bai
    Abstract Hydroxyterminated polybutadiene (HTPB)-based polyurethaneurea (PU), HTPB-PU, was synthesized by two-step polymerization and was firstly used as membrane materials to recover aroma, ethyl acetate (EA), from aqueous solution by pervaporation (PV). The effects of the number,average molecular weight (Mn) of HTPB, EA in feed, operating temperature, and membrane thickness on the PV performance of HTPB-PU membranes were investigated. The membranes demonstrated high EA permselectivity as well as high EA flux. The DSC result showed two transition temperatures in the HTPB-PU membrane and contact angle measurements revealed the difference of hydrophobicity of the membrane at both sides, which were induced by glass plate and air, respectively, due to movement of the soft hydrophobic polybutadiene (PB) segments in HTPB-PU chains. Furthermore, the PV performance of the HTPB-PU membrane with the hydrophobic surface facing the feed was much better than that with the hydrophilic surface. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 552,559, 2007 [source]

    High-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry for the determination of flocoumafen and brodifacoum in whole blood

    Mi-cong Jin
    Abstract A high-performance liquid chromatographic,tandem mass spectrometric (HPLC,MS,MS) assay was developed and validated to determine quantitatively flocoumafen and brodifacoum in whole blood using warfarin as an internal standard (IS). Liquid,liquid extraction, using ethyl acetate, was used to isolate flocoumafen, brodifacoum and the IS from the biological matrix. Detection was performed on a mass spectrometer by negative electrospray ionization (ESI) in multiple reaction monitoring (MRM) mode. The calibration curves were linear (r2 > 0.998) in the concentration range of 0.1,100.0 ng ml,1 with a lower limit of quantification of 0.05 ng ml,1 for flocoumafen, and 0.1 ng ml,1 for brodifacoum in whole blood. Intra-day and inter-day relative standard deviations (RSDs) were less than 8.0% and 10.8%, respectively. Recoveries of flocoumafen and brodifacoum ranged from 78.0% to 83.7%. This assay can be used to determine trace flocoumafen and brodifacoum in whole blood to investigate suspected poisoning of human and animals. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    Surface properties and catalytic behavior of MoO3/SiO2 in esterification of acetic acid with ethanol

    Abd El-Aziz A Said
    Abstract A series of MoO3/SiO2 catalysts was prepared by an impregnation method with Mo loadings ranging from 1 to 50 wt%. The original and calcined samples at 400 °C were characterized by thermogravimetry (TG), differential thermogravimetry (DTG), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infra-red (FTIR) spectroscopy, and nitrogen adsorption measurements. The surface acidity and basicity of the catalysts were investigated by the dehydration,dehydrogenation of isopropanol and the chemisorption of pyridine. The catalytic esterification of acetic acid with ethanol was carried out at 220 °C in a conventional fixed-bed reactor at 1 atm using air as a carrier gas. The results clearly revealed that silica,molybdena catalysts were active and selective towards the formation of ethyl acetate. Moreover, the catalyst containing 20 wt% MoO3 was the most active and selective one. The results emphasize the importance of the surface acid sites together with the specific surface area of the prepared catalyst, towards ester formation. Copyright © 2005 Society of Chemical Industry [source]