Search for: esters
0.034 seconds
Total 84 records

    Novel keggin-type polyoxometalate nanocatalysts for michael addition polymerizations

    , Article Materials Chemistry and Physics ; Volume 199 , 2017 , Pages 79-87 ; 02540584 (ISSN) Karimi Ahmadabad, F ; Pourayoubi, M ; Bakhshi, H ; Sharif University of Technology
    Keggin-type polyoxometalate (POM) nanoparticles based on [PW12O40]3- and [SiW12O40]4- with Ag+ and (ZrO)2+ cations were prepared under ultrasound irradiation. The results of SEM and XRD revealed the average size of particles in the range of 24–95 nm. The moles of crystallization water per mole of nanocatalysts were in the range of 3–9. EDX spectra confirmed the successful replacement of protons of H3PW12O40 and H4SiW12O40 with Ag+ and (ZrO)2+ cations. These nanoparticles were used as heterogeneous catalysts for the synthesis of a poly (amido-ester) at room temperature. All polymers were fully characterized. Although employing the nanocatalyst resulted in at least 22% improvement in the... 

    Characterization and determination of fatty acids in fish oil using gas chromatography-mass spectrometry coupled with chemometric resolution techniques

    , Article Journal of Chromatography A ; Volume 1024, Issue 1-2 , 2004 , Pages 165-176 ; 00219673 (ISSN) Jalali Heravi, M ; Vosough, M ; Sharif University of Technology
    Elsevier  2004
    Characterization and determination of a complex mixture of fatty acid methyl esters was performed for commercial fish oil using two-dimensional GC-MS data coupled with resolution techniques. Various principle component analysis methods such as significant factor analysis and fixed size moving window evolving factor analysis were used for the number of factors, zero concentration and selective regions. Then, the convoluted chromatograms were resolved into pure chromatograms and mass spectra using heuristic evolving latent projections (HELP) method. Fatty acids of C16:1ω7, C18:4ω3, C18:1ω11, C18:1ω9, C18:0, C20:2ω6, C20:1ω9, C 22:1ω11, C22:1ω9 and C24:1ω9 were resolved and identified by using... 

    Novel approach for liquid-liquid phase equilibrium of biodiesel (canola and sunflower) + glycerol + methanol

    , Article Industrial and Engineering Chemistry Research ; Vol. 53, issue. 2 , 2014 , pp. 855-864 ; ISSN: 08885885 Hakim, M ; Abedini Najafabadi, H ; Pazuki, G ; Vossoughi, M ; Sharif University of Technology
    In this study, a novel experimental approach was used to overcome the lack of phase equilibrium information to obtain data that is more applicable to industrial situations. Liquid-liquid equilibrium (LLE) data, tie-lines, and phase boundaries were carried out for two systems of canola oil methyl esters (containing 1 wt % KOH) + glycerol + methanol and sunflower oil methyl esters (containing 1 wt % KOH) + glycerol + methanol at three different temperatures (303.15, 313.15, and 323.15 K). The quality of data was also ascertained using Othmer-Tobias correlations. The experimental LLE data was also correlated by the nonrandom two-liquid (NRTL) and the Wilson-NRF Gibbs free energy models. The... 

    Production of low ester (LM) pectin by de-esterification of high ester (HM) apple pectin

    , Article Scientia Iranica ; Volume 12, Issue 3 , 2005 , Pages 306-310 ; 10263098 (ISSN) Alemzadeh, I ; Saifkordi, A. A ; Kahforooshan, D ; Nahid, P ; Sharif University of Technology
    Sharif University of Technology  2005
    In this paper, LM pectin production from commercial apple pectin by using acid, alkali and ammonia methods in the presence of ethanol was studied. Also, the effect of different parameters such as, temperature, time, acid, alkali and ammonia treatment in LM pectin production were evaluated. In all the experiments, low temperature showed a better influence from a recovery, purity and low de-polymerization viewpoint. Optimum conditions in the acid method reached at pH = 2, t = 17 hrs and T = 30°C, in the alkaline method reached at pH = 11, t = 3 hrs and T = 5°C and in the ammonia method reached at 2 N ammonia and T = 5°C, were determined. © Sharif University of Technology  

    Lithium perchlorate promoted highly regioselective ring opening of epoxides under solvent-free conditions

    , Article Catalysis Communications ; Volume 8, Issue 12 , December , 2007 , Pages 2198-2203 ; 15667367 (ISSN) Azizi, N ; Mirmashhori, B ; Saidi, M. R ; Sharif University of Technology
    A simple and efficient synthesis of diol diesters, protected chlorohydrins, chlorohydrins and β-hydroxy azides with acetyl or benzoyl, TMSN3 and TMSCl groups has been achieved by ring opening of epoxides with acetic anhydride, acetyl chloride or benzoyl chloride and TMSN3 using catalytic amount of lithium perchlorate under solvent-free conditions. All reactions proceeded in short times and afforded the corresponding products in good to excellent yields under mild reaction conditions. LiClO4 shows enhanced reactivity for the ring opening of epoxides under solvent-free conditions, therefore, reducing the reaction times dramatically and improved the yields and amount of catalyst. © 2007... 

    FeCl3 as an efficient and new catalyst for the thia-Fries rearrangement of aryl sulfinates

    , Article Tetrahedron Letters ; Volume 42, Issue 45 , 2001 , Pages 8119-8121 ; 00404039 (ISSN) Matloubi Moghaddam, F ; Dekamin, M. G ; Ghaffarzadeh, M ; Sharif University of Technology
    Aryl arenesulfinates rearrange to the corresponding arenesulfinyl phenols via a thia-Fries rearrangement on catalysis by anhydrous FeCl3 in dry dichloromethane at room temperature in good to excellent yields. © 2001 Published by Elsevier Science Ltd  

    Facile synthesis of highly substituted 2-pyrone derivatives via a tandem Knoevenagel condensation/lactonization reaction of β-formyl-esters and 1,3-cyclohexadiones

    , Article Tetrahedron Letters ; Vol. 55, issue. 18 , April , 2014 , p. 2908-2911 ; ISSN: 00404039 Moghaddam, F. M ; Mirjafary, Z ; Javan, M. J ; Motamen, S ; Saeidian, H ; Sharif University of Technology
    A mild and efficient tandem process for the synthesis of new highly substituted 2-pyrones starting from commercially available 2-arylacetic acids has been developed. The synthesis is based on the Knoevenagel condensation of 1,3-cyclohexadiones with various β-formyl-esters, followed by lactonization in the presence of nano ZnO (20 mol %). Moderate to high yields and readily available cheap starting materials are the key features of the present method  

    Effects of physicochemical characteristics of magnetically recoverable biocatalysts upon fatty acid methyl esters synthesis from oils

    , Article Renewable Energy ; Volume 116 , 2018 , Pages 613-622 ; 09601481 (ISSN) Esmaeilnejad Ahranjani, P ; Kazemeini, M ; Singh, G ; Arpanaei, A ; Sharif University of Technology
    Elsevier Ltd  2018
    This study reports the importance of physicochemical characteristics of the core-shell structured polymer-coated Fe3O4 cluster@SiO2 nanocomposite particles for designing the biocatalysts used for transesterification of soybean oil. To demonstrate this issue, two different types of polymer molecules such as polyethylenimine (PEI) and polyacrylic acid (PAA) each with two different molecular weights are employed. The highest fatty acid methyl esters (FAMEs) synthesis yield values are achieved by the lipases immobilized onto the low- and high-molecular-weight PEI-coated particles as compared to those of the low- and high-molecular-weight PAA-coated particles (i.e., ∼64.8% and ∼73.1% versus... 

    ZnO nanoparticles: An efficient nanocatalyst for the synthesis of β-acetamido ketones/esters via a multi-component reaction

    , Article Catalysis Communications ; Volume 9, Issue 2 , 2008 , Pages 299-306 ; 15667367 (ISSN) Mirjafary, Z ; Saeidian, H ; Sadeghi, A ; Matloubi Moghaddam, F ; Sharif University of Technology
    A convenient one-pot multi-component reaction of aromatic aldehydes, enolizable ketones or β-keto esters and acetonitrile in the presence of acetyl chloride and 10 mol% ZnO nanoparticles for the synthesis of β-acetamido ketones/esters at room temperature is described. © 2007 Elsevier B.V. All rights reserved  

    Efficient method for oxidation of ketones to esters with 4-aminoperoxybenzoic acid supported on silica gel

    , Article Synthetic Communications ; Volume 38, Issue 12 , 2008 , Pages 2037-2042 ; 00397911 (ISSN) Ghazanfari, D ; Hashemi, M. M ; Shahidi Zandi, M ; Sharif University of Technology
    4-Aminoperoxybenzoic acid supported on silica gel was found to be a versatile and efficient oxidant for the oxidation of ketones to esters. Copyright © Taylor & Francis Group, LLC  

    Enzymatic synthesis of amoxicillin with immobilized penicillin G acylase

    , Article Scientia Iranica ; Volume 17, Issue 1 C , 2010 , Pages 106-113 ; 10263098 (ISSN) Alemzadeh, I ; Borghei, G ; Vafi, L ; Roostaazad, R ; Sharif University of Technology
    The synthesis of amoxicillin with immobilized penicillin G acylase (PGA) in aqueous medium was investigated. The parameters studied were: time course of amoxicillin production, concentration of substrates: hydroxyphenylglycine methyl ester (HPGM) and 6-aminopeicillanic acid (6-APA) and the. effect of enzyme (PGA) content and pH, under variable and constant conditions and temperature variations. In the study of two substrate concentration on amoxicillin production, impressive results were obtained for a 1/3 ratio of 6-amino penicillanic acid (6-APA) and hydroxyl-phenylglycine methyl ester (HPGM). The. synthesis of amoxicillin was preferable at constant pH rather than a variable one. Other... 

    Green biodiesel production from various plant oils using nanobiocatalysts under different conditions

    , Article Bioenergy Research ; Volume 13, Issue 2 , 2020 , Pages 552-562 Esmaeilnejad Ahranjani, P ; Kazemeini, M ; Arpanaei, A ; Sharif University of Technology
    Springer  2020
    The lipase-immobilized polyethyleneimine (PEI)- and polyacrylic acid (PAA)–coated magnetic silica nanocomposite particles (L-PEI-MS and L-PAA-MS, respectively) were prepared and applied at various transesterification reaction conditions. The reactions were carried out with soybean, sunflower, canola, and palm oils along with methanol or ethanol in the solvent-free and n-hexane systems. The highest fatty acid methyl ester (FAME) and fatty acid ethyl ester (FAEE) synthesis yields were obtained from the transesterification of palm oil, i.e., almost 7.7–10.2% higher than other oils. At the constant reaction conditions, the application of ethanol leads to higher (6.0–8.7%) reaction yields in... 

    The role of co-solvents in improving the direct transesterification of wet microalgal biomass under supercritical condition

    , Article Bioresource Technology ; Volume 193 , October , 2015 , Pages 90-96 ; 09608524 (ISSN) Abedini Najafabadi, H ; Vossoughi, M ; Pazuki, G ; Sharif University of Technology
    Elsevier Ltd  2015
    In this research, direct conversion of wet algal biomass into biodiesel using supercritical methanol was studied. In this process, microalgal lipids simultaneously was extracted and converted to biodiesel under high pressure and temperature conditions without using any catalyst. Several experiments have been performed to optimize the methanol amount and it has been revealed that the best performance was achieved by using methanol/wet biomass ratio of 8:1. The effect of using various co-solvents in increasing the efficiency of the supercritical process was investigated. It has been shown that hexane was the most effective co-solvent and its optimal ratio respect to wet biomass was 6:1. The... 

    Production of Food Emulsifier

    , M.Sc. Thesis Sharif University of Technology Amin Mahalati, Alireza (Author) ; Alemzadeh, Iran (Supervisor) ; Vossoughi, Manuchehr (Supervisor)
    This research relates to an improved method for making surfactant esters, especially sorbitan monostearate and tristearate. Sorbitan esters of fatty acid, stearate are derived from a reaction between sorbitan and fatty acid. Sorbitan fatty acid ester called sorbitan ester, are surfactants highly safe to use on human body and are widely used as a food additive in the production process as emulsifiers. Sorbitan esters are well known emulsifiers suitable for use in food, pharmaceutical products as well as many other applications. Despite its simple name, sorbitan ester is complex mixture of molecules. One such technique involves direct esterification of sorbitol or an intramolecular condensate... 

    Hydrazine-modified starch coated magnetic nanoparticles as an effective pH-responsive nanocarrier for doxorubicin delivery

    , Article Journal of Industrial and Engineering Chemistry ; Volume 39 , 2016 , Pages 203-209 ; 1226086X (ISSN) Zohreh, N ; Hosseini, S. H ; Pourjavadi, A ; Sharif University of Technology
    Korean Society of Industrial Engineering Chemistry  2016
    A novel, magnetic nanocarrier was successfully synthesized through a facile and economical producer in which Fe3O4 magnetic nanoparticles were coated by starch-g-poly (methyl methacrylate-co-PEG-acrylamide). The surface of nanocarrier was then modified by hydrazine to preparation of a pH-responsive carrier. The resulted nanocarrier was applied for delivery of doxorubicin (DOX) as an effective anti-cancer drug. DOX was reacted with hydrazine linkage on the surface of nanocarrier to form hydrazone bond. Due to the presence of numerous hydrazine groups on the surface of magnetic nanocarrier large amounts of DOX was loaded onto the carrier (327 mg g−1). © 2016 The Korean Society of Industrial... 

    Preparation of sorbitan stearate

    , Article 2nd International Multi-Conference on Engineering and Technological Innovation, IMETI 2009, Orlando, FL, 10 July 2009 through 13 July 2009 ; Volume 1 , 2009 , Pages 81-85 ; 193427268X (ISBN); 9781934272688 (ISBN) Amin Mahalati, A. R ; Alemzadeh, I ; Vossoughi, M ; Inter-American Organization for Higher Education (IOHE); International Institute of Informatics and Systemics (IIIS); Journal of Systemics, Informatics and Cybernetics (JSCI) ; Sharif University of Technology
    International Institute of Informatics and Cybernetics, IIIC  2009
    The present paper relates to an improved method for making surfactant esters, especially sorbitan monostearate and tristearate. Sorbitan esters of fatty acid, stéarate are derived from a reaction between sorbitan and fatty acid. Method of sorbitan ester production needs addition of catalyst. Sorbitan stéarate production was studied using chemical catalyst. Two steps process leading sorbitan production under atmospheric and vacuum pressure with acid catalyst resulted dehydrated product at optimal residence time of 195 min at 180°C for atmospheric conditions and optimalresidence time of 150 min at the same temperature respectively. Sorbitan stearate production was studied by utilizing sorbitan... 

    LiClO4-accelerated three-component Mannich-type reaction of diethyl malonate with imines: An efficient synthesis of β-amino esters under solvent-free conditions

    , Article Synthetic Communications ; Volume 38, Issue 22 , 2008 , Pages 4036-4044 ; 00397911 (ISSN) Aryanasab, F ; Saidi, M. R ; Sharif University of Technology
    LiClO4 is used as catalyst for direct Mannich-type reaction of aryl aldehydes, aryl amines, and diethyl malonic ester under solvent-free conditions. This three-component reaction afforded the corresponding β-amino esters in good yields with simple and environmentally benign procedure. Copyright © Taylor & Francis Group, LLC  

    ZrOCl2·8H2O on montmorillonite K10 accelerated conjugate addition of amines to α,β-unsaturated alkenes under solvent-free conditions

    , Article Tetrahedron ; Volume 62, Issue 4 , 2006 , Pages 672-677 ; 00404020 (ISSN) Hashemi, M. M ; Eftekhari-Sis, B ; Abdollahifar, A ; Khalili, B ; Sharif University of Technology
    At room temperature, ZrOCl2·8H2O on montmorillonite K10 efficiently catalyzes conjugate addition of amines to a variety of conjugated alkenes such as α,β-unsaturated carbonyl compounds, carboxylic esters, nitriles and amides under solvent-free conditions. The catalyst can be recycled for subsequent reactions without any appreciable loss of efficiency. © 2005 Elsevier Ltd. All rights reserved  

    Olfactory response of two different Bactrocera fruit flies (Diptera: Tephritidae) on banana, guava, and mango fruits

    , Article Journal of King Saud University - Science ; Volume 33, Issue 5 , July , 2021 ; 10183647 (ISSN) Jaleel, W ; Saeed, R ; Zeeshan Shabbir, M ; Azad, R ; Ali, S ; Sial, M. U ; Aljedani, D. M ; Ghramh, H. A ; Khan, K. A ; Wang, D ; He, Y ; Sharif University of Technology
    Elsevier B.V  2021
    Bactrocera dorsalis and B. correcta (Diptera: Tephritidae) are economically important pests of fruits and have caused serious damage to fruits for the last several years worldwide. In China, B. correcta is second economic pest of fruits after B. dorsalis. Considering the importance of Integrated Pest Management (IPM) programs, Information regarding host preference and fitness of both Bactrocera species are necessary for better management strategies. Therefore, the current study explains the response of both Bactrocera species on banana, guava, and mango fruits. The cultivar of banana, guava, and mango fruits used first time in this study. Therefore, the volatile/aromatic components of... 

    KF/Al2O3-mediated Michael addition of thiols to electron-deficient olefins

    , Article Synthetic Communications ; Volume 35, Issue 18 , 2005 , Pages 2427-2433 ; 00397911 (ISSN) Moghaddam, F. M ; Bardajee, G. R ; Veranlou, R. O. C ; Sharif University of Technology
    Potassium fluoride supported on alumina efficiently catalyzes Michael addition of aromatic and aliphatic thiols to a variety of conjugated alkenes such as α,β-unsaturated carbonyl compounds, carboxylic esters, amides, nitriles and chalcones. The Michael adducts are produced in good to excellent yields and relatively in short times. The catalyst can be recycled for subsequent reactions without any appreciable loss of efficiency. Copyright © Taylor & Francis, Inc