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esterification
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DFT investigations for "Fischer" esterification mechanism over silica-propyl-SO3H catalyst: Is the reaction reversible?
, Article Computational and Theoretical Chemistry ; Volume 1071 , 2015 , Pages 27-32 ; 2210271X (ISSN) ; Fattahi, A ; Sharif University of Technology
Elsevier
2015
Abstract
For the first time, the mechanism of Fischer esterification between acetic acid and ethanol over silica-functionalized propylsulfonic acid (silica-propyl-SO3H) catalyst was explored by means of computational modeling techniques. For this purpose, 6-edge-atom cage-like cluster comprising Si-O-Si sequences has been selected to represent the surface of the catalyst. The results indicate that the reaction goes through concerted transition states. In all optimized structures no proton (H+) transfer occurs from catalyst to the substrates and the role of the catalyst is via the activation of the substrates through the formation of strong hydrogen bonds (H-bonds). Furthermore, the energetic diagram...
Production of novel applicable derivatives from biodiesel glycerin
, Article Green Processing and Synthesis ; 2017 ; 21919542 (ISSN) ; Isenmann, A. F ; Abrishamkar, A ; Sharif University of Technology
Abstract
Glycerin (glycerol) is a co-product of biodiesel production that is widely produced and is available at a low cost. To date, various applications have been investigated and introduced for biodiesel glycerin. In this study, a number of valuable products were produced using biodiesel glycerin and formic acid as the main reactants. Allyl alcohol is one of the valuable chemicals produced from glycerin monoformate. Efficient production of this product requires successful completion of the first section of the reaction, which is an equilibrium reaction. The highest feasible yield achieved was about 83% (based on the consumption of formic acid) at 120-140°C without the addition of any catalysts....
Production of novel applicable derivatives from biodiesel glycerin
, Article Green Processing and Synthesis ; Volume 7, Issue 4 , 2018 , Pages 323-333 ; 21919542 (ISSN) ; Isenmann, A. F ; Abrishamkar, A ; Sharif University of Technology
Walter de Gruyter GmbH
2018
Abstract
Glycerin (glycerol) is a co-product of biodiesel production that is widely produced and is available at a low cost. To date, various applications have been investigated and introduced for biodiesel glycerin. In this study, a number of valuable products were produced using biodiesel glycerin and formic acid as the main reactants. Allyl alcohol is one of the valuable chemicals produced from glycerin monoformate. Efficient production of this product requires successful completion of the first section of the reaction, which is an equilibrium reaction. The highest feasible yield achieved was about 83% (based on the consumption of formic acid) at 120-140°C without the addition of any catalysts....
Surfactant production by an enzymatic method
, Article Enzyme and Microbial Technology ; Volume 33, Issue 1 , 2003 , Pages 33-37 ; 01410229 (ISSN) ; Alemzadeh, I ; Sharif University of Technology
Elsevier Inc
2003
Abstract
Glucose was acylated with palmitic acid using two kinds of lipases. The reactions were performed in the presence of an organic solvent. Solvent effect and molecular sieve effect and also the effect of enzyme amount and influence of molar ratio of substrates on glucose palmitate production with lipase from Rhizomucor miehei (Palatase® M) were studied. Application of molecular sieves together with open system increased palmitic acid conversion in the reaction mixture. Glucose palmitate was obtained in 41.18% conversion in hexane at 40°C with Palatase® M. Glucose palmitate was also synthesized with lipase from Candida antarctica (Novozyme 435). Esterification of palmitic acid with glucose...
Optimization of catalytic activity of sulfated titania for efficient synthesis of isoamyl acetate by response surface methodology
, Article Monatshefte fur Chemie ; Volume 146, Issue 12 , December , 2015 , Pages 1949-1957 ; 00269247 (ISSN) ; Sadehvand, M ; Azad, A ; Dekamin, M. G ; Jalali Heravi, M ; Mollahosseini, A ; Amani, M ; Tadjarodi, A ; Sharif University of Technology
Springer-Verlag Wien
2015
Abstract
TiO2 nanoparticles were synthesized by sol-gel method using titanium tetraisopropoxide. Sulfate ions were introduced on the titania by impregnation method using sulfuric acid as precursor of sulfate ions. Fourier transform infrared and energy-dispersive X-ray spectroscopy, X-ray fluorescence as well as X-ray diffraction, scanning electron microscopy, and BET methods were used for the characterization of the obtained nanoparticles. The esterification of isoamyl alcohol with acetic acid was investigated to prove the catalytic activity of the TiO2 nanoparticles under solvent-free conditions. Response surface methodology was applied to optimize the effect of some parameters such as the molar...
Preparation of Titania based solid strong acid and study of its catalytic activity in esterification of Phthalic anhydride and Sebacic acid
, Article Materials Letters ; Volume 60, Issue 6 , 2006 , Pages 715-719 ; 0167577X (ISSN) ; Gholami, M. R ; Sharif University of Technology
2006
Abstract
Esterification of Phthalic anhydride with 2-Octanol and Sebacic acid with Ethanol has been studied in the presence of Sulfated Titania. This study showed that Sulfated Titania has strong catalytic effect on esterification reactions. The effect of some factors such as reaction temperature, molar ratio of acid to alcohol, amount of catalyst used, reaction time, calcination temperature, drying temperature and calcination atmosphere has been investigated. Equilibrium composition achieved in 80 min for Diethyl Sebacate and 20 min for Dioctyl Phthalate in various conditions. © 2005 Elsevier B.V. All rights reserved
Fluorometric variable-temperature kinetics investigations of the transesterification reaction of procaine with aliphatic alcohols
, Article Journal of Pharmacy and Pharmaceutical Sciences ; Volume 7, Issue 1 , 2004 , Pages 88-91 ; 14821826 (ISSN) ; Haghighi, S ; Gholami, M. R ; Sharif University of Technology
2004
Abstract
Purpose. Variable-Temperature Kinetics has been used to obtain the rate constants of the reaction at various temperatures during one kinetic run. Methods. Pseudo-first-order rate constants for the transesterification of procaine with aliphatic alcohols ethanol, n-propanol and tert-butanol were obtained by the fluorescence spectroscopy using the variable-temperature kinetics (VTK) method. Results. The activation parameters of the reactions were calculated (24-28 kcal.mol-1). The half-life of the procaine decreases in the ethanol solution compared with the other alcoholic solutions in the presence of sodium ethoxide. Conclusions. The investigation time of the reactions is reduced to one-tenth...
Study on the catalytic activity and theoretical modeling of a novel dual acidic mesoporous silica
, Article RSC Advances ; Volume 4, Issue 32, 2014 , 2014 , Pages 16647-16654 ; ISSN: 20462069 ; Fattahi, A ; Sharif University of Technology
Abstract
A novel mesoporous silica-functionalized dual Brønsted acidic species has been introduced as an efficient catalyst for solvent-free esterification of fatty acids with ethanol. The structure of the catalyst has been characterized by FT-IR spectroscopy, thermal gravimetric analysis (TGA), TEM and N2 adsorption-desorption. TGA of catalyst 1 showed no weight loss before 200 °C, indicating a high degree of hydrophobicity of the surface of the mesoporous silica. TEM images and nitrogen adsorption-desorption showed no noticeable changes to the structure of the catalyst before and after acid treatment. pH metric analysis was performed for the catalyst to determine the loading of the acidic sites....
Application of Enzymatic Method for Production of Biofuel from Domestic Oily Seed Resources
, M.Sc. Thesis Sharif University of Technology ; Kariminia, Hamid Reza (Supervisor) ; Shayegan, Jalaleddin (Supervisor)
Abstract
The enzymatic transesterification of castor oil with methanol in a solvent free media is carried out using lipase catalyst. The influence of several operation conditions on the production of biodiesel was analyzed i.e. the amount of enzyme, molar ratio of methanol to castor oil, reaction temperature and reaction time. It is observed that with increase in molar ratio, reaction time and enzyme amount, the amount of product (biodiesel) increased. When reaction temperature increased, the amount of biodiesel increased firstly and then decreased. The optimum conditions for the reaction were as follows: enzyme amount 300 mg, molar ratio of methanol to oil 9:1 and temperature 55°C. The maximum...
Supported cobalt oxide nanoparticles as efficient catalyst in esterification and amidation reactions
, Article Catalysis Communications ; Volume 59 , January , 2014 , Pages 122-126 ; 15667367 (ISSN) ; Raessi, M ; Arancon, R. A. D ; Saidi, M. R ; Luque, R ; Sharif University of Technology
Elsevier
2014
Abstract
Co/SBA-15 nanoparticle catalysts (CoNP) were prepared using a commonly adapted synthetic route and then utilised for esterification and amidation reactions using aromatic and linear chain compounds for the production of long chain esters and amides. The study shows that the use of CoNP catalysts favours the use of aromatic reactants with electron donating substituents specifically in the para position. For the amidation reaction, good to excellent yields were obtained demonstrating tolerance towards differently substituted aromatic compounds. Overall, the synthesized catalysts proved to be efficient and highly versatile, and recyclable under the investigated conditions
Efficient fatty acid esterification using silica supported Brønsted acidic ionic liquid catalyst: Experimental study and DFT modeling
, Article Chemical Engineering Journal ; Vol. 250 , 2014 , Pages 35-41 ; ISSN: 13858947 ; Hashemi, M. M ; Sharif University of Technology
Abstract
A task-specific Brønsted acidic ionic liquid (BAIL), 1-benzyl-3-methylimidazolium hydrogensulfate ([BnMIm]HSO4), was prepared and confined onto the high surface area silica gel. The catalyst has shown extraordinary activity in comparison of homogeneous ionic liquid (IL) system for Fischer esterification of fatty acid with ethanol. The ester derivatives were synthesized in high yields and catalyst was easily separated from the reaction mixture by simple filtration. The structure of the catalyst is theoretically modelized to investigate the unusual catalytic activity. Hence, a hydroxylated cage-like nano-cluster, H6Si8O12(OH)2, was selected to mimic the surface of silica gel. The interactions...
Production of Food Emulsifier
, M.Sc. Thesis Sharif University of Technology ; Alemzadeh, Iran (Supervisor) ; Vossoughi, Manuchehr (Supervisor)
Abstract
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...
Synthesis and Application of Acidic and Hydrophobic Ionic Liquids in Mannich Reaction and Esterification of Fatty Acids
, M.Sc. Thesis Sharif University of Technology ; Mahmoodi Hashemi, Mohammed (Supervisor)
Abstract
The current study deals with application of a surfactant-like Brønsted acidic ionic liquid (IL) 1-dodecyl-3-methylimidazolium hydrogensulfate (catalys 1) for Mannich reaction at room temperature. The reaction has been efficiently proceeds in water as solvent without using any harmful and expensive organic additives. Our observation has been shown that the reaction is selective for cyclohexanone and no product was observed by using cyclopentanone at room temperature. Density functional theory (DFT) calculations were performed to provide evidence about the nature of reactivity of the cyclohexanone/cyclopentanone. The activity of the catalyst 2 (1-dodecyl-2,3-dimethylimidazolium...
Preparation, Characterization and Catalytic Application of Some Polyoxometalates for Esterification Reaction
, M.Sc. Thesis Sharif University of Technology ; Rahman Setayesh, Shahrbanoo (Supervisor)
Abstract
Catalytic esterification of acetic acid with 1-hexanol was investigated over polyoxometalates. H3PW12O40 and H3PMo6W6O40 polyoxometalates with keggin structures were synthesized. Catalytic activity and recyclability of them were improved by loading on the γ-Al2O3 with impregnation method and Cs, K and NH4 salts preparing.Catalysts were characterized by XRD, SEM, FT-IR, BET, DRS and NMR techniques. According to XRD's results, catalysts have ace-centered cubic crystal systems. Loading on supports and preparing the salts do not destroy the structures of polyoxometalates. SEM images show the uniformity of catalysts' surface and catalysts' fixing on the support. It was seen that the keggin...
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) ; 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
Abstract
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...
A study on plant polymer: pectin production and modification
, Article International Journal of Engineering, Transactions B: Applications ; Volume 23, Issue 2 , 2010 , Pages 107-114 ; 1728-144X (ISSN) ; Sharif University of Technology
Abstract
Pectin from two different plant sources: apple and sugar beet was studied. Apple pectin was modified by chemical treatments such as: acid, alkali and ammonia, so as to obtain an ester level equal to or less than 50 %, which is described as low methoxyl (LM) pectin. LM pectin form gels with significant characteristic. In this study, de-esterification of apple pectin with acid treatment resulted in gel specification with higher molecular weight and viscosity. Acid treatment resulted in pectin with average molecular weight of 32000 Dalton. Pectin was extracted from sugar beet pulp by acid and alkali treatments. The quality of gel formation and water uptake was improved using sugar source...
Characterisation of nanocrystalline sulfated titania modified with transition metals and aluminum as solid acids for esterification
, Article Progress in Reaction Kinetics and Mechanism ; Volume 41, Issue 1 , 2016 , Pages 57-66 ; 14686783 (ISSN) ; Abolhasani, E ; Ghasemi, S ; Sharif University of Technology
Science Reviews 2000 Ltd
2016
Abstract
TiO2, transition metal (Cr, Mn, Fe, Co, Ni, Cu, and Zn)- and aluminum-doped TiO2 nanoparticles were prepared by the sol-gel technique. The sulfated catalysts were prepared by the impregnation method with H2SO4 solution. The catalysts were characterised by X-ray diffraction (XRD), BET surface area measurement, diffuse reflectance spectroscopy (DRS), and Fourier transform infrared (FTIR) techniques. The sulfate content of the metal-incorporated samples was considerably higher than for SO4 2-/TiO2. The metal doping brought about a considerable reduction in the extent of sulfate loss from the catalyst surface due to the wide dispersion on the surface. The SO4 2-/TiO2 and SO4 2-/M/TiO2...
Enhanced recovery and recycling of catalyst by post-impregnation of γ-Al2O3 with 12-tungstophosphoric acid for esterification reaction
, Article Canadian Journal of Chemical Engineering ; Volume 96, Issue 5 , 2018 , Pages 1176-1184 ; 00084034 (ISSN) ; Rahman Setayesh, S ; Sharif University of Technology
Wiley-Liss Inc
2018
Abstract
12-tungstophosphoric acid, polyoxometalate with Keggin structure, and γ-Al2O3 were synthesized. Loading of 12-tungstophosphoric acid (HPW) on γ-Al2O3 was performed by the post-impregnation method. The catalysts were characterized by XRD, SEM, FTIR, BET, and DRS techniques. According to the pertinent observation, using the post-impregnation method promises the stability of polyoxometalate Keggin structure after loading on γ-Al2O3 support. The stability of 20 %HPW/Al2O3 was also confirmed by a leaching test. Textural characterization demonstrates that HPW on the γ-Al2O3 had a much larger surface area as compared with the pure HPW. The 20 %HPW/Al2O3 exhibited roughly high activity toward an...
Synthesis of CaO Impregnated on Carbon Nano Tube for Biodiesel Production
, M.Sc. Thesis Sharif University of Technology ; Khorashe, Farhad (Supervisor) ; Tabatabaei, Meisam (Supervisor) ; Rashidi, Alimorad (Supervisor)
Abstract
In the current work, jatropha oil was studied in the hetrogenious solid catalytic transesterfication reaction. For this perpous, KOH/CNT catalyst which was prepared by dry impregnation method was used. SEM, XRD and TGA were applied for the catalyst characterization. The results showed that for the KOH/CNT catalyst, by increasing the loading of KOH, the activity of the catalyst increased and the most active catalyst was prepared by 20% loading of KOH. The optimum conditions for transesterfication reaction in the percense of this catalyst were: 4.7% catalyst weigth and the 24.5 molar ratio of methanol to oil and also the reaction time of 2 houres which the rate of reaction at this time is...
Mechanisms of Conjugated Linoleic acid and Enriched Glycerides Production as Neutraceuticals Food
, Ph.D. Dissertation Sharif University of Technology ; Alemzadeh, Iran (Supervisor) ; Vossughi, Manochehr (Co-Advisor)
Abstract
Dietary CLA production for medicinal purposes needs a safe and selective process. Biological production methods meet this goal. In this study, the microbial species that was suitable for CLA production was selected; then the CLA produced by bioconversion methods was utilized to produce CLA-enriched triglycerides by trans-esterification. Also the biochemical kinetics of CLA production and esterification reactions to produce CLA-enriched triglycerides was studied. In the presence of two substrates, the kinetics of enzymatic reaction was studied. Then the factors influencing on the microbial yield and CLA production including reaction conditions (reaction time, cell concentration and substrate...