- Isoamyl acetate synthesis in imidazolium-based ionic liquids using packed bed enzyme microreactor
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The acylation of isoamyl alcohol with acetic anhydride catalyzed by immobilized Candida antarctica lipase B was studied in ionic liquids (ILs) based on quaternary imidazolium cations with alkyl, alkenyl, alkynyl, benzyl, alkoxyl or N-aminopropyl side chains. Among the tested ILs, the highest enzyme activity together with the highest isoamyl acetate yield were obtained in [C 7mmim][Tf2N]. No loss of lipase B activity was observed during one-month incubation in this hydrophobic IL without the presence of substrates. Isoamyl acetate synthesis using [C7mmim][Tf2N] as solvent was further studied in a continuously operated miniaturized enzymatic packed bed reactor at various flow rates and temperatures. Up to 92% isoamyl acetate yield could be obtained within 15 min by using 0.5 M acetic anhydride and 1.5 M isoamyl alcohol inlet concentrations at 55°C, corresponding to the volumetric productivity of 61 mmol l-1 min -1, which to the best of our knowledge is the highest reported so far for this reaction. No decrease in productivity was experienced during the subsequent runs of continuous microbioreactor operation performed within 14 consecutive days. The benefits of reactor miniaturization along with the green solvent application were therefore successfully exploited for the development of a sustainable flavour ester production.
- Cvjetko, Marina,Vorkapi?-Fura?, Jasna,?nidar?i?-Plazl, Polona
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- Nanosized tin dioxide - Unexplored carrier for lipase immobilization
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A lipase from Rhizopus delemar (RhDL) was adsorbed on two tin dioxides with different textural characteristics (nanoSnO2-A-RhD and nanoSnO 2-B-RhD). All biochemical characteristics obtained for them were compared with those for RhDL on silica. NanoSnO2-A exhibited the highest protein loading capacity (75%), however, the highest specific activity was measured for nanoSnO2-B-RhD (33.8 U/mg prot.). The immobilization enhanced thermal-, pH- and solvent stability of RhDL. For example, nanoSnO 2-A-RhD is still fully active after one-hour heating at 60°C and preserved 70% of its activity at pH 9. When applied in the isoamyl acetate synthesis, a complete conversion of substrates was obtained with nanoSnO 2-A-RhD in hexane and SBA-15-RhD in hexadecane for 12 h. The performance of the three biocatalysts in several consecutive cycles was estimated as well.
- Guncheva, Maya,Dimitrov, Momtchil,Zhiryakova, Diana
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- Lipase-catalysed esterification in supercritical carbon dioxide and in hexane
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Isoamyl acetate was synthesised in high yields (>90%) via lipase catalysed acylation of the corresponding alcohol by ammonium acetate in supercritical carbon dioxide (SCCD) and by acetic acid in hexane, The esterification rate was higher in hexane. The product yield depended sharply on the reagent concentrations in hexane whereas it was nearly independent on the pressure and temperature of the SCCD.
- Vija, Heiki,Telling, Artur,Tougu, Vello
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- Isoamyl acetate preparation from reaction of vinyl acetate and Isoamyl alcohol catalyzed by H-ZSM-5 zeolite: a kinetic study
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Microporous H-ZSM-5 zeolite having good crystallinity and with the presence of Br?nsted acid sites exclusively, was prepared by hydrothermal treatment of Expanded Perlite. The as-prepared H-ZSM-5 was used as heterogeneous catalyst for the reaction between vinyl acetate and isoamyl alcohol, as a greener alternative for the traditional preparation of isoamyl acetate. In this reaction, isoamyl acetate was generated by an acyl nucleophilic substitution mechanism, mediated by an acetylated zeolite complex, while acetaldehyde diisoamyl acetal has been produced as a secondary product due to a nucleophilic addition to acetaldehyde carbonyl carbon. The reaction was studied under different alcohol/ester molar ratio, supporting a second order kinetics when working under excess of one reactant. Moreover, an Eley-Rideal kinetic model has been suggested for a reaction mechanism of five steps, involving the ketalization of isoamyl alcohol and acetaldehyde as a parallel reaction that competes with transesterification.
- Corregidor, Pablo F.,Acosta, Delicia E.,Gonzo, Elio E.,Destéfanis, Hugo A.
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- Optimization of catalytic activity of sulfated titania for efficient synthesis of isoamyl acetate by response surface methodology
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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 ratio of acetic acid to alcohol, catalyst loading, reaction temperature, and reaction time on the yield of the isoamyl acetate. The TiO2 nanoparticles were proved to be an excellent heterogeneous catalyst for isoamyl acetate synthesis under solvent-free conditions affording a high yield of 94 % under the following optimal conditions: molar ratio of acetic acid to alcohol (1:7), catalyst loading (3.2 wt% with respect to the acetic acid), the reaction temperature (130 °C), and the reaction time (300 min). Graphical abstract: [Figure not available: see fulltext.]
- Afshar, Shahrara,Sadehvand, Maryam,Azad, Alireza,Dekamin, Mohammad G.,Jalali-Heravi, Mehdi,Mollahosseini, Afsaneh,Amani, Mansoor,Tadjarodi, Azadeh
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- A novel method to quantify the activity of alcohol acetyltransferase Using a SnO2-based sensor of electronic nose
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Alcohol acetyltransferase (AATFase) extensively catalyzes the reactions of alcohols to acetic esters in microorganisms and plants. In this work, a novel method has been proposed to quantify the activity of AATFase using a SnO2-based sensor of electronic nose, which was determined on the basis of its higher sensitivity to the reducing alcohol than the oxidizing ester. The maximum value of the first-derivative of the signals from the SnO2-based sensor was therein found to be an eigenvalue of isoamyl alcohol concentration. Quadratic polynomial regression perfectly fitted the correlation between the eigenvalue and the isoamyl alcohol concentration. The method was used to determine the AATFase activity in this type of reaction by calculating the conversion rate of isoamyl alcohol. The proposed method has been successfully applied to determine the AATFase activity of a cider yeast strain. Compared with GC-MS, the method shows promises with ideal recovery and low cost.
- Hu, Zhongqiu,Li, Xiaojing,Wang, Huxuan,Niu, Chen,Yuan, Yahong,Yue, Tianli
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- Heterogeneous catalysed esterification of acetic acid with isoamyl alcohol: Kinetic studies
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Kinetics of heterogeneous catalyzed esterification of acetic acid with isoamyl alcohol was studied with a cation-exchange resin catalyst, Purolite CT-175, in a stirred batch reactor to synthesize a value added ester, isoamyl acetate. About 97% (wt/wt) of the catalyst particles were within the size range 600-850 μm, and the remainder were within 180-500μm. The equilibrium conversion of acetic acid increased from ~ 80% at a feed mole ratio (alcohol to acid) of 2:1 to 95% at a feed mole ratio (alcohol to acid) of 10:1. The optimum catalyst loading based on the current findings was 10% (wt/wt). The equilibrium conversion of acetic acid increased slightly with an increase in temperature and increased appreciably with an excess of isoamyl alcohol in the reacting system. CT-175 catalyst could be repeatedly used without sacrificing its catalytic activity. Langmuir-Hinshelwood-Hougen-Watson (LHHW) model gave a better representation of the kinetic behavior for all practical purposes on the reaction kinetics studied under the given conditions. According to the LHHW mechanism, acetic acid adsorbed on one catalytic center reacted with isoamyl alcohol adsorbed on another catalytic center to give isoamyl acetate and water each adsorbed on one center.
- Teo,Saha
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- Effect of the properties of MFI zeolites on the esterification of isopentyl acetate
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Fusel oil is a by-product from the fermentation of sugar to produce ethanol. With the increase in ethanol production in the last years, thousands of liters of fusel oil are also generated. Thus, alternatives for reusing fusel oil involving the transformation of isopentanol, its main constituent, into products relevant to industry have aroused interest. In this work, the use of MFI zeolites with different contents of aluminum in the transformation of isopentyl into its ester, isopentyl acetate, was studied. Its main objective was to investigate the effects of the aluminum content of zeolites on textural and chemical properties and how they influence the catalytic activity. In the work it was verified that the catalysts with larger external surface obtained better catalytic performance, suggesting that, due to the small pore diameter of the MFI structure, the reaction is limited by the effects of internal diffusion and occurs mainly at the external surface of the MFI particles.
- Ribeiro, Maria E.,Franke, Karen N.,Lima, Patrícia M.,Cardoso, Dilson
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- Enhanced synthesis of isoamyl acetate using an ionic liquid-alcohol biphasic system at high hydrostatic pressure
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Isoamyl acetate has a banana flavor that can be considered a "natural" ingredient when synthesized using a lipase-catalyzed reaction. Production of isoamyl acetate was up to 10-fold higher with free lipase versus immobilized Candida antarctica lipase B (CALB) after 3 h at 300 MPa and 80 °C in 1-butyl-3-methylimidazolium hexafluoro-phosphate, isoamyl alcohol biphasic system. Rate of catalysis by free CALB was 15-fold greater at 500 MPa, 40 °C than at 0.1 MPa, 40 °C and 14-fold at 500 MPa, 80 °C than at 0.1 MPa, 80 °C. Activation energy of free lipase calculated between 40 and 80 °C at 0.1 MPa (55.6 ± 4.2 kJ mol-1) or 300 MPa (56.2 ± 4.6 kJ mol-1) was not significantly different. Similarly, activation volume (ΔV?) of free lipase calculated between 0.1 and 500 MPa at 40 °C (-16.1 ± 1.5 cm 3 mol-1) or 80 °C (-16.7 ± 1.4 cm3 mol-1) was not significantly different. After treatment at high pressure and upon pressure release, the free lipase was temporarily suspended in a semi-solid IL phase. This study is the first to combine the use of a room temperature ionic liquid (RTIL) and high hydrostatic pressure (HHP) for enhanced enzyme catalysis.
- Eisenmenger, Michael J.,Reyes-De-Corcuera, Jose I.
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- Novel nanostructured tin dioxide as promising carrier for Candida rugosa lipase
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This is the first report on lipase immobilization on nanostructured tin dioxide. The material was applied as a support for Candida rugosa lipase. All biocatalytic characteristics obtained for this novel biocatalyst (nano-SnO 2-CRL) were compared with those for lipase immobilized on polypropylene (PP-CRL). Nano-SnO2-CRL has shown a specific activity eight times higher than that found for PP-CRL. The tin dioxide preparation preserved up to 45% of the initial lipase activity after 1 h incubation at pH 10.0, while PP-CRL was completely inactivated. The immobilization on the inorganic carrier enhanced lipase thermal stability. Upon heating for 1 h at 55 °C, nano-SnO2-CRL retained 77% active, while PP-CRL was half inactivated. The synthetic activity and the effect of several parameters on isoamyl acetate production for both biocatalysts were evaluated. Among four tested acyl donors, acetic anhydride was the most efficient for nano-SnO 2-CRL. The reaction proceeded with a high reaction rate and resulted in 88.2% yield of the target ester for 2 h. Among various solvents, n-decane proved to be the best for both catalysts. The increase in the reaction temperature from 50 °C to 60 °C enhanced the reaction rate 1.5 and 1.7 fold, for nano-SnO2-CRL and PP-CRL, respectively. A considerable decline in activity for both enzyme preparations was observed after the second esterification run due to prolonged heating and probably also to inhibition by substrates and product.
- Guncheva, Maya,Dimitrov, Momtchil,Zhiryakova, Diana
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- Green, efficient and economical coal fly ash based phosphomolybdic acid catalysts: preparation, characterization and application
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Abstract: Cost-effective, efficient and green solid acid catalysts have been synthesized by incipient wetness impregnation of various weight fractions of phosphomolybdic acid (5, 10, 15 and 25 wt. %) on mechanically and thermally activated coal fly ash. N2 adsorption–desorption, XRD, FT-IR, SEM, SEM–EDX, TEM, TGA, UV–Vis DRS, solid state 31P MAS NMR were used for characterization of as synthesized catalysts. Catalytic active sites were developed on inert surface of coal fly ash by using various activation techniques whose performance was assessed over a series of acylation of various aliphatic alcohols. For rapid and higher catalytic activity, reactions were conducted in microwave heating mode. Impregnation of phosphomolybdic acid generates Lewis acidic sites on coal fly ash surface as inferred by pyridine adsorbed FT-IR studies which were then utilized in acylation reactions. Various reaction parameters like weight fraction of catalysts, molar ratio of reactants, time, temperature, etc. were optimized for attaining highest conversion %. The catalyst with 15 wt. % of phosphomolybdic acid was found to be more efficient and could be recycled up to five reaction cycles with analogous conversion %. Negligible leaching of catalyst was confirmed by hot filtration test. This work suggests an alternative approach for valorisation of industrial solid waste, coal fly ash in development of innovative, economical solid catalysts. Graphic abstract: [Figure not available: see fulltext.].
- Malpani, Sakshi Kabra,Goyal, Deepti,Katara, Stuti,Rani, Ashu
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p. 3017 - 3034
(2021/02/26)
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- Synthesis, Characterisation, and Determination of Physical Properties of New Two-Protonic Acid Ionic Liquid and its Catalytic Application in the Esterification
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A new ionic liquid was synthesised, and its chemical structure was elucidated by FT-IR, 1D NMR, 2D NMR, and mass analyses. Some physical properties, thermal behaviour, and thermal stability of this ionic liquid were investigated. The formation of a two-protonic acid salt namely 4,4′-trimethylene-N,N′-dipiperidinium sulfate instead of 4,4′-trimethylene-N,N′-dipiperidinium hydrogensulfate was evidenced by NMR analyses. The catalytic activity of this ionic liquid was demonstrated in the esterification reaction of n-butanol and glacial acetic acid under different conditions. The desired acetate was obtained in 62-88 % yield without using a Dean-Stark apparatus under optimal conditions of 10 mol-% of the ionic liquid, an alcohol to glacial acetic acid mole ratio of 1.3: 1.0, a temperature of 75-100°C, and a reaction time of 4 h. α-Tocopherol (α-TCP), a highly efficient form of vitamin E, was also treated with glacial acetic acid in the presence of the ionic liquid, and O-acetyl-α-tocopherol (Ac-TCP) was obtained in 88.4 % yield. The separation of esters was conducted during workup without the utilisation of high-cost column chromatography. The residue and ionic liquid were used in subsequent runs after the extraction of desired products. The ionic liquid exhibited high catalytic activity even after five runs with no significant change in its chemical structure and catalytic efficiency.
- Shahnavaz, Zohreh,Zaharani, Lia,Khaligh, Nader Ghaffari,Mihankhah, Taraneh,Johan, Mohd Rafie
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p. 165 - 172
(2020/10/26)
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- Method for synthesizing ester through catalytic esterification of ionic liquid
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The invention relates to a method for synthesizing ester through catalytic esterification of ionic liquid. The method comprises the following step: carrying out an esterification reaction on carboxylic acid and an organic matter containing a hydroxyl group under the catalysis of the ionic liquid to obtain an esterification product, wherein the general formula of the ionic liquid is [Bu3PR]N(CF3SO2)2, and R is a C8-C16 straight chain or branched chain alkyl group. According to the above technical scheme, the method for synthesizing the ester through catalytic esterification of the ionic liquid is high in catalyst catalytic activity, high in reaction selectivity, few in by-products, high in reaction rate and high in catalyst recycling performance.
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Paragraph 0028-0030; 0035-0039
(2021/06/22)
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- A pronounce approach on the catalytic performance of mesoporous natural silica toward esterification of acetic acid with iso-amyl, benzyl, and cinnamyl alcohols
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Catalytic esterification of acetic acid with iso-amyl, benzyl, and cinnamyl alcohols in the liquid phase over unmodified natural silica catalyst has been studied. The virgin and calcined catalysts were characterized by thermal analyses (Thermogravimetry (TG) and diffrential thermal analysis (DTA)), X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared (FTIR), scanning electron microscope (SEM), and N2 sorption analyses. The acidity of natural silica catalysts was investigated using isopropyl alcohol dehydration and chemisorption of pyridine and dimethyl pyridine. The results indicated that most of the acidic sites are of Br?nsted type and of intermediate strength. The effect of different parameters such as reaction time, molar ratio, catalyst dosage, and calcination temperature was studied. Natural silica catalyst exhibited excellent catalytic performance with a selectivity of 100% to acetate esters formation. The maximum yields of isoamyl, benzyl, and cinnamyl acetate esters obtained in the batch conditions were 80, 81, and 83%, respectively. Whereas on adopting a simple distillation technique, these yields were successfully improved to higher values of 97, 98, and 90%, respectively. Experimental results manifested that the reaction followed Langmuir–Hinshelwood mechanism. Finally, the catalyst could be completely recycled without loss of its activity after four cycles of the esterification reactions.
- Abd El-Wahab, Mohamed M. M.,El-Gamal, Nadia O.,Goda, Mohamed N.,Said, Abd El-Aziz A.
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- Efficient Enzymatic Preparation of Flavor Esters in Water
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A straightforward biocatalytic method for the enzymatic preparation of different flavor esters starting from primary alcohols (e.g., isoamyl, n-hexyl, geranyl, cinnamyl, 2-phenethyl, and benzyl alcohols) and naturally available ethyl esters (e.g., formate, acetate, propionate, and butyrate) was developed. The biotransformations are catalyzed by an acyltransferase from Mycobacterium smegmatis (MsAcT) and proceeded with excellent yields (80-97%) and short reaction times (30-120 min), even when high substrate concentrations (up to 0.5 M) were used. This enzymatic strategy represents an efficient alternative to the application of lipases in organic solvents and a significant improvement compared with already known methods in terms of reduced use of organic solvents, paving the way to sustainable and efficient preparation of natural flavoring agents.
- Perdomo, Igor Chiarelli,Gianolio, Stefania,Pinto, Andrea,Romano, Diego,Contente, Martina Letizia,Paradisi, Francesca,Molinari, Francesco
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p. 6517 - 6522
(2019/06/20)
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- 'Clean' hydrolase reactions using commercial washing powder
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We report the use of commercial laundry powder as a biocatalyst for a range of lipase-catalysed reactions including (trans)esterification, ester hydrolysis and chemoenzymatic epoxidation reactions. The enzymatic laundry powder exhibited excellent stability and recyclability, making it a readily available and cheap biocatalyst for chemical transformations.
- Zhang, Jie,Tonin, Fabio,Zhang, Wuyuan,Hagedoorn, Peter-Leon,Mallée, Lloyd,Hollmann, Frank
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p. 24039 - 24042
(2019/08/15)
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- Manganese-mediated acetylation of alcohols, phenols, thiols, and amines utilizing acetic anhydride
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Manganese(II) chloride-catalyzed acetylation of alcohols, phenols thiols and amines with acetic anhydride is reported. This method is environment-friendly and economically viable as it involves inexpensive, relatively benign catalyst, mild reaction condition, and simple workup. Acetylation is performed under the solvent-free condition at ambient temperature and acetylated products obtained in good to excellent yields. Primary, secondary heterocyclic amines, and phenols with various functional groups are smoothly acetylated in good yields. This method exhibits exquisite chemoselectivity, the amino group is preferentially acetylated in the presence of a hydroxyl/thiol group.
- Jain, Isha,Sharma, Ramandeep,Malik, Payal
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supporting information
p. 2952 - 2960
(2019/09/13)
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- Performance of different immobilized lipases in the syntheses of short- and long-chain carboxylic acid esters by esterification reactions in organic media
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Short-chain alkyl esters and sugar esters are widely used in the food, pharmaceutical and cosmetic industries due to their flavor and emulsifying characteristics, respectively. Both compounds can be synthesized via biocatalysis using lipases. This work aims to compare the performance of commercial lipases covalently attached to dry acrylic beads functionalized with oxirane groups (lipases from Candida antarctica type B—IMMCALB-T2-350, Pseudomonas fluorescens—IMMAPF-T2-150, and Thermomyces lanuginosus—IMMTLL-T2-150) and a home-made biocatalyst (lipase from Pseudomonas fluorescens adsorbed onto silica coated with octyl groups, named PFL-octyl-silica) in the syntheses of short- and long-chain carboxylic acid esters. Esters with flavor properties were synthetized by esterification of acetic and butyl acids with several alcohols (e.g., ethanol, 1-butanol, 1-hexanol, and isoamyl alcohol), and sugar esters were synthetized by esterification of oleic and lauric acids with fructose and lactose. All biocatalysts showed similar performance in the syntheses of short-chain alkyl esters, with conversions ranging from 88.9 to 98.4%. However, in the syntheses of sugar esters the performance of PFL-octyl-silica was almost always lower than the commercial IMMCALB-T2-350, whose conversion was up to 96% in the synthesis of fructose oleate. Both biocatalysts showed high operational stability in organic media, thus having great potential for biotransformations.
- de Lima, Lionete Nunes,Mendes, Adriano Aguiar,Fernandez-Lafuente, Roberto,Tardioli, Paulo Waldir,Camargo Giordano, Raquel de Lima
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- Reaction method accompanied by production of gas component
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The present invention relates to a reaction method comprising a step of supplying a liquid containing at least one raw material compound and a low-boiling compound having a standard boiling point lower than a standard boiling point of the raw material compound to a flow channel, a step of heating the liquid to produce a liquid reaction product and a gas component by a reaction of the raw material compound, and a step of separating a liquid phase containing the reaction product from a gas phase containing the gas component and the low-boiling compound.
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Page/Page column 18
(2018/11/23)
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- Method for synthesizing ester through quaternary phosphonium salt ionic liquid catalyzed esterification
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The invention discloses a method for synthesizing an ester through quaternary phosphonium salt ionic liquid catalyzed esterification. The method is characterized in that the esterification product is obtained through an esterification reaction of carboxylic acid and a hydroxyl group-containing organic matter under the catalysis of a quaternary phosphonium salt ion liquid, wherein the general formula of the quaternary phosphonium salt ion liquid is [Bu3PR]X, R is a C6-C16 linear or branched alkyl group, and X is a p-C7H7SO, CF3SO, HSO or H2PO. The method for synthesizing the ester through quaternary phosphonium salt ionic liquid catalyzed esterification has the advantages of high catalytic activity, high reaction selectivity, few byproducts, and high recycling performance of the catalyst.
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Paragraph 0073-0079; 0082-0085
(2017/08/31)
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- Quaternary phosphonium salt ionic liquid, and preparation method and use thereof
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The invention discloses a quaternary phosphonium salt ionic liquid. The general formula of the quaternary phosphonium salt ion liquid is [Bu3PR]X, R is a C6-C16 linear or branched alkyl group, and X is a p-C7H7SO, CF3SO, HSO or H2PO. The invention also provides a preparation method of the quaternary phosphonium salt ion liquid. The method is characterized in that a first quaternary phosphonium salt and a protonic acid undergoes an ion exchange reaction under an ion exchange reaction condition to obtain a contact product, wherein the general formula of the first quaternary phosphonium salt a is [Bu3PR]Z, R is a C6-C16 linear or branched alkyl group, and Z is halogen; and the protonic acid is a p-C7H7SO3H, CF3SO3H, HsSO4 or H3PO4. The invention also provides a use of the quaternary phosphonium salt ion liquid in catalysis of an esterification reaction. The quaternary phosphonium salt ionic liquid has the advantages of high catalytic activity, high reaction selectivity, few byproducts and high recycling performance when used in the catalysis of the esterification reaction of carboxylic acid and a hydroxyl group-containing organic matter.
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Paragraph 0081; 0082; 0083; 0084
(2017/09/01)
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- Green synthesis of isoamyl acetate via silica immobilized novel thermophilic lipase from Bacillus aerius
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Isoamyl acetate, a pear or banana flavor, is widely used in food, beverage, cosmetic, and pharmaceutical industries. In the present work, lipase from Bacillus aerius was immobilized on silica gel matrix in the presence of a cross-linking agent, glutaraldehyde, and its efficiency in synthesizing isoamyl acetate using esterification reaction was studied. The esterification of acetic acid and isoamyl alcohol by silica-bound lipase was studied as a function of time and temperatures. The incubation time of 10 h, temperature of 55°C, substrate molar ratio 1: 1, and the amount of lipase as 1% were found to be optimal for the esterification reaction. The bound lipase catalyzed the esterification of acetic acid by isoamyl alcohol with the yield of about 68% under the optimized reaction conditions. The product was identified as isoamyl acetate using gas-liquid chromatography, nuclear magnetic resonance, and Fourier transform IR spectroscopy analysis by the presence of an ester group at the wavenumber of 1720.5 cm-1.
- Narwal, Sunil Kumar,Saun, Nitin Kumar,Dogra, Priyanka,Gupta, Reena
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- Deep eutectic solvent choline chloride·2CrCl3·6H2O: An efficient catalyst for esterification of formic and acetic acid at room temperature
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A highly efficient and selective method for esterification of formic and acetic acid with alcohols has been achieved at room temperature, with the choline chloride (ChCl)/chromium(iii) chloride hexahydrate (CrCl3·6H2O) deep eutectic solvent as a catalyst. High yields and good selectivities of organic esters are obtained using DES [ChCl][CrCl3·6H2O]2 with the molar ratio 5:1 (carboxylic acids:alcohols) at room temperature in 24 h. The ease of recovery and reusability of DES with high catalytic activity makes this method efficient and practical.
- Cao, Jin,Qi, Bin,Liu, Jun,Shang, Yuhan,Liu, Huiwen,Wang, Wenjing,Lv, Jia,Chen, Zhiyan,Zhang, Haibo,Zhou, Xiaohai
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p. 21612 - 21616
(2016/03/08)
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- Highly efficient and recyclable acetylation of phenols and alcohols by nickel zirconium phosphate under solvent-free conditions
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Nickel zirconium phosphate nanoparticles have been used as an efficient catalyst for the acetylation of a wide range of alcohols and phenols with acetic anhydride in good to excellent yields under solvent-free conditions. The steric and electronic properties of the different substrates had a significant influence on the reaction conditions required to achieve the acetylation. The catalyst used in the current study was characterized by inductively coupled plasma optical emission spectroscopy, X-ray diffraction, N2 adsorption-desorption, scanning electron microscopy, and transmission electron microscopy. This nanocatalyst could also be recovered and reused at least six times without any discernible decrease in its catalytic activity.
- Hajipour, Abdol Reza,Karimi, Hirbod,Kohi, Afshin
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- A powerful tool for acid catalyzed organic addition and substitution reactions
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A novel green chemistry tool for acid catalyzed reactions has been developed. The multipurpose tool is based on the ability of dry solid materials to donate protons (H+) to starting materials combined with the simultaneous use of a nucleophile (e.g. NaI). The methods enable the following reactions to be conducted at 20-50 °C: selective addition of iodine or alcohols to more substituted carbon in R2CCH2 systems (R ≠ H), esterification reactions, e.g. free fatty acids with methanol, and at higher temperatures, (60-100 °C): esterification of free fatty acids with hindered alcohols (isopropanol), addition of iodine to CC bonds, opening of oxygen(s) containing heterocyclic rings, selective substitution of primary OH groups to iodine in the presence of other functional groups or secondary alcohol groups, esterification of alcohols with nitriles (R-CN), transesterification of fatty acid triglycerides to biodiesel and selective derivatization of primary hydroxyl groups (-CH2OH) over secondary moieties of sugars without any protection. Most of the reactions were also performed by a re-used Dowex cation exchange resin.
- Turhanen, Petri A.,Veps?l?inen, Jouko J.
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p. 26218 - 26222
(2015/10/20)
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- Acetylation of alcohols and phenols under solvent-free conditions using iron zirconium phosphate
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Iron zirconium phosphate (ZPFe) nanoparticles were found to function as an efficient catalyst for the acetylation of a wide range of alcohols and phenols using acetic anhydride, generating good to excellent yields under solvent-free conditions. The steric and electronic properties of various substrates had a significant influence on the reaction conditions required to achieve the acetylation. The catalyst used in the current study was characterized by inductively coupled plasma-optical emission spectrometry, X-ray diffraction, N2 adsorption-desorption, scanning electron microscopy, and transmission electron microscopy. These analyses revealed that the interlayer distance in the catalyst increased from 7.5 to 9.3 ? when Fe3+ was intercalated between the layers, whereas the crystallinity of the material was reduced. This nanocatalyst could also be recovered and reused at least six times without any discernible decrease in its catalytic activity. This new method for the acetylation of alcohols and phenols has several important advantages, including mild and environmentally friendly reaction conditions, as well as good to excellent yields and a facile work-up.
- Hajipour, Abdol R.,Karimi, Hirbod,Masti, Amir
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p. 595 - 602
(2015/09/28)
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- Baeyer-Villiger oxidation of cyclohexanone by molecular oxygen with Fe-Sn-O mixed oxides as catalysts
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Fe-Sn-O mixed oxides were synthesized and used as catalysts for Baeyer-Villiger oxidation of cyclohexanone, which showed both high catalytic activity and selectivity. X-ray powder diffraction and scanning electron microscopy suggested that the Fe-Sn-O catalysts had a tetragonal structure with a grain size of 29.3 nm. An ε-caprolactone yield as high as 98.8% was obtained in a small-scale experiment (5 mmol of cyclohexanone). In a scale-up test (20 mmol of cyclohexanone), the cyclohexanone conversion and ε-caprolactone yield were 96.7 and 96.5%, respectively. In addition, the catalysts can be reused five times without any major decline in catalytic activity.
- Ma, Yongli,Liang, Zhengyong,Feng, Shuxiao,Zhang, Yadong
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p. 450 - 455
(2015/06/30)
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- Synthesis of lipase nano-bio-conjugates as an efficient biocatalyst: Characterization and activity-stability studies with potential biocatalytic applications
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In the present study, we have synthesized lipase-nano-bio-conjugates via immobilization of various lipases on multiwall carbon nano-tubes (MCNT), in order to construct an efficient and recyclable biocatalytic system. In a screening study lipase Pseudomonas fluorescens (PFL) acted as an efficient biocatalyst (lipase-nano-bio-conjugates) which showed higher retention of lipase activity and protein loading. Consequently the immobilization support : lipase (MCNT : PFL) composition was screened in which MCNT : PFL (2 : 1) was calculated as a robust biocatalyst composition which showed higher activity retention and protein loading. This nano-bio-conjugate was then characterized in detail with physical and biochemical techniques using SEM, TEM, FTIR, Km, Vmax, catalytic efficiency and (%) water content analysis. This developed biocatalyst was further used for practical biocatalytic applications such as O-acylation reactions. Various reaction parameters were optimized in detail like reactant molar ratio (2 : 3.5), solvent, MCNT : PFL biocatalyst amount (36 mg), temperature (50°C) etc. The developed biocatalytic protocol was then extended to synthesize several (twenty-two) industrially important acylated moieties with an excellent yield, these products are well characterized by 1HNMR, 13CNMR and GCMS analysis. Moreover in the present study, we have reviewed the potential industrial applications of various synthesized compounds. Also, we have studied the thermodynamic aspect which demonstrated more feasibility of use of immobilized MCNT : PFL lipase over free lipase. Interestingly, immobilized MCNT : PFL lipase showed 2.3 fold higher catalytic activity than free PFL. Besides this, the biocatalyst was efficiently recycled for up to five cycles. Thus the present protocol demonstrated, (i) synthesis of nano-bio-conjugates as a bio-catalyst, (ii) detailed physical-biochemical characterization of nano-bio-conjugates, (iii) optimization of the biocatalytic protocol (iv) practical biocatalytic applications along with a mechanistic study (v) a thermodynamic feasibility study and (vi) recyclability study. 2015
- Badgujar, Kirtikumar Chandulal,Sasaki, Takehiko,Bhanage, Bhalchandra Mahadeo
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p. 55238 - 55251
(2015/07/07)
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- MONOMER, POLYMER, RESIST COMPOSITION, AND PATTERNING PROCESS
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A polymer comprising recurring units derived from a (meth)acrylate monomer of tertiary ester type having branched alkyl on alicycle is used to form a resist composition. When subjected to exposure, PEB and organic solvent development, the resist composition is improved in dissolution contrast.
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- Aza-crown ether complex cation ionic liquids: Preparation and applications in organic reactions
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Aza-crown ether complex cation ionic liquids (aCECILs) were devised, fabricated, and characterized by using NMR spectroscopy, MS, thermogravimetric differential thermal analysis (TG-DTA), elemental analysis and physical properties. These new and room-temperature ILs were utilized as catalysts in various organic reactions, such as the cycloaddition reaction of CO2 to epoxides, esterification of acetic acid and alcohols, the condensation reaction of aniline and propylene carbonate, and Friedel-Crafts alkylation of indole with aldehydes were investigated carefully. In these reactions, the ionic liquid exhibited cooperative catalytic activity between the anion and cation. In addition, the aza-[18-C-6HK][HSO4]2 was the best acidic catalyst in the reactions of esterification and Friedel-Crafts alkylation under mild reaction conditions. Jewel in the crown: Nine new and room-temperature aza-crown ether complex ionic liquids (aCECILs) composed of multiple cations and anions were fabricated through a convenient procedure (see scheme). Some of them were used as catalysts in various organic reactions, such as the cycloaddition reaction of CO2 to propylene oxide, esterification of acetic acid and alcohols, the condensation of aniline and propylene carbonate, and Friedel-Crafts alkylation of indole with aldehydes.
- Song, Yingying,Cheng, Chen,Jing, Huanwang
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p. 12894 - 12900
(2015/03/30)
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- Acetylation of alcohols and phenols under solvent-free conditions using copper zirconium phosphate
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Copper zirconium phosphate nanoparticles have been used as an efficient catalyst for the acetylation of a wide range of alcohols and phenols with acetic anhydride in good to excellent yields under solvent-free conditions. The steric and electronic properties of the different substrates had a significant influence on the reaction conditions required to achieve the acetylation. The catalyst used in the current study was characterized by inductively-coupled plasma optical emission spectroscopy, energy dispersive spectroscopy, X-ray diffraction, N2 adsorption-desorption, scanning electron microscopy, and transmission electron microscopy. These analyses revealed that the interlayer distance in the catalyst increased from 7.5 to 8.0 ? when Cu2+ was intercalated between the layers, whereas the crystallinity of the material was reduced. This nanocatalyst could also be recovered and reused at least six times without any discernible decrease in its catalytic activity. This new method for the acetylation of alcohols and phenols has several key advantages, including mild and environmentally friendly reaction conditions, as well as good to excellent yields and a facile work-up.
- Hajipour, Abdol R.,Karimi, Hirbod
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p. 1982 - 1989
(2015/09/28)
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- A synthesis of copper based metal-organic framework for O-acetylation of alcohols
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A novel metal-organic framework, Cu-BDC was synthesized by static hydrothermal method using innocuous solvents and characterized by several techniques such as powder XRD, ESR, TG-DTA, elemental analysis, ICP-AES, SEM, EDXS, FT-IR, BET surface area, pore volume and pore size. The catalytic performance of Cu-BDC was explored for O-acetylation of alcohols under solvent-free conditions at room temperature. The catalyst exhibited remarkable activity and reusability affording the desired products in excellent yields.
- Singh, Savita J.,Kale, Sandip R.,Gawande, Manoj B.,Velhinho,Jayaram, Radha V.
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- Expanding ester biosynthesis in Escherichia coli
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To expand the capabilities of whole-cell biocatalysis, we have engineered Escherichia coli to produce various esters. The alcohol O-acyltransferase (ATF) class of enzyme uses acyl-CoA units for ester formation. The release of free CoA upon esterification with an alcohol provides the free energy to facilitate ester formation. The diversity of CoA molecules found in nature in combination with various alcohol biosynthetic pathways allows for the biosynthesis of a multitude of esters. Small to medium volatile esters have extensive applications in the flavor, fragrance, cosmetic, solvent, paint and coating industries. The present work enables the production of these compounds by designing several ester pathways in E. coli. The engineered pathways generated acetate esters of ethyl, propyl, isobutyl, 2-methyl-1-butyl, 3-methyl-1-butyl and 2-phenylethyl alcohols. In particular, we achieved high-level production of isobutyl acetate from glucose (17.2 g l -1). This strategy was expanded to realize pathways for tetradecyl acetate and several isobutyrate esters.
- Rodriguez, Gabriel M,Tashiro, Yohei,Atsumi, Shota
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p. 259 - 265
(2014/04/03)
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- Lewis basic ionic liquid as an efficient and facile catalyst for acetylation of alcohols, phenols, and amines under solvent-free conditions
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The Lewis basic ionic liquid 1,8-diazabicyclo[5.4.0]undec-7-en-8-ium acetate was employed for the acetylation of various phenols, alcohols, and amines in good-to-excellent yields at 50 C under solvent-free conditions in a short time. Compared with existing methods based on conventional catalysts and toxic solvents, the reported method is simple, mild and environmentally viable. Furthermore, the ionic liquid was conveniently separated from the products and easily recycled to catalyze other acetylation reactions with excellent yields. .
- Ji, Li,Qian, Chao,Chen, Xin-Zhi
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p. 369 - 374
(2013/05/21)
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- Rasta resin-TBD as a reusable catalyst for transesterification reactions
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Rasta resin-TBD has been synthesized and used to catalyze a wide range of transesterification reactions, including biodiesel synthesis and ring-opening polymerizations. It was found to be a more efficient heterogeneous catalyst than a related polystyrene-based analogue based on the Merrifield resin architecture involving divinylbenzene cross-linking. In the reactions studied rasta resin-TBD was separated from the desired products simply by filtration, and it could be regenerated and reused numerous times without significant loss of catalytic activity. Georg Thieme Verlag Stuttgart · New York.
- Yang, Yun-Chin,Leung, Dennis Y.C.,Toy, Patrick H.
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supporting information
p. 1870 - 1874
(2013/09/12)
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- A clean enzymatic process for producing flavour esters by direct esterification in switchable ionic liquid/solid phases
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A clean biocatalytic approach for producing flavour esters using switchable ionic liquid/solid phases as reaction/separation media has been developed. The phase behaviour of different IL/flavour acetyl ester (geranyl acetate, citronellyl acetate, neryl acetate and isoamyl acetate) mixtures was studied at several concentrations, resulting for all cases in fully homogeneous liquid media at 50 °C, and solid systems at room temperature. By using an iterative centrifugation protocol on the solid IL/flavour ester mixtures at controlled temperatures, the solid IL phase and the liquid flavour ester phase can be easily separated. The excellent suitability of an immobilized Candida antarctica lipase B (Novozym 435) catalyst in the esterification reaction between an aliphatic carboxylic acid (acetic, propionic, butyric or valeric) and a flavour alcohol (isoamyl alcohol, nerol, citronellol or geraniol) in N,N′,N′′,N′′′-hexadecyltrimethyl-ammonium bis(trifluoromethylsulfonyl)imide ([C16tma][NTf2])IL has been demonstrated, the product yield being improved up to 100% under appropriate reaction conditions (enzyme amount, dehydrating molecular sieves, etc.) at 50 °C. The enzymatic synthesis of sixteen different flavour esters was carried out in [C16tma][NTf2] by means of this approach, providing products of up to 0.757 g mL-1 concentration after IL separation. The residual activity of the enzyme/IL system during seven consecutive operation cycles was shown to be practically unchanged after reuse.
- Lozano, Pedro,Bernal, Juana M.,Navarro, Alicia
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p. 3026 - 3033
(2013/01/15)
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- Investigation of steapsin lipase for kinetic resolution of secondary alcohols and synthesis of valuable acetates in non-aqueous reaction medium
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In present study, the application of steapsin lipase (as a biocatalyst) was investigated for kinetic resolution of secondary alcohols (1-phenyl ethanol and their derivatives) using vinyl acetate as an activated acyl donor. The enzymatic protocol was optimized for various reaction parameters such as effect of the molar ratio, solvent, temperature, time and biocatalyst loading to obtain best reaction conditions. On optimization, developed enzymatic methodology provided considerable enantiomeric excess of the product (up to 92% ee) at 55 °C in n-hexane as a solvent. Furthermore using the developed protocol, synthesis of several industrially important acetates was successfully achieved with excellent yield (up to 99%). During acetate synthesis, the biocatalyst was remarkably reused for eight consecutive recycles without any significant loss in its catalytic activity. This revealed the good potential of steapsin lipase for application in organic solvents.
- Dhake, Kishor P.,Deshmukh, Krishna M.,Wagh, Yogesh S.,Singhal, Rekha S.,Bhanage, Bhalchandra M.
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experimental part
p. 15 - 23
(2012/06/29)
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- Aromas Kit
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An Aromas kit uses containers of certain discrete molecules to provide odors suitable for an olfactory education of wine properties. The disclosed molecules may be found within certain wines and provide a useful olfactory reference when smelling a finished wine sample, even when the wine sample contains a myriad of other conflicting or competing molecule smells.
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- Modified grape seed oils
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Edible oils are described which are extracted from dried fermented grape seeds isolated from a fermented grape pomace that has undergone fermentation, e.g., primary fermentation during wine making. The edible oils contain distinguishing flavor and fragrance chemicals evidenced by organoleptic evaluation and chemical analysis, in which these chemicals are substantially lacking in grape seed oils that have been similarly extracted from grape seeds isolated from non-fermented grape pomace.
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- Green syntheses of biobased solvents
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The design of bioproducts implies the use of renewable carbon but also the conversion of this carbon through clean processes. This step is often a limiting one if we consider the whole life cycle "from the raw materials to the fate of the products". We proposed, in this work, to adapt conventional methods to the conversion of a natural raw material, the fusel oil, a co-product generated by ethanol industry to prepare acetates, carbonates and isovalerates. Selected conditions are compared to conventional routes to quantify their ecoefficiency and to check their potential development for the preparation of new biosolvents. In another step, we have calculated the volatile organic compound amount emitted during the production of a new cosmetic formulation using the fusel oil derivatives. This complete but simple example shows how to identify a real competitive alternative to the usual production chains.
- Bandres, Matthieu,De Caro, Pascale,Thiebaud-Roux, Sophie,Borredon, Marie-Elisabeth
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experimental part
p. 636 - 646
(2012/04/10)
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- Task-oriented use of ionic liquids: Efficient acetylation of alcohols and phenols
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The ionic liquid 1-butyl-3-methylimidazolium acetate proves to be an excellent reaction medium for the acetylation of alcohols and phenols, providing better conditions than the acidic 1-butyl-3-methylimidazolium bisulfate. Reactions were carried at room temperature, with only a 10% excess of acylating agent and with no other solvent or catalyst added.
- López, Ignacio,Bravo, José Luis,Caraballo, Manuel,Barneto, José Luis,Silvero, Guadalupe
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scheme or table
p. 3339 - 3341
(2011/06/28)
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- Iron (III) phosphate as a green and reusable catalyst promoted chemo selective acetylation of alcohols and phenols with acetic anhydride under solvent free conditions at room temperature
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Iron (III) phosphate was employed as an efficient catalyst for the chemo selective acetylation of alcohols and phenols under solvent free condition at room temperature and with high yields. Iron (III) phosphate is also a potential green catalyst due to solid intrinsically, reusable and with high catalytic activity.
- Behbahani,Farahani,Oskooie
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experimental part
p. 633 - 637
(2011/10/08)
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- PROCESS FOR PRODUCTION OF ALKYL TIN ALKOXIDE COMPOUND, AND PROCESS FOR PRODUCTION OF CARBONATE ESTER USING THE COMPOUND
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The present invention provides a process for producing : a compound represented by XOR2; a dialkyl tin dialkoxide compound having one tin atom, two Sn-R1 bonds and two Sn-OR2 bonds; and/or a tetraalkyl dialkoxy distannoxane compound having one Sn-O-Sn bond, in which each tin atom of the tetraalkyl dialkoxy distannoxane compound has two Sn-R1 bonds and one Sn-OR2 bond, the process comprising reacting in the absence of a catalyst at least one alkyl tin compound selected from the group consisting of i) and ii) below: i) a dialkyl tin compound having one tin atom, two Sn-R1 (wherein R1 represents an alkyl group) bonds, and two Sn-OX bonds (wherein OX is a group in which HOX that is a conjugate acid of OX is a Bronsted acid having a pKa of from 0 to 6.8); and ii) a tetraalkyl distannoxane compound having one Sn-O-Sn bond, in which each tin atom of the tetraalkyl distannoxane compound has two Sn-R1 bonds and one Sn-OX bond (wherein OX is a group in which HOX that is a conjugate acid of OX is a Bronsted acid having a pKa of from 0 to 6.8); and a carbonic acid ester represented by R2OCOOR2 (wherein R2 represents a linear or branched, saturated or unsaturated hydrocarbon group, a hydrocarbon group having a saturated or unsaturated cyclic hydrocarbon substituent, or a Y-CH2- group (wherein Y represents an alkyl polyalkylene group, an aromatic group or a cyclic saturated or unsaturated alkylene ether group)), and/or an alcohol represented by R2OH (wherein R2 is the same as defined above).
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Page/Page column 64-65
(2010/09/17)
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- Process for Production of Alkyl Tin Alkoxide Compound, and Process for Production of Carbonic Acid Ester Using the Compound
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The present invention provides a process for producing: a compound represented by XOR2; a dialkyl tin dialkoxide compound having one tin atom, two Sn—R1 bonds and two Sn—OR2 bonds; and/or a tetraalkyl dialkoxy distannoxane compound having one Sn—O—Sn bond, in which each tin atom of the tetraalkyl dialkoxy distannoxane compound has two Sn—R1 bonds and one Sn—OR2 bond, the process comprising reacting in the absence of a catalyst at least one alkyl tin compound selected from the group consisting of i) and ii) below: i) a dialkyl tin compound having one tin atom, two Sn—R1 (wherein R1 represents an alkyl group) bonds, and two Sn—OX bonds (wherein OX is a group in which HOX that is a conjugate acid of OX is a Bronsted acid having a pKa of from 0 to 6.8); andii) a tetraalkyl distannoxane compound having one Sn—O—Sn bond, in which each tin atom of the tetraalkyl distannoxane compound has two Sn—R1 bonds and one Sn—OX bond (wherein OX is a group in which HOX that is a conjugate acid of OX is a Bronsted acid having a pKa of from 0 to 6.8); anda carbonic acid ester represented by R2OCOOR2 (wherein R2 represents a linear or branched, saturated or unsaturated hydrocarbon group, a hydrocarbon group having a saturated or unsaturated cyclic hydrocarbon substituent, or a Y—CH2— group (wherein Y represents an alkyl polyalkylene group, an aromatic group or a cyclic saturated or unsaturated alkylene ether group)), and/oran alcohol represented by R2OH (wherein R2 is the same as defined above).
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Page/Page column 48
(2010/12/18)
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- Comparative study of acetylation of alcohols and phenols with different acetylating agents using zinc chloride as catalyst under solvent free conditions at room temperature
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Efficient acetylation of 1°, 2° and 3°, benzylic alcohols and phenols under solvent free conditions at room temperature in presence of less toxic, easily available and in-expensive catalyst ZnCl2, using acetic anhydride or acetyl chloride as an acetylating agent. On comparative study of these two acetylating agents, the acetyl chloride seemed to be better acetylating agent.
- Yadav, Prakrati,Lagarkha, Rekha,Balla, Zahoor Ahmad
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experimental part
p. 5155 - 5158
(2012/07/28)
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- Production of aroma esters by immobilized Candida rugosa and porcine pancreatic lipase into calcium alginate gel
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Candida rugosa lipase (CRL) and porcine pancreatic lipase (PPL) were immobilized into calcium alginate (Ca-Alg) gel beads by means of entrapment and were used to produce three industrially important flavour esters, namely isoamyl acetate (banana flavour), ethyl valerate (green apple flavour) and butyl acetate (pineapple flavour). Immobilization conditions were optimized in terms of sodium alginate (Na-Alg) and CaCl2 concentrations by determination of the entrapped enzyme amount as well as by esterification of 4-nitrophenol and acetic acid. The best results were obtained at 2.5% Na-Alg and 2.5 M CaCl2 for CRL while at 2.5% Na-Alg and 2.0 M CaCl2 for PPL. On carrying out flavour syntheses in solvent-free medium and also in hexane medium, higher ester yields were obtained in hexane medium for all esters and both types of lipases. Ester esterification efficiency increased in parallel with both enzyme concentrations at immobilization medium and the immobilized lipase amount in esterification medium. Maximum ester production was observed between 40 and 50 °C for CRL and PPL. Besides, the effect of substrate concentrations on ester conversion was remarkable. The best ester yield was obtained for isoamyl acetate when immobilized PPL was used.
- Ozyilmaz, Gul,Gezer, Esra
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experimental part
p. 140 - 145
(2010/11/02)
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- MODIFIED GRAPE SEED OILS
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Edible oils are described which are extracted from dried fermented grape seeds isolated from a fermented grape pomace that has undergone fermentation, e.g., primary fermentation during wine making. The edible oils contain distinguishing flavor and fragrance chemicals evidenced by organoleptic evaluation and chemical analysis, in which these chemicals are substantially lacking in grape seed oils that have been similarly extracted from grape seeds isolated from non-fermented grape pomace.
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- Protic acid immobilized on solid support as an extremely efficient recyclable catalyst system for a direct and atom economical esterification of carboxylic acids with alcohols
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(Chemical Equation Presented) A convenient and clean procedure of esterification is reported by direct condensation of equimolar amounts of carboxylic acids with alcohols catalyzed by an easy to prepare catalyst system of perchloric acid immobilized on silica gel (HClO4-SiO2). The direct condensation of aryl, heteroaryl, styryl, aryl alkyl, alkyl, cycloalkyl, and long-chain aliphatic carboxylic acids with primary/secondary alkyl/cycloalkyl, allyl, propargyl, and long-chain aliphatic alcohols has been achieved to afford the corresponding esters in excellent yields. Chiral alcohol and N-t-Boc protected chiral amino acid also resulted in ester formation with the representative carboxylic acid or alcohol without competitive N-t-Boc deprotection and detrimental effect on the optical purity of the product demonstrating the mildness and chemoselectivity of the procedure. The esters of long-chain (>C10) acids and alcohols are obtained in high yields. The catalyst is recovered and recycled without significant loss of activity. The industrial application of the esterification process is demonstrated by the synthesis of prodrugs of ibuprofen and a few commercial flavoring agents. Other protic acids such as H2SO4, HBr, TfOH, HBF4, and TFA that were adsorbed on silica gel were less effective compared to HClO4-SiO2 following the order HClO4-SiO 2 ? H2SO4-SiO2 > HBr-SiO 2 > TfOH-SiO2 ? HBF4-SiO2 ≈ TFA-SiO2. When HClO4 was immobilized on other solid supports the catalytic efficiency followed the order HClO4-SiO 2 > HClO4-K10 > HClO4-Al 2O3 (neutral) > HClO4-Al2O 3 (acidic) > HClO4-Al2O3 (basic).
- Chakraborti, Asit K.,Singh, Bavneet,Chankeshwara, Sunay V.,Patel, Alpesh R.
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supporting information; experimental part
p. 5967 - 5974
(2009/12/24)
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- Ruthenium(III) chloride catalyzed acylation of alcohols, phenols, and thiols in room temperature Ionic liquids
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Ruthenium(III) chloride-catalyzed acylation of a variety of alcohols, phenols, and thiols was achieved in high yields under mild conditions (room temperature) in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]). The ionic liquid and ruthenium catalyst can be recycled at least 10 times. Our system not only solves the basic problem of ruthenium catalyst reuse, but also avoids the use of volatile acetonitrile as solvent.
- Xi, Zhiwen,Hao, Wenyan,Wang, Pingping,Cai, Mingzhong
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experimental part
p. 3528 - 3537
(2009/12/24)
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- PROCESS FOR PRODUCTION OF DIALKYLTIN DIALKOXIDES
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An object of the present invention is to provide a process for producing a dialkyl tin compound from a composition of deactivated forms of a dialkyl tin catalyst, and to provide a process for producing the dialkyl tin catalyst from the dialkyl tin compound and using the dialkyl tin catalyst to produce a carbonic acid ester. According to the present invention, a process for producing a dialkyl tin compound is provided that subjects a composition of the deactivated forms of the dialkyl tin catalyst, formed when producing an ester compound, to an alkyl group redistribution reaction and/or dealkylation reaction.
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Page/Page column 41
(2009/07/25)
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- Zirconia supported undecatungstophosphate: Synthesis and characterization of a bifunctional catalyst
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The synthesized supported undecatungstophosphate has been proven to be successful for acid catalyzed as well as oxidation reactions, especially, in obtaining 98.5% conversion of styrene and 100% selectivity for benzaldehyde.
- Shringarpure, Pragati,Patel, Anjali
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scheme or table
p. 3953 - 3955
(2009/02/03)
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