- Electrochemical Tandem Olefination and Hydrogenation Reaction with Ammonia
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An electrochemical Horner-Wadsworth-Emmons/hydrogenation tandem reaction was achieved using ammonia as electron and proton donors. The reaction could give two-carbon-elongated ester and nitrile from aldehyde or ketones directly. This reaction could proceed with a catalytic amount of base or even without a base. The ammonia provides both the electron and proton for this tandem reaction and enables the catalyst-free hydrogenation of an α,β-unsaturated HWE intermediate. More than 40 examples were reported, and functional groups, including heterocycles and hydroxyl, were tolerated.
- Zhang, Xiaofeng,Jiang, Runze,Cheng, Xu
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p. 16016 - 16025
(2021/08/24)
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- Novel synthesized microporous ionic polymer applications in transesterification of Jatropha curcas seed oil with short Chain alcohol
-
New suites of sulfonic acid-functionalized microporous ionic polymers (PIPs) catalysts were synthesized with polymer, alkyl bromides, and 1, 3-propane sultone via a two-step procedure. The synthesized microporous PIP catalysts were characterized using FT-IR, SEM-Mapping, XPS, N2 adsorption–desorption isotherms, solid NMR spectroscopy, and element analysis. Esterification of several fatty acids with ethanol, which was used as a model reaction in the stabilization of Jatropha curcas seed oil, was checked over functionalized PIP. We tested the catalytic performance of PIP-C8 on the synthesis of fatty acid esters via the transesterification of J. curcas seed oil with a mixture of short-chain alcohols such as ethanol, ethanol–to–diethyl carbonate (1;1 molar ratio), and ethanol–to–dimethyl carbonate (1:1 molar ratio) with 170 mg of PIP-C8 at reflux temperature with agitation. The PIP-C8 catalyst was particularly effective, having achieved yields of 85%, 94%, and 70% for J. curcas seed oil with ethanol, J. curcas seed oil with ethanol–to–DEC, and J. curcas seed oil with ethanol–to–DMC, respectively, under the optimized reaction conditions. The catalyst could be recycled more than five times without significant deactivation. Kinetic studies performed at different temperatures revealed that the conversion of oleic acid to an ethyl ester follows a first-order reaction. The best catalysts with microporous structure (average pore diameter: 1.7–1.9 nm, pore volume: 0.23–0.33 cm3 g–1) and –SO3H density (0.70–0.84 mmol/gcat) were obtained by 1, 3-propane sultone of the chemically activated. The results indicate that the site activity of functionalized microporous ionic polymer materials shows promising approach for the development of environmentally friendly technology.
- Chang, Tao,Hao, Yongjing,Jinxi, Jinxi,Kai, Kai,Panchal, Balaji,Qin, Shenjun,Sun, Yuzhuang,Zhao, Cunling,Zhao, Qiaojing,Zhu, Zheng
-
-
- NATURAL BIOSURFACTANT OF ESTER AND MANUFACTURING METHOD THEREOF
-
The present invention relates to an ester natural surfactant and a manufacturing method thereof. The present invention relates to an eco-friendly ester natural surfactant having excellent solubility in water and biodegradability, and a manufacturing method thereof. The present invention relates to an ester natural surfactant, and more particularly, to an ester natural surfactant and a method for preparing the same. (by machine translation)
- -
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Paragraph 0125; 0126; 0129-0132
(2020/12/11)
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- Fatty alcohol synthesis from fatty acids at mild temperature by subsequent enzymatic esterification and metal-catalyzed hydrogenation
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Fatty alcohols are important products in chemical industry to be used in the formulation of surfactants and lubricants. This work describes a two step approach for the production of myristyl alcohol under neat conditions by combining a lipase catalyzed esterification of myristic acid and myristyl alcohol with a ruthenium catalyzed hydrogenation of the intermediate myristyl myristate. The esterification was carried out in a bubble column reactor with the commercial immobilized lipase B from Candida antarctica as a biocatalyst, while the hydrogenation was conducted under pressurized conditions being catalyzed by the homogeneous chemocatalyst Ru-Macho-BH. By investigating the reaction steps separately, comparable reaction rates were found for the esterification of short chain and long chain alcohols. Additionally, the hydrogen pressure could be reduced to 35 bar compared to the current industrial Lurgi process. Characterization of cross interactions by the reactants myristic acid and sodium myristate in the hydrogenation demonstrates that the metal catalyst was completely deactivated, even at a low amount of 0.5 mol% of myristic acid. Complete conversion of myristic acid in the esterification with equal amounts of myristic acid and myristyl alcohol was obtained, overcoming any limitation in the hydrogenation. In comparison to the Lurgi process starting also from fatty acid and fatty alcohols, the chemoenzymatic two step reaction sequence could be realized at lower reaction temperatures of 60 and 100 °C as well as lower hydrogen pressures of 35 bar. This journal is
- Betke, Tobias,Gr?ger, Harald,Kleber, Joscha,Liese, Andreas,Schlipk?ter, Kim E.
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p. 7862 - 7867
(2020/11/02)
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- Preparation method of long-chain ester
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The invention relates to the field of organic synthesis and provides a preparation method of long-chain ester, which comprises the following steps: carrying out esterification reaction of the carboxylic acid and the alcohol through a catalyst and obtaining a long-chain ester phase and a water phase post the standing and layering of the reaction liquid; the catalyst comprises ionic liquid or eutectic solvent; purifying and separating the long-chain ester phase to obtain high-purity long-chain ester; introducing the residual substance again into the esterification reaction system for reaction after the water in the water phase is removed. The yield and the purity of the long-chain ester prepared by the invented method are as high as 99.8% and 99% respectively as indicated by the embodiment of the preparation method.
- -
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Paragraph 0121; 0122; 0123
(2019/03/23)
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- Medium-chain fatty acids from Eugenia winzerlingii leaves causing insect settling deterrent, nematicidal, and phytotoxic effects
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Eugenia winzerlingii (Myrtaceae) is an endemic plant from the Yucatan peninsula. Its organic extracts and fractions from leaves have been tested on two phloem-feeding insects, Bemisia tabaci and Myzus persicae, on two plant parasitic nematodes, Meloidogyne incognita and Meloidogyne javanica, and phytotoxicity on Lolium perenne and Solanum lycopersicum. Results showed that both the hexane extract and the ethyl acetate extract, as well as the fractions, have strong antifeedant and nematicidal effects. Gas chromatography-mass spectrometry analyses of methylated active fractions revealed the presence of a mixture of fatty acids. Authentic standards of detected fatty acids and methyl and ethyl derivatives were tested on target organisms. The most active compounds were decanoic, undecanoic, and dodecanoic acids. Methyl and ethyl ester derivatives had lower effects in comparison with free fatty acids. Dose-response experiments showed that undecanoic acid was the most potent compound with EC50 values of 21 and 6 nmol/cm2 for M. persicae and B. tabaci, respectively, and 192 and 64 nmol for M. incognita and M. javanica, respectively. In a phytotoxicity assay, medium-chain fatty acids caused a decrease of 38-52% in root length and 50-60% in leaf length of L. perenne, but no effects were observed on S. lycopersicum. This study highlights the importance of the genus Eugenia as a source of bioactive metabolites for plant pest management.
- Cruz-Estrada, Angel,Ruiz-Sánchez, Esaú,Cristóbal-Alejo, Jairo,González-Coloma, Azucena,Andrés, María Fe,Gamboa-Angulo, Marcela
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- Monomyristin and monopalmitin derivatives: Synthesis and evaluation as potential antibacterial and antifungal agents
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In the present work, monoacylglycerol derivatives, i.e., 1-monomyristin, 2-monomyristin, and 2-monopalmitin were successfully prepared from commercially available myristic acid and palmitic acid. The 1-monomyristin compound was prepared through a transesterification reaction between ethyl myristate and 1,2-O-isopropylidene glycerol, which was obtained from the protection of glycerol with acetone, then followed by deprotection using Amberlyst-15. On the other hand, 2-monoacylglycerol derivatives were prepared through enzymatic hydrolysis of triglycerides in the presence of Thermomyces lanuginosa lipase enzymes. The synthesized products were analyzed using fourier transform infrared (FTIR) spectrophotometer, gas or liquid chromatography-mass spectrometer (GC-MS or LC-MS), and proton and carbon nuclear magnetic resonance (1H- and13C-NMR) spectrometers. It was found that monomyristin showed high antibacterial and antifungal activities, while 2-monopalmitin did not show any activity at all. The 1-monomyristin compound showed higher antibacterial activity against Staphylococcus aureus and Aggregatibacter actinomycetemcomitans and also higher antifungal activity against Candida albicans compared to the positive control. Meanwhile, 2-monomyristin showed high antibacterial activity against Escherichia coli. The effect of the acyl position and carbon chains towards antibacterial and antifungal activities was discussed.
- Jumina,Nurmala, Asma,Fitria, Anggit,Pranowo, Deni,Sholikhah, Eti Nurwening,Kurniawan, Yehezkiel Steven,Kuswandi, Bambang
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- Sulfonic acid-functionalized organic knitted porous polyaromatic microspheres as heterogeneous catalysts for biodiesel production
-
The use of renewable energy sources decreases the consequences of greenhouse gas emission from fossil fuels. Biodiesel, an easily burning and biodegradable fuel, is an alternative to conventional diesel fuel. The esterification of long-chain fatty acids and transesterification of triglycerides are two major reactions widely used to convert vegetable oils or animal fats into biodiesel. As solid acid catalysts are considered promising candidates for biodiesel production, we have synthesized a series of organic knitted porous polyaromatics (OPPs) using pyrene, anthracene, and naphthalene as monomers via Friedel-Crafts alkylation, followed by crosslinking reactions. The resultant polymers showed good surface morphology, stability and swelling property, high capacity for functionalization due to the unreacted bromomethyl groups on the surface, and excellent hydrophobicity. The sulfonated polymer microspheres obtained by the surface sulfonation showed good surface acidity; thus, they can be employed as heterogeneous solid acid catalysts for the esterification of long-chain fatty acids and transesterification of triglycerides, and they are reusable without any leaching of functional groups.
- Varyambath, Anuraj,Kim, Mi-Ra,Kim, Il
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p. 12745 - 12753
(2018/08/04)
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- P-Sulfonic acid calix[4]arene-functionalized alkyl-bridged organosilica in esterification reactions
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Two new p-sulfonic acid calix[4]arene- and p-sulfonic acid calix[6]arene-functionalized organosilica have been synthesized using a sol-gel method and applied as heterogeneous catalysts in esterification reactions. The catalytic performance was evaluated using the esterification of carboxylic acids with ethanol, and good catalytic activity (i.e., 55-88%) was observed under the optimum reaction conditions. This study reports the first promising example of the successful employment of calix[n]arenes as a heterogeneous catalyst for catalytic esterification. The catalyst was easily separated by filtration and reused five times without any significant loss of activity.
- De Assis,Abranches,Braga,Zu?iga,Sathicq,Romanelli,Sato,Fernandes
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p. 24285 - 24289
(2016/03/15)
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- Use of Lecitase-Ultra immobilized on styrene-divinylbenzene beads as catalyst of esterification reactions: Effects of ultrasounds
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Abstract In this work it was evaluated for the first time, the ester synthesis catalyzed by the phospholipase Lecitase-Ultra immobilized styrene-divinylbenzene beads (MCI-Lecitase), comparing the mechanical stirring and the ultrasonic energy. It was studied the specificity of the enzyme using carboxylic acids from C4 to C18, as well as the effects of alcohol chain, organic solvents, biocatalyst content, reaction temperature and substrate concentration. Caprylic and myristic acids were those with the highest reaction rates and yields, using ethanol as substrate. The shorter the alcohol chain, the higher the enzyme activity. Regarding the secondary alcohols, while MCI-Lecitase had no activity versus isopropanol, using 2-pentanol the activity was similar to that with 1-pentanol. Comparing the agitation systems, MCI-Lecitase presented an initial reaction rate more than 2-times higher in the ultrasound-assisted reaction than under traditional mechanical stirring. Moreover, under ultrasonic energy the maximum rate was achieved using 0.5 M of substrates, while under mechanical stirring the maximum enzyme activity was reached at 0.3 M of substrates. Concerning the operational stability, MCI-Lecitase was quite unstable, losing its activity after 6 reaction cycles. By adding molecular sieves in the reaction medium, MCI-Lecitase retained 30% of its initial activity after 6 cycles.
- Alves, Joana S.,Garcia-Galan, Cristina,Danelli, Daiane,Paludo, Natália,Barbosa, Oveimar,Rodrigues, Rafael C.,Fernandez-Lafuente, Roberto
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- Efficient, stable, and reusable Lewis acid-surfactant-combined catalyst: One-pot Biginelli and solvent-free esterification reactions
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Cerium(III) trislaurylsulfonate (Ce(LS)3), a Lewis acid and surfactant combined catalyst, was prepared and characterized by SEM, SEM-EDX, XRD, NMR, FT-IR, TG, and elemental analysis. Ce(LS)3 was found to be stable and efficient to catalyze one-pot Biginelli and solvent-free esterification reactions. Furthermore, Ce(LS)3 is easy to recycle after reaction by pouring into cold water and filtration. Present work will shed deep insight into the understanding of the catalytic nature of LASCs, and extend its application in important organic transformations.
- Qiu, Yunfeng,Sun, Hongnan,Ma, Zhuo,Xia, Wujiong
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-
- METHOD OF PRODUCING SATURATED ALKYL ESTERS/ACIDS
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Disclosed herein is the production of saturated alkyl esters or acids from furan materials. The starting compounds contain furan, ketone, and ester or acid functional groups and may be biologically-derived. The method includes hydrogenating the starting compound to form a reduced mixture. The method further includes hydrodeoxygenation of the reduced mixture to yield a saturated alkyl ester or acid. The saturated alkyl ester or acid can be unbranched or branched. The ester and acid products have a wide variety of applications and may be further processed into surfactants, solvents, and lubricants suitable for use in consumer products.
- -
-
Paragraph 0066; 0067
(2013/03/28)
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- Novel and highly efficient SnBr2-catalyzed esterification reactions of fatty acids: The notable anion ligand effect
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In this work, the efficiency of Lewis acid catalysts, SnX2 (X = F-, Cl-, Br-, or -OAc), was investigated on the esterification reactions of fatty acids (i.e., myristic, palmitic, stearic, oleic, linoleic, and linoleic) with different alcohols (i.e., methyl, ethyl, propyl, isopropyl, and butyl alcohol). Tin(II) bromide was the most active catalyst in all reactions studied. We investigated the effects of main reaction parameters, such as catalyst concentration, temperature, and nature of alcohol and fatty acid. The highest activity of SnBr2 catalyst was discussed in terms of its lower activation energy, higher Lewis acid strength, and higher softness of anionic ligand. Finally, the SnBr 2 catalyst can be easily recovered and reused without loss of catalytic activity. Graphical Abstract: Effect of the tin catalyst nature on the oleic acid esterification with ethyl alcohol. [Figure not available: see fulltext.]
- Ferreira, Arthur Batista,Cardoso, Abiney Lemos,Da Silva, Marcio Jose
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p. 1240 - 1246
(2014/01/06)
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- Ultrasound-assisted synthesis of aliphatic acid esters at room temperature
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This work describes the ultrasound-assisted synthesis of saturated aliphatic esters from synthetic aliphatic acids and either methanol or ethanol. The products were isolated in good yields after short reaction times under mild conditions.
- Hobuss, Cristiane B.,Venzke, Dalila,Pacheco, Bruna S.,Souza, Alexander O.,Santos, Marco A.Z.,Moura, Sidnei,Quina, Frank H.,Fiametti, Karina G.,Vladimir Oliveira,Pereira, Claudio M.P.
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experimental part
p. 387 - 389
(2012/04/23)
-
- Antimicrobial evaluation of 4-methylsulfanyl benzylidene/3-hydroxy benzylidene hydrazides and QSAR studies
-
A series of 4-methylsulfanyl benzylidene/3-hydroxy benzylidene hydrazides (1-20) was synthesized and tested for in vitro antimicrobial activity against S. aureus, B. subtilis, E. coli, C. albicans and A. niger. The results of antimicrobial studies indicated that 3-phenylacrylic acid-(3-hydroxybenzylidene) -hydrazide, 16, was the most effective as it showed both bactericidal and fungicidal properties and other compounds possessed bacteriostatic/fungistatic activity. The multi-target QSAR model demonstrated that the topological parameter, Balaban topological index (J) is effective in describing the antimicrobial activity of synthesized substituted hydrazides. Springer Science+Business Media, LLC 2010.
- Kumar, Davinder,Narang, Rakesh,Judge, Vikramjeet,Kumar, Devinder,Narasimhan, Balasubramanian
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experimental part
p. 382 - 394
(2012/08/27)
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- P-Sulfonic acid calix[n]arenes as homogeneous and recyclable organocatalysts for esterification reactions
-
Esterification yields were significantly improved using calix[n]arenes catalysts under simple conditions. p-Sulfonic acid calix[4]arene and p-sulfonic acid calix[6]arene were powerful organocatalysts in several esterification reactions, which showed activity comparable or even superior to other well-established acids catalysts, such as, sulfuric acid, p-toluenesulfonic acid, and p-hydroxybezenesulfonic acid described in the literature.
- Fernandes, Sergio Antonio,Natalino, Ricardo,Gazolla, Poliana Aparecida Rodrigues,Da Silva, Márcio José,Jham, Gulab Newandram
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experimental part
p. 1630 - 1633
(2012/04/17)
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- Lipase-catalyzed transformations using poly(ethylene glycol) as solvent
-
Candida antarctica lipase catalyzes a number of elementary reactions like alcoholysis, ammoniolysis and aminolysis in poly(ethylene glycol) (PEG) media. Reaction rates were comparable to or better than those observed in conventional organic reaction media and ionic liquids. It is envisaged that PEGs could have added benefits for performing biotransformations with highly polar substrates, which are sparingly soluble in common organic solvents.
- Kidwai, Mazaahir,Poddar, Roona,Bhardwaj, Saurav
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experimental part
p. 113 - 118
(2011/12/15)
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- Synthesis, antimicrobial evaluation and QSAR studies of 3-ethoxy-4-hydroxybenzylidene/4-nitrobenzylidene hydrazides
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A series of 3-ethoxy-4-hydroxybenzylidene/4-nitrobenzylidene hydrazides (1-20) was synthesized and tested for in vitro antimicrobial activity. The results of antimicrobial studies indicated that the compounds having dinitro, methoxy, hydroxy and nitro substituents on phenyl ring of the aromatic acids were most active ones. The QSAR investigation indicated the importance of the topological parameter, third order molecular connectivity index ( 3χ) in describing the antimicrobial activity of synthesized hydrazides.
- Kumar, Davinder,Kapoor, Archana,Thangadurai, Ananda,Kumar, Pradeep,Narasimhan, Balasubramanian
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experimental part
p. 1293 - 1296
(2012/01/07)
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- Separation of secondary alcohols via enzymatic kinetic resolution using fatty esters as reusable acylating agents
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A two consecutive step procedure for the resolution-separation of secondary alcohols employing ethyl tetradecanoate in the presence of lipase allowed the enzymatic kinetic resolution of two target molecules, 1-phenylethanol and 6-methylhept-5-en-2-ol. (S)-1-Phenylethanol was isolated in a yield of 47% with an ee of 94% and (R)-1-phenylethanol in a yield of 51% with an ee of 95%. (S)-6-Methylhept-5-en-2-ol was isolated in a yield 47% and an ee of 87% and (R)-6-methylhept-5-en-2-ol in a yield 49% and an ee of 90%.
- Monteiro, Carlos M.,Lourenco, Nuno M.T.,Afonso, Carlos A.M.
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experimental part
p. 952 - 956
(2010/08/06)
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- Novel H3PW12O40: Catalysed esterification reactions of fatty acids at room temperature for biodiesel production
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The catalytic activity of Bronsted acids on fatty acid (FA) esterification at room temperature has been investigated. Noticeably, the H 3PW12O40 heteropolyacid (HPW) showed a very high activity than other catalysts herein evaluated, i.e. p-toluene sulfonic acid and sulfuric acid. High yields in ethyl esters (ca. 90%) were reached after a 4 h reaction at 25 °C on a HPW catalysed reactions. Despite the fact that HPW catalyst was used in a homogeneous phase, it could be efficiently recovered and reused through out a simple recycling protocol, without any activity loss. The effects of alcohol and the FA nature on yield reaction were also investigated.
- De Godoi Silva, Vinicius Wilker,Laier, Leticia Oliveira,Silva, Marcio Jose Da
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experimental part
p. 207 - 211
(2010/08/03)
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- Benzylidene/2-chlorobenzylidene hydrazides: Synthesis, antimicrobial activity, QSAR studies and antiviral evaluation
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A series of benzylidene hydrazides (1-20) was synthesized and tested, in vitro, for antibacterial, antifungal and antiviral activities. The microbial screening results indicated that compounds having chloro and nitro substituents were the most active ones. The antiviral evaluation depicted that compounds 9 and 19 were active against Vesicular stomatitis virus (VSV) in HeLa cell cultures. QSAR investigations indicated that the multi-target QSAR model was effective in describing the antimicrobial (antibacterial and antifungal) activity over the one-target QSAR models. Further the mt-QSAR model indicated that the topological parameters, second order molecular connectivity index (2χ) and third order Kier's alpha shape index (κα3) are effective in describing the antimicrobial activity of synthesized hydrazides.
- Kumar, Davinder,Judge, Vikramjeet,Narang, Rakesh,Sangwan, Sonia,De Clercq, Erik,Balzarini, Jan,Narasimhan, Balasubramanian
-
experimental part
p. 2806 - 2816
(2010/08/20)
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- Cobalt-catalyzed cross-coupling reaction between functionalized primary and secondary alkyl halides and aliphatic Grignard reagents
-
The coupling of primary and secondary unactivated alkyl bromides with alkyl-Grignard reagents was performed in good yields under mild conditions by using a new catalytic system: consisting of cobalt chloride and tetramethylethylenediamine (CoCl2·2 LiI, 4TMEDA). The reaction is very chemoselective since ketone, ester and nitrile functions are tolerated.
- Cahiez, Gerard,Chaboche, Christophe,Duplais, Christophe,Giulliani, Arianna,Moyeux, Alban
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supporting information; experimental part
p. 1484 - 1488
(2009/07/01)
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- Design, synthesis, antibacterial, and QSAR studies of myristic acid derivatives
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A series of esters and amides of myristic acid was synthesized and tested in vitro for antibacterial activity against Gram-positive and Gram-negative bacteria. All the compounds showed activity comparable to that of the standard drug, ciprofloxacin. The structural characteristics governing antibacterial activity of myristic acid derivatives was studied using QSAR methodology. The results showed that the antibacterial activity could be modeled using the topological descriptor, valence molecular connectivity index. The predictive ability of the models was cross-validated by construction of a test set. The low residual activity and high cross-validated r2 values ( rcv2 ) observed indicated the predictive ability of the developed QSAR models.
- Narasimhan, Balasubramanian,Mourya, Vishnukant,Dhake, Avinash
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p. 3023 - 3029
(2008/09/20)
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- Novel chemistry of abdominal defensive glands of nymphalid butterfly Agraulis vanillae
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Abdominal defensive glands of both sexes of the Gulf fritillary butterfly, Agraulis vanillae (Linnaeus) (Nymphalidae:Heliconiinae) emit a pronounced odor when disturbed. We have identified 6-methyl-5-hepten-2-one; oleic, palmitic, and stearic esters of the corresponding alcohol 6-methyl-5-hepten-2-ol; hexadecyl acetate; 1,16-hexadecanediol diacetate; and 1,15-hexadecanediol diacetate in the glandular exudate. Since we have determined that free-flying birds or birds in a butterfly conservatory discriminate against A. vanillae as prey, we suggest that the constituents in the glands may play a defensive role against potential avian predators.
- Ross, Gary N.,Fales, Henry M.,Lloyd, Helen A.,Jones, Tappey,Sokoloski, Edward A.,Marshall-Batty, Kimberly,Blum, Murray S.
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p. 1219 - 1228
(2007/10/03)
-
- Investigation of the photo-fries rearrangements of two 2-naphthyl alkanoates by experiment and theory. Comparison with the acid-catalyzed reactions
-
A detailed investigation of the photochemistry of 2-naphthyl acetate (1a) and 2-naphthyl myristate (1b) has been conducted under a variety of conditions. Factors related to the reactions such as temperature and solvent type have been explored. The results, most easily interpreted by photo-Fries type processes, are contrasted with those from the Lewis-acid catalyzed (dark) Fries reactions of 1a. They are also compared to the predictions of semiempirical and ab initio calculations using 2-naphthyl propanoate (1c) and species derived from it as models. Unsuccessful triplet sensitization experiments with benzophenone and calculations point to the excited singlet states of 1 as the immediate precursor to the acyl/2-naphthoxy radical pairs that recombine to form keto intermediates 2, reform 1, or diffuse apart and eventually yield 2-naphthol (4); enolization of 2 results in the isolated rearrangement products, n-acyl-2-naphthols (n-3). Static and dynamic fluorescence studies provide some insights into the nature of the lysis process. Irradiation of a mixture of appropriately labeled derivatives of 1 led to none of the expected "cross-over" products, indicating that the intermediates 2 arise from recombination of radical pairs from the same parent molecule. Irradiation of 1b in ethanol and 1-octanol provides no evidence for the intermediacy of dodecylketene and supports out-of-cage mechanisms as the exclusive source of 4. There are indications of subtle solvent effects and a conformational dependence on the distribution of photoproducts.
- Cui, Changxing,Wang, Xiaochun,Weiss, Richard G.
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p. 1962 - 1974
(2007/10/03)
-
- The Esterification of Carboxylic Acid with Alcohol over Hydrous Zirconium Oxide
-
The esterification of carboxylic acids with alcohols proceeded efficienly with hydrous zirconium oxide to give the corresponding esters in the vapor phase, in the liquid phase, and in an autoclave.The steric hindrance of carboxylic acids and alcohols affected the esterification by lowering the reactivity.With a rise in the reaction temperature, the conversion of the carboxylic acid increased.The dehydration of alcohols was prevented by using hydrous zirconium oxide in spite of the high reaction temperature.The reaction rate is first-order with respect to the concentration of the catalyst and an alcohol and is inversely proportional to thta of the carboxylic acid.Transesterification also proceeded efficiently.
- Takahashi, Kyoko,Shibagaki, Makoto,Matsushita, Hajime
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p. 2353 - 2361
(2007/10/02)
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