- Highly efficient self-esterification of aliphatic alcohols using supported gold nanoparticles under mild conditions
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Long aliphatic esters were prepared by the one-step catalytic self-esterification of primary alcohols using molecular oxygen as a green oxidant and supported gold nanoparticles (Au NPs) as catalyst. This heterogeneous catalyst achieved high activity and selectivity in a wide range of less reactive straight-chain alcohols (C4-C12) at atmospheric pressure O2 and near ambient temperature (45?°C). Under optimised conditions, the catalyst with Au loading of 3?wt% achieved the highest catalytic activity and selectivity. The AuNP catalysts are efficient and readily recyclable. The finding of this study may inspire further studies on new efficient catalytic systems for a wide range of organic syntheses using supported AuNP catalysts.
- Wang, Fan,Xiao, Qi,Han, Pengfei,Sarina, Sarina,Zhu, Huaiyong
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- Aerobic oxidation and oxidative esterification of alcohols through cooperative catalysis under metal-free conditions
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The ABNO@PMO-IL-Br material obtained by anchoring 9-azabicyclo[3.3.1]nonane-3-oneN-oxyl (keto-ABNO) within the mesopores of periodic mesoporous organosilica with bridged imidazolium groups is a robust bifunctional catalyst for the metal-free aerobic oxidation of numerous primary and secondary alcohols under oxygen balloon reaction conditions. The catalyst, furthermore, can be successfully employed in the first metal-free self-esterification of primary aliphatic alcohols affording valued esters.
- Karimi, Babak,Ghahremani, Mina,Vali, Hojatollah,Ciriminna, Rosaria,Pagliaro, Mario
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- Lipase-catalyzed reactions in ionic liquids.
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[reaction:see text] Candida antarctica lipase was shown to catalyze alcoholysis, ammoniolysis, and perhydrolysis reactions using the ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate or hexafluorophosphate as reaction media. Reaction rates were generally comparable with, or better than, those observed in organic media.
- Madeira Lau,van Rantwijk,Seddon,Sheldon
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- One-step synthesis of nitriles by the dehydrogenation-amination of fatty primary alcohols over Cu/m-ZrO2
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An effective method for one-step synthesis of nitriles employing C 2-C8 fatty primary alcohols and ammonia over 5%Cu/m-ZrO2 has been found. The conversion of alcohols and selectivity of nitriles obtained are > 96 and > 87 wt.%, respectively, and are obviously influenced by the C2-substitution rather than the chain length of fatty primary alcohols. Cu/m-ZrO2 was characterized by XRD, H 2-TPR, CO2-TPD and NH3-TPD. It is revealed that a substantial amount of Cu species over m-ZrO2 is in highly dispersed CuO. A plausible mechanism is proposed and supported by different experiments, and aldehyde generation is an important step in the reaction mechanism.
- Hu, Yunfeng,Jin, Shuhan,Zhang, Zhichao,Zhang, Likun,Deng, Jun,Zhang, Hongsheng
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- A quantitative comparison between conventional and bio-derived solvents from citrus waste in esterification and amidation kinetic studies
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(R)-(+)-Limonene, which is available in large quantities from citrus waste, and its close derivative p-cymene are shown herein to be viable yet sustainable solvents for amidation and esterification reactions.
- Clark, James H.,MacQuarrie, Duncan J.,Sherwood, James
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- Enzymatic alcoholysis of alkoxymethyl alkanoates: A possible approach for the kinetic resolution of tertiary alcohols
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The pivaloyloxymethyl and butanoyloxymethyl derivatives of tert-butanol and linalool (1.4) are readily accepted by hydrolases. Linalool derivative 4b is alcoholysed stereoselectively by Candida rugosa lipase (E=9.7).
- Franssen, Maurice C.R.,Goetheer, Earl L.V.,Jongejan, Hugo,De Groot, Aede
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- Use of salt hydrates to buffer optimal water level during lipase catalysed in synthesis in organic media: A practical procedure for organic chemists
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Enzyme catalyzed reactions in mainly organic media depend very much on the amount of water in the system. We have shown that addition of appropriate solid salt hydrates to the reaction mixture is a simple and convenient method to obtain optimal water level conditions throughout the reaction. As a model reaction the esterification of butanoic acid with butanol catalysed by lipase from Candida rugosa was chosen. Variations in the amount of enzyme, in the solvent and in the concentration of reactants were made.
- Kvittingen, Lise,Sjursnes, Birte,Anthonsen, Thorleif,Halling, Peter
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- Genome Mining of Oxidation Modules in trans-Acyltransferase Polyketide Synthases Reveals a Culturable Source for Lobatamides
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Bacterial trans-acyltransferase polyketide synthases (trans-AT PKSs) are multimodular megaenzymes that biosynthesize many bioactive natural products. They contain a remarkable range of domains and module types that introduce different substituents into growing polyketide chains. As one such modification, we recently reported Baeyer–Villiger-type oxygen insertion into nascent polyketide backbones, thereby generating malonyl thioester intermediates. In this work, genome mining focusing on architecturally diverse oxidation modules in trans-AT PKSs led us to the culturable plant symbiont Gynuella sunshinyii, which harbors two distinct modules in one orphan PKS. The PKS product was revealed to be lobatamide A, a potent cytotoxin previously only known from a marine tunicate. Biochemical studies show that one module generates glycolyl thioester intermediates, while the other is proposed to be involved in oxime formation. The data suggest varied roles of oxygenation modules in the biosynthesis of polyketide scaffolds and support the importance of trans-AT PKSs in the specialized metabolism of symbiotic bacteria.
- Ueoka, Reiko,Meoded, Roy A.,Gran-Scheuch, Alejandro,Bhushan, Agneya,Fraaije, Marco W.,Piel, J?rn
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- Iridium-catalyzed oxidative dimerization of primary alcohols to esters using 2-butanone as an oxidant
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Oxidative dimerization of primary alcohols with 2-butanone in the presence of an amino alcohol-based Ir bifunctional catalyst was accomplished for the first time. The reaction proceeds with 1-2 mol% of the catalyst and 0.3 mol equivalents of K2CO3 in 2-butanone at room temperature to give the corresponding dimeric esters in 30-93% yield. Georg Thieme Verlag Stuttgart.
- Suzuki, Takeyuki,Matsuo, Tomohito,Watanabe, Kazuhiro,Katoh, Tadashi
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- Conversion of biomass-derived butanal into gasoline-range branched hydrocarbon over Pd-supported catalysts
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For production of gasoline-range branched hydrocarbon from butanal, Pd catalysts supported on different metal oxides were applied. Among the prepared catalysts, Pd/ZrO2 showed the complete butanal conversion with the formation of C7-to-C9 branched hydrocarbon (75% yield). Additionally, the ratios of O/C and straight-chain to branched hydrocarbon (n-C/br-C) were found to be 0.005 and 0.17, respectively. This indicates that an adequate combination of Pd dispersion and amphoteric ZrO2 character promoted hydrodeoxygenation, C-C coupling and isomerization reactions. Consequently, both Pd dispersion and acid-base properties of supports are suggested to play a pivotal role in producing gasoline-range hydrocarbon at a high yield.
- Kim, Sung Min,Lee, Mi Eun,Choi, Jae-Wook,Suh, Dong Jin,Suh, Young-Woong
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- Crystal structure, thermal decomposition mechanism and catalytic performance of hexaaquaaluminum methanesulfonate
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Hexaaquaaluminum methanesulfonate crystals, [Al(H2O)6][CH3SO3]3 were synthesized by a hydrothermal reaction of Al(OH)3 with methanesulfonic acid. Single-crystal diffraction determination revealed that Al3+ was coordinated by six water molecules in octahedral geometry, while the CH3SO3 – anion connected with Al3+ through coordinated water molecules by hydrogen bonds. The six-coordinate environment of Al was also determined by 27Al MAS NMR measurement. Thermogravimetric analysis and Fourier transform infrared spectroscopy showed that the decomposition intermediate at 265–365?°C was Al2(μ-OH)(CH3SO3)5 and the final product was amorphous Al2O3 residue with about 0.8 wt% SO3 at 520–800?°C. A pure phase of [Al(H2O)6][CH3SO3]3 was confirmed by powder X-ray diffraction analysis. Esterification of n-butyric acid with n-butanol and ketalization of cyclohexanone with glycol catalyzed by [Al(H2O)6][CH3SO3]3 and Al2(μ-OH)(CH3SO3)5, respectively, proceeded in 100% yield by continuously removing the produced water. In the case of tetrahydropyranylation of n-butanol at room temperature in dichloromethane, the catalytic activity of [Al(H2O)6][CH3SO3]3 was much lower than that of Al2(μ-OH)(CH3SO3)5. Furthermore, both [Al(H2O)6][CH3SO3]3 precursor and Al2(μ-OH)(CH3SO3)5 catalysts could be recycled.
- Wang, Rui,Li, Rongrong,Jiang, Heng,Gong, Hong,Bi, Yanfeng
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- Hydrocarbon oxidation catalyzed by self-folded metal-coordinated cavitands
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Functionalized cavitands have been shown to self-fold via coordination of Fe(ii) salts and effect catalytic C-H oxidation reactions of unfunctionalized alkanes under mild aqueous conditions in the presence of tert-butyl hydroperoxide as co-oxidant. Secondary and tertiary C-H bonds can be converted to ketones and alcohols, respectively, and ethers can be converted to esters. The cavitands retain the catalytic metal throughout the reaction, and can be recovered by filtration. The Royal Society of Chemistry 2012.
- Djernes, Katherine E.,Padilla, Melissa,Mettry, Magi,Young, Michael C.,Hooley, Richard J.
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- Homoleptic lanthanide amides as homogeneous catalyst for the Tishchenko reaction
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Known for about 25 years, the bis(trimethylsilyl)amides of Group 3 metals and lanthanides, M[N(SiMe3)2]3, are well suited as highly efficient catalysts for the dimerization of aldehydes [Tishchenko reaction, Eq. (1)].
- Berberich, Helga,Roesky, Peter W.
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- Enhanced reactivities toward amines by introducing an imine arm to the pincer ligand: Direct coupling of two amines to form an imine without oxidant
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Dehydrogenative homocoupling of primary alcohols to form esters and coupling of amines to form imines was accomplished using a class of novel pincer ruthenium complexes. The reactivities of the ruthenium pincer complexes for the direct coupling of amines to form imines were enhanced by introducing an imine arm to the pincer ligand. Selective oxidation of benzylamines to imines was achieved using aniline derivatives as the substrate and solvent.
- He, Li-Peng,Chen, Tao,Gong, Dirong,Lai, Zhiping,Huang, Kuo-Wei
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- Self-Condensation of n-Butyraldehyde over Solid Base Catalysts
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The catalytic properties of various solid bases for self-condensation of n-butyraldehyde in liquid phase were studied to elucidation the factors governing the activity and selectivity.For alkaline earth oxide catalysts and γ-alumina catalyst, aldol condensation ocurred, followed by Tishchenko-type cross-esterification of n-butyraldehyde with the dimer produced by the aldol condensation to form trimeric glycol ester.Alkali ion-modified alumina catalysts exhibited a high selectivity for the aldol condensation dimer, the trimeric glycol ester being formed little.Both basic and acidic sites on the surfaces of the alkaline earth oxides and γ-alumina were assumed to contribute to Tishchenko-type cross-esterification.The suppression of Tischenko-type cross-esterification.The suppression of Tischenko-type cross-esterification for alkali ion-modified alumina catalysts is due to the absence of acidic sites on the surfaces.The catalytic performances of alumina-supported magnesium oxide exhibited lower activity but higher selectivity to trimeric glycol ester than MgO.This catalytic feature was caused by the lower basicity and higher acidity on the surface of alumina-supported magnesium oxide as compared with MgO.The activity of alkali ion-exchanged zeolites was lowest among the catalysts examined in this study.The modification of zeolites with excess alkali ions improved the activity.
- Tsuji, Hideto,Yagi, Fuyuki,Hattori, Hideshi,Kita, Hideaki
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- Mixing conditions for enzyme catalysis in organic solvents
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When performing enzyme catalysed reactions in organic solvents the agitation method may have an influence on the result. It has been observed that stirring with magnet bars may cause a considerable decrease in the reaction rate, probably due to damage to the enzyme. This applies to both free and immobilised enzyme. However, use of a shaker or an over-head stirrer does not inactivate the enzyme.
- Kvittingen, Lise,Sjursnes, Birte,Halling, Peter,Anthonsen, Thorleif
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- Facile Ester Synthesis on Ag-Modified Nanoporous Au: Oxidative Coupling of Ethanol and 1-Butanol Under UHV Conditions
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A dilute Ag alloy of nanoporous Au (npAu) has been shown to self-couple methanol with 100 % selectivity and high conversion under catalytic flow conditions. However, because prior studies in flow reactors showed difficulty in self-coupling ethanol and 1-butanol over npAu in flow reactors, the inherent capability on npAu for self-coupling of ethanol and 1-butanol was examined under ultrahigh vacuum conditions on identical npAu catalysts. This study shows that the oxygen-covered Ag-modified npAu does efficiently effect the self-coupling of ethanol and 1-butanol under UHV conditions. The coupling is initiated by adsorbed atomic oxygen formed from O2 dissociation via a chemisorbed molecular state. The amount of ester formed increases with the degree of oxygen precoverage at the expense of aldehyde production. Repeated annealing of the catalyst above 550 K for temperature programmed reaction changes the ligament and pore sizes, affecting the product distribution, but high reactivity is sustained over many heating cycles. (Figure Presented).
- Stowers, Kara J.,Madix, Robert J.,Biener, Monika M.,Biener, Juergen,Friend, Cynthia M.
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- Esterification of carboxylate-based ionic liquids with alkyl halides
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A facile reaction of 1-ethyl-3-methylimidazolium acetate ([EMIm]Ac) with dichloromethane at room temperature was observed with esters among the products. This esterification can be exploited for mild solvent-free esterification with a range of other carboxylate-based ionic liquids and alkyl halides. The Royal Society of Chemistry.
- Zhao, Bin,Greiner, Lasse,Leitner, Walter
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- Organoaluminum cations for carbonyl activation
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In search of stable, yet reactive aluminum Lewis acids, we have isolated an organoaluminum cation, [(Me2NC6H4)2Al(C4H8O)2]+, coordinated with two labile tetrahydrofuran ligands. Its catalytic performance in aldehyde dimerization reveals turn-over frequencies reaching up to 6000 h-1, exceeding that of the reported main group catalysts. The cation is further demonstrated to catalyze hydroelementation of ketones. Mechanistic investigations reveal that aldehyde dimerization and ketone hydrosilylation occur through carbonyl activation.
- Kannan, Ramkumar,Chambenahalli, Raju,Kumar, Sandeep,Krishna, Athul,Andrews, Alex P.,Jemmis, Eluvathingal D.,Venugopal, Ajay
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- Deuterium kinetic isotopic study for hydrogenolysis of ethyl butyrate
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The hydrogenation of ethyl butyrate, n-butyric acid, and n-butyraldehyde to their corresponding alcohol(s) has been studied over a γ-Al 2O3-supported cobalt catalyst using a high-pressure fixed-bed reactor in the temperature range of 473-493 K. H2-D 2-H2 switching experiments show that ethyl butyrate and n-butyric acid follow an inverse kinetic isotope effect (KIE) (i.e. r H/rD = 0.50-0.54), whereas n-butyraldehyde did not display any KIE (i.e. rH/rD = 0.98). DRIFTS experiments were performed over the support and catalyst to monitor the surface species formed during the adsorption of ethyl butyrate and n-butyric acid at atmospheric pressure and the desired temperature. Butanoate and butanoyl species are the stable surface intermediates formed during hydrogenation of ethyl butyrate. Hydrogenation of butanoate to a partially hydrogenated intermediate is likely involved in the rate-determining step of ethyl butyrate and butyric acid hydrogenation.
- Gnanamani, Muthu Kumaran,Jacobs, Gary,Keogh, Robert A.,Davis, Burtron H.
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- Symmetric esters by Tischtschenko reaction of aldehydes catalyzed by bi- and tridentate catalysts derived from catechol or gallol, trimethylaluminum and isopropanol
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New inexpensive aluminum-based bidentate and tridentate chelates were found to be efficient catalysts for the Tischtschenko reaction of aldehydes. The conversion of n-butanal to n-butyl n-butyrate using catechol-derived catalysts at room temperature was complete (the yield of the butyrate was 99%) in two hours. High yields of symmetric esters were obtained in the case of n-alkyl and α-branched aliphatic aldehydes whereas reactivity of unsaturated aldehydes was found to be poor. Selected reactive intermediates were studied computationally at the (pBP)/DNPP level using the Spartan program. The results of computational studies indicate that in the case of the catechol-derived catalyst bidentate chelation of two aluminum atoms to an oxygen atom of aldehyde to form a structure '(O-Al)2O=CAld.' is less favorable than monodentate chelation to one aluminum atom activated by the other aluminum to form a structure 'O-Al-O-Al-O=CAld.'. The structure of this activated monodentate system clearly resembles more closely the transition state of the hydride-transfer step of the Tischtschenko reaction than the corresponding non-activated monodentate system 'O-Al'+'O-Al-O=CAld.'.
- Simpura, Ilkka,Nevalainen, Vesa
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- Ruthenium PNN(O) Complexes: Cooperative Reactivity and Application as Catalysts for Acceptorless Dehydrogenative Coupling Reactions
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The novel tridentate PNNOH pincer ligand LH features a reactive 2-hydroxypyridine functionality as well as a bipyridyl-methylphosphine skeleton for meridional coordination. This proton-responsive ligand coordinates in a straightforward manner to RuCl(CO)(H)(PPh3)3 to generate complex 1. The methoxy-protected analogue LMe was also coordinated to Ru(II) for comparison. Both species have been crystallographically characterized. Site-selective deprotonation of the 2-hydroxypyridine functionality to give 1′ was achieved using both mild (DBU) and strong bases (KOtBu and KHMDS), with no sign of involvement of the phosphinomethyl side arm that was previously established as the reactive fragment. Complex 1′ is catalytically active in the dehydrogenation of formic acid to generate CO-free hydrogen in three consecutive runs as well as for the dehydrogenative coupling of alcohols, giving high conversions to different esters and outperforming structurally related PNN ligands lacking the NOH fragment. DFT calculations suggest more favorable release of H2 through reversible reactivity of the hydroxypyridine functionality relative to the phosphinomethyl side arm.
- De Boer, Sandra Y.,Korstanje, Ties J.,La Rooij, Stefan R.,Kox, Rogier,Reek, Joost N. H.,Van Der Vlugt, Jarl Ivar
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- Microwave radiation can increase the rate of enzyme-catalysed reactions in organic media
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Irradiating a hydrated lipase enzyme suspended in organic media using microwaves (2.45 GHz, 50°C) enhanced the reaction rate by 2-3 fold over classical heating and the apparent non-thermal effects observed were dependent on the hydration state of the enzyme in the organic medium.
- Parker, Marie-Claire,Besson, Thierry,Lamare, Sylvain,Legoy, Marie-Dominique
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- Acceptorless dehydrogenative coupling of alcohols catalysed by ruthenium PNP complexes: Influence of catalyst structure and of hydrogen mass transfer
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Base-free catalytic acceptorless dehydrogenative homo-coupling of alcohols to esters under neat conditions was investigated using a combined organometallic synthesis and kinetic modelling approach. The considered bifunctional ruthenium aliphatic PNP complexes are very active, affording TONs up to 15,000. Notably, gas mass transfer issues were identified, which allowed us to rationalize previous observations. Indeed, the reaction kinetics are limited by the rate of transfer from the liquid phase to the gas phase of the hydrogen co-produced in the reaction. Mechanistically speaking, this relates to the interconverting couple amido monohydride/amino bishydride. Overcoming this by switching into the chemical regime leads to an initial turnover frequency increase from about 2000 up to 6100?h?1. This has a significant impact when considering assessment of novel or reported catalytic systems in this type of reaction, as overlooking of these engineering aspects can be misleading.
- Zhang, Lei,Raffa, Guillaume,Nguyen, Duc Hanh,Swesi, Youssef,Corbel-Demailly, Louis,Capet, Frédéric,Trivelli, Xavier,Desset, Simon,Paul, Sébastien,Paul, Jean-Fran?ois,Fongarland, Pascal,Dumeignil, Franck,Gauvin, Régis M.
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- Tuning acidity in zirconium-based metal organic frameworks catalysts for enhanced production of butyl butyrate
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Three isostructural zirconium-based metal organic frameworks (MOFs), UiO-66, UiO-66(COOH)2 and UiO-66(NH2) were synthesized, fully characterized and efficiently used as active and recyclable catalysts for the esterification reaction of butyric acid to produce a green fuel additive, butyl butyrate. The catalytic activities of the used structures were comparable, and mostly better, than other heterogeneous acid catalyst reported in the literature. Moreover, 90% conversion was achieved by employing the most acidic member, UiO-66(COOH)2, which is close to the 95% conversion obtained by the conventional liquid catalyst H2SO4. Using the synthesized MOFs, large variations in the conversion to butyl butyrate were obtained which was the base of a detailed investigation on the origin of their catalytic activities. The analysis of the TGA results helped estimate the number of structural defects in each studied MOF. Interestingly, it was concluded that, for the MOFs with different organic linkers, the catalytic activity was not directly related to the number of defects. Further analysis was done to investigate the alternative parameters that could be behind this difference in catalytic activity, and the parameters included but were not limited to the surface area of the MOFs, their particle size, the linkers’ active sites, and their accessibility through effective mass transfer. Although a combination of these factors were found to contribute to the superior catalytic activity of UiO-66(COOH)2, however, its exceptional conversion was mainly attributed to the effect of the additional active acid functional groups grafted onto its organic linker, along with its smaller particle size which allowed for better mass transfer and accessibility of the active site Furthermore, two kinetic models were successfully developed and used to determine the different kinetic parameters of the esterification reaction and to study their dependence on the different characteristics of the MOFs. With this knowledge, catalytic activity of MOFs can be engineered from a laboratory prototype and optimized by tuning the functional groups of the organic linkers to serve as effective catalysts for the production of fine chemicals such as biofuels.
- Jrad, Asmaa,Abu Tarboush, Belal J.,Hmadeh, Mohamad,Ahmad, Mohammad
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- Oxidation of ethers to esters by photo-irradiation with benzil and oxygen
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A novel method for the conversion of ethers to esters by photo-oxidation using benzil and molecular oxygen, and its plausible reaction mechanism participated by benzoylperoxy radical are described.
- Seto, Hideharu,Yoshida, Keigo,Yoshida, Shigeo,Shimizu, Takeshi,Seki, Hiroshi,Hoshino, Mikio
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- An antimony(V) substituted Keggin heteropolyacid, H4PSbMo 11O40: Why is its catalytic activity in oxidation reactions so different from that of H4PVMo11O 40?
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An antimony(V) containing α-Keggin type acidic polyoxometalate, H4PSbMo11O40, was prepared by reacting NaMoO4, H3PO4 and Sb2O3 in the presence of aqua regia to appraise its reactivity compared to the well known vanadate analog, H4PVMo11O40. Characterization was by X-ray diffraction, MALDI-TOF MS, IR, UV-vis and 31P NMR spectroscopy. Catalytic redox reactions, such as oxidative dehydrogenation using O2 and N2O as terminal oxidants were studied and showed very different reactivity of H4PSbMo 11O40 versus H4PVMo11O40. It was found by DFT calculations that in contrast to analogous H 4PVMo11O40 where vanadium centered catalysis is observed, in H4PSbMo11O40 catalysis is molybdenum and not antimony centered.
- Goldberg, Hila,Kumar, Devesh,Sastry, G. Narahari,Leitus, Gregory,Neumann, Ronny
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- Biobased n-Butanol Prepared from Poly-3-hydroxybutyrate: Optimization of the Reduction of n-Butyl Crotonate to n-Butanol
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Using metabolic engineering approaches, the biopolymer poly-3-hydroxybutyrate (P3HB) can be overproduced in organisms such as bacteria and plants. Thermolysis of P3HB, either in isolated form or within biomass, yields crotonic acid, a potential bioderived platform chemical. Reduction of crotonic acid provides n-butanol, which has value as a fuel and as a commodity chemical. Herein, we report optimization work on the hydrogenation of the n-butyl ester of crotonic acid to n-butanol and the potential of this chemistry to be incorporated into the production of bio-n-butanol from P3HB containing biomass.
- Schweitzer, Dirk,Mullen, Charles A.,Boateng, Akwasi A.,Snell, Kristi D.
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- Biocatalytic synthesis of new copolymers from 3-hydroxybutyric acid and a carbohydrate lactone
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Lipase-catalyzed reaction of 3-hydroxybutyric acid with d-glucono-δ-lactone at 5:1 molar ratio and 80°C yielded a mixture of moderate molecular weight linear and cyclic oligomers. The most efficient biocatalyst, Candida antarctica B lipase (Novozyme 435), allowed the synthesis of new oligomeric compounds with ring-opened gluconolactone units included in the oligomeric chain, without previous derivatization of the sugar, or activation of the acid monomer. The reaction medium nature had an important influence on the product composition. Although the main copolymer amount was synthesized in tert-butanol/dimethylsulfoxide medium, the highest polymerization degrees, up to 9 for the copolymer, and 10 for the 3-hydroxybutyric acid homopolymer co-product, were achieved in solventless conditions.
- Kakasi-Zsurka, Sandor,Todea, Anamaria,But, Andrada,Paul, Cristina,Boeriu, Carmen G.,Davidescu, Corneliu,Nagy, Lajos,Kuki, Akos,Keki, Sandor,Peter, Francisc
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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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- Efficient dimeric esterification of alcohols with NBS in water using l-proline as catalyst
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The L-proline-catalyzed oxidation of aliphatic primary alcohols with N-bromosuccimide (NBS) in water at room temperature to afford the corresponding dimeric esters in good to excellent yields was described. This pathway of dimeric esterification was proved to be very simple and environmentally friendly.
- Liu, Xiuhong,Wu, Jun,Shang, Zhicai
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- Buffer-mediated activation of Candida antarctica lipase B dissolved in hydroxyl-functionalized ionic liquids
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Ionic-liquid buffer having phosphate anion was synthesized for the development of buffered enzymatic ionic liquid systems. Both the conformation and transesterification activity of Candida antarctica lipase B (CALB) dissolved in the hydroxyl-functionalized ionic liquids were buffer dependent. Intrinsic fluorescence studies indicated that the CALB possessed a more compact conformation in the medium consisted of ionic liquid buffer having phosphate anion and hydroxyl-functionalized ionic liquids like 1-(1-hydroxyethyl)-3- methyl-imidazolium tetrafluoroborate and 1-(1-hydroxyethyl)-3-methyl-imidazolium nitrate. High activity and outstanding stability could be obtained with the CALB enzyme in the buffered ionic liquids for the transesterification.
- Ou, Guangnan,Yang, Jing,He, Biyan,Yuan, Youzhu
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- Cobalt-Catalyzed Acceptorless Dehydrogenative Coupling of Primary Alcohols to Esters
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A novel catalytic system with a tripodal cobalt complex is developed for efficiently converting primary alcohols to esters. KOtBu is found essential to the transformation. A preliminary mechanistic study suggests a plausible reaction route that involves an initial Co-catalyzed dehydrogenation of alcohol to aldehyde, followed by a Tishchenko-type pathway to ester mediated by KOtBu.
- Paudel, Keshav,Pandey, Bedraj,Xu, Shi,Taylor, Daniela K.,Tyer, David L.,Torres, Claudia Lopez,Gallagher, Sky,Kong, Lin,Ding, Keying
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- One-step solvent-free aerobic oxidation of aliphatic alcohols to esters using a tandem Sc-Ru?MOF catalyst
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Esters are an important class of chemicals in industry. Traditionally, ester production is a multi-step process involving the use of corrosive acids or acid derivatives (e.g. acid chloride, anhydride, etc.). Therefore, the development of a green synthetic protocol is highly desirable. This work reports the development of a metal-organic framework (MOF) supported tandem catalyst that can achieve direct alcohol to ester conversion (DAEC) using oxygen as the sole oxidizing agent under strictly solvent-free conditions. By incorporating Ru nanoparticles (NPs) along with a homogeneous Lewis acid catalyst, scandium triflate, into the nanocavities of a Zr MOF, MOF-808, the compound catalyst, Sc-Ru?MOF-808, can achieve aliphatic alcohol conversion up to 92% with ester selectivity up to 91%. A mechanistic study reveals a unique “via acetal” pathway in which the alcohol is first oxidized on Ru NPs and rapidly converted to an acetal on Sc(iii) sites. Then, the acetal slowly decomposes to release an aldehyde in a controlled manner for subsequent oxidation and esterification to the ester product. To the best of our knowledge, this is the first example of DAEC of aliphatic alcohols under solvent-free conditions with high conversion and ester selectivity.
- Feng, Tingkai,Li, Conger,Li, Tao,Zhang, Songwei
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p. 1474 - 1480
(2022/03/08)
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- Disproportionation of aliphatic and aromatic aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions
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Disproportionation of aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions often requires the application of high temperatures, equimolar or excess quantities of strong bases, and is mostly limited to the aldehydes with no CH2 or CH3 adjacent to the carbonyl group. Herein, we developed an efficient, mild, and multifunctional catalytic system consisting AlCl3/Et3N in CH2Cl2, that can selectively convert a wide range of not only aliphatic, but also aromatic aldehydes to the corresponding alcohols, acids, and dimerized esters at room temperature, and in high yields, without formation of the side products that are generally observed. We have also shown that higher AlCl3 content favors the reaction towards Cannizzaro reaction, yet lower content favors Tishchenko reaction. Moreover, the presence of hydride donor alcohols in the reaction mixture completely directs the reaction towards the Meerwein–Ponndorf–Verley reaction. Graphic abstract: [Figure not available: see fulltext.].
- Sharifi, Sina,Sharifi, Hannah,Koza, Darrell,Aminkhani, Ali
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p. 803 - 808
(2021/07/20)
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- Solvent-free oxidation of straight-chain aliphatic primary alcohols by polymer-grafted vanadium complexes
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Oxidovanadium(IV) complexes [VO(tertacac)2] (1), [VO(dipd)2] (2), and [VO(phbd)2] (3) were synthesized by reacting [VO(acac)2] with 2,2,6,6-tetramethyl-3,5-hepatanedione, 1,3-diphenyl-1,3-propanedione, and 1-phenyl-1,3-butanedione, respectively. Imidazole-modified Merrifield resin was used for the heterogenization of complexes 1–3. During the process of heterogenization, the V4+ center in complex 2 converts into V5+, whereas the other two complexes 1 and 3 remain in the oxidovanadium(IV) state in the polymer matrix. Theoretically, calculated IPA values of 1–3 suggest that 2 is prone to oxidation compared with 1 and 3, which was also supported by the absence of EPR lines in 5. Polymer-supported complexes Ps-Im-[VIVO(tertacac)2] (4), Ps-Im-[VVO2(dipd)2] (5), and Ps-Im-[VIVO(phbd)2] (6) were applied for the solvent-free heterogenous oxidation of a series of straight-chain aliphatic alcohols in the presence of H2O2 at 60°C and showed excellent substrate conversion specially for the alcohols with fewer carbon atoms. Higher reaction temperature improves the substrate conversion significantly for the alcohols containing more carbon atoms such as 1-pentanol, 1-hexanol, and 1-heptanol while using optimized reaction conditions. However, alcohols with fewer carbon atoms seem less affected by reaction temperatures higher than the optimized temperature. A decreasing trend in the selectivity(%) of carboxylic acid was observed with increasing carbon atoms among the examined alcohols, whereas the selectivity towards aldehydes increased. The order of efficiency of the supported catalysts is 4 > 6 > 5 in terms of turnover frequency (TOF) values and substrate conversion, further supported by theoretical calculations.
- Chaudhary, Nikita,Haldar, Chanchal,Kachhap, Payal
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- Dual utility of a single diphosphine-ruthenium complex: A precursor for new complexes and, a pre-catalyst for transfer-hydrogenation and Oppenauer oxidation
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The diphosphine-ruthenium complex, [Ru(dppbz)(CO)2Cl2] (dppbz = 1,2-bis(diphenylphosphino)benzene), where the two carbonyls are mutually cis and the two chlorides are trans, has been found to serve as an efficient precursor for the synthesis of new complexes. In [Ru(dppbz)(CO)2Cl2] one of the two carbonyls undergoes facile displacement by neutral monodentate ligands (L) to afford complexes of the type [Ru(dppbz)(CO)(L)Cl2] (L = acetonitrile, 4-picoline and dimethyl sulfoxide). Both the carbonyls in [Ru(dppbz)(CO)2Cl2] are displaced on reaction with another equivalent of dppbz to afford [Ru(dppbz)2Cl2]. The two carbonyls and the two chlorides in [Ru(dppbz)(CO)2Cl2] could be displaced together by chelating mono-anionic bidentate ligands, viz. anions derived from 8-hydroxyquinoline (Hq) and 2-picolinic acid (Hpic) via loss of a proton, to afford the mixed-tris complexes [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], respectively. The molecular structures of four selected complexes, viz. [Ru(dppbz)(CO)(dmso)Cl2], [Ru(dppbz)2Cl2], [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], have been determined by X-ray crystallography. In dichloromethane solution, all the complexes show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry on the complexes shows redox responses within 0.71 to -1.24 V vs. SCE. [Ru(dppbz)(CO)2Cl2] has been found to serve as an excellent pre-catalyst for catalytic transfer-hydrogenation and Oppenauer oxidation.
- Mukherjee, Aparajita,Bhattacharya, Samaresh
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p. 15617 - 15631
(2021/05/19)
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- Isonitrile ruthenium and iron PNP complexes: synthesis, characterization and catalytic assessment for base-free dehydrogenative coupling of alcohols
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Neutral and ionic ruthenium and iron aliphatic PNHP-type pincer complexes (PNHP = NH(CH2CH2PiPr2)2) bearing benzyl,n-butyl ortert-butyl isocyanide ancillary ligands have been prepared and characterized. Reaction of [RuCl2(PNHP)]2with one equivalent CN-R per ruthenium center affords complexes [RuCl2(PNHP)(CNR)] (R = benzyl,1a, R =n-butyl,1b, R =t-butyl,1c), with cationic [RuCl(PNHP)(CNR)2]Cl2a-cas side-products. Dichloride species1a-creact with excess NaBH4to afford [RuH(PNHP)(BH4)(CN-R)]3a-c, analogues to benchmark Takasago catalyst [RuH(PNHP)(BH4)(CO)]. Reaction of1a-cwith a single equivalent of NaBH4results in formation of [RuHCl(PNHP) (CN-R)] (4a-c), from which3a-ccan be prepared upon reaction with excess NaBH4. Use of one equivalent of NaHBEt3with4aand4caffords bishydrides [Ru(H)2(PNHP)(CN-R)]5aand5c. Deprotonation of4cby KOtBu generates amido derivative [RuH(PNP)(CN-t-Bu)] (6, PNP =?N(CH2CH2PiPr2)2), unstable in solution. Addition of excess benzylisonitrile to4aprovides cationic hydride [RuH(PNHP) (CN-CH2Ph)2]Cl (7). Concerning iron chemistry, [Fe(PNHP)Br2] reacts with one equivalent of benzylisonitrile to afford [FeBr(PNHP)(CNCH2Ph)2]Br (8). The outer-sphere bromide anion can be exchanged by salt metathesis with NaBPh4to generate [FeBr(PNHP) (CNCH2Ph)2](BPh4) (9). Cationic hydride species [FeH(PNHP) (CN-t-Bu)2](BH4) (10) is prepared from consecutive addition of excess CN-t-Bu and NaBH4on [Fe(PNPH)Br2]. Ruthenium complexes3a-care active in acceptorless alcohol dehydrogenative coupling into ester under base-free conditions. From kinetic follow-up, the trend in initial activity is3a≈3b> [RuH(PNHP)(BH4)(CO)] ?3c; for robustness, [RuH(BH4)(CO)(PNHP)] >3a>3b?3c. Hypotheses are given to account for the observed deactivation. Complexes3b,3c,4a,4c,5c,7,cis-8and9were characterized by X-ray crystallography.
- Nguyen, Duc Hanh,Merel, Delphine,Merle, Nicolas,Trivelli, Xavier,Capet, Frédéric,Gauvin, Régis M.
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p. 10067 - 10081
(2021/08/03)
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- Zr-MOF-808 as Catalyst for Amide Esterification
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In this work, zirconium-based metal–organic framework Zr-MOF-808-P has been found to be an efficient and versatile catalyst for amide esterification. Comparing with previously reported homogeneous and heterogeneous catalysts, Zr-MOF-808-P can promote the reaction for a wide range of primary, secondary and tertiary amides with n-butanol as nucleophilic agent. Different alcohols have been employed in amide esterification with quantitative yields. Moreover, the catalyst acts as a heterogeneous catalyst and could be reused for at least five consecutive cycles. The amide esterification mechanism has been studied on the Zr-MOF-808 at molecular level by in situ FTIR spectroscopic technique and kinetic study.
- Villoria-del-álamo, Beatriz,Rojas-Buzo, Sergio,García-García, Pilar,Corma, Avelino
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supporting information
p. 4588 - 4598
(2020/12/25)
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- IrIII-Catalyzed direct syntheses of amides and esters using nitriles as acid equivalents: A photochemical pathway
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An unprecedented IrIII[df(CF3)ppy]2(dtbbpy)PF6-catalyzed simple photochemical process for direct addition of amines and alcohols to the relatively less reactive nitrile triple bond is described herein. Various amides and esters are synthesized as the reaction products, with nitriles being the acid equivalents. A mini-library of different types of amides and esters is made using this mild and efficient process, which uses only 1 mol% of photocatalyst under visible light irradiation (λ = 445 nm). The reaction strategy is also efficient for gram-scale synthesis.
- Talukdar, Ranadeep
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supporting information
p. 5303 - 5308
(2020/04/17)
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- A robust NNP-type ruthenium (II) complex for alcohols dehydrogenation to esters and pyrroles
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A Ru (II) complex bearing pyridyl-based benzimidazole-phosphine tridentate NNP ligand was synthesized and structurally characterized by NMR, IR. The complex can efficiently and selectively catalyze the acceptorless dehydrogenation of primary alcohols to esters under relatively mild conditions and the synthesis of pyrroles by means of the reactions of secondary alcohols and β-amino alcohols through acceptorless deoxygenation condensation.
- Chai, Huining,Zhang, Guangyao,Tan, Weiqiang,Ma, Jiping
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- Predicting a Sharp Decline in Selectivity for Catalytic Esterification of Alcohols from van der Waals Interactions
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Controlling the selectivity of catalytic reactions is a critical aspect of improving energy efficiency in the chemical industry; thus, predictive models are of key importance. Herein the performance of a heterogeneous, nanoporous Au catalyst is predicted for the complex catalytic self-coupling of the series of C2–C4 alkyl alcohols, based solely on the known kinetics of the elementary steps of the catalytic cycle for methanol coupling, using scaling methods augmented by density functional theory. Notably, a sharp decrease in selectivity for ester formation with increasing molecular weight to favor the aldehyde due to van der Waals interactions of reaction intermediates with the surface was predicted and subsequently verified quantitatively by experiment. Further, the agreement between theory and experiment clearly demonstrates the efficacy of this approach for building a predictive model of catalytic behavior for a homologous set of reactants using a small set of experimental information.
- Friend, Cynthia M.,Luneau, Mathilde,Madix, Robert J.,Reece, Christian
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supporting information
p. 10864 - 10867
(2020/05/08)
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- Metal complex catalysts and method for catalytically reducing carboxylic acids
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The invention relates to a metal complex catalyst, which contains at least one of metal complexes with a chemical formula comprising a structural unit represented by a formula I. According to the invention, the center metal of the metal complex catalyst is iridium, and the metal complex catalyst is composed of pentamethylcyclopentadienyl, a bitetrahydropyrimidine ligand and proper coordination anions; the metal complex catalyst has activity on a carboxylic acid reduction reaction, and a carboxylic acid compound is reduced into an alcohol compound in the presence of hydrogen; and the method ismild in reaction condition, can be carried out at room temperature, and is good in catalytic performance and high in reduction product yield.
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Paragraph 0085-0144; 0147; 0148; 0167; 0168; 0178-0179
(2020/06/20)
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- Development and Validation of a Novel Free Fatty Acid Butyl Ester Gas Chromatography Method for the Determination of Free Fatty Acids in Dairy Products
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Accurate quantification of free fatty acids in dairy products is important for both product quality control and legislative purposes. In this study, a novel fatty acid butyl ester method was developed, where extracted free fatty acids are converted to butyl esters prior to gas chromatography with flame ionization detection. The method was comprehensively validated to establish linearity (20-700 mg/L; R2 > 0.9964), limits of detection (5-8 mg/L), limits of quantification (15-20 mg/L), accuracy (1.6-5.4% relative error), interday precision (4.4-5.3% relative standard deviation), and intraday precision (0.9-5.6% relative standard deviation) for each individual free fatty acid. A total of 17 dairy samples were analyzed, covering diverse sample matrices, fat content, and degrees of lipolysis. The method was compared to direct on-column injection and fatty acid methyl ester methods and overcomes limitations associated with these methods, such as either column-phase absorption or deterioration, accurate quantification of short-chain free fatty acids, and underestimation of polyunsaturated free fatty acid.
- Mannion, David T.,Furey, Ambrose,Kilcawley, Kieran N.
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p. 499 - 506
(2019/01/08)
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- Amorphous SiO2 catalyst for vapor-phase aldol condensation of butanal
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Vapor-phase aldol condensation of butanal to form 2-ethyl-2-hexenal was carried out over several oxide catalysts such as SiO2-Al2O3, Al2O3, ZrO2, and SiO2. Catalysts with moderate and strong acid sites such as Al2O3 and SiO2-Al2O3 were active for the reaction in the initial period, whereas they deactivated rapidly. In contrast, SiO2 with weak acidity showed a low but a stable catalytic activity for the formation of 2-ethyl-2-hexenal. Thermogravimetric analyses of the samples used after the reactions indicate that SiO2 has the smallest amount of carbonaceous species that contributed to its stable activity among the tested catalysts. SiO2 catalysts with different pore sizes and specific surface areas were examined: SiO2 with a mean pore diameter of 10 nm and a surface area of 295 m2 g?1 showed the best catalytic performance and gave a 2-ethyl-2-hexenal selectivity of 90% at a conversion of 48% at 240 °C. In the catalytic test using deuterated SiO2, which was prepared by contacting SiO2 with deuterated water before the reaction, it was confirmed by a mass spectrometer that the deuterium atom of SiOD was transferred to a 2-ethyl-2-hexenal molecule during the reaction. It is indicated that silanol groups on the SiO2 surface played a role as an active site.
- Sun, Daolai,Yamada, Yasuhiro,Sato, Satoshi
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p. 113 - 119
(2018/11/25)
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- Aldehyde effect and ligand discovery in Ru-catalyzed dehydrogenative cross-coupling of alcohols to esters
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The presence of different aldehydes is found to have a significant influence on the catalytic performance when using PN(H)P type ligands for dehydrogenation of alcohols. Accordingly, hybrid multi-dentate ligands were discovered based on an oxygen-transfer alkylation of PNP ligands by aldehydes. The relevant Ru-PNN(PO) system provided the desired unsymmetrical esters in good yields via acceptorless dehydrogenation of alcohols. Hydrogen bonding interactions between the phosphine oxide moieties and alcohol substrates likely assisted the observed high chemoselectivity.
- Jiang, Xiaolin,Zhang, Jiahui,Zhao, Dongmei,Li, Yuehui
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supporting information
p. 2797 - 2800
(2019/03/27)
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- Silica-Supported MnII Sites as Efficient Catalysts for Carbonyl Hydroboration, Hydrosilylation, and Transesterification
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Manganese, the third most abundant transition-metal element after iron and titanium, has recently been demonstrated to be an effective homogeneous catalyst in numerous reactions. Herein, the preparation of silica-supported MnII sites is reported using Surface Organometallic Chemistry (SOMC), combined with tailored thermolytic molecular precursors approach based on Mn2[OSi(OtBu)3]4 and Mn{N(SiMe3)2}2?THF. These supported MnII sites, free of organic ligands, efficiently catalyze numerous reactions: hydroboration and hydrosilylation of ketones and aldehydes as well as the transesterification of industrially relevant substrates.
- Ghaffari, Behnaz,Mendes-Burak, Jorge,Chan, Ka Wing,Copéret, Christophe
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supporting information
p. 13869 - 13873
(2019/11/11)
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- PHENANTHROLINE BASED PINCER COMPLEXES USEFUL AS CATALYSTS FOR THE PREPARATION OF METHANOL FROM CARBONDIOXIDE
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The present invention relates to a novel phenonthroline based pincer complexes and process for preparation thereof. The present invention also provides a one pot process for the conversion of carbon dioxide to methanol in the presence of a molecularly defined pincer-type single-site Ru-catalyst and secondary amine. Further the present invention provides the use of phenonthroline based pincer complexes for the esterification of alcohols and hydrogenation of esters under mild conditions.
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Paragraph 0135
(2018/04/02)
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- Cross-Dehydrogenating Coupling of Aldehydes with Amines/R-OTBS Ethers by Visible-Light Photoredox Catalysis: Synthesis of Amides, Esters, and Ureas
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A straightforward synthesis of amides, ureas, and esters is reported by visible-light cross-dehydrogenating coupling (CDC) of aldehydes (or amine carbaldehydes) and amines/R-OTBS ethers by photoredox catalysis. The reaction is found to be general and high yielding. A plausible mechanistic pathway has been proposed for these transformations and is supported by appropriate controlled experiments.
- Pandey, Ganesh,Koley, Suvajit,Talukdar, Ranadeep,Sahani, Pramod Kumar
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supporting information
p. 5861 - 5865
(2018/09/21)
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- Oxidative esterification of primary alcohols at room temperature under aqueous medium
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Oxidative esterification of aliphatic primary alcohols with bromide and bromate couple in aqueous acidic medium at room temperature is reported with a wide range of substrate scope for both aliphatic and cyclic alcohols and obtained excellent yields of products.
- Reddy, N. Naresh Kumar,Ravi, Chitrakar,Adimurthy, Subbarayappa
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p. 1663 - 1670
(2018/06/15)
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- Alkane oxidation catalysed by a self-folded multi-iron complex
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A preorganised ligand scaffold is capable of coordinating multiple Fe(II) centres to form an electrophilic CH oxidation catalyst. This catalyst oxidises unactivated hydrocarbons including simple, linear alkanes under mild conditions in good yields with selectivity for the oxidation of secondary CH bonds. Control complexes containing a single metal centre are incapable of oxidising unstrained linear hydrocarbons, indicating that participation of multiple centres aids the CH oxidation of challenging substrates.
- Mettry, Magi,Moehlig, Melissa Padilla,Gill, Adam D.,Hooley, Richard J.
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p. 120 - 128
(2016/11/09)
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- Rethinking the Claisen–Tishchenko Reaction
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Pincer-type complexes [OsH2(CO){PyCH2NHCH2CH2NHPtBu2}] and [OsH2(CO){HN(CH2CH2PiPr2)2}] catalyze the disproportionation reaction of aldehydes via an outer-sphere bifunctional mechanism achieving turnover frequencies up to 14 000 h?1. The N?H group of the catalysts is a key player in this process, elucidated with the help of DFT calculations.
- Morris, Stacey A.,Gusev, Dmitry G.
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supporting information
p. 6228 - 6231
(2017/05/19)
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- ABE Condensation over Monometallic Catalysts: Catalyst Characterization and Kinetics
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Herein, we present work on the catalyst development and the kinetics of acetone-butanol-ethanol (ABE) condensation. After examining multiple combinations of metal and basic catalysts reported in the literature, Cu supported on calcined hydrotalcites (HT) was found to be the optimal catalyst for the ABE condensation. This catalyst gave a six-fold increase in reaction rates over previously reported catalysts. Kinetic analysis of the reaction over CuHT and HT revealed that the rate-determining step is the C?H bond activation of alkoxides that are formed from alcohols on the Cu surface. This step is followed by the addition of the resulting aldehydes to an acetone enolate formed by deprotonation of the acetone over basic sites on the HT surface. The presence of alcohols reduces aldol condensation rates, as a result of the coverage of catalytic sites by alkoxides.
- Goulas, Konstantinos A.,Gunbas, Gorkem,Dietrich, Paul J.,Sreekumar, Sanil,Grippo, Adam,Chen, Justin P.,Gokhale, Amit A.,Toste, F. Dean
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p. 677 - 684
(2017/02/26)
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- A TEMPO-like nitroxide combined with an alkyl-substituted pyridine: An efficient catalytic system for the selective oxidation of alcohols with iodine
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An efficient method for the oxidation of alcohols to aldehydes or ketones in a two-phase CH2Cl2/NaHCO3 (aq.) system, using iodine and catalytic amounts of 4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxyl and 2,4,6-trimethylpyridine, was developed. The performance of the method was demonstrated by the selective oxidation of 37 variously substituted alcohols in ≥90% yield, including the gram-scale synthesis of the important chemical 2,5-diformylfuran from biomass-derived 5-hydroxylmethylfurfural.
- Kashparova, Vera P.,Klushin, Victor A.,Zhukova, Irina Yu.,Kashparov, Igor S.,Chernysheva, Daria V.,Il'chibaeva, Irina B.,Smirnova, Nina V.,Kagan, Efim Sh.,Chernyshev, Victor M.
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supporting information
p. 3517 - 3521
(2017/10/05)
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- Oxidative Transformations of Biosourced Alcohols Catalyzed by Earth-Abundant Transition Metals
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The catalytic acceptorless dehydrogenative oxidation of biosourced alcohols into carboxylic acid salts was achieved using earth-abundant Fe and Mn complexes that feature aliphatic PNP pincer ligands in good to excellent yields. The Fe derivatives were characterized by using 57Fe NMR spectroscopy. Mn pincer catalysts are catalytically more efficient than their Fe counterparts thanks to their robustness under basic conditions. Attempts to generate aldehydes from alcohols were not successful using the Fe and Mn species, but a commercially available Ru analogue achieves this transformation selectively under very mild conditions in the presence of a large excess of acetone as a hydrogen acceptor.
- Nguyen, Duc Hanh,Morin, Yohann,Zhang, Lei,Trivelli, Xavier,Capet, Frédéric,Paul, Sébastien,Desset, Simon,Dumeignil, Franck,Gauvin, Régis M.
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p. 2652 - 2660
(2017/07/28)
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- OZONE-ACTIVATED NANOPOROUS GOLD AND METHODS OF ITS USE
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The invention relates to nanoporous gold nanoparticle catalysts formed by exposure of nanoporous gold to ozone at elevated temperatures, as well as methods for production of esters and other compounds.
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-
Paragraph 21; 22; 23
(2018/01/17)
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- Manganese Pincer Complexes for the Base-Free, Acceptorless Dehydrogenative Coupling of Alcohols to Esters: Development, Scope, and Understanding
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Aliphatic PNP pincer-supported earth-abundant manganese(I) dicarbonyl complexes behave as effective catalysts for the acceptorless dehydrogenative coupling of a wide range of alcohols to esters under base-free conditions. The reaction proceeds under neat conditions, with modest catalyst loading and releasing only H2 as byproduct. Mechanistic aspects were addressed by synthesizing key species related to the catalytic cycle (characterized by X-ray structure determination, multinuclear (1H, 13C, 31P, 15N, 55Mn) NMR, infrared spectroscopy, inter alia), by studying elementary steps connected to the postulated mechanism, and by resorting to DFT calculations. As in the case of related ruthenium and iron PNP catalysts, the dehydrogenation results from cycling between the amido and amino-hydride forms of the PNP-Mn(CO)2 scaffold. For the dehydrogenation of alcohols into aldehydes, our results suggest that the highest energy barrier corresponds to the hydrogen release from the amino-hydride form, although its value is close to that of the outer-sphere dehydrogenation of the alcohol into aldehyde. This contrasts with the ruthenium and iron catalytic systems, where dehydrogenation of the substrate into aldehyde is less energy-demanding compared to hydrogen release from the cooperative metal-ligand framework.
- Nguyen, Duc Hanh,Trivelli, Xavier,Capet, Frédéric,Paul, Jean-Fran?ois,Dumeignil, Franck,Gauvin, Régis M.
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p. 2022 - 2032
(2017/08/14)
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- MANGANESE BASED COMPLEXES AND USES THEREOF FOR HOMOGENEOUS CATALYSIS
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The present invention relates to novel manganese complexes and their use, inter alia, for homogeneous catalysis in (1) the preparation of imine by dehydrogenative coupling of an alcohol and amine; (2) C-C coupling in Michael addition reaction using nitriles as Michael donors; (3) dehydrogenative coupling of alcohols to give esters and hydrogen gas (4) hydrogenation of esters to form alcohols (including hydrogenation of cyclic esters (lactones) or cyclic di-esters (di- lactones), or polyesters); (5) hydrogenation of amides (including cyclic dipeptides, lactams, diamide, polypeptides and polyamides) to alcohols and amines (or diamine); (6) hydrogenation of organic carbonates (including polycarbonates) to alcohols or hydrogenation of carbamates (including polycarbamates) or urea derivatives to alcohols and amines; (7) dehydrogenation of secondary alcohols to ketones; (8) amidation of esters (i.e., synthesis of amides from esters and amines); (9) acylation of alcohols using esters; (10) coupling of alcohols with water and a base to form carboxylic acids; and (11) preparation of amino acids or their salts by coupling of amino alcohols with water and a base. (12) preparation of amides (including formamides, cyclic dipeptides, diamide, lactams, polypeptides and polyamides) by dehydrogenative coupling of alcohols and amines; (13) preparation of imides from diols.
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Paragraph 00352-00353
(2017/09/05)
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- 2,2,5,5-Tetramethyltetrahydrofuran (TMTHF): A non-polar, non-peroxide forming ether replacement for hazardous hydrocarbon solvents
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An inherently non-peroxide forming ether solvent, 2,2,5,5-tetramethyltetrahydrofuran (2,2,5,5-tetramethyloxolane), has been synthesized from readily available and potentially renewable feedstocks, and its solvation properties have been tested. Unlike traditional ethers, its absence of a proton at the alpha-position to the oxygen of the ether eliminates the potential to form hazardous peroxides. Additionally, this unusual structure leads to lower basicity compared with many traditional ethers, due to the concealment of the ethereal oxygen by four bulky methyl groups at the alpha-position. As such, this molecule exhibits similar solvent properties to common hydrocarbon solvents, particularly toluene. Its solvent properties have been proved by testing its performance in Fischer esterification, amidation and Grignard reactions. TMTHF's differences from traditional ethers is further demonstrated by its ability to produce high molecular weight radical-initiated polymers for use as pressure-sensitive adhesives.
- Byrne, Fergal,Forier, Bart,Bossaert, Greet,Hoebers, Charly,Farmer, Thomas J.,Clark, James H.,Hunt, Andrew J.
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supporting information
p. 3671 - 3678
(2017/08/15)
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- Dehydrogenation properties of ZnO and the impact of gold nanoparticles on the process
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The article presents the results of catalytic and surface properties of pure zinc oxide synthesized by hydrothermal method and surface-doped with gold nanoparticles. As a test reaction, the catalytic transformation of n-butyl alcohol towards the dehydrogenation or bimolecular condensation of symmetric ketone or an ester was studied. The tested materials catalyse both consecutive reactions, wherein the transformation towards the ketone is dependent on the presence of surface oxygen vacancies, whose concentration depends on the temperature. In turn, the transformation to the ester occurs in the presence of gold nanoparticles deposited on the surface of zinc oxide. The difference in work function of electrons from these materials create a change in the electron concentration in the surface area and will shift the balance of the coupling reaction of hydrogen with lattice oxygen, which prefers the formation of aldehyde and ester. The results were compared with the catalytic properties of other previously studied oxide systems in this group of changes. This analysis enabled the development of the mechanism of transformation and explanation of the impact of gold on the kinetics of the process.
- Suchorska-Wo?niak, Patrycja,Rac, Olga,Klimkiewicz, Roman,Fiedot, Marta,Teterycz, Helena
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p. 135 - 145
(2016/01/29)
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- Synthesis of butyrate using a heterogeneous catalyst based on polyvinylpolypyrrolidone
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A heterogeneous polyvinylpolypyrrolidone supported Br?nsted acidic catalyst ([PVPP-BS]HSO4) was used to synthesize butyrate in this paper. The prepared catalysts were characterized by FT-IR, TG, and FESEM and their catalytic activity in butyric acid esterification with benzyl alcohol was investigated. The influencing factors such as the amount of catalyst, reaction temperature, and reaction time were carefully studied. Under the optimized condition with the butyric acid to benzyl alcohol mole ratio of 1 : 1.2 and the reaction temperature of 130°C, the yield of benzyl butyrate reached 96.8 % within 4 h in the presence of 8 mass % of catalyst. Moreover, the catalyst could be reused six times without noticeable drop in activity. This catalyst was also used to synthesize other kinds of butyrates achieving the butyrate yield above 90 %.
- Wang, Song,Chang, Qian-Qian,Shawgi, Nazar,Li, San-Xi,Zhang, Lin-Nan
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p. 538 - 544
(2016/03/05)
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- The selective oxidation of: N -butanol to butyraldehyde by oxygen using stable Pt-based nanoparticulate catalysts: An efficient route for upgrading aqueous biobutanol
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Supported Pt nanoparticles are shown to be active and selective towards butyraldehyde in the base-free oxidation of n-butanol by O2 in an aqueous phase. The formation of butyric acid as a by-product promoted the leaching of Pt and consequently the activity of the catalysts decreased upon reuse. Characterisation showed that the degree to which Pt leached from the catalysts was related to both the metal-support interaction and metal particle size. A catalyst active and stable (1% metal leaching) in the aqueous reaction medium was obtained when Pt nanoparticles were supported on activated carbon and prepared by a chemical vapour impregnation method. The presence of n-butanol in the aqueous medium is required to inhibit the over oxidation of butyraldehyde to butyric acid. Consequently, high selectivities towards butyraldehyde can only be obtained at intermediate n-butanol conversion.
- Gandarias, Inaki,Nowicka, Ewa,May, Blake J.,Alghareed, Shaimaa,Armstrong, Robert D.,Miedziak, Peter J.,Taylor, Stuart H.
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p. 4201 - 4209
(2016/07/06)
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- Ionization basis for activation of enzymes soluble in ionic liquids
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Background: The complex interactions between electrolytes and proteins have been studied for more than a century. However, understanding is not yet complete and does not provide a basis for predicting the activity of enzymes in ionic media. The use of ionic liquids (ILs) as reaction medium has opened up new opportunities for better understanding of the mechanism of enzymatic catalysis. Although a number of properties of ILs have been correlated with enzyme function, these relationships are not completely understood at a molecular level. Methods: We propose that ILs must be able to promote ionization of protein ionizable groups in order to dissolve active enzymes. The biocompatible IL need to possess a functional group with large donor number and acceptor number in both cationic and anionic units, each of which is based on a high dielectric constant lead structure. We designed and synthesized two series of ILs and determined their ionizing-dissociating abilities and activities of lipases soluble in these new ILs. Results: The results showed that the ionizing-dissociating abilities of ILs paralleled the catalytic activity trend of lipases dissolved in the ILs. The activities of lipases soluble in the newly designed ILs were comparable to those in water. Conclusions: We can conclude that ionizing-dissociating abilities of an IL can be used as a basis for predicting the activity of enzymes soluble in the IL. General significance Ionization basis for activation of enzymes gives a deeper understanding of the behavior of enzymes in non-aqueous media at a molecular level.
- Ou, Guangnan,He, Biyan,Halling, Peter
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p. 1404 - 1408
(2016/04/20)
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- DEHYDROGENATION CATALYST, AND CARBONYL COMPOUND AND HYDROGEN PRODUCTION METHOD USING SAID CATALYST
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Objects of the present invention are to provide a novel dehydrogenation reaction catalyst, to provide a method that can produce a ketone, an aldehyde, and a carboxylic acid with high efficiency from an alcohol, and to provide a method for efficiently producing hydrogen from an alcohol, formic acid, or a formate, and they are accomplished by a catalyst containing an organometallic compound of Formula (1).
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Paragraph 0176
(2016/10/31)
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- Oxidative dimerization of alcohols in the presence of nitroxyl radical–iodine catalytic system
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Pyridine catalyzes oxidation of alcohols with 4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxyl–iodine catalytic system at room temperature. Symmetric esters are formed in good yields.
- Kashparova,Kashparov,Zhukova, I. Yu.,Astakhov,Ilchibaeva,Kagan, E. Sh.
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p. 2423 - 2426
(2016/12/24)
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- Dicopper Complexes with Anthyridine-Based Ligands: Coordination and Catalytic Activity
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Two new anthyridine-based ligands, 5-phenyl-2,8-bis(2-pyridinyl)-1,9,10-anthyridine (L3) and 5-phenyl-2,8-bis(6′-bipyridinyl)-1,9,10-anthyridine (L4), were designed for accommodation of dimetallic systems with the metal ions separated by 5 ?. Complexation of Cu(ClO4)2 with L3 and L4 provided the corresponding dicopper complexes [{Cu2(L3)(H2O)4(CH3CN)2}(ClO4)4] (3) and [{Cu2(L4)(μ-ClO4)2}(PF6)2] (4), respectively. Both complexes were characterized by spectroscopic methods, and the detail structural features were further confirmed by X-ray crystallography. Structural analyses of 3 and 4 reveal the Cu···Cu distances in the complexes being 4.9612(7) and 5.013 (2) ?, respectively. Both complexes are active in the catalytic oxidation of benzyl alcohols into the corresponding aldehydes. Furthermore, complex 4 appears to be a good catalyst for the oxidative coupling of primary alcohols into the corresponding esters with the use of hydrogen peroxide as the oxidant in an aqueous medium. The possible cooperative interactions between the metal ions during the catalysis are discussed.
- Huang, Da-Wei,Liu, Yi-Hung,Peng, Shie-Ming,Liu, Shiuh-Tzung
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p. 151 - 158
(2016/02/05)
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- Method For Synthesising Esters
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A method for synthesising a second ester from a first ester, the method including the following steps: a) placing a first ester and a catalyst in the presence of dihydrogen such as to obtain a first alcohol and a second alcohol; b) extracting the second alcohol from the reaction medium; c) reacting the first alcohol with the catalyst of step a) in order to obtain a second ester and dihydrogen; and d) recirculating the dihydrogen obtained in step c) by injecting same into step a).
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Paragraph 0078; 0081
(2016/10/27)
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- Method for preparing aliphatic (cycloaliphatic) ester compound
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The invention relates to a mild-condition method for preparing an aliphatic (cycloaliphatic) ester compound, particularly preparation of an alkyl cyclohexanecarboxylate compound. The ester compound can serve as an environment-friendly plasticizer in plastics, so that the occurrence of side reactions such as polymerization, etherification and the like of aliphatic alcohol compounds in the existing esterification processes under high-temperature conditions is avoided. The method comprises the specific reaction steps: (a) preparing aliphatic chloro-formate in a reaction rectification tower in the absence of a catalyst/solvent; and (b) catalyzing an aliphatic (cycloaliphatic) Grignard reagent to react with the aliphatic chloro-formate by a metal manganese compound, so as to produce the ester compound.
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Paragraph 0050; 0051
(2017/01/02)
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- Direct hydrogenation of biobased carboxylic acids mediated by a nitrogen-centered tridentate phosphine ligand
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A novel nitrogen-centered tridentate ligand was identified from a series of multidentate ligands and applied for the direct hydrogenation of 9 biogenic acids into alcohols, lactones and esters with high yields. Comparison of substrates and ruthenium precursors suggested that the RuII hydride cationic species was more active to transform acids than the corresponding lactone or esters.
- Deng, Li,Kang, Bin,Englert, Ulli,Klankermayer, Jürgen,Palkovits, Regina
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p. 177 - 180
(2016/02/05)
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- Selective oxidation of n-butanol using gold-palladium supported nanoparticles under base-free conditions
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The base-free selective catalytic oxidation of n-butanol by O2 in an aqueous phase has been studied using Au-Pd bimetallic nanoparticles supported on titania. Au-Pd/TiO2 catalysts were prepared by different methods: wet impregnation, physical mixing, deposition-precipitation and sol immobilisation. The sol immobilisation technique, which used polyvinyl alcohol (PVA) as the stabilizing agent, gave the catalyst with the smallest average particle size and the highest stable activity and selectivity towards butyric acid. Increasing the amount of PVA resulted in a decrease in the size of the nanoparticles. However, it also reduced activity by limiting the accessibility of reactants to the active sites. Heating the catalyst to reflux with water at 90°C for 1 h was the best method to enhance the surface exposure of the nanoparticles without affecting their size, as determined by TEM, X-ray photoelectron spectroscopy and CO chemisorption analysis. This catalyst was not only active and selective towards butyric acid but was also stable under the operating conditions.
- Gandarias, Inaki,Miedziak, Peter J.,Nowicka, Ewa,Douthwaite, Mark,Morgan, David J.,Hutchings, Graham J.,Taylor, Stuart H.
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p. 473 - 480
(2015/03/04)
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- Primary alkanols: oxidative homocondensation in water and cross-condensation in methanol
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Water was used as a reaction medium and a reagent in oxidation of primary alkanols to dimeric esters and alkanoic acids using either molecular bromine or a hydrogen peroxide—hydrobromic acid mixture as the oxidants. The similar reaction in methanol produced methyl alkanoates.
- Nikishin,Sokova,Terent′ev,Kapustina
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p. 2845 - 2850
(2016/09/28)
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- Ozone-activated nanoporous gold: A stable and storable material for catalytic oxidation
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We report a new method for facile and reproducible activation of nanoporous gold (npAu) materials of different forms for the catalytic selective partial oxidation of alcohols under ambient pressure, steady flow conditions. This method, based on the surface cleaning of npAu ingots with ozone to remove carbon documented in ultrahigh vacuum conditions, produces active npAu catalysts from ingots, foils, and shells by flowing an ozone/dioxygen mixture over the catalyst at 150 °C, followed by a temperature ramp from 50 to 150 °C in a flowing stream of 10% methanol and 20% oxygen. With this treatment, all three materials (ingots, foils, and shells) can be reproducibly activated, despite potential carbonaceous poisons resulting from their synthesis, and are highly active for the selective oxidation of primary alcohols over prolonged periods of time. The npAu materials activated in this manner exhibit catalytic behavior substantially different from those activated under different conditions previously reported. Once activated in this manner, they can be stored and easily reactivated by flow of reactant gases at 150 °C for a few hours. They possess improved selectivity for the coupling of higher alcohols, such as 1-butanol, and are not active for carbon monoxide oxidation. This ozone-treated npAu is a functionally new catalytic material.
- Personick, Michelle L.,Zugic, Branko,Biener, Monika M.,Biener, Juergen,Madix, Robert J.,Friend, Cynthia M.
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p. 4237 - 4241
(2015/11/11)
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