- The first Negishi cross-coupling reaction of two alkyl centers utilizing a Pd-N-heterocyclic carbene (NHC) catalyst
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(Chemical Equation Presented) The development of an NHC-based system capable of cross-coupling sp3-sp3 centers in high yield has been a long-standing challenge. This communication describes the use of a Pd-NHC catalytic system that achieves room-temperature Negishi cross-couplings of unactivated, primary bromides and alkyl organozinc reagents with a variety of functionality.
- Hadei, Niloufar,Kantchev, Eric Assen B.,O'Brien, Christopher J.,Organ, Michael G.
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- A convenient approach to enantioenriched cyclopropanes bearing electron-withdrawing functionalities
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1,2-Disubstituted cyclopropanes with different electron-withdrawing groups were accessed stereospecifically from similarly functionalized γ-hydroxy-α,β-unsaturated compounds. Georg Thieme Verlag Stuttgart.
- Krawczyk, Henryk,Wasek, Katarzyna,Kedzia, Jacek
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- Improving Catalyst Activity in Hydrocarbon Functionalization by Remote Pyrene–Graphene Stacking
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A copper complex bearing an N-heterocyclic carbene ligand with a pyrene “tail” attached to the backbone has been prepared and supported on reduced graphene oxide (rGO). The free and supported copper materials have been employed as homogeneous and heterogeneous catalysts in the functionalization of hydrocarbons such as n-hexane, cyclohexane, and benzene through incorporation of the CHCO2Et unit from ethyl diazoacetate. The graphene-anchored complex displays higher reaction rates and induces higher yields than its soluble counterpart, features that can be rationalized in terms of a decrease in electron density at the metal center due to a remote net electronic flux from the supported copper complex to the graphene surface.
- Ballestin, Pilar,Ventura-Espinosa, David,Martín, Santiago,Caballero, Ana,Mata, Jose A.,Pérez, Pedro J.
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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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- Structural investigation of perfluorocarboxylic acid derivatives formed in the reaction with N,N-dimethylformamide dialkylacetals
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A structural investigation of perfluorocarboxylic acid derivatives formed in the reaction with N,N-dimethylformamide dialkylacetals employing several techniques of mass spectrometry (MS) is described. Two derivatizing reagents, dimethylformamide dimethyl acetal (DMF-DMA) and dimethylformamide diethylacetal (DMF-DEA) were used. In contrast to carboxylic acids, perfluorocarboxylic acids are not able to form alkyl esters as the main product in this reaction. We found that perfluorooctanoic acid (PFOA) forms a salt with N,N-dimethylformamide dialkylacetals. This salt undergoes a further reaction inside the injection block of a gas chromatograph (GC) by loss of CO2 and then forms 1,1-perfluorooctane-(N,N,N,N-tetramethyl)-diamine. The GC-MS experiments using both electron ionization (EI) and positive-ion chemical ionization (PCI) revealed that the same reaction products are formed with either derivatizing reagent. Subjecting the perfluorocarboxylic acid derivative to electrospray ionization (ESI) and direct analysis in real time (DART), both positive- and negative-ion modes indicated that cluster ions are formed. In the positive-ion mode, this cluster ion consists of two iminium cations and one PFOA anion, while in the negative-ion mode, it comprises two PFOA anions and one cation. The salt structure was further confirmed by liquid injection field desorption/ionization (LIFDI) as well as infrared (IR) spectroscopy. We propose a simple mechanism of N,N,N′,N′-tetramethylformamidinium cation formation. The structure elucidation is supported by specific fragment ions as obtained by GC-EI-MS and GC-PCI-MS analyses.
- H. Gross, Jürgen,Schuhen, Katrin,Stró?yńska, Monika
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- Oxidative esterification of aliphatic aldehydes and alcohols with ethanol over gold nanoparticle catalysts in batch and continuous flow reactors
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Selective esterification of aliphatic aldehydes and alcohols with ethanol in the absence of a base is a more difficult reaction than that with methanol. Gold nanoparticles on ZnO were found to catalyze the oxidative esterification of octanal to ethyl octanoate with high selectivity. In addition, it was found that Au/ZnO was the most effective catalyst for yielding the desired ethyl ester without a base by direct esterification of 1-octanol with ethanol. As far as we know, this is the first report on oxidative esterification to give aliphatic ethyl esters from less reactive aliphatic alcohols and aldehydes without a base. The optimal size of gold NPs ranged from 2 to 6 nm and the presence of Au(0) was indispensable for this reaction. Au/ZnO exhibited the highest catalytic activity in both batch and flow reactors. The conversion was maintained for more than 20 h with 95% selectivity to the desired ethyl ester in the flow system.
- Taketoshi,Ishida,Murayama, Toru,Honma, Tetsuo,Haruta, Masatake
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- Hindered organoboron groups in organic chemistry. 20. Alkylations and acylations of dimesitylboron stabilised carbanions
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The alkylation of carbanions derived from alkyldimesitylboranes is an efficient process leading to prim-RBMes2, sec-RBMes2 and tert-RBMes2, all of which can be derived from MeBMes2. Subsequent oxidation gives a general synthesis for prim-ROH. Seconary alkanols are also produced on oxidation, but the release of t-alkanols has not been accomplished in an efficient fashion. Studies are given of the acylation of dimesitylboron stabilised carbanions.
- Pelter,Warren,Wilson
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- Tandem one-pot conversion of aldehydes into ethyl esters
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A facile one-pot synthesis of ethyl esters from aldehydes has been developed. This tandem process involves the formation of a nitrile intermediate obtained from the reaction of an aldehyde with hydroxylamine hydrochloride in dimethylsulfoxide (DMSO) at 100°C and the subsequent reaction of the nitrile with ethanol and sulfuric acid at 130°C. The resulting ethyl ester products were produced in good yields (65-90%) and high purity (>95%).
- Siler, Patrick J.,Chill, Samuel T.,Mebane, Robert C.
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- 1-methylimidazolium chlorosulfate ([HMIm]SO3Cl): A novel ionic liquid with dual bronsted-lewis acidity
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A novel acidic ionic liquid, 1-methylimidazolium chlorosulfate ([HMIm]SO3Cl), with dual Bransted-Lewis acidity was synthesized. This compound provided better catalytic performance in esterification and dehydration of fructose to 5-hydroxy-methylfurfural (HMF) than acidic ionic liquids with only Bronsted or Lewis acidity.
- Bao, Quanxi,Qiao, Kun,Tomida, Daisuke,Yokoyama, Chiaki
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- Towards the rational design of palladium-N-heterocyclic carbene catalysts by a combined experimental and computational approach
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A combined experimental and computational approach towards the development of Pd-NHC catalysts is described. A range of benzimidazolylidinium ligands incorporating electron-rich and electron-poor substituents were prepared and evaluated in the Suzuki reaction. The most electron-rich ligand showed the highest catalytic activity. Based on this information, the first alkyl-alkyl Negishi cross-coupling reaction protocol was developed. Evaluation of N,N′-diaryl-(4,5-dihydro)imidazolylilidinium ligands showed a strong dependence on the steric topography around the metal centre. A computational study of the most active ligand in the Negishi reaction, its Pd(0) and PdCl 2-complexes and related structures were modelled at the B3LYP/DZVP and HF/3-21G levels of theory. The potential energy hypersurfaces flattened with increase in ligand size. Binding energies were computed for carbene/Pd(0) adducts (in the range ～31-40 kcal mol-1), roughly double that for PH3 (～16 kcal mol-1). Weak intramolecular interactions were found using AIM analyses.
- O'Brien, Christopher J.,Kantchev, Eric Assen B.,Chass, Gregory A.,Hadei, Niloufar,Hopkinson, Alan C.,Organ, Michael G.,Setiadi, David H.,Tang, Ting-Hua,Fang, De-Cai
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- Selective esterification reaction involving hexaalkyl guanidinium chloride catalyst
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A new efficient and selective esterification reaction of carboxylic acids with chloroformates is described using silica-supported catalyst (PBGSiCl). The chemioselectivity of the reaction was high particularly for sterically hindered carboxylic acids supported by a single pathway reaction.
- Gros,Le Perchec,Gauthier,Senet
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- Single-step preparation and catalytic activity of mesoporous MCM-41 and SBA-15 silicas functionalized with perfluoroalkylsulfonic acid groups analogous to Nafion
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Preparation of hybrid organic-inorganic MCM-41 and SBA-15 silicas functionalized with perfluoroalkylsulfonic acid groups has been achieved in a single step by reacting the mesoporous silicas with 1,2,2-trifluoro-2-hydroxy-1- trifluoromethylethane sulfonic acid β-sultone; the catalysts showed higher activity than commercial Nafion-silica composite for the esterification of long chain fatty acids with ethanol.
- Alvaro, Mercedes,Corma, Avelino,Das, Debasish,Fornes, Vicente,Garcia, Hermenegildo
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- "Nafion"-functionalized mesoporous MCM-41 silica shows high activity and selectivity for carboxylic acid esterification and Friedel-Crafts acylation reactions
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Hybrid organic-inorganic MCM-41 silicas functionalized with perfluoroalkylsulfonic acid groups analogous to that of Nafion were prepared in a simple single step by a condensation reaction between surface silanol groups of the mesoporous silicas and 1,2,2-trifluoro-2-hydroxy-1-trifluoromethyl-ethane sulfonic acid Beta-sultone. The catalysts showed very high activity for the esterification of long-chain fatty acids with ethanol and high-molecular-weight alcohols with essentially complete selectivity at high conversion (>95%). Acylation of anisole was also possible, with high selectivity for 4-methoxyacetophenone. The catalysts showed more activity conversion than commercial Nafion-silica composite catalysts.
- Alvaro, Mercedes,Corma, Avelino,Das, Debasish,Fornes, Vicente,Garcia, Hermenegildo
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- Tin-free reductive photochemical carboxymethylation of olefins with α- alkylthioacetates
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An efficient tin-free reductive photochemical carboxymethylation of olefins with α-alkylthioacetates is developed, which (a) is an experimentally simple technique furnishing substituted derivatives of fatty acids in moderate to good yields, (b) is compatible with polar/protic functional groups and solvents, (c) does not require a special reducing reagent, (d) is fairly insensitive to the presence of dissolved oxygen and, generally, does not require degassing prior to irradiation. The critical feature of the mechanism is the 'reluctance' of short-lived MeS' to group- transfer, resulting in hydrogen abstraction from the media.
- Deng, Lisa X.,Kutateladze, Andrei G.
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- Lipase-embedded silica nanoparticles with oil-filled core-shell structure: Stable and recyclable platforms for biocatalysts
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Lipase enzyme was embedded within silica nanoparticles with oil-filled core-shell structure. The enzyme embedded within such architecture retained all of its activity and showed high catalytic performance both in water and in organic media with optimal stability and recyclability. The Royal Society of Chemistry 2012.
- Kuwahara, Yasutaka,Yamanishi, Takato,Kamegawa, Takashi,Mori, Kohsuke,Che, Michel,Yamashita, Hiromi
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- Stability of sulfated zirconia and the nature of the catalytically active species in the transesterification of triglycerides
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Sulfated zirconia (SZ) exhibits remarkable activity for various hydrocarbon reactions under mild conditions and is of interest for biodiesel synthesis. Nevertheless, to date no detailed study has addressed its activity and stability in liquid polar media such as alcohols, although a number of papers have suggested the possibility for some sulfur leaching. This paper presents an investigation into the activity and stability of a commercial SZ catalyst for the liquid-phase transesterification of triglycerides at 120 °C. The kinetics of tricaprylin (TCP) transesterification with a series of aliphatic alcohols (methanol, ethanol, and n-butanol) were investigated at 120 °C and 6.8 atm in a Parr batch reactor. It was found that the catalytic activity for TCP conversion decreased as the number of carbons in the alkyl chain of alcohol increased, most likely as a result of increased steric hindrance. The SZ catalyst exhibited significant activity loss with subsequent reaction cycles. The characterization of used catalysts after their exposure to various alcohols at 120 °C showed that the SO2-4 moieties in SZ were permanently removed. The SO2-4 species were leached out, most likely as sulfuric acid, which further reacted with alcohols to form monoalkyl and dialkyl sulfate species, as demonstrated by 1H NMR studies. This was in essence the main route for catalyst deactivation. Our findings conclusively demonstrate for the first time that in alcoholic-liquid media at higher temperatures, SZ deactivates by leaching of its active sites, most likely leading to significant homogeneous rather than heterogeneous catalysis.
- Suwannakarn, Kaewta,Lotero, Edgar,Goodwin Jr., James G.,Lu, Changqing
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- Functionalization of non-activated C-H bonds of alkanes: An effective and recyclable catalytic system based on fluorinated silver catalysts and solvents
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The complexes Fn-Tp 4Bo,3R fAg(L) (Fn-Tp 4Bo,3R f=a perfluorinated hydrotris(indazolyl) borate ligand; L=acetone or tetrahydrofuran) efficiently catalyze the functionalization of non-activated alkanes such as hexane, 2,3-dimethylbutane, or 2-methylpentane by insertion of CHCO 2Et units (from N2CHCO2Et, ethyl diazoacetate, EDA) into their C-H bonds. The reactions are quantitative (EDA-based), with no byproducts derived from diazo coupling being formed. In the case of hexane, the functionalization of the methyl C-H bonds has been achieved with the highest regioselectivity known to date with this diazo compound. This catalytic system also operates under biphasic conditions by using fluorous solvents such as Fomblin or perfluorophenanthrene. Several cycles of catalyst recovery and reuse have been performed, with identical chemo- and regioselectivities. Copyright
- Fuentes, M. Angeles,Munoz, Bianca K.,Jacob, Kane,Vendier, Laure,Caballero, Ana,Etienne, Michel,Perez, Pedro J.
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- Copper catalyzed C(sp3)-H bond alkylation via photoinduced ligand-to-metal charge transfer
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Utilizing catalytic CuCl2 we report the functionalization of numerous feedstock chemicals via the coupling of unactivated C(sp3)-H bonds with electron-deficient olefins. The active cuprate catalyst undergoes Ligand-to-Metal Charge Transfer (LMCT) to enable the generation of a chlorine radical which acts as a powerful hydrogen atom transfer reagent capable of abstracting strong electron-rich C(sp3)-H bonds. Of note is that the chlorocuprate catalyst is an exceedingly mild oxidant (0.5 V vs SCE) and that a proposed protodemetalation mechanism offers a broad scope of electron-deficient olefins, offering high diastereoselectivity in the case of endocyclic alkenes. The coupling of chlorine radical generation with Cu reduction through LMCT enables the generation of a highly active HAT reagent in an operationally simple and atom economical protocol.
- Treacy, Sean M.,Rovis, Tomislav
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supporting information
p. 2729 - 2735
(2021/03/01)
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- Preparation process of capryloyl hydroxamic acid
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The invention relates to the field of chemical synthesis, and particularly discloses a preparation process of capryloyl hydroxamic acid, which comprises the following steps: preparing ethyl n-caprylate, and preparing the capryloyl hydroxamic acid, wherein the ethyl n-caprylate is prepared by the following steps: mixing 1-1.5 kg of n-caprylic acid with 0.35-0.7 kg of ethanol, adding solid superacid, performing heating reflux for 5-7 hours, filtering to obtain precipitate and filtrate, and performing reduced pressure distillation on the filtrate to obtain the ethyl n-caprylate, and the obtainedprecipitate is washed and roasted to obtain the solid superacid, and the solid superacid is recycled to the preparation step of the ethyl n-caprylate for use. By using the solid superacid catalyst, the environmental friendliness of the esterification reaction in the n-capryloyl hydroxamic acid preparation process is improved.
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Paragraph 0034-0045
(2021/01/30)
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- Fully recyclable Br?nsted acid catalyst systems
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Homogeneous and heterogeneous sulfonic acid catalysts are some of the most common catalysts used in organic chemistry. This work explores an alternative scheme using a fully recyclable polymeric solvent (a poly-α-olefin (PAO)) and soluble PAO-anchored polyisobutylene (PIB)-bound sulfonic acid catalysts. This PAO solvent is nonvolatile and helps to exclude water by its nonpolar nature which in turn drives reactions without the need for distillation of water, avoiding the need for excess reagents. This highly nonpolar solvent system uses polyisobutylene (PIB) bound sulfonic acid catalysts that are phase-anchored in solvents like PAO. The effectivenes of these catalysts was demonstrated by their use in esterifications, acetalizations, and multicomponent condensations. These catalysts and the PAO solvent phase show excellent recyclability in schemes where products are efficiently separated. For example, this non-volatile polymeric solvent and the PIB-bound catalyst can be recycled quantitatively when volatile products are separated and purified by distillation. In other cases, product purification can be effected by product self-separation or by extraction.
- Watson, Christopher B.,Kuechle, Adrianna,Bergbreiter, David E.
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p. 1266 - 1273
(2021/02/26)
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- Preparation process of octanoximic acid (by machine translation)
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The preparation process, comprises the following steps, preparing ethyl acetate, n-octanoic acid ethyl ester and hydroxylamine under the action of sulfuric acid by heating and refluxing :(a) to ;(b) hours to prepare the octanoximic acid, composite catalyst. 30. The preparation method of the octanoximic acid comprises the following steps: sodium acetate and sodium carbonate 60 °C are subjected to hydroxyoximation reaction under the action of a composite catalyst and refluxed 1.5 and 4 hours to prepare the octanoximic acid preparation technology . The technical proposal is as, The method for preparing the octanoximic acid comprises the following steps. 1:0.01. 1:0.03,sup. 1:0.4 .time 1:0.6 10.3.3 (by machine translation)
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Paragraph 0023-0036
(2020/03/09)
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- 'Clean' hydrolase reactions using commercial washing powder
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We report the use of commercial laundry powder as a biocatalyst for a range of lipase-catalysed reactions including (trans)esterification, ester hydrolysis and chemoenzymatic epoxidation reactions. The enzymatic laundry powder exhibited excellent stability and recyclability, making it a readily available and cheap biocatalyst for chemical transformations.
- Zhang, Jie,Tonin, Fabio,Zhang, Wuyuan,Hagedoorn, Peter-Leon,Mallée, Lloyd,Hollmann, Frank
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p. 24039 - 24042
(2019/08/15)
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- Transfer Hydrogenation of Alkenes Using Ethanol Catalyzed by a NCP Pincer Iridium Complex: Scope and Mechanism
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The first general catalytic approach to effecting transfer hydrogenation (TH) of unactivated alkenes using ethanol as the hydrogen source is described. A new NCP-type pincer iridium complex (BQ-NCOP)IrHCl containing a rigid benzoquinoline backbone has been developed for efficient, mild TH of unactivated C-C multiple bonds with ethanol, forming ethyl acetate as the sole byproduct. A wide variety of alkenes, including multisubstituted alkyl alkenes, aryl alkenes, and heteroatom-substituted alkenes, as well as O- or N-containing heteroarenes and internal alkynes, are suitable substrates. Importantly, the (BQ-NCOP)Ir/EtOH system exhibits high chemoselectivity for alkene hydrogenation in the presence of reactive functional groups, such as ketones and carboxylic acids. Furthermore, the reaction with C2D5OD provides a convenient route to deuterium-labeled compounds. Detailed kinetic and mechanistic studies have revealed that monosubstituted alkenes (e.g., 1-octene, styrene) and multisubstituted alkenes (e.g., cyclooctene (COE)) exhibit fundamental mechanistic difference. The OH group of ethanol displays a normal kinetic isotope effect (KIE) in the reaction of styrene, but a substantial inverse KIE in the case of COE. The catalysis of styrene or 1-octene with relatively strong binding affinity to the Ir(I) center has (BQ-NCOP)IrI(alkene) adduct as an off-cycle catalyst resting state, and the rate law shows a positive order in EtOH, inverse first-order in styrene, and first-order in the catalyst. In contrast, the catalysis of COE has an off-cycle catalyst resting state of (BQ-NCOP)IrIII(H)[O(Et)···HO(Et)···HOEt] that features a six-membered iridacycle consisting of two hydrogen-bonds between one EtO ligand and two EtOH molecules, one of which is coordinated to the Ir(III) center. The rate law shows a negative order in EtOH, zeroth-order in COE, and first-order in the catalyst. The observed inverse KIE corresponds to an inverse equilibrium isotope effect for the pre-equilibrium formation of (BQ-NCOP)IrIII(H)(OEt) from the catalyst resting state via ethanol dissociation. Regardless of the substrate, ethanol dehydrogenation is the slow segment of the catalytic cycle, while alkene hydrogenation occurs readily following the rate-determining step, that is, β-hydride elimination of (BQ-NCOP)Ir(H)(OEt) to form (BQ-NCOP)Ir(H)2 and acetaldehyde. The latter is effectively converted to innocent ethyl acetate under the catalytic conditions, thus avoiding the catalyst poisoning via iridium-mediated decarbonylation of acetaldehyde.
- Wang, Yulei,Huang, Zhidao,Leng, Xuebing,Zhu, Huping,Liu, Guixia,Huang, Zheng
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supporting information
p. 4417 - 4429
(2018/04/05)
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- Efficient Catalytic Greenhouse Gas-Free Hydrogen and Aldehyde Formation from Alcohols
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Catalytic preparation of hydrogen and aldehyde(s) from alcohols, including bioalcohols, without production of carbon monoxide or carbon dioxide.
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Paragraph 0059; 0060
(2017/11/07)
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- 8 - hydroxy quinoline sensitive ionic liquid preparation and its catalytic long-chain fatty acid b method of esterification of
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The invention discloses a preparation method of a temperature sensitive ionic liquid, and a method for catalyzing long-chain fatty acid esterification by using the ionic liquid. A general formula (I) shown in the specification represents the structure of the temperature sensitive ionic liquid, the ionic liquid is formed by a 8-hydroxyquinoline cation and anions comprising a tetrafluoroborate radical, a methane sulfonate radical, a bisulfate ion and a dihydrogen phosphate radical, and the solubility of ionic liquid in ethanol is temperature sensitive. The introduction of a hydroxy group to 8-position of aquinoline ring greatly increases the acidity and improves the esterification reaction yield. The ionic liquid can be mixed with ethanol to form one phase at a high temperature, and the ionic liquid and a product rapidly separate to different phases at room temperature or a low temperature, so the whole reaction system ensures high catalytic efficiency of a homogeneous reaction and makes separation and recovery simple, avoids the limitations of limited two-phase catalytic efficiency and the disadvantage of difficult ion liquid recovery of homogeneous catalysis, and accords with the principle of green chemistry. The esterification yield of the esterification reaction of the long-chain fatty acid under the catalysis of the ionic liquid reaches 90.6-95.5%.
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Paragraph 0058; 0059; 0060; 0061; 0062; 0063-0067
(2017/06/22)
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- Water as the Reaction Medium for Intermolecular C-H Alkane Functionalization in Micellar Catalysis
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A series of alkanes CnH2n+2 have been functionalized in water as the reaction medium, using a silver-based catalyst, upon the insertion of carbene (CHCO2Et from N2CHCO2Et) groups into the carbon-hydrogen bonds of hexane, cyclohexane, or 2-methylbutane, among others. The regioselectivity toward the distinct reaction sites is identical to that found in neat alkane, the water-based system allowing the use of a much shorter excess of the hydrocarbon. This is the first example of the intermolecular functionalization of alkanes with this strategy in water. The functionalized alkanes partially undergo the incorporation of a second carbene unit to provide α-(acyloxy)acetates, in an unprecedented tandem reaction of this nature.
- álvarez, María,Gava, Riccardo,Rodríguez, Manuel R.,Rull, Silvia G.,Pérez, Pedro J.
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p. 3707 - 3711
(2017/06/09)
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- By using low-temperature co- melt solvent a method of catalytic ester (by machine translation)
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The invention discloses a method of utilizing low-temperature co- melt solvent catalytic ester method, will be 0.05-0.5 mole of sharemelt solvent of low-temperature co-preprocessing, 1-5 mole of share alcohol and 1-10 mole of share of acid in the reaction vessel, stirring and heating, 25-200 ° C reaction under 2-96h, then the reaction fluid settlement , liquid, organic is accepted after passing an examination the level , get the esterification reaction products of the; reaction after the treatment and recovery of low-temperature co- melt solvent the preprocessing, can be reused. This invention utilizes the easy preparation of low-temperature co- melt solvent the preprocessing of catalytic esterification reaction, the reaction front is homogeneous, can be formed after the reaction of the two-phase reaction in the process of direct dehydration, without adding other dehydrating agent, has the advantages of simple operation, the reaction efficiency is high, corrosion of small equipment, less side reactions, the product quality is good, no pollution to the environment, and the like, it has broad application prospects. (by machine translation)
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Paragraph 0050; 0051
(2017/01/17)
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- Reactivity of a Carbon-Supported Single-Site Molybdenum Dioxo Catalyst for Biodiesel Synthesis
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A single-site molybdenum dioxo catalyst, (Oc)2Mo(=O)2@C, was prepared via direct grafting of MoO2Cl2(dme) (dme = 1,2-dimethoxyethane) on high-surface-area activated carbon. The physicochemical and chemical properties of this catalyst were fully characterized by N2 physisorption, ICP-AES/OES, PXRD, STEM, XPS, XAS, temperature-programmed reduction with H2 (TPR-H2), and temperature-programmed NH3 desorption (TPD-NH3). The single-site nature of the Mo species is corroborated by XPS and TPR-H2 data, and it exhibits the lowest reported MoOx Tmax of reduction reported to date, suggesting a highly reactive MoVI center. (Oc)2Mo(=O)2@C catalyzes the transesterification of a variety of esters and triglycerides with ethanol, exhibiting high activity at moderate temperatures (60-90 °C) and with negligible deactivation. (Oc)2Mo(=O)2@C is resistant to water and can be recycled at least three times with no loss of activity. The transesterification reaction is determined experimentally to be first order in [ethanol] and first order in [Mo] with Δ;H? = 10.5(8) kcal mol-1 and Δ;S? = -32(2) eu. The low energy of activation is consistent with the moderate conditions needed to achieve rapid turnover. This highly active carbon-supported single-site molybdenum dioxo species is thus an efficient, robust, and low-cost catalyst with significant potential for transesterification processes.
- Mouat, Aidan R.,Lohr, Tracy L.,Wegener, Evan C.,Miller, Jeffrey T.,Delferro, Massimiliano,Stair, Peter C.,Marks, Tobin J.
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p. 6762 - 6769
(2016/10/18)
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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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- Agent having neurotrophic factor-like activity
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The present invention provides a pharmaceutical agent having high safety and a neurotrophic factor-like activity, which contains, as an active ingredient, any one compound included in fatty acids each having 8 carbon atoms (C8) or having 10 carbon atoms (C10) to 12 carbon atoms (C12) or fatty acid esters thereof, such as 3,7-dimethyloctanoic acid ethyl ester, geranicacidethyl ester, and the like, eachof whichhas 8 carbonatoms (C8), decanoic acid methyl ester, trans-2-decenoic acid, trans-2-decenoic acid methyl ester, trans-2-decenoic acid ethyl ester, trans-2-decenoic acid-2-decenyl ester, trans-2-decenoic acid cyclohexyl ester, trans-2-decenoic acid isopropyl ester, trans-3-decenoic acid methyl ester, trans-9-decenoic acid methyl ester, and the like, each of which has 10 carbon atoms (C10), trans-10-undecenoic acid methyl ester, trans-10-undecenoic acid ethyl ester, and the like, each of which has 11 carbon atoms (C11), and dodecanoic acid, and the like, each of which has 12 carbon atoms (C12), or salts thereof or prodrugs thereof.
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Paragraph 0047-0048
(2016/01/25)
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- Gold nanoparticles supported on metal oxides as catalysts for the direct oxidative esterification of alcohols under mild conditions
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Gold nanoparticles supported on metal oxides were used to catalyze the direct oxidative esterification of alcohols; esters were obtained using molecular oxygen as an oxidant under ambient temperature and pressure. Higher activities for the reaction between the benzyl alcohol and methanol were obtained over Au/CeO2 and Au/ZrO2 than Au/TiO2 (anatase), Au/HT (hydrotalcite) and Au/Al2O3. These catalysts were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), atomic absorption spectroscopy (AAS) and X-ray photoelectron spectroscopy (XPS). The distribution of gold nanoparticles was uniform; no change of chemical states occurred for supports and gold nanoparticles after the catalysts were reused 10 times. The oxidative esterification of various alcohols over these catalysts could also occur under optimized reaction conditions. The substituted benzyl alcohols and cinnamyl alcohols were more active than heterocyclic alcohols and aliphatic alcohols because their α-H could be eliminated more easily during the induction of adsorbed dioxygen. Self-oxidative esterification was available for benzyl alcohol in inert solvents with low polarity indexes. A reaction mechanism was proposed for the synthesis of esters from alcohols with molecular oxygen.
- Wei, Huili,Li, Jingyi,Yu, Jing,Zheng, Jianwei,Su, Haiquan,Wang, Xiaojing
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- Rhodium(iii)-catalyzed C-H allylation of electron-deficient alkenes with allyl acetates
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Rhodium-catalyzed C-H allylation of acrylamides with allyl acetates is reported. The use of weakly coordinating directing group resulted in high reaction efficiency, broad functionality tolerance and excellent γ-selectivity, which opens a new synthetic pathway for the access of 1,4-diene skeletons.
- Feng, Chao,Feng, Daming,Loh, Teck-Peng
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supporting information
p. 342 - 345
(2015/01/09)
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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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- Functionalization of CnH2n+2 Alkanes: Supercritical Carbon Dioxide Enhances the Reactivity towards Primary Carbon-Hydrogen Bonds
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The functionalization of the primary sites of alkanes is one of the more challenging areas in catalysis. In this context, a novel effect has been discovered that is responsible for an enhancement in the reactivity of the primary C-H bonds of alkanes in a catalytic system. The copper complex Cu(NCMe) (=hydrotris{[3,5-bis(trifluoromethyl)-4-bromo]-pyrazol-1-yl}borate) catalyzes the functionalization of CnH2n+2 with ethyl diazoacetate upon inserting the CHCO2Et unit into C-H bonds. In addition, the selectivity of the reaction toward the primary sites significantly increased relative to that obtained in neat alkane upon using supercritical carbon dioxide as the reaction medium. This was attributed to the effect of the carbon dioxide molecules that withdraw electron density from the fluorine atoms of the ligand, which enhances the electrophilic nature of the metal center. DFT studies validated this proposal.
- Gava, Riccardo,Olmos, Andrea,Noverges, Bárbara,Varea, Teresa,Funes-Ardoiz, Ignacio,Belderrain, Tomás R.,Caballero, Ana,Maseras, Feliu,Asensio, Gregorio,Pérez, Pedro J.
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p. 3254 - 3260
(2015/10/28)
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- Cloning and expression of a Baeyer-Villiger monooxygenase oxidizing linear aliphatic ketones from Dietzia sp. D5
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A Baeyer-Villiger monooxygenase has been identified in the genome sequence of Dietzia sp. D5. Sequence similarity search revealed that the enzyme belongs to a group of BVMOs that are closely related to ethionamide monooxygenase from Mycobacterium tuberculosis (EthA). The BVMO was expressed in E. coli BL21-CodonPlus(DE3)-RP and the best expression was achieved when the E. coli cells were cultivated in terrific broth (TB) at 15 °C and induced with 0.1 mM of IPTG. Since the purified enzyme did not show any measurable activity, the substrate scope of the BVMO has been determined using whole-cell and crude cell extract systems. The enzyme was most active towards linear aliphatic substrates. However, it has shown a moderate degree of conversion for cyclobutanone, 2-methylcyclohexanone, bicyclo[3.2.0]hept-2-en-6-one, phenylacetone and thioanisole. There was no detectable conversion of ethionamide, cyclohexanone and acetophenone.
- Bisagni, Serena,Smus?, Justyna,Chávez, Georgina,Hatti-Kaul, Rajni,Mamo, Gashaw
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p. 161 - 169
(2014/12/11)
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- The dual role of ionic liquid BmimBF4, precursor of N-heterocyclic carbene and solvent, in the oxidative esterification of aldehydes
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Room temperature ionic liquid BmimBF4 (1-butyl-3- methylimidazolium tetrafluoroborate) has been utilized in the N-heterocyclic carbene-catalyzed oxidation of aldehydes to yield esters. In the presence of MnO2 as oxidant and of DBU and caesium carbonate as bases, aromatic, heteroaromatic and aliphatic esters have been isolated in good to excellent yields. The recyclability of the used ionic liquid along with the excess of inorganic reagents has been proved. The simple and cheap BmimBF4 ionic liquid played the dual role of precatalyst and solvent. This is the first time that such a reaction has been carried out with an ionic liquid as solvent.
- Chiarotto, Isabella,Feroci, Marta,Sotgiu, Giovanni,Inesi, Achille
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p. 8088 - 8095
(2013/08/23)
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- Cross-coupling of alkyl halides with aryl or alkyl Grignards catalyzed by dinuclear Ni(ii) complexes containing functionalized tripodal amine-pyrazolyl ligands
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Structurally distinctive dinuclear Ni(ii) complexes with furan or thiophene tethered amine-pyrazolyl tripodal hybrid ligands have been synthesized and crystallographically characterized. All complexes are catalytically active towards cross-coupling of aryl/alkyl Grignard reagents with β-H containing alkyl halides at room temperature in the presence of N,N,N',N'- tetramethylethylenediamine (TMEDA). The catalytic efficacy of the complexes is dependent on the tether substituent at the central amine. Two species, Ni(ii) TMEDA and Mg(ii) TMEDA complexes, have been isolated from the catalytic reaction mixtures under different conditions. Some ligand-stabilized Ni(ii) and Mg(ii) bimetallic species have also been identified in the ESI-MS spectra.
- Xue, Fei,Zhao, Jin,Hor, T. S. Andy
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p. 5150 - 5158
(2013/04/10)
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- METHOD FOR CONTINUOUSLY PREPARING CARBOXYLIC ACID ESTER
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A method for continuously preparing a carboxylic acid ester is disclosed. In the method of the present invention, a vertical reactor is filled with a solid catalyst, a carboxylic acid and an alcohol are introduced into a lower part of the vertical reactor, esterification is performed to form an esterized mixture, the esterized mixture is output from an upper part of the vertical reactor, and distillation is performed to isolate the carboxylic acid ester. The method of the present invention is simple, easily controlled and environmental friendly, and has significantly high conversion rate and selectivity.
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Paragraph 0024; 0026
(2013/11/19)
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- Reductive bromine atom-transfer reaction
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Atom-transfer radical (ATR) reactions of alkenes with R-X usually give products having new C-C and C-X bonds at the adjacent carbons. However, when the reaction was carried out under irradiation using a low-pressure Hg lamp, addition/reduction products were obtained in good yield. Hydrogen bromide, formed by H-abstraction of a bromine radical from alkenes, is likely to play a key role in the reductive ATR reaction.
- Sumino, Shuhei,Fusano, Akira,Ryu, Ilhyong
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supporting information
p. 2826 - 2829
(2013/07/19)
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- P-Sulfonic acid calix[n]arenes as homogeneous and recyclable organocatalysts for esterification reactions
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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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- Catalytic hydrocarbon functionalization with gold complexes containing n-heterocyclic carbene ligands with pendant donor groups
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A series of silver and gold complexes bearing N-heterocyclic carbene ligands with a -CH2CO2Et pendant group attached to one N atom of the NHC ligand have been prepared. The catalytic properties of the gold complexes toward the decomposition of ethyl diazoacetate (N2CHCO 2Et) and the transfer of the carbene CHCO2Et group to benzene and hexane have been investigated. A somewhat different reaction outcome has been found for this family of gold catalysts compared with the parent IPrAuCl catalyst. Gold-based catalysts containing NHC ligands with potentially coordinating pendant groups have been tested in the functionalization of Caspa2-H and Caspa3-H bonds by carbene insertion from ethyl diazoacetate, showing moderate catalytic activity.
- Delgado-Rebollo, Manuela,Beltran, Aalvaro,Prieto, Auxiliadora,Mar Diaz-Requejo,Echavarren, Antonio M.,Perez, Pedro J.
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experimental part
p. 1380 - 1386
(2012/05/31)
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- Modified grape seed oils
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Edible oils are described which are extracted from dried fermented grape seeds isolated from a fermented grape pomace that has undergone fermentation, e.g., primary fermentation during wine making. The edible oils contain distinguishing flavor and fragrance chemicals evidenced by organoleptic evaluation and chemical analysis, in which these chemicals are substantially lacking in grape seed oils that have been similarly extracted from grape seeds isolated from non-fermented grape pomace.
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- Ester synthesis using Candida rugosa lipase immobilized on magnetic nanoparticles
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Magnetic nanoparticles were synthesized by co-precipitation under hydrothermal conditions. The average diameter of the magnetic nanoparticles was found to be in the range of 15 ± 5 nm with an average surface area of 112.15 m2 g-1. Immobilization of lipase on magnetite nanoparticles was confirmed by FTIR, differential scanning calorimetry and thermal gravimetric analysis. The activation energy of the free enzyme was 1.9-fold higher than that of the immobilized lipase for hydrolytic reactions. Additionally, the lower KM and higher Vmax values of the immobilized enzyme for hydrolysis of 4-nitrophenyl palmitate indicated an increased efficiency of the immobilized lipase. The immobilized lipase exhibited higher esterification efficiency compared with free lipase for synthesis of ethyl isovalerate. It also exhibited fairly good reusability, with about 8.5% reduction in esterification efficiency for ethyl isovalerate synthesis over ten cycles of reuse.
- Dandavate, Vrushali,Keharia, Haresh,Madamwar, Datta
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experimental part
p. 37 - 45
(2012/04/10)
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- Intermetallic coinage metal-catalyzed functionalization of alkanes with ethyl diazoacetate: Gold as a ligand
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The complexes [Au2M2(C6F5) 4(NCMe)2]n (M = Cu, 1; M = Ag, 2) have been tested as catalysts for the functionalization of alkanes by the carbene insertion methodology, using ethyl diazoacetate as the carbene source. Moderate to high conversions have been obtained. The observed selectivities seem to favor the proposal that the active metal for catalysis is the Cu/Ag center, the Au(C6F5)2 unit acting as a spectator ligand in both cases.
- Fuentes, M. ángeles,Rodríguez-Castillo, María,Monge, Miguel,Olmos, M. Elena,López-De-Luzuriaga, Jose M.,Caballero, Ana,Pérez, Pedro J.
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experimental part
p. 146 - 149
(2011/06/22)
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- Sodium borohydride-mediated transesterification
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In the presence of sodium borohydride, esters react with alcohols with formation of the corresponding esters. The reaction is sensitive to the solvent, structure of the ester, and is often concurrent with reduction. Thioesters containing an ester group can be selectively cleaved by the reagent. Both esters and thioesters attached to solid support are resistant toward sodium borohydride. The in situ prepared sodium tetraalkoxyborate is introduced as an efficient reagent and catalyst for transesterification.
- Sereda, Grigoriy,Pothula, Swetha,Dreessen, James
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scheme or table
p. 1312 - 1321
(2010/07/05)
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- INFANT FORMULA CONTAINING AN AROMA COMPOSITION FOR USE AS FRAGRANCE
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The invention relates to a nutraceutical composition such as infant formula or infant food comprising a) a defined aroma composition; b) a methodology for developing, maintaining certain aroma constituents in the infant formula and an aroma or fragrance composition to be used to increase the acceptance of a person or an object by the baby or new born.
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- Development and assessment of green synthesis of hydrazides
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An expeditious, solvent free one pot method for the preparation of hydrazides from corresponding acids directly under microwave irradiation is developed. The method has been assessed using green chemistry measures and found superior to conventional method with higher E(environmental) factor, atom economy, atom efficiency, carbon efficiency, reaction mass efficiency.
- Saha, Ajoy,Kumar, Rajesh,Kumar, Rajendra,Devakumar
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experimental part
p. 526 - 531
(2010/10/03)
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- Green synthesis of 5-substituted-1,3,4-thiadiazole-2-thiols as new potent nitrification inhibitors [1]
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(Chemical Equation Presented) A fast, efficient synthesis of 5-substituted-1,3,4-thiadiazole-2-thiols was successfully developed, assessed using green chemistry matrices, and compounds were screened for their in vitro nitrification inhibitory activity. The greener method was superior with higher energy efficiency, E(nvironmental) factor, atom economy, atom efficiency, carbon efficiency, and reaction mass efficiency.
- Saha, Ajoy,Kumar, Rajesh,Kumar, Rajendra,Devakumar
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experimental part
p. 838 - 845
(2010/10/04)
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- MODIFIED GRAPE SEED OILS
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Edible oils are described which are extracted from dried fermented grape seeds isolated from a fermented grape pomace that has undergone fermentation, e.g., primary fermentation during wine making. The edible oils contain distinguishing flavor and fragrance chemicals evidenced by organoleptic evaluation and chemical analysis, in which these chemicals are substantially lacking in grape seed oils that have been similarly extracted from grape seeds isolated from non-fermented grape pomace.
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- Highly selective metal catalysts for intermolecular carbenoid insertion into primary C-H bonds and enantioselective C-C bond formation
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(Figure Presented) Primary C-H bond activation! A Rh complex of bis-pocket porphyrin I catalyzes carbenoid insertion into the C-H bonds of n-alkanes with a primary/secondary selectivity (per C-H bond) of up to 11.4:1 (see picture). Enantioselective secondary C-H bond functionalization catalyzed by a Rh complex of Halterman's chiral porphyrin features up to 93% ee. These reactions exhibit up to 6477 turnovers after the catalyst was recycled five times.
- Thu, Hung-Yat,Tong, Glenna So-Ming,Huang, Jie-Sheng,Chan, Sharon Lai-Fung,Deng, Qing-Hai,Che, Chi-Ming
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supporting information; scheme or table
p. 9747 - 9751
(2009/05/30)
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- Scandium triflate catalyzed transesterification of carboxylic esters
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The direct transesterification of carboxylic esters is efficiently catalyzed with Sc(OTf)3 (10 mol%) in boiling alcoholic solvent. Methyl, ethyl, isopropyl, and allyl esters were prepared from a broad range of different substrates in high yields. The application of microwave irradiation led to significantly reduced reaction times. Georg Thieme Verlag Stuttgart.
- Remme, Nicole,Koschek, Katharina,Schneider, Christoph
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p. 491 - 493
(2007/12/27)
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- Use of 2,4-undecanedione as a liquid chelating ion exchanger for the recovery of various metal ions
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A liquid chelating ion exchanger containing β-diketo group has been synthesized using octanoic acid and characterized by FTIR and UV visible spectroscopy. The synthesized ion exchanger has been used for the extraction of various metal ions such as Ni(II), Zn(II), Cd(II), Co(II), Hg(II) and Ce(II). The concentration of the extracted metal ions has been determined by AAS. The effect of different parameters have been studied and use of 2,4 undecanedione lor the removal of mentioned metal ions from industrial effluents, and water from river and domestic water has been proposed.
- Vithlani, Niki,Patel, Anjali
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p. 290 - 292
(2008/02/12)
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- Hydroalkoxycarbonylation of olefins in the presence of palladium phosphine complexes: High activity and regioselectivity
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Several types of catalyst systems were examined in the olefin hydroalkoxycarbonylation reaction. The systems contained Pd(PPh 3)4, PdCl2(PPh3)2, or some other palladium compounds as a principal component. The second component (promoter) was p-toluenesulfonic acid or diphenyl(m-sulfophenyl)phosphine, which combines both the ligand and promoter functions. An important feature of these systems is their high activity in the hydroalkoxycarbonylation of ethylene and a high regioselectivity (83-100%) in the hydroalkoxycarbonylation of α-olefins with respect to linear products. Thus, it was unnecessary to introduce additional stabilizing ligands to augment the catalyst and promoter. The esters obtained can find application in the pharmaceutical industry and perfumery, as well as in other industries. Nauka/Interperiodica 2006.
- Chepaikin,Bezruchenko,Suerbaev,Shalmagambetov
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p. 117 - 121
(2007/10/03)
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- Extraction of copper(II) and lead(II) ions using liquid chelating ion exchanger: 2,4-Undecanedione
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A liquid chelating ion exchanger (LCE) containing β-diketo group has been synthesized using octanoic acid (C8H16O2) as the starting material and characterized by BP, FT-IR and UV-visible spectroscopy. The synthesized LCE was used for the extraction of Cu and Pb metal ions. Based on these studies, the optimum conditions for extraction of Cu and Pb metal ions from different effluents have been proposed.
- Vithalani, Niki,Patel, Anjali
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p. 1285 - 1287
(2008/09/20)
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