- Unraveling the role of low coordination sites in a cu metal nanoparticle: A step toward the selective synthesis of second generation biofuels
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The acidity of a prereduced Cu/SiO2 catalyst was extensively investigated by means of FT-IR of adsorbed pyridine and by titration with 2-phenylethylamine in cyclohexane. Comparison with the parent CuO/SiO 2 material, which was alread
- Scotti, Nicola,Dangate, Milind,Gervasini, Antonella,Evangelisti, Claudio,Ravasio, Nicoletta,Zaccheria, Federica
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- Selective oxidation of primary alkanols into the "symmetrical" esters with the H2O2-MBr-HCl system
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Oxidation of linear or branched primary alkanols with H2O 2-MBr (M = Li, Na, K)-HCl system in water affords the corresponding "symmetrical" esters in almost quantitative yield.
- Nikishin,Sokova,Kapustina
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Read Online
- Valeric Biofuel Production from γ-Valerolactone over Bifunctional Catalysts with Moderate Noble-Metal Loading
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SiO2-Al2O3-supported Ru, Ir and Pt-based catalysts with moderate metal loading (1 %) were tested for the first time in the production of pentyl valerate (PV) in liquid phase from γ-valerolactone, pentanol (in excess) and H2. The acidity of these bifunctional catalysts, plays a key role in the one-pot process comprising two consecutive acid-catalyzed reactions and a metal-catalyzed one. Metal dispersion also shown to be relevant for the conversion of the pentyl pentenoate intermediate into PV by hydrogenation over the metal sites. Pt/SA catalyst with the highest surface acidity and metal dispersion reached optimal GVL conversion with a PV yield of 90.0 % after 10 h, exhibiting a PV productivity of 300 mmol/gM.h, i. e. a value between three and four times higher than the best result reported until now (91.8 mmol/gM.h). These findings highlight the potential that noble metal-based catalyst with moderate metal loading have in the valorization of biomass-derived platform molecules such as γ-valerolactone.
- Martínez Figueredo, Karla G.,Virgilio, Emanuel M.,Segobia, Darío J.,Bertero, Nicolás M.
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- Performance of Candida rugosa lipase supported on nanocellulose-silica-reinforced polyethersulfone membrane for the synthesis of pentyl valerate: Kinetic, thermodynamic and regenerability studies
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The present study reports the groundwork for preparing a greener catalyst, Candida rugosa lipase (CRL), supported on biomass-based nanocellulose-silica-reinforced polyethersulfone membrane (NC-SiO2-PES) and proved its stability in synthesizing pentyl valerate. The NC-SiO2-PES/CRL-catalyzed synthesis of the ester exhibited a ping-pong bi-bi mechanism, with a high Vmax value and low Km value over the free CRL, confirming the former's greater substrate affinity. The kinetics data demonstrated that the NC-SiO2-PES/CRL was catalytically more efficient than its free counterpart. The lower Michaelis-Menten constant of NC-SiO2-PES/CRL for pentanol (Km,B = 43.53 mM) than valeric acid (Km,A = 82.03 mM) indicates that pentanol was favored over the latter. Pertinently, the higher thermal deactivation values of NC-SiO2-PES/CRL indicated that the NC-SiO2-PES membrane successfully enhanced CRL thermal stability, and the process followed first-order kinetics (R2 > 0.95). The NC-SiO2-PES/CRL has a slightly greater activation energy (Ea) and activation energy for thermal denaturation (Ed) over the free CRL. NC-SiO2-PES/CRL also exhibited extended operational stability, with a robust half-life of ~150 h and the absence of leached protein after 60 min of agitation. The NC-SiO2-PES/CRL's ability to be regenerated chemically and ultrasonically and reused without significant loss in enzyme activity denotes its potential cost-saving to produce pentyl valerate.
- Chandren, Sheela,Elias, Nursyafiqah,Lau, Woei Jye,Wahab, Roswanira Abdul
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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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supporting information
p. 8897 - 8900
(2021/09/10)
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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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- 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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- 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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- USE OF A RUTHENIUM CATALYST COMPRISING A TETRADENTATE LIGAND FOR HYDROGENATION OF ESTERS AND/OR FORMATION OF ESTERS AND A RUTHENIUM COMPLEX COMPRISING SAID TETRADENTATE LIGAND
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The present invention relates to the use of a transition metal catalyst TMC1, which comprises a transition metal M selected from metals of groups 7, 8, 9 and 10 of the periodic table of elements according to IUPAC and a tetradentate ligand of formula I wherein R1 are identical or different and are each an organic radical having from 1 to 40 carbon atoms, and R2 are identical or different and are each an organic radical having from 1 to 40 carbon atoms, as catalyst in processes for formation of compounds comprising at least one carboxylic acid ester functional group -O-C(=O)- starting from at least one primary alcohol and/or hydrogenation of compounds comprising at least one carboxylic acid ester functional group -O-C(=O)-. The present invention further relates to a process for hydrogenation of a compound comprising at least one carboxylic acid ester functional group -O-C(=O)-, to a process for the formation of a compound comprising at least one carboxylic acid ester functional group -O-C(=O)- by dehydrogenase coupling of at least one primary alcohol with a second alcoholic OH-group, to a transition metal complex comprising the tetradentate ligand of formula I and to a process for preparing said transition metal complex.
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Page/Page column 27
(2019/08/20)
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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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- Study of Precatalyst Degradation Leading to the Discovery of a New Ru0 Precatalyst for Hydrogenation and Dehydrogenation
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The complex Ru-MACHO (1) is a widely used precatalyst for hydrogenation and dehydrogenation reactions under basic conditions. In an attempt to identify the active catalyst form, 1 was reacted with a strong base. The formation of previously unreported species was observed by NMR and mass spectrometry. This observation indicated that complex 1 quickly degraded under basic conditions when no substrate was present. X-ray crystallography enabled the identification of three complexes as products of this degradation of complex 1. These complexes suggested degradation pathways which included ligand cleavage and reassembly, along with reduction of the ruthenium atom. One of the decomposition products, the Ru0 complex [Ru(N(CH2CH2PPh2)3)CO] (5), was prepared independently and studied. 5 was found to be active, entirely additive-free, in the acceptorless dehydrogenation of aliphatic alcohols to esters. The hydrogenation of esters catalyzed by 5 was also demonstrated under base-free conditions with methanol as an additive. Protic substrates were shown to add reversibly to complex 5, generating RuII-hydrido species, thus presenting a rare example of reversible oxidative addition from Ru0 to RuII and reductive elimination from RuII to Ru0.
- Anaby, Aviel,Schelwies, Mathias,Schwaben, Jonas,Rominger, Frank,Hashmi, A. Stephen K.,Schaub, Thomas
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supporting information
p. 2193 - 2201
(2018/07/25)
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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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supporting information
p. 4478 - 4481
(2018/08/09)
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- Ruthenium complexes featuring cooperative phosphine-pyridine-iminophosphorane (PNN) ligands: Synthesis, reactivity and catalytic activity
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The coordination to ruthenium(ii) centres of two phosphine-pyridine-iminophosphorane ligands LR (PPh2CH2(C6H3N)CH2NPR3, R = Ph or Cy) differing by the nature of the substituent of the PN phosphorus was explored. Coordination to [RuCl2(PPh3)3] afforded the complexes [RuLRCl2(PPh3)] that were successfully deprotonated at the acidic phosphinomethyl position. With LCy, coordination led to a mixture of two isomers. The complexes [RuLRHCl(PPh3)] were similarly obtained from [RuHCl(PPh3)3]. The stability of these complexes depends on the ligand substitution pattern; with LPh a CH activation process took place, while [RuLCyHCl(PPh3)] was thermally stable. Deprotonation of this latter complex was achieved and gave a catalytically competent species for the acceptorless dehydrogenative coupling of alcohols.
- Cheisson, Thibault,Mazaud, Louis,Auffrant, Audrey
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p. 14521 - 14530
(2018/10/31)
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- Preparation of valeric acid and valerate esters from biomass-derived levulinic acid using metal triflates + Pd/C
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Recently, great attention has been paid to the study of the conversion of biomass-derived compounds to value-Added chemicals. Levulinic acid (LA) is a versatile and valuable chemical and its various applications have been described. The selective conversion of biomass-derived LA to produce valeric acid and valerate esters was successfully performed in the presence of H2, in which metal triflates and Pd/C were used as the catalysts. Under optimal conditions, a 99% conversion of LA and a 92% selectivity of valeric acid was obtained with Hf(OTf)4 and Pd/C as the catalysts at a relatively low temperature of 150 °C. Moreover, the metal center of the catalyst, the solvent, the reaction temperature and other reaction conditions were studied. In addition, the results of the recycling experiment exhibited that the catalysts continued to have a satisfactory activity after being reused 5 times.
- Zhou, Jian,Zhu, Rui,Deng, Jin,Fu, Yao
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p. 3974 - 3980
(2018/09/11)
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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 00386
(2017/09/05)
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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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- Highly efficient transformation of Γ-valerolactone to valerate esters over structure-controlled copper/zirconia catalysts prepared via a reduction-oxidation route
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Design and development of novel and efficient catalysts are crucial but challenging for the catalytic conversion of biomass and derivatives to fuels and chemicals. In this paper, a novel separate nucleation and aging steps assistant reduction-oxidation strategy was developed to synthesis CuO/ZrO2 complex precursor with homogeneously distributed Cu and Zr components, which can be used as an ideal precursor for the synthesis of highly dispersed Cu/ZrO2 catalyst. Characterization results revealed that homogeneous dispersion of CuO, high surface area of ZrO2 support with controlled porous structure, and strong interaction between CuO and ZrO2 in CuO/ZrO2 precursor could lead to the enhanced Cu dispersion and the formation of Cu+ active centers. The synthesized Cu/ZrO2 catalysts exhibited excellent catalytic performance (85.4% conversion of GVL and 98.0% selectivity of pentyl valerate) in the catalytic transformation of GVL to valerate esters, more efficient than that of Cu/ZrO2-CP and Cu/ZrO2-CH catalysts prepared via co-precipitation and chemisorption hydrolysis methods, respectively. The superior catalytic performance was mainly attributed to both the cooperation of Cu0 and Cu+ species and the highly dispersed surface Cu0, thereby improving the adsorption and polarization of C[dbnd]O bond in GVL and the following dissociation of H2 to produce active hydrogen for the hydrogenation step during the catalytic transformation of GVL. Moreover, such copper-based catalysts exhibited potential applications in the exploitation and utilization of biomass resources with significantly enhanced efficiency.
- Liu, Shanshan,Fan, Guoli,Yang, Lan,Li, Feng
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p. 180 - 188
(2017/07/10)
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- A levulinic acid by the method of preparation valeric acid and pentanoate (by machine translation)
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The present invention provides a process for preparing valeric acid and by levulinic acid formylvalerate ester, to levulinic acid as a starting material, the hydrogenation catalyst and trifluoromethanesulfonic acid metal salt as a catalyst, the hydrogen atmosphere catalytic hydrogenolysis reaction, to obtain the valeric acid, continue to valeric acid as the raw material, trifluoromethanesulfonic acid metal salt as catalyst, adding alcohol compound to carry out the esterification reaction, to obtain pentanoate. The invention described in the laevulinic acid preparation valeric acid and formylvalerate ester, it has simple process, mild reaction conditions, high product yield, easy to be purified, environment-friendly and the like, and is suitable for large-scale industrial production. (by machine translation)
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Paragraph 0055-0057
(2017/08/30)
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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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- Non-plasmonic metal nanoparticles as visible light photocatalysts for the selective oxidation of aliphatic alcohols with molecular oxygen at near ambient conditions
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Nanoparticles (NPs) of Pd and Pt were used for the selective oxidation of aliphatic alcohols with molecular oxygen as an oxidant at near ambient temperatures under visible light irradiation. Distinct final products were obtained under identical reaction conditions, aliphatic esters formed over the Pd NPs while aldehydes formed over the Pt NPs. The reason for this different product selectivity is proven to be due to the much stronger interaction of Pd NPs with alcohol and aldehyde compared to Pt NPs. The photocatalytic activity is tuneable by light intensity or a moderate change in the reaction temperature.
- Tana, Tana,Guo, Xiao-Wei,Xiao, Qi,Huang, Yiming,Sarina, Sarina,Christopher, Phillip,Jia, Jianfeng,Wu, Haishun,Zhu, Huaiyong
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p. 11567 - 11570
(2016/10/03)
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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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- 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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p. 331 - 343
(2016/07/06)
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- 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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- Catalytic Ester Metathesis Reaction and Its Application to Transfer Hydrogenation of Esters
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We report a Ru-complex-catalyzed ester metathesis reaction where an unsymmetrical ester such as ethyl hexanoate can be transformed to a mixture of starting material, hexyl ethanoate, ethyl acetate, and hexyl hexanoate in equal proportions, as expected from a classical metathesis reaction with 0.2 mol % catalyst. A 20× excess of low boiling alcohol, such as ethanol, allows for the transfer of an acyl moiety to the sacrificial low boiling ethyl acetate product, while significantly increasing the functional group tolerance and substrate scope; yields of alcohols can reach 90%, which represents an attractive alternative to current high H2 pressure hydrogenation protocols for Ru-based ester reduction chemistry. Both reactions have not been reported previously in the field of Ru-catalyzed transformations of the ester functionality.
- Dubey, Abhishek,Khaskin, Eugene
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p. 3998 - 4002
(2016/07/06)
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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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- Direct macrolactonization of seco acids via hafnium(IV) catalysis
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Efficient direct macrolactonization of seco acids can be catalyzed by Hf(OTf)4 in high yields, forming water as the sole byproduct. The Hf(OTf)4 catalyst possesses unique reactivity characteristics relative to other Lewis acids, as it promotes macrolactonization over hydrolysis even in the presence of excess water. In addition to forming a variety of macrolactones and benzolactones (55-90%), intermolecular direct esterifications of carboxylic acids and alcohols were also possible and demonstrated compatibility with common carbamate, silyl ether, alkoxymethyl ether, and acetal protecting groups. All of the macrolactonization and esterification processes developed are operationally simple, "one-pot" reactions that exploit a commercially available catalyst without the need for slow addition or azeotropic techniques.
- De Léséleuc, Mylene,Collins, Shawn K.
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p. 1462 - 1467
(2015/03/14)
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- Catalytic transformation of aliphatic alcohols to corresponding esters in o2 under neutral conditions using visible-light irradiation
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Selective oxidation of aliphatic alcohols under mild and base-free conditions is a challenging process for organic synthesis. Herein, we report a one-pot process for the direct oxidative esterification of aliphatic alcohols that is significantly enhanced by visible-light irradiation at ambient temperatures. The new methodology uses heterogenerous photocatalysts of gold-palladium alloy nanoparticles on a phosphate-modified hydrotalcite support and molecular oxygen as a benign oxidant. The alloy photocatalysts can absorb incident light, and the light-excited metal electrons on the surface of metal nanoparticles can activate the adsorbed reactant molecules. Tuning the light intensity and wavelength of the irradiation can remarkably change the reaction activity. Shorter wavelength light (550 nm) drives the reaction more efficiently than light of longer wavelength (e.g., 620 nm), especially at low temperatures. The phosphate-exchanged hydrotalcite support provides sufficient basicity (and buffer) for the catalytic reactions; thus, the addition of base is not required. The photocatalysts are efficient and readily recyclable. The findings reveal the first example of using "green" oxidants and light energy to drive direct oxidative esterification of aliphatic alcohols under base-free, mild conditions.
- Xiao, Qi,Liu, Zhe,Bo, Arixin,Zavahir, Sifani,Sarina, Sarina,Bottle, Steven,Riches, James D.,Zhu, Huaiyong
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p. 1956 - 1966
(2015/03/04)
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- An extracellular solvent stable alkaline lipase from Pseudomonas sp. DMVR46: Partial purification, characterization and application in non-aqueous environment
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The biosynthesis of esters is currently of much commercial interest because of the increasing popularity and demand for natural products among consumers. Biotransformation and enzymatic methods of ester synthesis are more effective when performed in non-aqueous media. In present study, an organic solvent stable Pseudomonas sp. DMVR46 lipase was partially purified by acetone precipitation and ion exchange chromatography with 28.95-fold purification. The molecular mass of the lipase was found to be ~32 kDa. The partially purified lipase was optimally active at 37 °C and pH 8.5. The enzyme showed greater stability toward organic solvents such as isooctane, cyclohexane and n-hexane retaining more than 70% of its initial activity. The metal ions such as Ca2+, Ba2+ and Mg2+ had stimulatory effects on lipase activity, whereas Co2+ and Zn2+ strongly inhibited the activity. Also lipase exhibited variable specificity/hydrolytic activity toward different 4-nitrophenyl esters. DMVR46 lipase was further immobilized into AOT-based organogels used for the synthesis of flavor ester pentyl valerate in presence of organic solvents. The organogels showed repeated use of enzyme with meager loss of activity even upto 10 cycles. The solvent-stable lipase DMVR46 thus proved to be an efficient catalyst showing an attractive potency for application in biocatalysis under non-aqueous environment.
- Patel, Vrutika,Nambiar, Shruti,Madamwar, Datta
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p. 1673 - 1681
(2015/02/19)
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- A method for esterification reaction rate prediction of aliphatic monocarboxylic acids with primary alcohols in 1,4-dioxane based on two parametrical taft equation
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Esterification reaction rates of aliphatic monocarboxylic acids with primary alcohols in 1,4-dioxane as inert solvent were investigated. Acids were esterified with 1-propanol and alcohols with acetic acid as model reactants at a constant temperature of 60°C, at a fixed ionic strength and pH in a batch reactor with a constant volume. For evaluation of reaction rates, an exact kinetic equation for the equilibrium reaction was applied. Under these conditions and for low reactants, concentrations reaction rate depends only on the structure of reactants and, therefore, can be predicted by a correlation equation with two Taft coefficients (inductive and steric effects). From these equations, it is possible to estimate the esterification reaction rate constant for other acid-alcohol pairs. This methodology may also be suitable for other kinetic systems measured under comparable experimental conditions.
- Vojtko, Jan,Tomcik, Peter
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p. 189 - 196
(2014/02/14)
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- Well-defined iron catalysts for the acceptorless reversible dehydrogenation-hydrogenation of alcohols and ketones
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Acceptorless dehydrogenation of alcohols, an important organic transformation, was accomplished with well-defined and inexpensive iron-based catalysts supported by a cooperating PNP pincer ligand. Benzylic and aliphatic secondary alcohols were dehydrogenated to the corresponding ketones in good isolated yields upon release of dihydrogen. Primary alcohols were dehydrogenated to esters and lactones, respectively. Mixed primary/secondary diols were oxidized at the secondary alcohol moiety with good chemoselectivity. The mechanism of the reaction was investigated using both experiment and DFT calculations, and the crucial role of metal-ligand cooperativity in the reaction was elucidated. The iron complexes are also excellent catalysts for the hydrogenation of challenging ketone substrates at ambient temperature under mild H2 pressure, the reverse of secondary alcohol dehydrogenation.
- Chakraborty, Sumit,Lagaditis, Paraskevi O.,F?rster, Moritz,Bielinski, Elizabeth A.,Hazari, Nilay,Holthausen, Max C.,Jones, William D.,Schneider, Sven
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p. 3994 - 4003
(2015/01/16)
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- Facile and efficient gold-catalyzed aerobic oxidative esterification of activated alcohols
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A facile and efficient methodology is presented for the direct oxidative esterification of alcohols with alcohols catalyzed by NaAuCl4. Just in the presence of a low catalytic amount of base additive, the newly developed catalytic system proceeds with high selectivity and broad substrate scope under mild conditions with dioxygen or air as the environmentally benign terminal oxidant. Various alcohols including benzylic and allylic alcohols were smoothly reacted with methanol and even with long-chain aliphatic alcohols, affording the desired products in good to excellent yields (up to 95% yield). The present system showed high catalytic activity with a TOF up to 219 h-1. Kinetic studies of the reaction process provide fundamental insights into the catalytic pathway, and a possible reaction pathway was proposed based on the results of the control experiments. XPS, TEM, and UV-vis were carried out to characterize the chemical state of the Au catalyst in the present catalytic system. The results indicate that the Au nanoparticles were generated in situ and supported on K2CO3, forming a simple, recyclable and selective catalyst system for the direct oxidative esterification of alcohols. the Partner Organisations 2014.
- Wang, Lianyue,Li, Jun,Dai, Wen,Lv, Ying,Zhang, Yi,Gao, Shuang
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p. 2164 - 2173
(2014/04/17)
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- New generation biofuels: γ-Valerolactone into valeric esters in one pot
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Ethyl valerate and pentyl valerate, suitable as a gasoline additive and diesel component respectively, can be obtained in a one pot one step reaction from γ-valerolactone, readily available from lignocellulosic biomass. The reaction takes place in ethanol under H2 through nucleophilic addition of the alcohol to the carboxylic group giving hydroxypentanoate, dehydration to pentenoate and hydrogenation to the saturated ester. The bifunctional catalyst used consists of a non noble metal, namely copper, supported on an amorphous weakly acidic material, therefore representing an interesting alternative to Pt-zeolite catalysts. Pentyl valerate can be obtained in one pot with conversions >90% and selectivity up to 83%.
- Chan-Thaw, Carine E.,Marelli, Marcello,Psaro, Rinaldo,Ravasio, Nicoletta,Zaccheria, Federica
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p. 1302 - 1306
(2013/03/29)
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- Electroorganic synthesis of esters and ketones at the platinum anode in aqueous medium
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Elcctroorganic synthesis of esters from the saturated primary aliphatic alcohols and ketones from the secondary aliphatic alcohols have been carried out in electrooxidation at the platinum anode in aqueous medium. This is an important reaction because of high oxidation potential of alcohols. Electrochemical oxidation has been carried out under controlled potential electrolysis at room temperature in a three electrode cell assembly containing two platinum electrodes In the form of square plates as working as well as counter electrode and saturated calomel electrode was used as a reference electrode. The structures of compounds were confirmed from the IR, NMR, inass spectral and microanalyses. The products formed during the electrooxidation of ethanol, propanol, 1-butanol, 1-pentanol, 2-butanol and sec-butyl alcohol are reported here.
- Kumar, Sanjeev
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p. 739 - 744
(2013/08/23)
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- Ruthenium-catalyzed self-coupling of primary and secondary alcohols with the liberation of dihydrogen
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The dehydrogenative self-condensation of primary and secondary alcohols has been studied in the presence of RuCl2(IiPr)(p-cymene). The conversion of primary alcohols into esters has been further optimized by using magnesium nitride as an additive, which allows the reaction to take place at a temperature and catalyst loading lower than those described previously. Secondary alcohols were dimerized into racemic ketones by a dehydrogenative Guerbet reaction with potassium hydroxide as the additive. The transformation gave good yields of the ketone dimers with a range of alkan-2-ols, whereas more substituted secondary alcohols were unreactive. The reaction proceeds by dehydrogenation to the ketone, followed by an aldol reaction and hydrogenation of the resulting enone.
- Makarov, Ilya S.,Madsen, Robert
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supporting information
p. 6593 - 6598
(2013/07/26)
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- Selective oxidation of alcohols to esters using heterogeneous Co 3O4-N@C catalysts under mild conditions
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Novel cobalt-based heterogeneous catalysts have been developed for the direct oxidative esterification of alcohols using molecular oxygen as benign oxidant. Pyrolysis of nitrogen-ligated cobalt(II) acetate supported on commercial carbon transforms typical homogeneous complexes to highly active and selective heterogeneous Co3O4-N@C materials. By applying these catalysts in the presence of oxygen, the cross and self-esterification of alcohols to esters proceeds in good to excellent yields.
- Jagadeesh, Rajenahally V.,Junge, Henrik,Pohl, Marga-Martina,Radnik, Joerg,Brueckner, Angelika,Beller, Matthias
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supporting information
p. 10776 - 10782
(2013/08/23)
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- Catalytic conversion of biomass-derived levulinic acid to valerate esters as oxygenated fuels using supported ruthenium catalysts
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The development of the catalytic conversion of biomass-based platform molecules into oxygenated fuel molecules is of great significance in order to reduce the dependence on fossil resources and to solve environmental problems. Alkyl valerate esters were proven to have the potential to be renewable additives of gasoline and diesel. In this work, we studied the hydrogenation of levulinic acid (LA) to valerate esters over supported Ru catalysts, and found that the acidity was an important factor for the catalyst performance. A bifunctional catalyst Ru/SBA-SO3H was developed as an active catalyst, and a highest yield of 94% to ethyl valerate (EV) was achieved. The catalyst was characterized by nitrogen adsorption/desorption methods, X-ray power diffraction (XRD), transmission electron spectroscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The effects of reaction conditions were comprehensively investigated and probable reaction pathways were proposed and verified. The conversion of LA to various alkyl valerate esters can also be catalyzed by the bifunctional catalyst. In addition, supported Cu and Ni catalysts were also screened under similar reaction conditions as Ru-based catalysts, and the combination of Ni/SBA-15 and SBA-SO3H exhibited activity for the conversion of LA to EV.
- Pan, Tao,Deng, Jin,Xu, Qing,Xu, Yang,Guo, Qing-Xiang,Fu, Yao
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p. 2967 - 2974
(2013/10/08)
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- PHOSPHO-AMINO PINCER-TYPE LIGANDS AND CATALYTIC METAL COMPLEXES THEREOF
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The present invention provides phospho-amino pincer-type ligands, metal complexes thereof, and catalytic methods comprising such metal complexes.
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Page/Page column 10
(2013/02/27)
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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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experimental part
p. 75 - 83
(2011/11/05)
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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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experimental part
p. 5208 - 5211
(2012/09/05)
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- Selective acceptorless conversion of primary alcohols to acetals and dihydrogen catalyzed by the ruthenium(II) complex Ru(PPh3) 2(NCCH3)2(SO4)
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The complex bis(acetonitrile)bis(triphenylphosphine)ruthenium(II) sulfate [Ru(PPh3)2(NCCH3)2(SO4)], fully characterized spectroscopically and by a single crystal X-ray study, catalyzes at 110 °C the direct transformation of primary alcohols to the corresponding acetals with liberation of molecular hydrogen. The formation of acetals proceeds via direct substitution of the hydroxy group of the hemiacetal intermediate by an alcohol molecule. The closely related bis(triphenylphosphine) ruthenium(II) acetate [Ru(PPh3)2(OAc)2] catalyzes the conversion of primary alcohols to the corresponding esters rather than acetals. Copyright
- Kossoy, Elizaveta,Diskin-Posner, Yael,Leitus, Gregory,Milstein, David
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experimental part
p. 497 - 504
(2012/04/23)
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- Dehydrogenative coupling of primary alcohols to form esters catalyzed by a ruthenium N-heterocyclic carbene complex
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The ruthenium complex [RuCl2(IiPr)(p-cymene)] catalyzes the direct condensation of primary alcohols into esters and lactones with the release of hydrogen gas. The reaction is most effective with linear aliphatic alcohols and 1,4-diols and is believed to proceed with a ruthenium dihydride as the catalytically active species.
- Solvhoj, Amanda,Madsen, Robert
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experimental part
p. 6044 - 6048
(2012/01/13)
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- PROCESS FOR PREPARING AN ESTER
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A process for preparing an ester of formula (I): R3CH2- (CR1R2)n-CH2-O-CO-(CR1R2)n-CH2R3 (I) wherein n is 1-3 and R1 and R2 are each, independently, a hydrogen atom or a carbon-linked organic group and R3 is a carbon-linked organic group, by hydrogenation of a reactant selected from: (a) a lactone of formula (II) wherein n is 1-3 and R1 and R2 are each, independently, a hydrogen atom or a carbon-linked organic group and R3 is a carbon-linked organic group; (b) an ester of a carboxylic acid of formula (III) R4-O-CO- (CR1R2)n-CO-R3 (III) wherein n is 1-3 and R1 and R2 are each, independently, a hydrogen atom or a carbon-linked organic group and R3 and R4 are a carbon-linked organic group; and c) a carboxylic acid of formula (IV) H-O-CO- (CR1R2)n-CO-R3 (IV) wherein n is 1-3 and R1 and R2 are each, independently, a hydrogen atom or a carbon-linked organic group and R3 is a carbon-linked organic group; which process involves contacting the reactant with a heterogeneous catalyst comprising a hydrogenating metal in the presence of hydrogen, wherein the catalyst is a zeolite-free heterogeneous catalyst comprising a hydrogenating metal supported on a metal oxide or a mixed oxide.
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Page/Page column 9-12
(2011/02/24)
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- Rhodium(III)-catalyzed dimerization of aldehydes to esters
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No sooner said than done: A rhodi- um(III) hydride complex is an outstandingly effective and selective catalyst for the dimerization of aldehydes to the corresponding esters (see scheme). Evidence for an unusual mechanism in catalysis by rhodium is given.
- Tejel, Cristina,Ciriano, Miguel A.,Passarelli, Vincenzo
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experimental part
p. 91 - 95
(2011/03/21)
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- Valeric biofuels: A platform of cellulosic transportation fuels
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(Chemical equation presented) Fueling the future: Valeric esters can be produced by acid hydrolysis of lignocellulose to levulinic acid, followed by hydrogenation to valeric acid and its subsequent esterification (see scheme). Valeric biofuels are fully compatible for blending with gasoline or diesel, and have passed a road trial of 250 000 km.
- Lange, Jean-Paul,Price, Richard,Ayoub, Paul M.,Louis, Jurgen,Petrus, Leo,Clarke, Lionel,Gosselink, Hans
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supporting information; experimental part
p. 4479 - 4483
(2010/08/21)
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- PROCESS FOR PREPARING AMIDES FROM ALCOHOLS AND AMINES
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The present invention provides a process for preparing amides, by reacting a primary amine and a primary alcohol in the presence of a Ruthenium catalyst, to generate the amide and molecular hydrogen. According to the process of the invention, primary amines are directly acylated by equimolar amounts of alcohols to produce amides and molecular hydrogen (the only byproduct) in high yields and high turnover numbers. This reaction is catalyzed by a Ruthenium complex, which is preferably based on a dearomatized PNN-type ligand of formula A1 or precursors thereof of formulae A2 or A3. Use of diamines in the reaction leads to bis-amides, whereas with a mixed primary/secondary amine substrate, chemoselective acylation of the primary amine group occurs.
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Page/Page column 7-8; 11
(2009/05/28)
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- PROCESS FOR CONVERTING LEVULINIC ACID INTO PENTANOIC ACID
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A process for converting levulinic acid into pentanoic acid, the process comprising the following steps: (a) contacting a feedstock comprising levulinic acid under hydrogenating conditions, in the presence of hydrogen, with a non-acidic heterogeneous hydrogenation catalyst comprising a hydrogenation metal supported on a solid catalyst carrier to obtain a first effluent comprising gamma valerolactone; (b) contacting at least part of the first effluent under hydrogenating conditions, in the presence of hydrogen, with a strongly acidic catalyst and a hydrogenation metal to obtain a second effluent comprising pentanoic acid, wherein step (b) is operated at a conversion per pass of at most 70 wt% to obtain the second effluent comprising pentanoic acid and unconverted gamma valerolactone, and wherein part of the unconverted gamma valerolactone is recycled to step (a) and/or step (b).
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Page/Page column 14-20
(2009/01/20)
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- Solvent-free oxidation of aliphatic alcohols with ceric ammonium nitrate-lithium bromide system
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Esters are formed during the solvent-free oxidation of primary aliphatic C5-C9 alcohols with Ce(NH4)2(NO 3)6-LiBr, whereas secondary octan-2-ol gives a mixture of isomeric 1-and 3-bromooctan-2-ones.
- Kapustina,Sokova,Gasanov,Nikishin
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p. 1501 - 1506
(2008/09/19)
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- Oxidative dimerization of primary alcohols to esters catalyzed by iridium complexes
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Primary alcohols undergo efficiently oxidative dimerization by iridium complexes under air without any solvent to form esters in fair to good yields. For instance, the reaction of 1-dodecanol in the presence of [IrCl(coe)2]2 (3 mol %) at 95 °C for 15 h produced dodecyl dodecanoate in 91% isolated yield. This is the first successful Ir-catalyzed oxidative dimerization of primary alcohols to esters using air as an oxidant. Various primary alcohols are converted to the corresponding esters in fair to good yields.
- Izumi, Aki,Obora, Yasushi,Sakaguchi, Satoshi,Ishii, Yasutaka
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p. 9199 - 9201
(2007/10/03)
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