- The 3rd degree of biomimetism: Associating the cavity effect, ZnII coordination and internal base assistance for guest binding and activation
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The synthesis and characterization of a resorcinarene-based tetra(imidazole) ligand is reported. The properties of the corresponding ZnII complex are studied in depth, notably by NMR spectroscopy. In MeCN, acid-base titration reveals that one out of the four imidazole arms is hemi-labile and can be selectively protonated, thereby opening a coordination site in the exo position. Quite remarkably, the 4th imidazole arm promotes binding of an acidic molecule (a carboxylic acid, a β-diketone or acetamide), by acting as an internal base, which allows guest binding as an anion to the metal center in the endo position. Most importantly, the presence of this labile imidazole arm makes the ZnII complex active for the catalyzed hydration of acetonitrile. It is proposed that it acts as a general base for activating a water molecule in the vicinity of the metal center during its nucleophilic attack to the endo-bound MeCN substrate. This system presents a unique degree of biomimetism when considering zinc enzymes: a pocket for guest binding, a similar first coordination sphere, a coordination site available for water activation in the cis position relative to the substrate and finally an internal imidazole residue that plays the role of a general base.
- Parrot,Collin,Bruylants,Reinaud
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- Formation of singlet molecular oxygen by the Radziszewski reaction between acetonitrile and hydrogen peroxide in the absence and presence of ketones
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Measurements of the infrared phosphorescence of singlet molecular oxygen (1O2) at 1270 nm have been used to demonstrate the formation of 1O2 by the Radziszewski reaction between acetonitrile and hydrogen peroxide. The kinetics of the Radziszewski reaction either alone or in the presence of ketones have been studied by this technique. The rate-determining step of the 1O2 formation of the reaction in the absence of ketones was found to be independent of both the concentration of acetonitrile and that of hydrogen peroxide. The kinetic data, the results of the volumetric measurements of the oxygen liberated and the results of the determination of the amount of 1O2 generated by the reaction are consistent with the assumption that the reaction between acetonitrile and hydrogen peroxide occurs via the heterolytic decomposition of the intermediate, peroxyacetimidic acid (PAIA), forming 1 mol acetamide and 0.5 mol 1O2 according to the stoichiometric equation: CH3CN + H2O2 → CH3C(=O)NH2 + 0.5 1O2. The rate constant of the heterolytic decomposition of PAIA was determined to be k8 = 1.2 × 10-3 dm3 mol-1 s-1 at T = 30°C. From the measurements at different pH values in the range 9.1 a(PAIA) value was estimated to be 11.1 at T = 30°C. The investigation of the reaction between acetonitrile and hydrogen peroxide by using N,N-dimethyl-4-oxopiperidinium nitrate as catalyst, has unequivocally shown that the rate of 1O2 formation is considerably enhanced by this ketone. For the ketone-catalysed decomposition of PAIA a rate law can be derived showing a first order dependence on the concentration of acetonitrile and hydrogen peroxide at a given pH. In accordance with the observed rate law are the results with acetonitrile in 50% acetone containing a tenfold excess of hydrogen peroxide at pH 8.2 and T = 60°C.
- Brauer, Hans-Dieter,Eilers, Beate,Lange, Andreas
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- Measurement and calculation of the rate constant for the reaction of isopropyl isocyanate with hydroxyl radical
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The rate constant for the gas-phase reaction of hydroxyl radical with isopropyl isocyanate (IIC) has been measured, relative to toluene, in the T =287-321 K range at atmospheric pressure in air. Ultraviolet photolysis of methyl nitrite served as the sourc
- Parker, James K.,Espada-Jallad, Cyntia,Parker, Claudia L.,Witt, John D.
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- EXAFS/FTIR Characterization and Selective Hydration of Acetonitrile on Silica-Supported *)4V6O19>
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Silica-supported *)4V6O19 exhibited high catalytic activities in the gas-phase hydration of acetonitrile towards acetamide at 350-473 K with selectivity of over 97percent and dehydrogenation of 2-propanol to acetone.EXAFS, XPS and FTIR studies suggested that thermal evacuation of silica-supported *)4V6O19> at 473 K led to the removal of the bridged oxygen atoms in the V6O19 framework.The resulting deoxygenated samples enhanced the acetonitrile hydration, while catalyzed the dehydration of 2-propanol to propene besides the dehydrogenation reaction, probably owing to the newly generated Lewis acid site.
- Yamaguchi, Masatsugu,Shido, Takafumi,Ohtani, Hiroko,Isobe, Kiyoshi,Ichikawa, Masaru
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- Hydrolysis of N-(1-Aminoalkyl)amides
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The hydrolysis of the title compounds involves the expulsion of an amide anion as a leaving group at basic pH, and probably an amide enol (imidoacid) as a leaving group at acidic pH.
- Loudon, G. Marc,Jacob, James
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- Catalytic hydration of benzonitrile and acetonitrile using nickel(0)
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The homogeneous catalytic hydration of benzo- and acetonitrile under thermal conditions was achieved using nickel(0) compounds of the type [(dippe)Ni(η2-NCR)] with R = phenyl or methyl (compounds 1 and 2, respectively), as the specific starting intermediates. Alternatively, the complexes may be prepared in situ by direct reaction of the precursor [(dippe)NiH]2 (3) with the respective nitrile. Hydration appears to occur homogeneously, as tested by mercury drop experiments, producing benzamide and acetamide, respectively. Addition of Bu4NI did not lead to catalysis inhibition, suggesting the prevalence of Ni(0) intermediates during catalysis. Hydration using analogous complexes of 3, such as [(dtbpe)NiH] 2 (4) and [(dcype)NiH]2 (5) was also addressed.
- Crestani, Marco G.,Arevalo, Alma,Garcia, Juventino J.
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- Unmasking the Action of Phosphinous Acid Ligands in Nitrile Hydration Reactions Catalyzed by Arene-Ruthenium(II) Complexes
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The catalytic hydration of benzonitrile and acetonitrile has been studied by employing different arene-ruthenium(II) complexes with phosphinous (PR2OH) and phosphorous acid (P(OR)2OH) ligands as catalysts. Marked differences in activity were found, depending on the nature of both the P-donor and η6-coordinated arene ligand. Faster transformations were always observed with the phosphinous acids. DFT computations unveiled the intriguing mechanism of acetonitrile hydration catalyzed by these arene-ruthenium(II) complexes. The process starts with attack on the nitrile carbon atom of the hydroxyl group of the P-donor ligand instead of on a solvent water molecule, as previously suggested. The experimental results presented herein for acetonitrile and benzonitrile hydration catalyzed by different arene-ruthenium(II) complexes could be rationalized in terms of such a mechanism.
- Tomás-Mendivil, Eder,Cadierno, Victorio,Menéndez, María I.,L?pez, Ram?n
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- Hydrolysis of Acetonitrile, Catalyzed by Octaacetatotetraplatinum(II). - High Reactivity of Coordination Sites Trans to the Pt-Pt Bond -
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The platinum(II) cluster, , catalyzes the hydrolysis of acetonitrile to acetamide in acetonitrile-water mixtures.Typical turnover number was 104 mol h-1 at 80 deg C.The catalyst was slowly deactivated by the accumulation of the less active acetamide-substituted species, as well as by its decomposition.
- Yamaguchi, Tadashi,Adachi, Hisako,Ito, Tasuku,Sasaki, Yoichi
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- Half-Sandwich Iridium Complexes Based on β-Ketoamino Ligands: Preparation, Structure, and Catalytic Activity in Amide Synthesis
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A series of β-ketoamino-based N,O-chelate half-sandwich iridium complexes with the general formula [Cp*IrClL] have been prepared in good yields. These air-insensitive iridium complexes showed desirable catalytic activity in an amide preparation under mild conditions. A number of amides with diverse substituted groups were furnished in a one-pot reaction with good-to-excellent yields through an amidation reaction of NH2OH·HCl with aldehydes in the presence of these iridium(III) precursors. The excellent catalytic activity, mild reaction conditions, and broad substrate scope gave this type of iridium catalyst potential for use in industry. All of the obtained iridium complexes were well characterized by different spectroscopy techniques. The exact molecular structure of complex 3 has been confirmed by single-crystal X-ray analysis.
- Wang, Yang,Guo, Wen,Guan, Ai-Lin,Liu, Shuang,Yao, Zi-Jian
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p. 11514 - 11520
(2021/07/31)
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- Hydration of Aliphatic Nitriles Catalyzed by an Osmium Polyhydride: Evidence for an Alternative Mechanism
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The hexahydride OsH6(PiPr3)2 competently catalyzes the hydration of aliphatic nitriles to amides. The main metal species under the catalytic conditions are the trihydride osmium(IV) amidate derivatives OsH3{κ2-N,O-[HNC(O)R]}(PiPr3)2, which have been isolated and fully characterized for R = iPr and tBu. The rate of hydration is proportional to the concentrations of the catalyst precursor, nitrile, and water. When these experimental findings and density functional theory calculations are combined, the mechanism of catalysis has been established. Complexes OsH3{κ2-N,O-[HNC(O)R]}(PiPr3)2 dissociate the carbonyl group of the chelate to afford κ1-N-amidate derivatives, which coordinate the nitrile. The subsequent attack of an external water molecule to both the C(sp) atom of the nitrile and the N atom of the amidate affords the amide and regenerates the κ1-N-amidate catalysts. The attack is concerted and takes place through a cyclic six-membered transition state, which involves Cnitrile···O-H···Namidate interactions. Before the attack, the free carbonyl group of the κ1-N-amidate ligand fixes the water molecule in the vicinity of the C(sp) atom of the nitrile.
- Babón, Juan C.,Esteruelas, Miguel A.,López, Ana M.,O?ate, Enrique
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p. 7284 - 7296
(2021/05/29)
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- Manganese-Pincer-Catalyzed Nitrile Hydration, α-Deuteration, and α-Deuterated Amide Formation via Metal Ligand Cooperation
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A simple and efficient system for the hydration and α-deuteration of nitriles to form amides, α-deuterated nitriles, and α-deuterated amides catalyzed by a single pincer complex of the earth-abundant manganese capable of metal-ligand cooperation is reported. The reaction is selective and tolerates a wide range of functional groups, giving the corresponding amides in moderate to good yields. Changing the solvent from tert-butanol to toluene and using D2O results in formation of α-deuterated nitriles in high selectivity. Moreover, α-deuterated amides can be obtained in one step directly from nitriles and D2O in THF. Preliminary mechanistic studies suggest the transformations contributing toward activation of the nitriles via a metal-ligand cooperative pathway, generating the manganese ketimido and enamido pincer complexes as the key intermediates for further transformations.
- Ben-David, Yehoshoa,Diskin-Posner, Yael,Kar, Sayan,Milstein, David,Zhou, Quan-Quan,Zou, You-Quan
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p. 10239 - 10245
(2021/08/24)
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- A CO2-mediated base catalysis approach for the hydration of triple bonds in ionic liquids
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Herein, we report a CO2-mediated base catalysis approach for the activation of triple bonds in ionic liquids (ILs) with anions that can chemically capture CO2 (e.g., azolate, phenolate, and acetate), which can achieve hydration of triple bonds to carbonyl chemicals. It is discovered that the anion-complexed CO2 could abstract one proton from proton resources (e.g., IL cation) and transfer it to the CN or CC bonds via a six-membered ring transition state, thus realizing their hydration. In particular, tetrabutylphosphonium 2-hydroxypyridine shows high efficiency for hydration of nitriles and CC bond-containing compounds under a CO2 atmosphere, affording a series of carbonyl compounds in excellent yields. This catalytic protocol is simple, green, and highly efficient and opens a new way to access carbonyl compounds via triple bond hydration under mild and metal-free conditions.
- Han, Buxing,Ke, Zhengang,Li, Ruipeng,Liu, Zhimin,Tang, Minhao,Wang, Yuepeng,Zeng, Wei,Zhang, Fengtao,Zhao, Yanfei
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supporting information
p. 9870 - 9875
(2021/12/27)
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- Metal-Free Solvent Promoted Oxidation of Benzylic Secondary Amines to Nitrones with H2O2
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An environmentally benign protocol for the generation of nitrones from benzylic secondary amines via catalyst-free oxidation of secondary amines using H2O2 in MeOH or CH3CN is described. This methodology provides a selective access to a variety of C-aryl nitrones in yields of 60 to 93%. Several studies have been performed to shed light on the reaction mechanism and the role of the solvent.
- Adrio, Javier,Amarante, Giovanni Wilson,Granato, álisson Silva
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p. 13817 - 13823
(2021/10/01)
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- Product selectivity controlled by manganese oxide crystals in catalytic ammoxidation
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The performances of heterogeneous catalysts can be effectively tuned by changing the catalyst structures. Here we report a controllable nitrile synthesis from alcohol ammoxidation, where the nitrile hydration side reaction could be efficiently prevented by changing the manganese oxide catalysts. α-Mn2O3 based catalysts are highly selective for nitrile synthesis, but MnO2-based catalysts including α, β, γ, and δ phases favour the amide production from tandem ammoxidation and hydration steps. Multiple structural, kinetic, and spectroscopic investigations reveal that water decomposition is hindered on α-Mn2O3, thus to switch off the nitrile hydration. In addition, the selectivity-control feature of manganese oxide catalysts is mainly related to their crystalline nature rather than oxide morphology, although the morphological issue is usually regarded as a crucial factor in many reactions.
- Hui, Yu,Luo, Qingsong,Qin, Yucai,Song, Lijuan,Wang, Hai,Wang, Liang,Xiao, Feng-Shou
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p. 2164 - 2172
(2021/09/20)
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- Half-Sandwich Iridium Complexes for the One-Pot Synthesis of Amides: Preparation, Structure, and Diverse Catalytic Activity
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Several types of air-stable N,O-coordinate half-sandwich iridium complexes containing Schiff base ligands with the general formula [Cp*IrClL] were synthesized in good yields. These stable iridium complexes displayed a good catalytic efficiency in amide synthesis. A variety of amides with different substituents were obtained in a one-pot procedure with excellent yields and high selectivities through the amidation of aldehydes with NH2OHHCl and nitrile hydration under the catalysis of complexes 1-4. The excellent and diverse catalytic activity, mild conditions, broad substance scope, and environmentally friendly solvent make this system potentially applicable in industrial production. Half-sandwich iridium complexes 1-4 were characterized by NMR, elemental analysis, and IR techniques. Molecular structures of complexes 2 and 3 were confirmed by single-crystal X-ray analysis.
- Fan, Xiao-Nan,Deng, Wei,Liu, Zhen-Jiang,Yao, Zi-Jian
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p. 16582 - 16590
(2020/11/13)
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- Catalyst, preparation method thereof and preparation method of amide compound
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The invention relates to a catalyst, a preparation method thereof, and a preparation method for hydrating nitrile groups into amides. The catalyst is used for catalyzing nitrile groups to be hydratedinto amides, and the structural general formula of the catalyst is shown in the specification. In the formula, a plurality of R are respectively and independently ones selected from aromatic groups, heteroaromatic groups and non-aromatic ring groups; a plurality of R are ones respectively and independently selected from linear alkyl groups and alkane aromatic groups; X is one selected from Cl and Br; and L is one selected from OTf, BF4, PF6 and SbF6. The catalyst can catalyze nitrile groups to be hydrated into amides, and the nitrile groups can be catalyzed to be hydrated into amides even at a low temperature (20-80 DEG C); besides, compared with existing common catalysts for catalyzing nitrile groups to be hydrated into amides, the catalyst has the advantages that the equivalent weight of the catalyst can be obviously reduced, and nitrile groups can reach a relatively high conversion rate when the equivalent weight of the catalyst is only 0.01 mol%-0.5 mol%; and meanwhile, the catalyst is wider in application range and can catalyze various nitrile compounds to be hydrated into amide compounds.
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Paragraph 0142-0146
(2020/01/12)
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- Arene-ruthenium(II)-phosphine complexes: Green catalysts for hydration of nitriles under mild conditions
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Three new arene-ruthenium(II) complexes were prepared by treating [{RuCl(μ-Cl)(η6-arene)}2] (η6-arene = p-cymene) dimer with tri(2-furyl)phosphine (PFu3) and 1,3,5-triaza-7-phosphaadamantane (PTA), respectively to obtain [RuCl2(η6-arene)PFu3] [Ru]-1, [RuCl(η6-arene)(PFu3)(PTA)]BF4 [Ru]-2 and [RuCl(η6-arene)(PFu3)2]BF4 [Ru]-3. All the complexes were structurally identified using analytical and spectroscopic methods including single-crystal X-ray studies. The effectiveness of resulting complexes as potential homogeneous catalysts for selective hydration of different nitriles into corresponding amides in aqueous medium and air atmosphere was explored. There was a remarkable difference in catalytic activity of the catalysts depending on the nature and number of phosphorus-donor ligands and sites available for catalysis. Experimental studies performed using structural analogues of efficient catalyst concluded a structural-activity relationship for the higher catalytic activity of [Ru]-1, being able to convert huge variety of aromatic, heteroaromatic and aliphatic nitriles. The use of eco-friendly water as a solvent, open atmosphere and avoidance of any organic solvent during the catalytic reactions prove the reported process to be truly green and sustainable.
- Vyas, Komal M.,Mandal, Poulami,Singh, Rinky,Mobin, Shaikh M.,Mukhopadhyay, Suman
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- Catalytic hydration of cyanamides with phosphinous acid-based ruthenium(ii) and osmium(ii) complexes: scope and mechanistic insights
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The synthesis of a large variety of ureas R1R2NC(O)NH2 (R1 and R2 = alkyl, aryl or H; 26 examples) was successfully accomplished by hydration of the corresponding cyanamides R1R2NCN using the phosphinous acid-based complexes [MCl2(η6-p-cymene)(PMe2OH)] (M = Ru (1), Os (2)) as catalysts. The reactions proceeded cleanly under mild conditions (40-70 °C), in the absence of any additive, employing low metal loadings (1 molpercent) and water as the sole solvent. In almost all the cases, the osmium complex 2 featured a superior reactivity in comparison to that of its ruthenium counterpart 1. In addition, for both catalysts, the reaction rates observed for the hydration of the cyanamide substrates were remarkably faster than those involving classical aliphatic and aromatic nitriles. Computational studies allowed us to rationalize all these trends. Thus, the calculations indicated that the presence of a nitrogen atom directly linked to the CN bond depopulates electronically the nitrile carbon by inductive effect when coordinated to the metal center, thus favouring the intramolecular nucleophilic attack of the OH group of the phosphinous acid ligand to this carbon. On the other hand, the higher reactivity of Os vs. Ru seems to be related with the lower ring strain on the incipient metallacycle that starts to form in the transition state associated with this key step in the catalytic cycle. Indirect experimental evidence of the generation of the metallacyclic intermediates was obtained by studying the reactivity of [RuCl2(η6-p-cymene)(PMe2OH)] (1) towards dimethylcyanamide in methanol and ethanol. The reactions afforded compounds [RuCl(η6-p-cymene)(PMe2OR)(NCNMe2)][SbF6] (R = Me (5a), Et (5b)), resulting from the alcoholysis of the metallacycle, which could be characterized by single-crystal X-ray diffraction. This journal is
- álvarez, Daniel,Cadierno, Victorio,Crochet, Pascale,González-Fernández, Rebeca,López, Ramón,Menéndez, M. Isabel
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p. 4084 - 4098
(2020/07/09)
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- Exploiting Chitin as a Source of Biologically Fixed Nitrogen: Formation and Full Characterization of Small-Molecule Hetero- And Carbocyclic Pyrolysis Products
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Pyrolysis of variously pretreated or untreated samples of chitin (1) and certain congeners at 150-350 °C afforded a range of platform molecules, as exemplified by compounds 4, 5, 6, 8, 12 and 13. All of these products have been fully characterized, including by single-crystal X-ray analysis. Pathways for the formation of them are proposed and theoretical studies of certain aspects of these described.
- Nikahd, Maryam,Mikusek, Jiri,Yu, Li-Juan,Coote, Michelle L.,Banwell, Martin G.,Ma, Chenxi,Gardiner, Michael G.
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p. 4583 - 4593
(2020/05/08)
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- Appraisal of Ruthenium(II)complexes of (4-phenoxyphenylazo)ligands for the synthesis of primary amides by dint of hydroxylamine hydrochloride and aldehydes
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A new family of O, N donor-functionalized (4-phenoxyphenylazo)-2-naphthol/4-substituted phenol-based ligands (HL1-HL4)has been synthesized. The prepared ligands were successfully utilized for the access of a series of ruthenium(II)carbonyl complexes of the type [Ru(L)Cl(CO)(EPh3)3](E = phosphine/arsine), (L = 1-(4-phenoxyphenylazo)-2-naphthol (HL1), 2-(4-phenoxyphenylazo)-4-chlorophenol (HL2), 2-(4-phenoxyphenylazo)-4-methylphenol (HL3)and 2-(4-phenoxyphenylazo)-4-methoxyphenol (HL4)). All of the ruthenium(II)carbonyl complexes and ligands have been fully characterized by FT-IR, UV–visible, 1H NMR, 31P NMR, mass spectrometry and CHN analysis. The ligands have been analyzed by 13C NMR. The UV–visible spectroscopic study reveals that both the ligands and Ru(II)complexes exhibit excellent charge transfer transitions. This is the basic criteria for the oxidative amidation reaction, which is an influential strategy for the transformation of oxygenated organic compounds to the profitable amides. However, this catalytic process makes more impact on the application of new divalent ruthenium(II)azo compounds as catalyst in a single-pot conversion of aldehydes to amides in the presence of NaHCO3.
- Vinoth, Govindasamy,Indira, Sekar,Bharathi, Madheswaran,Sounthararajan, Muniyan,Sakthi, Dharmalingam,Bharathi, Kuppannan Shanmuga
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- Metal-free nitrogen -doped carbon nanosheets: A catalyst for the direct synthesis of imines under mild conditions
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Herein, a highly stable, porous, multifunctional and metal-free catalyst was developed, which exhibited significant catalytic performance in the oxidation of amines and transfer hydrogenation of nitriles under mild conditions; this could be attributed to the presence of numerous active sites and their outstanding BET surface area. The obtained results showed that most of the yields of imines exceeded 90%, and the cycling performance of the catalyst could be at least seven runs without any decay in the reaction activity, which could be comparable to those of metal catalysts. Subsequently, a kinetic study has demonstrated that the apparent activation energy for the direct synthesis of imines from amines is 67.39 kJ mol-1, which has been performed to testify that the catalytic performances are rational. Via catalyst characterizations and experimental data, graphitic-N has been proven to be the active site of the catalyst. Hence, this study is beneficial to comprehend the mechanism of action of a metal-free N-doped carbon catalyst in the formation of imines.
- Wang, Kaizhi,Jiang, Pengbo,Yang, Ming,Ma, Ping,Qin, Jiaheng,Huang, Xiaokang,Ma, Lei,Li, Rong
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p. 2448 - 2461
(2019/05/17)
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- Hydration of nitriles using a metal-ligand cooperative ruthenium pincer catalyst
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Nitrile hydration provides access to amides that are important structural elements in organic chemistry. Here we report catalytic nitrile hydration using ruthenium catalysts based on a pincer scaffold with a dearomatized pyridine backbone. These complexes catalyze the nucleophilic addition of H2O to a wide variety of aliphatic and (hetero)aromatic nitriles in tBuOH as solvent. Reactions occur under mild conditions (room temperature) in the absence of additives. A mechanism for nitrile hydration is proposed that is initiated by metal-ligand cooperative binding of the nitrile.
- Guo, Beibei,Otten, Edwin,De Vries, Johannes G.
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p. 10647 - 10652
(2019/12/02)
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- Activation of nitriles by silver(I) N-heterocyclic carbenes: An efficient on-water synthesis of primary amides
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A first example of silver(I) N-heterocyclic carbene (Ag(I)-NHC) catalyzed on-water synthesis of primary amides by hydration of nitriles under mild reaction conditions is described. This organometallic catalytic system has excellent tolerance for various homo-aromatic, hetero-aromatic and aliphatic nitriles to afford primary amides in good yields in neat water.
- Thirukovela, Narasimha Swamy,Balaboina, Ramesh,Kankala, Shravankumar,Vadde, Ravindhar,Vasam, Chandra Sekhar
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supporting information
p. 2637 - 2641
(2019/03/21)
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- Trash to treasure: Eco-friendly and practical synthesis of amides by nitriles hydrolysis in WepPA
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The hydration of nitriles to amides in a water extract of pomelo peel ash (WEPPA) was realized with moderate to excellent yields without using external transition metals, bases or organic solvents. This reaction features a broad substrate scope, wide functional group tolerance, prominent chemoselectivity, and good reusability. Notably, a magnification experiment in this bio-based solvent at 100 mmol further demonstrated its practicability.
- Sun, Yajun,Jin, Weiwei,Liu, Chenjiang
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supporting information
(2019/11/11)
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- Coordination or Oxidative Addition? Activation of N-H with [Tp′Rh(PMe3)]
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A thermal reaction of amines, anilines, and amides with Tp′Rh(PMe3)(CH3)H (1, Tp′ = tris(3,5-dimethyl-pyrazolyl)borate) is described in this report. No N-H bond cleavage was observed for reactions between ammonia or unsubstituted aliphatic amines with the reactive fragment [Tp′Rh(PMe3)]. Instead, amine coordination products (κ2-Tp′)Rh(PMe3)(NHR1R2) (R1 = H, R2 = H, nPr, iPr, octyl; R1 = R2 = Et; R1, R2: pyrrolidine) were observed, and the crystal structure of (κ2-Tp′)Rh(PMe3)(NH2iPr) is reported. No coordination products were observed when 1 was reacted with 1,1,1,3,3,3-hexafluoropropan-2-amine, anilines, and amides. Instead, the oxidative addition products (κ3-Tp′)Rh(PMe3)(NHR)H (R = CH(CF3)2, C6H5, 3,5-dimethylbenzyl, C6F5, C(O)CH3, C(O)CF3) were observed. Both RhI-N coordination products (κ2-Tp′)Rh(PMe3)(NH2CH2CF3) and RhIII N-H addition products (κ3-Tp′)Rh(PMe3)(NHCH2CF3)H were generated when 1 was reacted with 2,2,2-trifluoroethylamine. Coordination products dissociate ammonia and amines in benzene much faster than oxidative addition products eliminate anilines and amides. The relative metal-nitrogen bond energies were studied using established kinetic techniques. Analysis of the relationship between the relative M-N bond strengths and N-H bond strengths showed a linear correlation with a slope = RM-N/N-H of 0.91 (10), indicating that the Rh-N bond strength varies in direct proportion to the N-H bond strength.
- Yuwen, Jing,Brennessel, William W.,Jones, William D.
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supporting information
p. 557 - 566
(2019/01/11)
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- Process for dissociating acetamidine hydrochloride with alpha-acetyl-gamma-butyrolactone sodium salt
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The invention relates to the technical field of vitamin B synthesis intermediates, in particular to a process for dissociating acetamidine hydrochloride with alpha-acetyl-gamma-butyrolactone sodium salt. The process comprises the following steps: making alpha-acetyl-gamma-butyrolactone sodium salt react with the acetamidine hydrochloride and separating products to obtain acetamidine and alpha-acetyl-gamma-butyrolactone. According to the process, the intermediate product alpha-acetyl-gamma-butyrolactone sodium salt in the synthesis step of the alpha-acetyl-gamma-butyrolactone reacts with the acetamidine hydrochloride, the alpha-acetyl-gamma-butyrolactone sodium salt utilize hydrochloric acid coordinated in the acetamidine hydrochloride to achieve the effect that the alpha-acetyl-gamma-butyrolactone sodium salt produces the alpha-acetyl-gamma-butyrolactone, and the hydrochloric acid in the acetamidine hydrochloride is removed to form acetamidine. Synchronous production of two target products is achieved, the steps are saved, and the process is environmentally friendly and increases the revenue.
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Paragraph 0064-0120
(2019/03/25)
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- Formation of carbon–nitrogen bonds in carbon monoxide electrolysis
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The electroreduction of CO2 is a promising technology for carbon utilization. Although electrolysis of CO2 or CO2-derived CO can generate important industrial multicarbon feedstocks such as ethylene, ethanol, n-propanol and acetate, most efforts have been devoted to promoting C–C bond formation. Here, we demonstrate that C–N bonds can be formed through co-electrolysis of CO and NH3 with acetamide selectivity of nearly 40% at industrially relevant reaction rates. Full-solvent quantum mechanical calculations show that acetamide forms through nucleophilic addition of NH3 to a surface-bound ketene intermediate, a step that is in competition with OH– addition, which leads to acetate. The C–N formation mechanism was successfully extended to a series of amide products through amine nucleophilic attack on the ketene intermediate. This strategy enables us to form carbon–heteroatom bonds through the electroreduction of CO, expanding the scope of products available from CO2 reduction.
- Jouny, Matthew,Lv, Jing-Jing,Cheng, Tao,Ko, Byung Hee,Zhu, Jun-Jie,Goddard, William A.,Jiao, Feng
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p. 846 - 851
(2019/09/03)
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- Silicon-Mediated Coupling of Carbon Monoxide, Ammonia, and Primary Amines to Form Acetamides
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For the first time, a direct transformation of CO, NH3, and primary amines into acetamides, mediated by a main-group element (silicon), is reported. Starting point is the selective deoxygenative reductive homocoupling of two CO molecules by the Fc-bis(silylene) 1 a (Fc=ferrocendiyl) as a reducing agent, which forms the ferrocendiyl-bridged disila(μ-O)(μ-CCO)ketene intermediate 2 a. Exposing 2 a to NH3 (1 bar, 298 K) and benzylamine yields the Fc-disiloxanediamines [Fc(RHNSi-O-SiNHR)] 5 a (R=H) and 5 b (R=benzyl) under release of the respective acetamides H3CC(O)NHR, as confirmed by 13C-isotope-labelling experiments. IR and NMR studies of the reaction reveal a four-step mechanism involving an N-silylated carboxamide that can be isolated and fully characterized. The striking reaction mechanism for this unprecedented transformation involves a facile Si?C bond cleavage and ammonolysis of a Si?O bond, and has been demonstrated experimentally and by quantum-chemical calculations.
- Luecke, Marcel-Philip,Kostenko, Arseni,Wang, Yuwen,Yao, Shenglai,Driess, Matthias
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supporting information
p. 12940 - 12944
(2019/07/18)
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- Corresponding amine nitrile and method of manufacturing thereof
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The invention relates to a manufacturing method of nitrile. Compared with the prior art, the manufacturing method has the characteristics of significantly reduced using amount of an ammonia source, low environmental pressure, low energy consumption, low production cost, high purity and yield of a nitrile product and the like, and nitrile with a more complex structure can be obtained. The invention also relates to a method for manufacturing corresponding amine from nitrile.
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Paragraph 0138; 0139; 0140; 0141; 0142
(2018/05/07)
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- Water-soluble superbulky (η6- p -cymene) ruthenium(ii) amine: An active catalyst in the oxidative homocoupling of arylboronic acids and the hydration of organonitriles
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A phosphine free water-soluble superbulky amine-ruthenium-arene complex (2) encompassing 2,6-bis(diphenylmethyl)-4-methylaniline was synthesised in good yield. 2 was characterized by FT-IR, 1H NMR, and 13C NMR spectroscopies, TGA and elemental analyses. The structure of 2 was confirmed by a single-crystal X-ray diffraction study. The ruthenium centre in 2 adopts the pseudo-octahedral geometry due to the η6-p-cymene ring and bulky aniline ligand along with two chloro groups. Besides, complex 2 was efficaciously employed as a catalyst in the hydration of organonitriles to amides. This reaction proceeds efficiently for a wide range of substrates in an environmentally benign medium and is an economically reasonable synthetic route to amides in good yields. In addition, 2 acts as an excellent catalyst in the oxidative homocoupling of arylboronic acids in water. A range of arylboronic acids undergo a homocoupling reaction in the presence of catalyst 2 to yield symmetrical biaryls in reasonable to good yields.
- Nirmala, Muthukumaran,Adinarayana, Mannem,Ramesh, Karupnaswamy,Maruthupandi, Mannarsamy,Vaddamanu, Moulali,Raju, Gembali,Prabusankar, Ganesan
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supporting information
p. 15221 - 15230
(2018/09/29)
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- Monomeric nickel hydroxide stabilized by a sterically demanding phosphorus-nitrogen PN3P-pincer ligand: synthesis, reactivity and catalysis
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A terminal nickel hydroxide complex (PN3P)Ni(OH) (3) bearing the 2nd generation phosphorus-nitrogen PN3P-pincer ligand has been synthesized and structurally characterized. As a nucleophile, 3 reacts with CO to afford the hydroxycarbonyl complex 4, (PN3P)Ni(COOH). 3 can also activate CO2 and CS2 to produce nickel bicarbonate (PN3P)Ni(OCOOH) (5) and bimetallic dithiocarbonate [(PN3P)NiS]2CO (6) respectively, as well as to promote aryl isocyanate and isothiocyanate insertion into the Ni-OH bond to give the corresponding (PN3P)NiEC(O)NHAr complexes (E = O, 7; E = S, 8). In addition, 3 catalyzes the nitrile hydration to various amides with well-defined intermediates (PN3P)Ni-NHC(O)R (R = Me, 9; R = Ph, 10).
- Yao, Changguang,Chakraborty, Priyanka,Aresu, Emanuele,Li, Huaifeng,Guan, Chao,Zhou, Chunhui,Liang, Lan-Chang,Huang, Kuo-Wei
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p. 16057 - 16065
(2018/11/30)
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- Highly Active Platinum Catalysts for Nitrile and Cyanohydrin Hydration: Catalyst Design and Ligand Screening via High-Throughput Techniques
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Nitrile hydration provides access to amides that are indispensable to researchers in chemical and pharmaceutical industries. Prohibiting the use of this venerable reaction, however, are (1) the dearth of biphasic catalysts that can effectively hydrate nitriles at ambient temperatures with high turnover numbers and (2) the unsolved challenge of hydrating cyanohydrins. Herein, we report the design of new "donor-acceptor"-type platinum catalysts by precisely arranging electron-rich and electron-deficient ligands trans to one other, thereby enhancing both the nucleophilicity of the hydroxyl group and the electrophilicity of the nitrile group. Leveraging a high-throughput, automated workflow and evaluating a library of bidentate ligands, we have discovered that commercially available, inexpensive DPPF [1,1′-ferrocenendiyl-bis(diphenylphosphine)] provides superior reactivity. The corresponding "donor-acceptor"-type catalyst 2a is readily prepared from (DPPF)PtCl2, PMe2OH, and AgOTf. The enhanced activity of 2a permits the hydration of a wide range of nitriles and cyanohydrins to proceed at 40 °C with excellent turnover numbers. Rational reevaluation of the ligand structure has led to the discovery of modified catalyst 2c, harboring the more electron-rich 1,1′-bis[bis(5-methyl-2-furanyl)phosphino] ferrocene ligand, which demonstrates the highest activity toward hydration of nitriles and cyanohydrins at room temperature. Finally, the correlation between the electron-donating ability of the phosphine ligands with catalyst efficiencies of 2a, 2c, 2d, and 2e in the hydration of nitrile 7 are examined, and the results support the "donor-acceptor" hypothesis.
- Xing, Xiangyou,Xu, Chen,Chen, Bo,Li, Chengcheng,Virgil, Scott C.,Grubbs, Robert H.
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supporting information
p. 17782 - 17789
(2019/01/04)
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- Design and Synthesis of Iminosydnones for Fast Click and Release Reactions with Cycloalkynes
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Emerging applications in the field of chemical biology are currently limited by the lack of bioorthogonal reactions allowing both removal and linkage of chemical entities on complex biomolecules. We recently discovered a novel reaction between iminosydnones and strained alkynes leading to two products resulting from ligation and fragmentation of iminosydnones under physiological conditions. We now report the synthesis of a panel of substituted iminosydnones and the structure reactivity relationship between these compounds and strained alkyne partners. This study identified the most relevant substituents, which allow to increase the rate of the transformation and to develop a bifunctional cleavable linker with improved kinetics.
- Riomet, Margaux,Decuypere, Elodie,Porte, Karine,Bernard, Sabrina,Plougastel, Lucie,Kolodych, Sergii,Audisio, Davide,Taran, Frédéric
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supporting information
p. 8535 - 8541
(2018/05/30)
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- One–pot green catalytic synthesis of primary amides in aqueous medium by CuII–immobilized silica–based magnetic retrievable nanocatalyst
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In order to develop a new nanocatalyst, a copper–birhodanine derivative complex crafted onto Fe3O4@SiO2nanoparticle [abbreviated as Fe3O4@SiO2–Ligand–Cu(II)] was synthesized and their structure characterized by different physicochemical techniques such as FT–IR, FE–SEM, XRD, EDX, TGA, AGFM, and ICP. This new magnetic nanoparticle revealed high catalytic performance for one–pot green synthesis of primary amides from aldehydes and NH2OH·HCl in water as a green solvent. The effects of catalyst amounts, reaction temperature, various bases and type of solvent on catalytic activity were also investigated. The catalyst was retrieved eight times without significant loss of its catalytic activity.
- Rezaei, Manuchehr,Amani, Kamal,Darvishi, Kamran
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- Synthesis method for organically synthesizing intermediate acetamide
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The invention discloses a synthesis method for organically synthesizing an intermediate acetamide. The synthesis method comprises the following steps of adding 3mol of methyl acetate solution and 4mol to 5mol of ammonia water into a reaction vessel, raising the temperature of a solution to 30 to 36 DEG C, controlling an agitating speed to be 130rpm to 150rpm, making an agitating time last for 80min to 110min, standing an obtained solution for 7h to 8h, carrying out reduced pressure distillation so that the volume of the solution is reduced by half, lowering the temperature of the solution to 5 to 10 DEG C, separating out a crystal, washing the crystal in sequence by using a diethyl ether solution and a methanol solution, and dehydrating the crystal with a dehydrating agent, so that a product acetamide is obtained, wherein the pressure of the reduced pressure distillation in the steps is 50kPa to 70kPa; the mass fraction of the diethyl ether solution in the steps is 80 to 86 percent.
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Paragraph 0014; 0015
(2017/07/07)
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- Controlled photocatalytic hydrolysis of nitriles to amides by mesoporous MnO2 nanoparticles fabricated by mixed surfactant mediated approach
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The solid-phase MnO2 nanoparticles fabricated by surfactant template method were exploited as the photocatalyst for the effective one-step synthesis of amides. Cationic or anionic surfactants and their combinations were used as porous templates to obtain the mesoporous MnO2 nanoparticles with variable pore volume (0.23–1.95?cm3/g). The morphological and structural observation of the material confirms the uniform facet structure (37.68?nm) of MnO2 nanoparticles. The surface elemental state was confirmed by XPS analysis confirming Mn 2p3/2 (642.5?eV) and Mn2p1/2 (654.7?eV) spin states, that are common for the tetravalent Mn ions. Presence of surfactant as stabilizer was also witnessed with a strong peak of C 1s (283–286?eV). The textural parameters obtained from XRD and Raman analysis depicted the β-phase and rutile type framework of MnO2. The selective conversion of nitriles to amides was studied without any acid by products under visible light irradiation in the basic/neutral medium. Amides were obtained from various substrates (nitriles) with excellent yields (70–90%).
- Mehta, Akansha,Basu, Soumen
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- Phosphinous Acid-Assisted Hydration of Nitriles: Understanding the Controversial Reactivity of Osmium and Ruthenium Catalysts
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The synthesis and catalytic behavior of the osmium(II) complexes [OsCl2(η6-p-cymene)(PR2OH)] [R=Me (2 a), Ph (2 b), OMe (2 c), OPh (2 d)] in nitrile hydration reactions is presented. Among them, the best catalytic results were obtained with the phosphinous acid derivative [OsCl2(η6-p-cymene)(PMe2OH)] (2 a), which selectively provided the desired primary amides in excellent yields and short times at 80 °C, employing directly water as solvent, and without the assistance of any basic additive (TOF values up to 200 h?1). The process was successful with aromatic, heteroaromatic, aliphatic, and α,β-unsaturated organonitriles, and showed a high functional group tolerance. Indeed, complex 2 a represents the most active and versatile osmium-based catalyst for the hydration of nitriles reported so far in the literature. In addition, it exhibits a catalytic performance similar to that of its ruthenium analogue [RuCl2(η6-p-cymene)(PMe2OH)] (4). However, when compared to 4, the osmium complex 2 a turned out to be faster in the hydration of less-reactive aliphatic nitriles, whereas the opposite trend was generally observed with aromatic substrates. DFT calculations suggest that these differences in reactivity are mainly related to the ring strain associated with the key intermediate in the catalytic cycle, that is, a five-membered metallacyclic species generated by intramolecular addition of the hydroxyl group of the phosphinous acid ligand to the metal-coordinated nitrile.
- González-Fernández, Rebeca,Crochet, Pascale,Cadierno, Victorio,Menéndez, M. Isabel,López, Ramón
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p. 15210 - 15221
(2017/10/12)
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- Efficient Hydration of Nitriles Promoted by Gallic Acid Derived from Renewable Bioresources
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An efficient gallic acid promoted nitriles hydration at room temperature with ethanol/water as a solvent has been developed. The present protocol offers a wide range of amides in moderate to good yields. Moreover, galla chinensis extract can serve as the promoter to perform the hydration, which also shows the potential utilization of natural feedstocks.
- Deng, Tao,Wang, Cheng-Zhang
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p. 1349 - 1353
(2017/04/14)
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- Ultrasound-assisted removal of Acid Red 17 using nanosized Fe3O4-loaded coffee waste hydrochar
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The Fe3O4-loaded coffee waste hydrochar (Fe3O4-CHC) was synthesized using a simple precipitation method. The as-prepared adsorbent was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and Fourier transform infrared spectroscopy (FT-IR). The EDX analysis indicated the presence of Fe in the structure of Fe3O4-CHC. The specific surface area of hydrochar increased from 17.2 to 34.7 m2/g after loading of Fe3O4 nanoparticles onto it. The prepared Fe3O4-CHC was used for removal of Acid Red 17 (AR17) through ultrasound-assisted process. The decolorization efficiency decreased from 100 to 74% with the increase in initial dye concentration and from 100 to 91 and 85% in the presence of NaCl and Na2SO4, respectively. The synthesized Fe3O4-CHC exhibited good stability in the repeated adsorption-desorption cycles. The high correlation coefficient (R2 = 0.997) obtained from Langmuir model indicated that physical and monolayer adsorption of dye molecules occurred on the Fe3O4-CHC surface. Furthermore, the by-products generated through the degradation of AR17 was identified by gas chromatography–mass spectrometry analysis.
- Khataee, Alireza,Kayan, Berkant,Kalderis, Dimitrios,Karimi, Atefeh,Akay, Sema,Konsolakis, Michalis
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- Revisiting a Classic Transformation: A Lossen Rearrangement Initiated by Nitriles and pseudo-Catalytic in Isocyanate
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The direct conversion of a hydroxamic acid to an amine has been accomplished in a single step in the synthesis of HIV drug candidate BMS-955176. This process utilizes catalytic base and proceeds under mild conditions (CH3CN, cat. DBU, 60 °C), without the need for strong electrophiles required for typical Lossen rearrangements, and can be applied to aliphatic and aromatic hydroxamic acids. Through investigation of the kinetics of this transformation, a mechanism was revealed involving a novel initiation pathway and a self-propagation cycle. The initiation pathway involves activation of hydroxamic acid by nitriles and subsequent Lossen rearrangement to generate the corresponding isocyanate. The isocyanate functions as a pseudo-catalyst for this system, leading to generation of product through a second Lossen rearrangement and regeneration of a new isocyanate molecule. Thorough mechanistic understanding allowed for this highly efficient process to be implemented on a 55 kg scale in 95.5% isolated yield.
- Strotman, Neil A.,Ortiz, Adrian,Savage, Scott A.,Wilbert, Christopher R.,Ayers, Sloan,Kiau, Susanne
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p. 4044 - 4049
(2017/04/27)
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- Highly chemoselective reduction of azides to amines by Fe(0) nanoparticles in water at room temperature
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A highly chemoselective reduction of aryl, heteroaryl, acyl and sulfonyl azides to the corresponding amines has been achieved by Fe(0) nanoparticles in water at room temperature in the absence of external hydride source. Several readily reducible functionalities including alkene, alkyne, S-S linkage, OTBDMS remain unaffected during reduction.
- Panja, Subir,kundu, Debasish,Ahammed, Sabir,Ranu, Brindaban C.
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supporting information
p. 3457 - 3460
(2017/08/10)
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- Method for preparing methallyl alcohol and amide simultaneously
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A method for preparing methallyl alcohol and amide simultaneously is characterized in that methylallyl carboxylate taken as a raw material and an amine compound taken as an ammonolysis agent react under the action of a catalyst to produce methallyl alcohol and an amide compound. The methylallyl carboxylate and the amine compound taken as the ammonolysis agent are firstly adopted, and the methallyl alcohol and the amide compound are obtained under the action of the catalyst. The reaction process is a bulk reaction, no solvents are added, almost no wastewater or salt are produced, and byproduct methyl allyl ether is not produced; the defect that a large number of wastewater is produced through hydrolysis is overcome due to adoption of ammonolysis, the methallyl alcohol and the amide compound are coproduced directly by use of ammonoysis, coupling production is realized, and the cost is reduced.
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Paragraph 0034-0035
(2017/11/29)
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- Method for preparing amide by metallic sodium catalyzed ester ammonolysis reaction
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The invention discloses a method for preparing amide by metallic sodium catalyzed ester ammonolysis reaction. The method is characterized in that ester and liquid ammonia are taken as raw materials, and metallic sodium is taken as a catalyst to perform reaction at a temperature of 90-140 DEG C in a high-pressure kettle; a molar ratio of the ester to ammonium is 1: (1.2 to 5.0); molar weight of the metallic sodium is 4-10% that of the ester; when reaction pressure is not lowered any longer, reaction is stopped to recycle the ammonium which is not reacted; and an obtained reaction product is post-treated to obtain a product. The method can be used for efficiently preparing the amide; and moreover, the raw materials are cheap and are low in toxicity, reaction activity is relatively high, dose of the catalyst is small, reaction speed is high, a reaction conversion rate is high, and the product is easily separated.
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Paragraph 0046; 0047; 0048; 0049; 0052; 0056; 0060; 0061
(2017/08/30)
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- Bis(allyl)-ruthenium(IV) complexes with phosphinous acid ligands as catalysts for nitrile hydration reactions
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Several mononuclear ruthenium(iv) complexes with phosphinous acid ligands [RuCl2(η3:η3-C10H16)(PR2OH)] have been synthesized (78-86% yield) by treatment of the dimeric precursor [{RuCl(μ-Cl)(η3:η3-C10H16)}2] (C10H16 = 2,7-dimethylocta-2,6-diene-1,8-diyl) with 2 equivalents of different aromatic, heteroaromatic and aliphatic secondary phosphine oxides R2P(O)H. The compounds [RuCl2(η3:η3-C10H16)(PR2OH)] could also be prepared, in similar yields, by hydrolysis of the P-Cl bond in the corresponding chlorophosphine-Ru(iv) derivatives [RuCl2(η3:η3-C10H16)(PR2Cl)]. In addition to NMR and IR data, the X-ray crystal structures of representative examples are discussed. Moreover, the catalytic behaviour of complexes [RuCl2(η3:η3-C10H16)(PR2OH)] has been investigated for the selective hydration of organonitriles in water. The best results were achieved with the complex [RuCl2(η3:η3-C10H16)(PMe2OH)], which proved to be active under mild conditions (60 °C), with low metal loadings (1 mol%), and showing good functional group tolerance.
- Tomás-Mendivil, Eder,Francos, Javier,González-Fernández, Rebeca,González-Liste, Pedro J.,Borge, Javier,Cadierno, Victorio
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p. 13590 - 13603
(2016/09/04)
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- Poly(amic acid) salt-stabilized silver nanoparticles as efficient and recyclable quasi-homogeneous catalysts for the aqueous hydration of nitriles to amides
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Water-soluble silver nanoparticles stabilized by poly(amic acid) salt (Ag-PAAS) were synthesized by a one-pot method and were characterized by using UV-vis absorption, transmission electron microscopy, powder X-ray diffraction, and ζ potential measurements. The Ag-PAAS catalyzed selective hydration of nitriles to amides in water allowed for not only highly efficient quasi-homogeneous catalytic reactions under mild conditions, but also an easy recovery and reuse of the catalyst attributed to the pH response of the PAAS.
- Li, Jun,Tang, Guannan,Wang, Yuchen,Wang, Ya,Li, Zixi,Li, Hengfeng
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p. 358 - 364
(2016/01/12)
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- Clean synthesis of primary to tertiary carboxamides by CsOH-catalyzed aminolysis of nitriles in water
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Using CsOH as the only catalyst and utilizing its "cesium effect", a clean synthesis of a wide range of primary, secondary, and tertiary carboxamides was achieved by aminolysis reactions of nitriles with ammonia, primary, or secondary amines in water. Studies on the control reactions revealed that the reactions with ammonia most probably proceed via an aminolysis path by the initial addition of ammonia to Cs-activated nitriles to form unsubstituted amidine intermediates, while the reactions with primary or secondary amines may proceed via a hydration/transamidation path by the initial hydration of the Cs-activated nitriles to form primary carboxamide intermediates followed by their transamidation with amines through the formation of substituted amidine intermediates.
- Li, Yang,Chen, Haonan,Liu, Jianping,Wan, Xujun,Xu, Qing
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supporting information
p. 4865 - 4870
(2016/10/06)
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- Synthesis of and catalytic nitrile hydration by a cationic tris(μ-hydroxo)diruthenium(II) complex having PMe3ligands
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While phenyl vinyl ether does not react with [Ru(η4-1,5-COD)(η6-1,3,5-COT)] (1)/PMe3, the C–O bond cleavage of phenyl vinyl ether occurs by 1/PMe3in the presence of water to give a tris(μ-hydroxo)diruthenium(II) complex [(Me3P)3Ru(μ-OH)3Ru(PMe3)3]+[OPh]?·HOPh (3·HOPh) with evolution of ethylene. The molecular structure of 3·HOPh is unequivocally determined by X-ray analysis. The most likely mechanism for the formation of 3·HOPh is protonation of [Ru(η4-1,5-COD)(PMe3)3] (2c) by water and subsequent insertion of phenyl vinyl ether into the resulting Ru–H bond followed by the β-phenoxide elimination and hydrolysis and dimerization of the phenoxoruthenium(II) species. Complex 3 acts as a catalyst for nitrile hydration. As a typical example, the hydration of benzonitrile was achieved by 3 (1.0 mol%) in 1,4-dioxane at 120 °C for 6 h to give benzamide quantitatively.
- Kiyota, Sayori,Kobori, Takako,Soeta, Hirofumi,Ichikawa, You-ichi,Komine, Nobuyuki,Komiya, Sanshiro,Hirano, Masafumi
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- Ruthenium(II) complexes incorporating salicylaldiminato-functionalized N-heterocyclic carbene ligands as efficient and versatile catalysts for hydration of organonitriles
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We describe a new synthetic procedure for synthesis of ruthenium(II) complexes containing salicylaldiminato functionalized mixed N-heterocyclic carbene (NHC) ligand and phosphine co-ligand. The complexes (3a-3d) have been obtained in good to excellent yields by transmetalation from the corresponding Ag-NHC complexes (2a-2d) as carbene transfer reagents. All the [Ru-NHC] complexes have been characterized by elemental analyses, spectroscopic methods as well as ESI mass spectrometry. The ligands 1a-1d show their versatility by switching to be O,N,C-chelating in these ruthenium(II) complexes. The resulting complexes have been evaluated as potential catalysts for the selective hydration of nitriles to primary amides, and related amide bond forming reactions, in environmentally friendly medium. The reaction tolerated ether, hydroxyl, nitro, bromo, formyl, pyridyl, benzyl and alkyl functional groups. The catalyst was stable for weeks and could be recovered and reused more than six times without significant loss of activity.
- Nirmala, Muthukumaran,Saranya, Gandhi,Viswanathamurthi, Periasamy
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p. 134 - 144
(2016/01/09)
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- Development of an empirical kinetic model for sonocatalytic process using neodymium doped zinc oxide nanoparticles
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The degradation of Acid Blue 92 (AB92) solution was investigated using a sonocatalytic process with pure and neodymium (Nd)-doped ZnO nanoparticles. The nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The 1% Nd-doped ZnO nanoparticles demonstrated the highest sonocatalytic activity for the treatment of AB92 (10 mg/L) with a degradation efficiency (DE%) of 86.20% compared to pure ZnO (62.92%) and sonication (45.73%) after 150 min. The results reveal that the sonocatalytic degradation followed pseudo-first order kinetics. An empirical kinetic model was developed using nonlinear regression analysis to estimate the pseudo-first-order rate constant (kapp) as a function of the operational parameters, including the initial dye concentration (5-25 mg/L), doped-catalyst dosage (0.25-1 g/L), ultrasonic power (150-400 W), and dopant content (1-6% mol). The results from the kinetic model were consistent with the experimental results (R2 = 0.990). Moreover, DE% increases with addition of potassium periodate, peroxydisulfate, and hydrogen peroxide as radical enhancers by generating more free radicals. However, the addition of chloride, carbonate, sulfate, and t-butanol as radical scavengers declines DE%. Suitable reusability of the doped sonocatalyst was proven for several consecutive runs. Some of the produced intermediates were also detected by GC-MS analysis. The phytotoxicity test using Lemna minor (L. minor) plant confirmed the considerable toxicity removal of the AB92 solution after treatment process.
- Khataee, Alireza,Vahid, Behrouz,Saadi, Shabnam,Joo, Sang Woo
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p. 146 - 155
(2015/10/05)
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- Generation and Reaction of Carbamoyl Anions in Flow: Applications in the Three-Component Synthesis of Functionalized α-Ketoamides
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Using a flow microreactor system, carbamoyllithium compounds were successfully generated and used for reactions with electrophiles to give various amides, including α-ketoamides. The present method could be applied to the three-component synthesis of functionalized α-ketoamides using a carbamoyllithium compound, methyl chloroformate, and a functionalized organolithium reagent. Go with the flow: Using a flow microreactor system, carbamoyllithium compounds were successfully generated and used to react with electrophiles to give various amides, including α-ketoamides. The method was applied to the three-component synthesis of functionalized α-ketoamides using a carbamoyllithium compound, methyl chloroformate, and a functionalized organolithium reagent. PMB=p-methoxybenzyl; FG=functional group.
- Nagaki, Aiichiro,Takahashi, Yusuke,Yoshida, Jun-Ichi
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supporting information
p. 5327 - 5331
(2016/04/26)
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- Homogeneous and silica-supported zinc complexes for the synthesis of propylene carbonate from propane-1,2-diol and carbon dioxide
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Three organozinc complexes have been synthesised and found to catalyse the carbonylation of propylene glycol with carbon dioxide to form propylene carbonate. A similar tethered organozinc complex was supported onto high loading aminopropyl functionalised hexagonal mesoporous silica and was also found to be catalytically active.
- Comerford, James W.,Hart, Sam J.,North, Michael,Whitwood, Adrian C.
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p. 4824 - 4831
(2016/07/11)
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- Selective Hydration of Nitriles to Amides Over Titania Supported Palladium Exchanged Vanadium Incorporated Molybdophosphoric Acid Catalysts
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Abstract: Titania supported palladium exchanged vanadium incorporated molybdophosphoric acid (PdMPAV1) catalysts were prepared and characterized by FT-IR, X-ray diffraction and Laser Raman spectroscopy. The characterization results confirmed the presence of vanadium and palladium into the primary and secondary structure of Keggin ion of heteropoly molybdate respectively. The PdMPAV1 was dispersed on support with intact Keggin ion structure. These catalysts were studied for selective hydration of nitriles to amides. The PdMPAV1was highly active compared to the molybdophosphoric acid containing either vanadium or palladium. The catalyst with 20?% PdMPAV1 dispersed on TiO2 showed highest activity compare to other catalysts. A variety of nitriles were tested over this catalyst and found that the catalyst was active to yield corresponding amides. Different reaction parameters were studied and optimum conditions were established. The PdMPAV1/TiO2 catalyst exhibited consistent activity during reuse. Graphical Abstract: [Figure not available: see fulltext.]
- Srinivasa Rao,Srivani,Dhana Lakshmi,Lingaiah
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p. 2025 - 2031
(2016/10/18)
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- Oxadiazoanthracene compounds for the treatment of diabetes
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The present invention provides methods of use of oxadiazoanthracene derivatives of the formula (I) and pharmaceutically acceptable salts thereof, wherein A, B, C, R, R1, R2, R3, R4 and R5 are as herein described, and wherein said methods of use include uses for the treatment of disorders and diseases, such as diabetes.
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- Selective hydration of nitriles to amides catalysed by PCP pincer supported nickel(ii) complexes
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The (PCP)Ni-OH complexes 2R (R = iPr, tBu, Cy) are effective catalyst precursors for the selective hydration of nitriles to the corresponding amides under relatively mild conditions (80 °C) and low catalyst loadings (0.05-0.5%). Substrate scope includes aliphatic, vinylic and aromatic nitriles, but substrates with protic groups poison the catalyst abruptly. The catalysts are effective because the electron rich nature of the PCP ligands and their steric bulk renders the hydroxo group labile.
- Borau-Garcia,Gutsulyak,Burford,Piers
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p. 12082 - 12085
(2016/01/15)
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- Chemoselective hydration of nitriles to amides using hydrated ionic liquid (IL) tetrabutylammonium hydroxide (TBAH) as a green catalyst
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A transition metal-free process, catalyzed by tetrabutylammonium hydroxide (TBAH), has been developed for the convenient and selective hydration of nitriles to the corresponding amides. The present process converts aromatic, aliphatic, and heteroaromatic nitriles with a wide variety of functional groups into amides. The regioselective hydration of one nitrile moiety in the presence of another nitrile group gives the present protocol high impact.
- Veisi, Hojat,Maleki, Behrooz,Hamelian, Mona,Ashrafi, Samaneh Sedigh
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p. 6365 - 6371
(2015/02/19)
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- Selective aerobic hydrolysis of nitriles to amides using cobalt(II)/zinc
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A novel protocol has been developed for the aerobic hydrolysis of nitriles to amides using cobalt(II)/zinc without using any strong acids and bases under solvent-free conditions. The reaction showed good performance for benzonitriles with sensitive groups such as ester and carboxylic acid.
- Keshipour, Sajjad,Shaabani, Ahmad
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p. 5071 - 5078
(2015/07/08)
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- Direct oxidative esterification of alcohols and hydration of nitriles catalyzed by a reusable silver nanoparticle grafted onto mesoporous polymelamine formaldehyde (AgNPs@mPMF)
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A nitrogen-rich mesoporous organic polymer was synthesized as a novel support. A silver nanoparticle was synthesized and grafted onto it. The prepared catalyst (AgNPs@mPMF) was characterized by powder X-ray diffraction (XRD), scanning electron microscopy(SEM) and energy dispersive X-ray spectrometry (EDS), thermogravimetric analysis (TGA), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflectance spectroscopy (DRS), N2 adsorption, Raman spectroscopy and EPR study. The catalytic activity was evaluated for the oxidative esterification reaction of alcohols and hydration of nitriles. The oxidative esterification reaction was carried out for various activated alcohols giving excellent yields of the corresponding ester products. The catalyst was also efficient in the hydration of nitriles. Both reactions were optimized by varying the bases, temperatures and solvents. The catalyst can be facilely recovered and reused six times without a significant decrease in its activity and selectivity.
- Ghosh, Kajari,Iqubal, Md. Asif,Molla, Rostam Ali,Mishra, Ashutosh,Kamaluddin,Islam, Sk Manirul
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p. 1606 - 1622
(2015/04/27)
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