- Efficient and chemoselective hydrogenation of aldehydes catalyzed by well-defined PN3-pincer manganese(ii) catalyst precursors: An application in furfural conversion
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Well-defined and air-stable PN3-pincer manganese(ii) complexes were synthesized and used for the hydrogenation of aldehydes into alcohols under mild conditions using MeOH as a solvent. This protocol is applicable for a wide range of aldehydes containing various functional groups. Importantly, α,β-unsaturated aldehydes, including ynals, are hydrogenated with the CC double bond/CC triple bond intact. Our methodology was demonstrated for the conversion of biomass derived feedstocks such as furfural and 5-formylfurfural to furfuryl alcohol and 5-(hydroxymethyl)furfuryl alcohol respectively.
- Gholap, Sandeep Suryabhan,Dakhil, Abdullah Al,Chakraborty, Priyanka,Li, Huaifeng,Dutta, Indranil,Das, Pradip K.,Huang, Kuo-Wei
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supporting information
p. 11815 - 11818
(2021/11/30)
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- Chemoselective transfer hydrogenation of aromatic and heterocyclic aldehydes by green chemically prepared cobalt oxide nanoparticles
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A new surfactant (quercetin) assisted hydrothermal method is used for the preparation of phase pure cobalt oxide (Co3O4) nanoparticles (Nps). The quercetin acted well as surfactant in producing size controlled Nps. The produced Nps were extensively characterized by various techniques to reveal its chemical composition, structure, morphology, size and thermal behavior. The main objective of the study is to employ the prepared material as heterogeneous catalyst for hydrogenation of therapeutically important aldehydes. The capability of the catalyst is appear to be good, since the yield of alcohols from structurally different aldehydes is adequate with short period of time. Also the catalyst is recyclable, stable, no need of addition of ligands for activation and environmentally benign.
- Krishnaveni,Lakshmi,Kaveri,Kadirvelu
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- Chemoselective Hydrogenation of Aldehydes under Mild, Base-Free Conditions: Manganese Outperforms Rhenium
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Several hydride Mn(I) and Re(I) PNP pincer complexes were applied as catalysts for the homogeneous chemoselective hydrogenation of aldehydes. Among these, [Mn(PNP-iPr)(CO)2(H)] was found to be one of the most efficient base metal catalysts for this process and represents a rare example which permits the selective hydrogenation of aldehydes in the presence of ketones and other reducible functionalities, such as C=C double bonds, esters, or nitriles. The reaction proceeds at room temperature under base-free conditions with catalyst loadings between 0.1 and 0.05 mol% and a hydrogen pressure of 50 bar (reaching TONs of up to 2000). A mechanism which involves an outer-sphere hydride transfer and reversible PNP ligand deprotonation/protonation is proposed. Analogous isoelectronic and isostructural Re(I) complexes were only poorly active.
- Glatz, Mathias,St?ger, Berthold,Himmelbauer, Daniel,Veiros, Luis F.,Kirchner, Karl
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p. 4009 - 4016
(2018/05/23)
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- Selective mono-reduction of pyrrole-2,5 and 2,4-dicarboxylates
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Pyrrole-2,5-dicarboxylates were rapidly and selectively reduced to the corresponding mono-alcohol using 3 eq of diisobutylaluminum hydride at 0°C. Pyrrole-2,4-dicarboxylate showed the same reactivity; however, the selectivity decreased with pyrrole-3,4-dicarboxylate. When the nitrogen atom of the pyrrole-2,5-dicarboxylate is protected with a benzyl group, selective mono-reduction does not occur. Considering that furan-2,5-dicarboxylates did not give the corresponding mono-alcohol under the same conditions, the unprotected nitrogen atom of pyrrole apparently plays an important role in this selective mono-reduction.
- Yasui, Eiko,Tsuda, Jyunpei,Ohnuki, Satoshi,Nagumo, Shinji
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p. 1262 - 1267
(2016/09/09)
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- Selective hydrogenation of furanic aldehydes using Ni nanoparticle catalysts capped with organic molecules
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Ni nanoparticles were synthesized by a colloidal method in the presence of organic surface-capping agents and used to catalyze the selective hydrogenation of unsaturated furanic aldehydes to furanic alcohols. The effects of the Ni nanoparticle size and surface organic layer were evaluated. Of the 3.7, 5.1, 6.8, and 10.4 nm Ni nanoparticles tested in selective furfural (FFR) hydrogenation to furfuryl alcohol (FFA), the 6.8 nm Ni nanoparticles exhibited the highest yield because access to the surface sites on the smaller and larger nanoparticles was blocked by the densely packed organic layer and by their agglomeration due to magnetic attraction, respectively. The capped Ni nanoparticles exhibited a high FFA yield of 96%, whereas significant over-hydrogenation was observed when uncapped calcined Ni/SiO2 catalysts with similarly sized Ni nanoparticles were employed. Steric hindrance of the Ni surface induced by the organic surface layer led to selective FFR hydrogenation to FFA. The capped Ni nanoparticles could be reused repeatedly without a significant loss in the FFA yield. They also exhibited high selectivity (>90%) in the hydrogenation of other unsaturated furanic aldehydes to their corresponding alcohols.
- Jeong, Hojin,Kim, Chanyeon,Yang, Sungeun,Lee, Hyunjoo
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p. 609 - 615
(2016/11/25)
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- Unsupported Nanoporous Gold Catalyst for Chemoselective Hydrogenation Reactions under Low Pressure: Effect of Residual Silver on the Reaction
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For the first time, H-H dissociation on an unsupported nanoporous gold (AuNPore) surface is reported for chemoselective hydrogenation of C=C, C=C, C=N, and C=O bonds under mild conditions (8 atm H2 pressure, 90 °C). Silver doping in AuNPore, which was inevitable for its preparation through a process of dealloying of Au-Ag alloy, exhibited a remarkable difference in catalytic activity between two catalysts, Au>99Ag1NPore and Au90Ag10NPore.The former was more active and the latter less active in H2 hydrogenation, while the reverse tendency was observed for O2 oxidation. This marked contrast between H2 reduction and O2 oxidation is discussed. Further, Au>99Ag1NPore showed a high chemoselectivity toward reduction of terminal alkynes in the presence of internal alkynes which was not achieved using supported gold nanoparticle catalysts and other previously known methods. Reductive amination, which has great significance in synthesis of amines due to its atom-economical nature, was also realized using Au>99Ag1NPore, and the Au>99Ag1NPore/H2 system showed a preference for the reduction of aldehydes in the presence of imines. In addition to this high chemoselectivity, easy recovery and high reusability of AuNPore make it a promising heterogeneous catalyst for hydrogenation reactions.
- Takale, Balaram S.,Feng, Xiujuan,Lu, Ye,Bao, Ming,Jin, Tienan,Minato, Taketoshi,Yamamoto, Yoshinori
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supporting information
p. 10356 - 10364
(2016/08/31)
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- Tin-containing hydrotalcite-like compounds as catalysts for the Meerwein-Ponndorf-Verley reaction
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Hydrotalcite-like compounds (HTs) containing Mg/Al or Mg/Al/Sn were prepared and used as precursors to obtain basic catalysts by calcination at 450 C. The catalysts were used in the Meerwein-Ponndorf-Verley (MPV) reaction of benzaldehyde and cyclohexanone in the presence of 2-propanol as hydrogen donor. The mixed oxide obtained by calcining the tin-containing HT was found to be more catalytically active than that obtained from the Mg/Al HT and the pure magnesium oxide. This result can be ascribed to the mechanism of the reaction, which involves acid-base sites on the catalyst surface. The most active catalyst was used in the MPV reactions of other carbonyl compounds including aldehydes and ketones with excellent conversion and selectivity.
- Jiménez-Sanchidrián, César,Ruiz, José Rafael
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p. 367 - 372
(2013/11/19)
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- Nickel phthalocyanine assisted highly efficient and selective carbonyl reduction in polyethylene glycol-400
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Nickel phthalocyanine with polyethylene glycol- 400 is described as a reusable green catalytic system for highly chemo- and regioselective reduction of carbonyl compounds to corresponding alcohols at room temperature. The catalytic system showed wide substrate scope covering aromatic, hetero aromatic and aliphatic carbonyl compounds with high turnover number and frequency. In the present study, 1,3- and 1,4-benzenedicarbaldehydes have been regioselectively reduced to corresponding alcohols for the first time. The catalyst was reused up to seven times without any significance loss in activity. Springer Science+Business Media, LLC 2012.
- Verma, Praveen Kumar,Sharma, Upendra,Kumar, Neeraj,Bala, Manju,Kumar, Vishal,Singh, Bikram
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experimental part
p. 907 - 913
(2012/10/07)
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- Nuclear magnetic resonance spectroscopical studies of 2-carbonyl derivatives of five-membered monohetero-cycles and determination of aromaticity indices
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1H And 13C chemical shifts of formyl, acetyl, benzoyl, and methoxycarbonyl derivatives of benzene, thiophene, pyrrole and furan in chloroform-d, methanol-d4, and DMSO-d6 are examined. Deviation of the signals of the ring protons and carbonyl carbons provide bases for estimating the indices of aromaticity of the heterocycles. The exceptionally large carbonyl stretching vibration of furan derivatives and correlations of the stretching frequencies with the reactivities of the carbonyl groups are discussed.
- Jeon, Kyu Ok,Yu, Ji Sook,Lee, Chang Kiu
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p. 2685 - 2705
(2007/10/03)
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- Microwave-accelerated crossed cannizzaro reaction using barium hydroxide under solvent-free conditions
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A solventless and expeditious method for the preparation of alcohols is described from aldehydes using barium hydroxide, Ba(OH)2.8H2O, and paraformaldehyde. A comparison of this microwave-accelerated Cannizzaro reaction to the one under conventional heating mode is also reported.
- Varma, Rajender S.,Naicker, Kannan P.,Liesen, Per J.
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p. 8437 - 8440
(2007/10/03)
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- A 13C Study of Hydroxymethyl Derivatives of Five-Membered Ring Heterocycles
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The 13C spectra of the hydroxymethyl derivatives of pyrrole, furan, 5,5-dimethylhydantoin, imidazole, thiophene, pyrazole, and phenol have been studied and assigned.The substituent parameters for the hydroxymethyl group in pyrrole, thiophene, furan and imidazole were determined.KEY WORDS 13C NMR Substituent parameters Hydroxymethyl group Pyrrole Furan Imidazole 5,5-Dimethylhydantoin Thiophene
- Katritzky, Alan R.,Law, Kam Wah
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p. 129 - 133
(2007/10/02)
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