- The Exploration of Sensitive Factors for the Selective Hydrogenation of α-Pinene Over Recyclable Ni-B/KIT-6 Catalyst
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The supported Ni-B/KIT-6 amorphous alloy catalyst was prepared by chemical reduction method for the hydrogenation reaction of α-pinene. The catalyst was characterized by XRD, BET, SEM–EDS, TEM, XPS, ICP and DLS, the influences of single factor of catalyst on its structure, morphology and performance were investigated and analyzed. It was found that the amount of Ni loading, preparation pH and B/Ni molar ratio had great effects on the reduction amount, dispersion and specific surface area of the catalyst, resulted in affecting the catalytic performance of the catalyst. The optimum synthesis conditions were at m(Ni2+)/m(KIT-6) = 1:3, pH 13 and n(B)/n(Ni) = 1.5, obtaining a 90.62% conversion of α-pinene and 97.67% selectivity of cis-pinane. In addition, the catalysts also exhibited better repeatability and stability. Graphic Abstract: [Figure not available: see fulltext.]
- Deng, Qiao,Hu, Tianding,Huang, Jinyan,Huang, Pengpeng,Jiang, Lihong,Shan, Shaoyun,Su, Hongying,Wang, Yaming,Yang, Wenjuan,Zheng, Yane,Zhi, Yunfei
-
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- Colloid and Nanosized Catalysts in Organic Synthesis: XXII. Hydrogenation of Cycloolefins Catalyzed by Immobilized Transition Metals Nanoparticles in a Three-Phase System
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The processes of unsaturated cyclic hydrocarbons hydrogenation in a three-phase gas-liquid-solid catalyst system in the presence of nanostructured nickel, cobalt, or iron catalysts in a flow reactor at 130°C and atmospheric pressure have studied. RX3Extra activated carbon, γ-Al2O3, NaX zeolite, and Purolite CT-175 cation-exchange resin have been used as supports; NaBH4 and NH2NH2·H2O were used as reducing agents. The catalytic activity of supported nanoparticles and their selectivity with respect to the product of exhaustive hydrogenation have been investigated.
- Nebykov,Popov, Yu. V.,Mokhov,Latyshova,Shcherbakova,Nemtseva,Shishkin
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p. 1985 - 1989
(2019/11/29)
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- Amine-Borane Dehydrogenation and Transfer Hydrogenation Catalyzed by α-Diimine Cobaltates
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Anionic α-diimine cobalt complexes, such as [K(thf)1.5{(DippBIAN)Co(η4-cod)}] (1; Dipp=2,6-diisopropylphenyl, cod=1,5-cyclooctadiene), catalyze the dehydrogenation of several amine-boranes. Based on the excellent catalytic properties, an especially effective transfer hydrogenation protocol for challenging olefins, imines, and N-heteroarenes was developed. NH3BH3 was used as a dihydrogen surrogate, which transferred up to two equivalents of H2 per NH3BH3. Detailed spectroscopic and mechanistic studies are presented, which document the rate determination by acidic protons in the amine-borane.
- Maier, Thomas M.,Sandl, Sebastian,Shenderovich, Ilya G.,Jacobi von Wangelin, Axel,Weigand, Jan J.,Wolf, Robert
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supporting information
p. 238 - 245
(2019/01/04)
-
- Highly selective and recyclable hydrogenation of α-pinene catalyzed by ruthenium nanoparticles loaded on amphiphilic core–shell magnetic nanomaterials
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A multifunctional nanomaterial (Fe3O4@SiO2@CX@NH2) comprising a magnetic core, a silicon protective interlayer, and an amphiphilic silica shell is successfully prepared. Ru nanoparticles catalyst loaded on Fe3O4@SiO2@CX@NH2 is used in hydrogenation of α-pinene for the first time. The novel nanomaterial with amphipathy can be used as a solid foaming agent to increase gas–liquid–solid three-phase contact and accelerate the reaction. Under the mild conditions (40?°C, 1?MPa H2, 3?h), 99.9% α-pinene conversion and 98.9% cis-pinane selectivity are obtained, which is by far the best results reported. Furthermore, the magnetic nanocomposite catalyst can be easily separated by an external magnet and reused nine times with high selectivity maintaining.
- Wu, Fang-Zhu,Yu, Feng-Li,Yuan, Bing,Xie, Cong-Xia,Yu, Shi-Tao
-
-
- Hydrogenation of hydrophobic substrates catalyzed by gold nanoparticles embedded in Tetronic/cyclodextrin-based hydrogels
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Hydrogenation of alkenes, alkynes and aldehydes was investigated under biphasic conditions using Au nanoparticles (AuNP) embedded into combinations of α-cyclodextrin (α-CD) and a poloxamine (Tetronic90R4). Thermo-responsive AuNP-containing α-CD/Tetronic90R4 hydrogels are formed under well-defined conditions of concentration. The AuNP displayed an average size of ca. 7 nm and a narrow distribution, as determined by TEM. The AuNP/α-CD/Tetronic90R4 system proved to be stable over time. Upon heating above the gel-to-sol transition temperature, the studied catalytic system allowed hydrogenation of a wide range of substrates such as alkenes, alkynes and aldehydes under biphasic conditions. Upon repeated heating/cooling cycles, the Au NP/α-CD/Tetronic90R4 catalytic system could be recycled several times without a significant decline in catalytic activity.
- Chevry,Menuel,Léger,No?l,Monflier,Hapiot
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p. 9865 - 9872
(2019/07/04)
-
- Efficient and selective reduction of α-pinene to cis-pinane by NaBH4 using NiCl2?6H2O/PEG-800/ethanol as the catalytic system
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The reduction of α-pinene by NaBH4 was achieved using NiCl2?6H2O in PEG-800/ethanol system under room temperature. Under the optimized conditions, the conversion of α-pinene and the selectivity of cis-pinane reached 97% and 98%, respectively. On the basis of TEM and a series of poisoning experiments, the nature of the active catalytic species for the reaction was discussed.
- Li, Kaoxue,Wang, Kang,Liu, Chuanchao,Yang, Xuhao,Chen, Xia,Ren, Yang,Cao, Shuhua,Liu, Meifang,Tai, Xishi,Li, Fahui
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p. 672 - 678
(2019/02/16)
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- The conversion of α-pinene to: Cis-pinane using a nickel catalyst supported on a discarded fluid catalytic cracking catalyst with an ionic liquid layer
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The concept of a solid catalyst coated with a thin ionic liquid layer (SCILL) was applied to the stereoselective hydrogenation of α-pinene. Nickel, a non-noble metal, was supported on a discarded fluid catalytic cracking catalyst (DF3C) and then modified with different loadings of the ionic liquid 1-ethanol-3-methylimidazolium tetrafluoroborate ([C2OHmim][BF4]). The resulting catalysts showed a range of conversions and selectivities for the hydrogenation of α-pinene. The SCILL catalysts afforded cis-pinane with high selectivity and their activity depended on the ionic liquid loading. For an ionic liquid loading of 10 wt%, although the catalytic activity was suppressed, the selectivity and conversion could reach above 98% and 99%, respectively. In addition, the catalyst remained stable after 13 runs and the activity was almost unchanged with the conversion maintained at approximately 99%. Thus, the ionic liquid layer not only improved the selectivity for cis-pinane but also protected the active site of the catalyst and prolonged the service lifetime of the catalyst. The SCILL catalytic system provides an example of an ionic liquid catalytic system which eliminates organic solvents from the catalytic process.
- Hu, Shunyou,Wang, Linlin,Chen, Xiaopeng,Wei, Xiaojie,Tong, Zhangfa,Yin, Lijiang
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p. 5978 - 5986
(2019/03/12)
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- Room Temperature Iron-Catalyzed Transfer Hydrogenation and Regioselective Deuteration of Carbon-Carbon Double Bonds
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An iron catalyst has been developed for the transfer hydrogenation of carbon-carbon multiple bonds. Using a well-defined β-diketiminate iron(II) precatalyst, a sacrificial amine and a borane, even simple, unactivated alkenes such as 1-hexene undergo hydrogenation within 1 h at room temperature. Tuning the reagent stoichiometry allows for semi- and complete hydrogenation of terminal alkynes. It is also possible to hydrogenate aminoalkenes and aminoalkynes without poisoning the catalyst through competitive amine ligation. Furthermore, by exploiting the separate protic and hydridic nature of the reagents, it is possible to regioselectively prepare monoisotopically labeled products. DFT calculations define a mechanism for the transfer hydrogenation of propene with nBuNH2 and HBpin that involves the initial formation of an iron(II)-hydride active species, 1,2-insertion of propene, and rate-limiting protonolysis of the resultant alkyl by the amine N-H bond. This mechanism is fully consistent with the selective deuteration studies, although the calculations also highlight alkene hydroboration and amine-borane dehydrocoupling as competitive processes. This was resolved by reassessing the nature of the active transfer hydrogenation agent: experimentally, a gel is observed in catalysis, and calculations suggest this can be formulated as an oligomeric species comprising H-bonded amine-borane adducts. Gel formation serves to reduce the effective concentrations of free HBpin and nBuNH2 and so disfavors both hydroboration and dehydrocoupling while allowing alkene migratory insertion (and hence transfer hydrogenation) to dominate.
- Espinal-Viguri, Maialen,Neale, Samuel E.,Coles, Nathan T.,MacGregor, Stuart A.,Webster, Ruth L.
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supporting information
p. 572 - 582
(2019/01/08)
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- Sodium borohydride-nickel chloride hexahydrate in EtOH/PEG-400 as an efficient and recyclable catalytic system for the reduction of alkenes
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An efficient, safe and one-pot convenient catalytic system has been developed for the reduction of alkenes using NaBH4-NiCl2·6H2O in EtOH/PEG-400 under mild conditions. In this catalytic system, a variety of alkenes (including trisubstituted alkene α-pinene) were well reduced and the Ni catalyst could be recycled.
- Li, Kaoxue,Liu, Chuanchao,Wang, Kang,Ren, Yang,Li, Fahui
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p. 7761 - 7764
(2018/03/01)
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- Air-Stable α-Diimine Nickel Precatalysts for the Hydrogenation of Hindered, Unactivated Alkenes
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Treatment of a mixture of air-stable nickel(II) bis(octanoate), Ni(O2CC7H15)2, and α-diimine ligand, iPrDI or CyADI (iPrDI = [2,6-iPr2-C6H3N=C(CH3)]2, CyADI = [C6H11N=C(CH3)]2) with pinacolborane (HBPin) generated a highly active catalyst for the hydrogenation of hindered, essentially unfunctionalized alkenes. A range of tri- and tetrasubstituted alkenes was hydrogenated and a benchtop procedure for the hydrogenation of 1-phenyl-1-cyclohexene on a multigram scale was demonstrated and represents an advance in catalyst activity and scope for the nickel-catalyzed hydrogenation of this challenging class of alkenes. Deuteration of 1,2-dimethylindene with the in situ-generated nickel catalyst with iPrDI exclusively furnished the 1,2-syn-d2-dimethylindane. With cyclic trisubstituted alkenes, such as 1-methyl-indene and methylcyclohexene, deuteration with the in situ generated nickel catalyst under 4 atm of D2 produced multiple deuterated isotopologues of the alkanes, signaling chain running processes that are competitive with productive hydrogenation. Stoichiometric studies, titration, and deuterium labeling experiments identified that the borane reagent served the dual role of reducing nickel(II) bis(carboxylate) to the previously reported nickel hydride dimer [(iPrDI)NiH]2 and increasing the observed hydrogenation activity. Performing the catalyst activation procedure with D2 gas and HBPin generated both HD and DBPin, establishing that the borane is involved in H2 activation as judged by 1H and 11B nuclear magnetic resonance spectroscopies.
- Léonard, Nadia G.,Chirik, Paul J.
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p. 342 - 348
(2018/01/17)
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- Method for preparing cis-pinane by catalyzing alpha-pinene hydrogenation by means of palladium-nickel bimetallic catalyst
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The invention relates to a method for preparing cis-pinane by catalyzing a hydrogenation reaction of alpha-pinene under the mild condition by taking palladium-nickel bimetallic nanoparticles with stable polyethylene oxide-polypropylene oxide-polyethylene oxide three-block copolymer (P123) micelle as a catalyst, and belongs to the field of catalyst preparation and application. According to the method for catalyzing the hydrogenation reaction of alpha-pinene by means of the palladium-nickel bimetallic catalyst in an aqueous medium, reacting under stirring is conducted for 3 h under the conditions of 0.7 MPa H2 and 50 DEG C, the conversion rate of alpha-pinene can reach 99.8%, and the selectivity of cis-pinane is 96.3%. The method is easy and convenient to operate and friendly to environment; especially, the bimetallic catalyst is adopted, the dosage of noble metal palladium is decreased, the catalyst cost is reduced, and the selectivity of cis-pinane is improved. An environment-friendly novel way is provided for selective preparation of cis-pinane.
- -
-
Paragraph 0020; 0023; 0025-0031
(2017/08/27)
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- Preparation of: Cis -pinane via α-pinene hydrogenation in water by using Ru nanoparticles immobilized in functionalized amphiphilic mesoporous silica
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Amphiphilic mesoporous silica modified with trimethoxy (3,3,3-trifluoropropyl) silane (TFPS) and (3-aminopropyl) trimethoxysilane (APTS) was prepared by one-step synthesis. The structure and morphology of the mesoporous silica were characterized and confirmed by solid-state nuclear magnetic resonance, X-ray diffraction (XRD), N2 adsorption-desorption, Fourier transfer infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Meanwhile, the thermostability of the amphiphilic mesoporous silica was detected by thermogravimetric (TG) technique. Highly dispersed Ru nanoparticles supported on such amphiphilic mesoporous silica (marked as Ru/MF@MN) were synthesized by wet impregnation method with the assistance of ultrasonic. The catalyst was characterized by X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES). In water medium, Ru/MF@MN was used in α-pinene hydrogenation to prepare cis-pinane. Under the optimum reaction conditions (35 °C, 2 MPa H2, 1 h, m (H2O):m (α-pinene):m (Ru/MF@MN) = 200:60:1), 99.9% α-pinene conversion and 98.9% cis-pinane selectivity were obtained. When Ru/MF@MN was recycled six times, the conversion slightly decreased and the selectivity was nearly unchanged.
- Xie, Lihua,Wang, Xiaoyan,Yu, Fengli,Yuan, Bing,Xie, Congxia,Yu, Shitao
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p. 51452 - 51459
(2017/11/15)
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- Colloidal and nanosized catalysts in organic synthesis: XV. Gas-phase hydrogenation of alkenes catalyzed by supported nickel nanoparticles
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Gas-phase hydrogenation of alkenes and their derivatives, catalyzed by nickel nanoparticles supported on zeolite or silica gel support occurs at 150–250°С and an atmospheric hydrogen pressure and results in a high conversion. The selectivity of the hydrogenation depends on the amount of hydrogen: at a low diene (triene)–hydrogen ratio, selective hydrogenation of one multiple bond in the substrate is possible.
- Popov, Yu. V.,Mokhov,Nebykov,Latyshova,Panov,Dontsova,Shirkhanyan,Shcherbakova
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p. 2589 - 2593
(2017/03/22)
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- Reduced graphene oxide supported nickel-palladium alloy nanoparticles as a superior catalyst for the hydrogenation of alkenes and alkynes under ambient conditions
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Addressed herein is the superior catalytic performance of reduced graphene oxide supported Ni30Pd70 alloy nanoparticles (rGO-Ni30Pd70) for the direct hydrogenation of alkenes and alkynes to alkanes, which surpasses the commercial Pd/C catalyst both in activity and stability. A variety of cyclic or aromatic alkenes and alkynes (a total of 17 examples) were rapidly reduced to the corresponding alkanes with high yields (>99%) via the presented direct hydrogenation protocol under ambient conditions. Compared to the commercially available Pd/C (10 wt%) catalyst, the rGO-Ni30Pd70 catalyst provided higher yields in shorter reaction times under the optimized conditions. Moreover, the rGO-Ni30Pd70 catalysts were more stable and durable than the commercial Pd/C catalysts by preserving their initial activity after five consecutive runs in the hydrogenation reactions.
- ?etinkaya, Yasin,Metin, ?nder,Balci, Metin
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p. 28538 - 28542
(2016/04/08)
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- Method for preparing cis-pinane through selective hydrogenation of alpha-pinene
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A method for preparing cis-pinane through selective hydrogenation of alpha-pinene is disclosed. According to the method, the mass ratio of alpha-pinene to a magnetic catalyst is 50:1-3, the reaction temperature is 140-180 DEG C, the hydrogenation pressure is 3.0-7.0 MPa, and the reaction time is 3.0-7.0 h, and thus cis-pinane is prepared. After the reaction is finished, the catalyst phase and the product phase are respectively recovered by utilizing an applied magnetic field. The catalyst phase can be directly reused without being processed. Under the technological conditions, the conversion rate of cis-pinane is larger than 96%, and the selectivity of cis-pinane is larger than 94%.
- -
-
Paragraph 0018
(2016/11/07)
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- Synthesis of silanized magnetic Ru/Fe3O4@SiO2 nanospheres and their high selectivity to prepare: Cis -pinane
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(3-Aminopropyl)-triethoxysilane (APTS) and (3-mercaptopropyl)-trimethoxysilane (MPTS) grafted SiO2-coated iron oxide (Fe3O4@SiO2) magnetic supports were prepared. Various noble metal nanoparticles such as Ru, Pt, Rh and Pd were directly grown on the surfaces of the magnetic supports with ultrasmall and nearly monodisperse sizes, especially the APTS grafted Fe3O4@SiO2 (Fe3O4@SiO2/APTS) nanospheres. The Fe3O4@SiO2/APTS/Ru catalyst demonstrated a high catalytic activity towards the hydrogenation of α-pinene to form cis-pinane. The conversion of α-pinene was 99.1% and the selectivity for cis-pinane reached 97.6% at 120 °C after 4 h. The Fe3O4@SiO2/APTS/Ru catalyst was easily separated from the reaction mixture when applying an external magnetic field, and the separated Fe3O4@SiO2/APTS/Ru had good reusability. After being reused eight times, the α-pinene conversion and the cis-pinane selectivity also can reach 97.8% and 96.9%, respectively.
- Liu, Yue,Li, Lu,Liu, Shiwei,Xie, Congxia,Yu, Shitao
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p. 81310 - 81317
(2016/10/12)
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- Magnetically recyclable Ru immobilized on amine-functionalized magnetite nanoparticles and its high selectivity to prepare cis-pinane
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cis-Pinane was efficient and selective prepared through the hydrogenation of α-pinene base on Ru nanoparticles stabilized by amine-functionalized magnetite nanoparticles (Fe3O4/NH2/Ru). The effects o`f changing carbon chain length on amine-functionalized catalyst formation have also been investigated. The characterization results showed that Ru nanoparticles could be efficient loaded by 1, 6-hexanediamine functionalized magnetite nanoparticles. At the same time, Fe3O4/1, 6-hexanediamine/Ru had good superparamagnetic properties and that the introduction of the amine-functionalized improved the monodispersity, morphological regularity and size uniformity of the Ru nanoparticles. The Fe3O4/1, 6-hexanediamine/Ru catalyst was completely recoverable with the simple application of an external magnetic field and the catalytic efficiency showed no obvious loss for the hydrogenation of α-pinene even after ten repeated cycles.
- Liu, Yue,Li, Lu,Liu, Shiwei,Xie, Congxia,Yu, Shitao
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p. 269 - 275
(2016/09/14)
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- Method for synthesizing cis-pinane by alpha-pinene continuous catalytic hydrogenation
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The invention discloses a method for synthesizing cis-pinane by alpha-pinene continuous catalytic hydrogenation, and belongs to the field of industrial catalysis of petrochemical engineering. A skeleton nickel capable of being used for a fixing bed hydrogenation process is taken as a catalyst (particle size distribution is 1-3mm and aluminum content is 23%), and a fixing bed continuous catalytic hydrogenation process is used to realize the alpha-pinene continuous catalytic hydrogenation to synthesize the cis-pinane. The method has the characteristics of simple process flow, convenience in posttreatment and high production efficiency, safety in the production process is increased, and the deactivation of the catalyst in the reaction process is avoided.
- -
-
Paragraph 0018; 0021
(2017/03/25)
-
- Postassembly Transformation of a Catalytically Active Composite Material, Pt@ZIF-8, via Solvent-Assisted Linker Exchange
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2-Methylimidazolate linkers of Pt@ZIF-8 are exchanged with imidazolate using solvent-assisted linker exchange (SALE) to expand the apertures of the parent material and create Pt@SALEM-2. Characterization of the material before and after SALE was performed. Both materials are active as catalysts for the hydrogenation of 1-octene, whereas the hydrogenation of cis-cyclohexene occurred only with Pt@SALEM-2, consistent with larger apertures for the daughter material. The largest substrate, β-pinene, proved to be unreactive with H2 when either material was employed as a candidate catalyst, supporting the contention that substrate molecules, for both composites, must traverse the metal-organic framework component in order to reach the catalytic nanoparticles.
- Stephenson, Casey J.,Hupp, Joseph T.,Farha, Omar K.
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supporting information
p. 1361 - 1363
(2016/02/27)
-
- Mild water-promoted ruthenium nanoparticles as an efficient catalyst for the preparation of cis-rich pinane
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Ruthenium (Ru) nanoparticles were prepared using polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer (P123) micelles in water as a stabilizing agent. The P123-Ru micellar catalyst was first used in the hydrogenation of α-pinene to pinane, and the selectivity for cis-pinane reached 98.9%. This result is attributed to the formation of vesicles. The isolated catalyst phase could be used seven times with no treatment, and its catalytic activity and selectivity were almost unchanged. The preparation process of the catalyst and hydrogenation reaction of α-pinene was under mild and environmentally friendly conditions. This research offers an effective method for the hydrogenation of α-pinene and provides a reference for other hydrophobic natural products in hydrogenation reactions.
- Hou, Shengli,Xie, Congxia,Zhong, Hua,Yu, Shitao
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p. 89552 - 89558
(2015/11/09)
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- Catalyst-free hydrogenation of alkenes and alkynes with hydrazine in the presence of oxygen
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A series of alkenes and alkynes was subjected to reduction with hydrazine hydrate in ethanol in the presence of oxygen. An efficient method was developed for the reduction of C-C double bonds and C-C triple bonds with diimide, generated in situ from hydrazine hydrate by oxidation with oxygen. The reduction process proceeded for 24-48? hours with high chemoselectivity and excellent yields. This reduction procedure offers synthetic advantages over metal-catalyzed hydrogenation as well as other systems. Georg Thieme Verlag Stuttgart New York.
- Menges, Nurettin,Balci, Metin
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p. 671 - 676
(2014/04/03)
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- Cyclodextrin-based systems for the stabilization of metallic(0) nanoparticles and their versatile applications in catalysis
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In order to better respond to environmental standards, the development of metal nanoparticles using green approaches has exponentially grown for the last decade. Cyclodextrins, which are cyclic oligosaccharides composed of 6(α), 7(β) or 8(γ) glucopyranose units, have appeared to be interesting candidates for the synthesis of metal nanoparticles. Indeed, through the ability to form inclusion complexes or supramolecular adducts with organic molecules or metal precursors, cyclodextrins can be successfully employed to stabilize size-controlled zerovalent metallic nanoparticles active for hydrogenation reactions carried out in aqueous or gas-phase media. In this summary of our works, we report that cyclodextrins could be used in various forms and environments: (i) in free form, (ii) in complexed form with appropriate guests molecules, (iii) in combination with polymer matrices, (iv) in thermosensitive hydrogels and (v) immobilized onto porous carbons supports. All these studies highlight the fact that cyclodextrins can be seen as multi-task agents for nanocatalysis.
- No?l, Sébastien,Léger, Bastien,Ponchel, Anne,Philippot, Karine,Denicourt-Nowicki, Audrey,Roucoux, Alain,Monflier, Eric
-
-
- Iridium(I) complexes with anionic N-heterocyclic carbene ligands as catalysts for the hydrogenation of alkenes in nonpolar media
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A series of lithium complexes of anionic N-heterocyclic carbenes that contain a weakly coordinating borate moiety (WCA-NHC) was prepared in one step from free N-heterocyclic carbenes by deprotonation with n-butyl lithium followed by borane addition. The reaction of the resulting lithium-carbene adducts with [M(COD)Cl]2 (M = Rh, Ir; COD = 1,5-cyclooctadiene) afforded zwitterionic rhodium(I) and iridium(I) complexes of the type [(WCA-NHC)M(COD)], in which the metal atoms exhibit an intramolecular interaction with the N-aryl groups of the carbene ligands. For M = Rh, the neutral complex [(WCA-NHC)Rh(CO)2] and the ate complex (NEt4)[(WCA-NHC) Rh(CO)2Cl] were prepared, with the latter allowing an assessment of the donor ability of the ligand by IR spectroscopy. The zwitterionic iridium-COD complexes were tested as catalysts for the homogeneous hydrogenation of alkenes, which can be performed in the presence of nonpolar solvents or in the neat alkene substrate. Thereby, the most active complex showed excellent stability and activity in hydrogenation of alkenes at low catalyst loadings (down to 10 ppm).
- Kolychev, Eugene L.,Kronig, Sabrina,Brandhorst, Kai,Freytag, Matthias,Jones, Peter G.,Tamm, Matthias
-
supporting information
p. 12448 - 12459
(2013/09/23)
-
- Radical chain reduction of alkylboron compounds with catechols
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The conversion of alkylboranes to the corresponding alkanes is classically per-formed via protonolysis of alkylboranes. This simple reaction requires the use of severe reaction conditions, that is, treatment with a carboxylic acid at high temperature (>150 °C). We report here a mild radical procedure for the transformation of organoboranes to alkanes. 4-tert-Butylcatechol, a well-established radical inhibitor and antioxidant, is acting as a source of hydrogen atoms. An efficient chain reaction is observed due to the exceptional reactivity of phenoxyl radicals toward alkylboranes. The reaction has been applied to a wide range of organoboron derivatives such as B- alkylcatecholboranes, trialkylboranes, pinacolboronates, and alkylboronic acids. Furthermore, the so far elusive rate constants for the hydrogen transfer between secondary alkyl radical and catechol derivatives have been experimentally determined. Interestingly, they are less than 1 order of magnitude slower than that of tin hydride at 80 °C, making catechols particularly attractive for a wide range of transformations involving C-C bond formation.
- Villa, Giorgio,Povie, Guillaume,Renaud, Philippe
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supporting information; experimental part
p. 5913 - 5920
(2011/06/16)
-
- A convenient methodology for the chemoselective reduction of a wide variety of functionalized alkenes
-
An efficient method to effect chemoselective reduction of alkenes (including trisubstituted olefins) possessing various sensitive and/or reducible groups such as acetals, allylic alcohols, benzyl ethers, epoxides, esters, halides, nitriles, and sulfones is reported. The reduction is facile at 0 °C in aqueous N,N-dimethylacetamide containing sodium borohydride in the presence of 15 mol % ruthenium(III) chloride. Regioselective reduction of dienes is also feasible if the double bonds are sufficiently different in their structural environment.
- Babler, James H.,White, Nicholas A.
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experimental part
p. 439 - 441
(2010/03/04)
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- Catalytic activity of the VIII group metals in the hydrogenation and isomerization of α- And β-pinenes
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The kinetic regularities of the liquid-phase hydrogenation and isomerization of α- and β-pinenes over the Pd/C, Ru/C, Rh/C, Pt/C, and Ir/C catalysts were studied at temperatures ranging from 20 to 100 °C and at hydrogen pressures of 1-11 bar using n-octane as the solvent. The hydrogenation and isomerization of α- and β-pinenes occur simultaneously on the Ru/C, Rh/C, Pt/C, and Ir/C catalysts, and the reaction mixture contains the products of double bond hydrogenation, viz., cis- and trans-pinanes. The Ru, Rh, and Pd metals have a higher catalytic activity in β-pinene isomerization than Ir and Pt. Among the VIII Group metals studied, the Pd-based catalyst has the highest catalytic activity in double bond isomerization of α- and β-pinenes. The general scheme of the mechanism of hydrogenation and isomerization of α- and β-pinenes on the Pd/C catalyst was proposed.
- Deliy,Simakova
-
body text
p. 2056 - 2064
(2010/05/02)
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- Methylated cyclodextrins: An efficient protective agent in water for zerovalent ruthenium nanoparticles and a supramolecular shuttle in alkene and arene hydrogenation reactions
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Zerovalent ruthenium(0) nanoparticles in the size range of 2.5 nm were easily prepared by chemical reduction of ruthenium salt with an excess amount of sodium borohydride and were efficiently stabilized by methylated cyclodextrins. The optimization of the catalytic system has been carried out in terms of stability and catalytic activity, considering the hydrogenation of olefinic compounds under biphasic liquid-liquid conditions. Efficient and controlled chemoselectivities were obtained in the hydrogenation of arene derivatives by the relevant choice of cavity and methylation degree of the cyclodextrins. Finally, the hydrogenation of α- and β-pinenes leads to the major formation of cis-pinanes, interesting synthons for fine chemistry, with high diastereoisomeric excesses. This journal is The Royal Society of Chemistry.
- Denicourt-Nowicki, Audrey,Ponchel, Anne,Monflier, Eric,Roucoux, Alain
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p. 5714 - 5719
(2008/09/17)
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- Selective reduction of mono- and disubstituted olefins by NaBH4 and catalytic RuCl3
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Direct use of the relatively inexpensive reagent, RuCl3 × H2O, as a catalyst for the reductions of olefins in the presence of water is reported. The combination of cheap and readily available sodium borohydride and a catalytic amount of RuCl3 × H2O selectively reduces mono- and disubstituted olefins, whereas trisubstituted olefins, unless activated, and benzyl ethers remain inert.
- Sharma, Pawan K.,Kumar, Surender,Kumar, Pawan,Nielsen, Poul
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p. 8704 - 8708
(2008/03/14)
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- Hydrogenation and Skeleton Rearrangements of α-Pinene on Heterogeneous Catalysts
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Hydrogenation and isomerization of α-pinene on heterogeneous catalysts were studied, and conditions were found for hydrogenation of pinene to cis-pinane on nickel catalysts and for its dehydrogenation to p-cymene on decationized zeolite Y.
- Bazhenov,Kas'yanova,Bokin,Kutepov,Khazipova,Travkin,Shchadneva,Khusnutdinov,Dzhemilev
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p. 234 - 237
(2007/10/03)
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- Rhodium catalyzed hydroformylation of β-pinene and camphene: effect of phosphorous ligands and reaction conditions on stereoselectivity
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The effect of phosphorous ligands on the rhodium catalyzed hydroformylation of β-pinene and camphene has been studied. In unmodified systems, β-pinene undergoes a fast isomerization to α-pinene. At longer reaction times and higher temperatures, the isomerization equilibrium is shifted resulting in the 80 percent chemoselectivity for β-pinene hydrofromylation products (97 percent trans). The addition of various diphosphines or phosphites improves the chemoselectivity and shifts the hydroformylation towards cis aldehyde 3a. Both the rate and diastereoselectivity of the hydroformylation of β-pinene are largely influenced by the basicity of auxiliary ligands, but surprisingly no correlation between their steric characteristics and the diastereoselectivity of the catalytic system has been revealed for the ligands with cone angles 128-165 deg. The systems with more basic ligands show lower activities, higher diastereoselectivities and usually higher chemoselectivities in the β-pinene hydroformylation. Camphene gives linear aldehyde 6, with virtually 100 percent regio- and chemoselectivity in both modified and unmodified systems. The addition of phosphorous ligands favors the formation of endo isomer 6b:6a/6b ca. 1/1.5 , whereas the ratio ca. 1/1 unmodified systems. Neither steric nor electronic parameters of the ligands have been found to influence significantly the diastereoselectivity of the camphene hydroformylation.
- Barros, Humberto J. V.,Ospina, Maria L.,Arguello, Eduardo,Rocha, William R.,Gusevskaya, Elena V.,Santos, Eduardo N. dos
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p. 150 - 157
(2007/10/03)
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- DERMATOLOGICAL COMPOSITIONS AND METHODS
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Disclosed are methods and compositions for regulating the melanin content of mammalian melanocytes; regulating pigmentation in mammalian skin, hair, wool or fur; treating or preventing various skin and proliferative disorders; by administration of various compounds, including alcohols, diols and/or triols and their analogues.
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- Catalytic Hydrogenation of α-Pinene and Its Derivatives
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Catalytic hydrogenation of α-pinene, verbenone (2,6,6-trimethyl-bicyclo[3,1,1]hept-2-en-4-one) and substituted bezylideneverbanylamines was studied under various conditions. Selective transformation of the initial compounds into the corresponding derivatives of the cis-pinane series is observed in the presence of nickel-magnesium oxide catalyst. Conditions were adjusted to provide conversion of α-pinene into cis-pinane with 98% yield. The verbenone was selectively reduced to cis-verbanone with pseudoequatorial location of the methyl at C2 atom. Reduction of the ortho-substituted bezylideneverbanylamines resulted in the corresponding individual N-R-2,6,6-trimethylbicyclo[3,1,1]hept-4-ylamines with pseudoequatorial location of the amino group at the C4 atom.
- Tereshko,Basalaeva,Kozlov,Tarasevich
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p. 787 - 791
(2007/10/03)
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- Rate constant of the α-pinene + atomic hydrogen reaction at 295 K
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The rate constant of the reaction of α-pinene with atomic hydrogen was determined at 295 K using the fast-flow reactor technique directly coupled to a mass spectrometric detection technique. The value was found to be equal to (9.8 ± 3.3) × 10-13 cm3 molecules-1 s-1 and independent of the helium pressure between 1 and 2 torr. The major reaction product formed is pinane showing that the stabilization of the adduct radical C10H17, followed by a subsequent hydrogen atom addition step, is the important reaction route.
- Vinckier,Van Hoof
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p. 527 - 534
(2007/10/03)
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- Chemoselectivity in Catalytic Transfer Hydrogenation - Reduction of Alkenes and Alkynes with the H2PO2-NH4+*H2O/Pd-C System
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The H2PO2-*H2O/Pd-C system acts as an unusually powerful reducing agent, which is able to reduce cyclooctene to cyclooctane, Δ9,10-octalin to decalins, α- and β-pinenes to pinanes at room temperature in high yield without the formation of byproducts.This system reduces each of these compounds or partly (alkynes to alkenes), depending on the competition between the transfer hydrogenation to give alkanes and the protonolysis to give hydrogen gas on the palladium catalyst. - Key Words: Chemoselectivity/ Protonolysis/ Transfer hydrogenation/ Alkenes, reduction of/ Alkynes, reduction of
- Khai, Bui The,Arcelli, Antionio
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p. 2265 - 2268
(2007/10/02)
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- Studies on the Oxidation of cis- and trans-Pinane with Molecular Oxygen
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The pinanes are preferably attacked at the tertiary C-H bond in 2-position, but products of the oxidative attack at the secondary C-H-bonds in 3- and 4-position are also found.At 100 deg C cis-pinane is attacked more easily than trans-pinane (kcis : ktrans = 6.4), the relative rates of attack at the secondary C-H bonds in positions 3 and 4 with respect to the tertiary C-H bond in 2-position were also determined (in cis-pinane ksec : ktert = 0.027; in trans-pinane ksec : ktert = 0.20).After the attack at the 2-C-H bond the radical formed can either react with oxygen to form the corresponding cis- and trans-peroxy radicals and further to give cis- and trans-2-hydroperoxy pinane or fragmentate to the monocyclic radical derived from α-terpinene, giving as a final products α-terpinene hydroperoxide and the bicyclic 8-hydroperoxy 4,4,8-trimethyl 2,3-dioxabicyclononane.The corresponding alcohols were found after reduction with sodium sulphite.The oxidation at position 2 of the pinanes delivers not only the cis- and trans-hydroperoxide but also, as short-lived intermediates, the corresponding 2-pinanyloxy radicals.These radicals fragmentate forming a carbon radical with cyclobutane structure whose oxidation products were identified.Besides fragmentation of the 2-pinanyloxy radical also an intramolecular H-transfer from the methyl group in 9-position to the oxygen of the trans-pinanyloxy radical takes place leading to 9-hydroperoxy trans-pinane-2-ol.
- Brose, Thomas,Pritzkow, Wilhelm,Thomas, Gerda
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p. 403 - 409
(2007/10/02)
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- A Facile Conversion of Alkenes to Alcohols with Benzyltriethylammonium Borohydride-Chlorotrimethylsilane
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A combination of benzyltrimethylammonium borohydride and chlorotrimethylsilane (1:1) in dichloromethane at 0 deg C has been found to be a convenient reagent system for the conversion of alkenes to alcohols, the hydroxy group of which is introduced in an anti-Markovnikov manner.
- Baskaran, Sundarababu,Gupta, Varsha,Chidambaram, Nallaperumal,Chandrasekaran, Srinivasan
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p. 903 - 904
(2007/10/02)
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- SELECTIVE CONVERSION OF PINANE INTO β-PINENE CATALYZED BY AN IRIDIUM PENTAHYDRIDE COMPLEX
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Pinane was catalytically converted into β-pinene with high selectivity by means of a soluble iridium pentahydride complex at 100 degC in the presence of 3,3-dimethylbut-1-ene as hydrogen acceptor.
- Lin, Yingrui,Ma, Dawei,Lu, Xiyan
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p. 407 - 410
(2007/10/02)
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