- Hydrogenation of aromatic aldehydes to aromatic hydrocarbons over Cu-HZSM-5 catalyst
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With benzaldehyde as a model compound, the hydrogenation of aromatic aldehydes to aromatic hydrocarbons was investigated. Cu-HZSM-5 exhibited excellent catalytic performance for the reaction. The obtained catalysts were characterized by N2 adsorption/desorption, N2O chemisorptions, X-ray diffraction, NH3-temperature programmed desorption and X-ray photoelectron spectroscopy. It was found that Cu 0 active species exhibited poor activity for the hydrogenation of benzene ring, while the strong acidity of HZSM-5 accelerated the hydrogenation reaction via hydrogen spillover phenomenon and the C-O activation effect. In addition, the catalyst was proved to be effective for the hydrogenation of a series of aromatic aldehydes to corresponding aromatic hydrocarbons.
- Kong, Xiangjin,Chen, Ligong
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- Electrocatalytic degradation of aspen lignin over Pb/PbO2 electrode in alkali solution
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Abstract A novel procedure about electrochemical catalysis degradation of aspen lignin with Pb/PbO2 anode in the three-dimensional electrode (TDE) reactor was investigated. SEM, XRD and cyclic voltammogram tests were employed to study the surface morphology, composition and the electrochemical redox performance of the fabricated Pb/PbO2 electrode. The lignin was cracked by OH and hydrogenated by [H] atom generated from alkaline water electrolysis, leading to the production of 4-methylanisole and other products. Raw material lignin concentration, current density, temperature and time were optimized. The pathway of electrocatalytic degradation and hydrogenation process of lignin in alkaline solution was also discussed.
- Wang, Yong-sheng,Yang, Fang,Liu, Zhi-hua,Yuan, Lu,Li, Gang
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- Pd(0)-CATALYZED ELECTRO-REDUCTIVE COUPLING OF ARYL HALIDES
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An efficient electro-reductive coupling of aryl bromides and iodides into biaryls has been performed by the electrolysis with Pd(0)- and/or Pd(II)-catalysts in a DMF-Et4NOTs-(Pb cathode) system. 4-Bromo- and 2-bromopyridines were also converted into the corresponding bipyridyls, respectively.
- Torii, Sigeru,Tanaka, Hideo,Morisaki, Kazuo
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- Iodothyronine Deiodinase Mimics. Deiodination of o,o'-Diiodophenols by Selenium and Tellurium Reagents
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To better understand, and in the extension mimic, the action of the three selenium-containing iodothyronine deiodinases, o,o'-diiodophenols were reacted under acidic conditions with sodium hydrogen telluride, benzenetellurol, sodium hydrogen selenide, or benzeneselenol and under basic conditions with the corresponding deprotonated reagents. Sodium hydrogen telluride was found to selectively remove one iodine from a variety of 4-substituted o,o'-diiodophenols, including a protected form of thyroxine (T4). Thus, it mimics the D1 variety of the iodothyronine deiodinases. Sodium telluride was a more reactive deiodinating agent toward o,o'-diiodophenols, often causing removal of both halogens. Benzenetellurol and sodium benzenetellurolate sometimes showed useful selectivity for monodeiodination. However, the products were often contaminated by small amounts of organotellurium compounds. Sodium hydrogen selenide, sodium selenide, benzeneselenol, and sodium benzeneselenolate were essentially unreactive toward o,o'-diiodophenols. To gain more insight into thyroxine inner-ring deiodination, substituted 2,6-diiodophenyl methyl ethers were treated with some of the chalcogen reagents. Reactivity and selectivity for monodeiodination varied considerably depending on the substituents attached to the aromatic nucleus. In general, it was possible to find reagents that could bring about the selective mono- or dideiodination of these substrates.
- Vasil'ev, Andrei A.,Engman, Lars
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- Reaction of borane-dimethyl sulfide complex with aromatic acids: Access to methyl compounds or to benzyl dimethyl sulphonium salts
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In certain conditions, the action of borane dimethyl sulfide (BMS) with aromatic carboxylic acids leads to the corresponding methyl derivatives or, in the presence of BF3, to the benzyl dimethyl sulphonium salts.
- Le Deit,Cron,Le Corre
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- Encapsulated Ni-Co alloy nanoparticles as efficient catalyst for hydrodeoxygenation of biomass derivatives in water
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Catalytic hydrodeoxygenation (HDO) is one of the most promising strategies to transform oxygen-rich biomass derivatives into high value-added chemicals and fuels, but highly challenging due to the lack of highly efficient nonprecious metal catalysts. Herein, we report for the first time of a facile synthetic approach to controllably fabricate well-defined Ni-Co alloy NPs confined on the tip of N-CNTs as HDO catalyst. The resultant Ni-Co alloy catalyst possesses outstanding HDO performance towards biomass-derived vanillin into 2-methoxy-4-methylphenol in water with 100% conversion efficiency and selectivity under mild reaction conditions, surpassing the reported high performance nonprecious HDO catalysts. Impressively, our experimental results also unveil that the Ni-Co alloy catalyst can be generically applied to catalyze HDO of vanillin derivatives and other aromatic aldehydes in water with 100% conversion efficiency and over 90% selectivity. Importantly, our DFT calculations and experimental results confirm that the achieved outstanding HDO catalytic performance is due to the greatly promoted selective adsorption and activation of C=O, and desorption of the activated hydrogen species by the synergism of the alloyed Ni-Co NPs. The findings of this work affords a new strategy to design and develop efficient transition metal-based catalysts for HDO reactions in water.
- Chen, Chun,Gong, Wanbing,Han, Miaomiao,Wang, Dongdong,Wang, Guozhong,Zhang, Haimin,Zhang, Jifang,Zhang, Yunxia,Zhao, Huijun
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- Co embedded within biomass-derived mesoporous N-doped carbon as an acid-resistant and chemoselective catalyst for transfer hydrodeoxygenation of biomass with formic acid
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An N-doped Co@C catalyst (Co@NC) is synthesized by a one-pot carbonization of biomass-derived glucose and harmless melamine with CoCl2 as the catalyst, where C and N resources could be transformed into highly graphitic N-doped carbon, while the coordinated Co2+ ions are reduced to uniform Co nanoparticles (NPs), which are embedded in N-doped graphitic structures. Under base-free conditions with formic acid (FA) as a hydrogen donor, the optimized Co@NC-700 (pyrolyzed at 700 °C) shows a highly efficient H2 generation from FA and the best activity for vanillin hydrodeoxygenation (HDO) with FA. For example, Co@NC-700 exhibits 15.4 times higher activity in comparison with uncovered Co on AC (Co/AC), and affords >95% vanillin conversion with 2-methoxy-4-methylphenol (MMP) as the sole product at 180 °C for 4 h. Compared with molecular hydrogen, Co@NC-700 gives a much higher activity and MMP selectivity for vanillin HDO with FA. The Co@NC-700 demonstrates enhanced acid resistance in acidic medium and adsorption of vanillin, and is recyclable and versatile for hydrogenating various unsaturated compounds. The superior performance of Co@NC-700 could be ascribed to N-derived defective sites on Co@NC, which could play multiple roles as base additives in FA dehydrogenation and as a metal-like active center in vanillin HDO.
- Yang, Huanhuan,Nie, Renfeng,Xia, Wang,Yu, Xiaolong,Jin, Dingfeng,Lu, Xinhuan,Zhou, Dan,Xia, Qinghua
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- DESULFURIZATION OF MERCAPTANS TO HYDROCARBONS BY CARBON MONOXIDE AND WATER IN THE PRESENCE OF COBALT CARBONYL
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Benzylic mercaptans and thiophenols undergo desulfurization when exposed to carbon monoxide and water, with cobalt carbonyl as the catalyst; carbonyl sulfide is evolved in these reactions.
- Shim, Sang Chul,Antebi, Shlomo,Alper, Howard
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- Syntheses, binding properties, and structures of seven new hemicarcerands each composed of two bowls bridged by three tetramethylenedioxy groups and a fourth unique linkage
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Treatment of 2 mol of the bowl-shaped tetrol 1 (derived originally from resorcinol and dihydrocinnamaldehyde) with 3 mol of TsO(CH2)4OTs gave diol 2. Eight compounds with different combinations of bridges were formed from 2 by treatment with Cs2CO3 and the following reagents in the presence of potential guests to give either free or complexed hemicarcerands as follows: ClCH2Br gave 4; TsO(CH2)2OTs gave 5; TsO(CH2)3OTs gave 6; MsO(CH2)4OMs gave 7, a known system; MsO(CH2)5OMs gave 8; 2,3-bis(bromomethyl)quinoxaline gave 9; 1,3-(ClCH2)2C6H4 gave 10; 2,6-bis(chloromethyl)pyridine gave 11. Thirty-six fully characterized new hemicarceplexes are reported which were prepared either directly from diol 2 by the "sealing in" of the guest during introduction of the fourth bridge, or by guest exchange driven by mass law at 25 to 160 °C. The guests ranged in size from CHCl3 to 1,2,3-(MeO)3C6H3. The incarcerated guests correlated with portal sizes of their hosts. Crystal structures of 8⊙4-MeC6H4OMe and 10⊙CHCl3 were determined. Changes in chemical shifts in 1H NMR spectra of incarcerated and free guests are interpreted in terms of their locations in the hosts' inner phases. The length and nature of the unique host bridge affects the chemical shifts of the other bridges. Force field calculations of structural models for N-methylpyrrolidinone incarcerated in 4-7 were made. Approximate half-lives for decomplexation were determined for complexes involving the larger hosts and guests. Force-field calculations were made of binding energies and activation energies for decomplexations of models of 7⊙N-methylpyrrolidinone, 80⊙N-methylpyrrolidinone, and 10⊙N-methylpyrrolidinone. The activation energies for decomplexation were dissected into intrinsic and constrictive components.
- Yoon, Juyoung,Sheu, Chimin,Houk,Knobler, Carolyn B.,Cram, Donald J.
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- Bromine-induced Photochemical Protodesilylation of Benzyltrimethylsilanes by Hydrogen Bromide
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Benzyltrimethylsilanes are efficiently converted into toluenes by a Br2-induced photochemical chain process in the presence of HBr.
- Baciocchi, Enrico,Crescenzi, Manuela,Giacco, Tiziana Del
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- Rapid coupling of methyl iodide with aryltributylstannanes mediated by palladium(0) complexes: A general protocol for the synthesis of 11CH3-labeled PET tracers
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The reaction of methyl iodide and (excess) aryltributylstannane to give a methylarene has been studied with the focus on the realization of rapid coupling for incorporation of short-lived radionuclides into bioactive organic compounds. The coupling of methyl iodide with tributylphenylstannane (40 equiv) is accomplished in >90% yield within 5 min at 60°C with a tri-o-tolylphosphine-bound, coordinatively unsaturated Pd(o) complex together with a Cu(I) salt and K2CO3 in DMF. This protocol is applicable to a variety of homo- and heteroaromatic tin compounds, to give the corresponding methylated derivatives. The effects of the tri-o-tolylphosphine ligand, a Cu(I) salt, and DMF are discussed. This new protocol provides a firm chemical basis for the synthesis of 11CH3-incorporated PET tracers.
- Suzuki, Masaaki,Doi, Hisashi,Bjoerkman, Margareta,Andersson, Yvonne,Langstroem, Bengt,Watanabe, Yasuyoshi,Noyori, Ryoji
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- Electrophilic Benzylidene(pentacarbonyl)-chromium(0) and -tungsten(0) Complexes: Isolation, Characterization, and an Unusual Thermolytic Reaction of the Tungsten Compounds
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The reaction of the anionic alkyl complexes of chromium and tungsten, NEt4+>- (M = Cr, R = OMe; M = W, R = OMe, Me, H) with HBF4*Et2O yields isolable, strongly electrophilic benzylidene(pentacarbonyl) complexes, (CO)5M=CH(p-C6H4R); thermolysis of the tungsten compounds gives μ-benzylidene(pentacarbonyltungsten) complexes, 2.
- Fischer, Helmut,Zeuner, Siegfried,Ackermann, Klaus
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- Diels-Alder reaction of tetraarylcyclopentadienones with benzo[: B] thiophene S, S-dioxides: An unprecedented de-oxygenation vs. sulfur dioxide extrusion
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Diels-Alder reaction of tetraarylcyclopentadienones with benzo[b]thiophene dioxides in xylenes at reflux led to the formation of tetra aryl-substituted dibenzothiophene as well as penta aryl-substituted benzene analogues depending on the influence of aryl substituents present on cyclopentadienones. The intermediate dihydrodibenzothiophene-dioxides underwent aromatization either through de-oxygenation or extrusion of sulfur dioxide to furnish substituted dibenzothiophenes or benzenes. This journal is
- Manikandan, Palani,Karunakaran, Jayachandran,Varathan, Elumalai,Schreckenbach, Georg,Mohanakrishnan, Arasambattu K.
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- Cross alkyl-aryl versus homo aryl-aryl coupling in palladium-catalyzed coupling of alkyl-gold(I) and aryl-halide
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Experiments on palladium-catalyzed cross-coupling of [AuMe(PPh 3)] with aryl iodides show that Ar-Ar homocoupling products are the main product or an abundant byproduct of the reaction. The percentage of cross-coupling product is higher for aryls with a larger σp Hammet parameter. The scrambling of organic groups via bimetallic intermediates explains the formation of these products. This scrambling can be observed and the activation energies partially quantified in some cases using as aryl C 6Cl2F3, which is relatively reluctant to coupling.
- Carrasco, Desiree,Perez-Temprano, Monica H.,Casares, Juan A.,Espinet, Pablo
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- Ceria-promoted Co@NC catalyst for biofuel upgrade: synergy between ceria and cobalt species
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Ceria-promoted Co@NC (NC, N doped carbon) catalysts are prepared by pyrolysis of biomass materials. Characterization results indicate that ceria and Co species facilitate the distribution of each other due to the formation of a Ce-O-Co solid solution. The specific surface area of the catalyst increased from 378.77 to 537.7 m2g?1viathe introduction of ceria. The electron transfer from Co to Ce further enhanced their interaction, and Co species facilitate the formation of more defective oxygen vacancies on ceria, which are beneficial to the activities of catalytic hydrogenation and catalytic transfer hydrogenation (CTH), respectively. Thus, Co/Ce@NC (0.99% Co loading) pyrolyzed at 850 °C exhibits excellent performance in the hydrodeoxygenation (HDO) of vanillin with high metal utilization. Catalytic hydrogenation and CTH coexisted in the presence of H2and ethanol, and >99% yield of creosol can be obtained in each of them. The reaction processes are monitored. No intermediate is found in aqueous media, while ethoxymethyl-4-methoxy-2-phenol is detected in ethanol. Moreover, Co/Ce@NC presents outstanding stability and general applicability. This work provides new insights into the construction of M@NC (M, metal) catalysts and the HDO process of biofuel upgrade.
- Wang, Bowei,Gao, Ruixiao,Zhang, Dan,Zeng, Yuyao,Zhang, Fangying,Yan, Xilong,Li, Yang,Chen, Ligong
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- Facile one-step synthesis of palladium tellurium alloy nanorods
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A palladium-tellurium binary alloy nanomaterial was synthesized by a one-pot reaction of bis(4-methoxyphenyltelluro)methane [(4-CH3O-C6H4Te)2CH2](1) and allylpalladium (II)chloride dimer [(η3-C3H5)2Pd2(μ-Cl2)] (2) in 1:1 ratio using methylene chloride as solvent at ambient conditions. In addition to the Pd20Te7 alloy nanomaterial (3) generated, a palliadum (II) tellurolate complex [PdC1(μ-TeC6H4-OCH3)Te(C6H4-OCH3)2]2 (6), and other organic and organotellurim compounds were isolated as byproducts using column chromatography. The palladium-tellurium binary alloy nanomaterial and other byproducts from the reaction were characterized by powder X-ray diffraction (PXRD), NMR, GC-MS, transmission electron microscopy (TEM), and single crystal X-ray diffractions (XRD) methods. The palladium-tellurium binary alloy nanomaterial was obtained as single-phase Pd20Te7 nanorods, under mild conditions. TEM results indicated that the nanorods are less than 15 nm in diameter and range from 40 to 200 nm in length. A nanomaterial mixture was isolated with two binary-phases Pd20Te7 and Pd10Te3 when benzene was used as solvent. Compound 6 was successfully tested for catalytic activity for the Heck Reaction and produced a mixture of PdTe2 with Pd13Te3 nanomaterials as byproducts.
- Mariappan, Kadarkaraisamy,Varapragasam, Shelton J.P.,Hansen, Matthew R.,Rasalingam, Shivatharsiny,Alaparthi, Madhubabu,Sykes, Andrew G.
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- Role of transalkylation reactions in the conversion of anisole over HZSM-5
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Conversion of anisole, a typical component of bio-oil, was studied over an HZSM-5 zeolite at varying space times (W/F), reaction temperatures, type of carrier gas, and concentration of water in the feed. Several bimolecular and unimolecular reactions are proposed to explain the evolution of products observed. The bimolecular reactions include the following transalkylation reactions: (a) anisoles to phenol and methylanisole; (b) phenol and methylanisole to cresols; (c) phenol and anisole to cresol and phenol; (d) methylanisole and cresol to phenol and xylenol. A pseudo first-order kinetic model based on these bimolecular reactions was found to describe well the observed product distribution as a function of W/F. It is observed that shape selectivity effects prevail over electrophilic substitution and thermodynamic equilibrium effects in the formation of methylanisole isomers. However, the opposite is true for the distribution of cresol isomers. The kinetic analysis indicates that the contribution of unimolecular reactions such as isomerization is much lower than that of bimolecular reactions. The carrier gas composition was found to have a moderate effect on catalyst activity. When H2 was used as a carrier, catalyst stability showed a moderate improvement in comparison to the runs under He. However, a remarkable increase in catalytic activity was observed upon the addition of water in the feed.
- Zhu, Xinli,Mallinson, Richard G.,Resasco, Daniel E.
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- Synthesis of benzylboronates via palladium-catalyzed borylation of benzyl halides with pinacolborane
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Various benzyl halides were borylated with pinacolborane in the presence of iPr2NEt and a catalytic amount of PdCl2(PPh3)2 to afford the corresponding benzylboronates in good yields.
- Murata, Miki,Oyama, Takashi,Watanabe, Shinji,Masuda, Yuzuru
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- C-C coupling reactivity of an alkylgold(III) fluoride complex with arylboronic acids
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Previously, alkylgold(III) fluorides have been proposed as catalytic intermediates that undergo C-C coupling with reagents such as arylboronic acids in Au(I)/Au(III) cross-coupling reactions. Here is reported the first experimental evidence for this elementary mechanistic step. Complexes of the type (NHC)AuMe (NHC = N-heterocyclic carbene) were oxidized with XeF2 to yield cis-(NHC)AuMeF2 products, which were found to be in equilibrium with their fluoride-dissociated, dimeric [(NHC)AuMe(μ-F)] 2[F]2 forms. In one case, a monomeric cis-(NHC)AuMeF 2 complex was favored exclusively in solution, and it was found to react with a variety of ArB(OH)2 reagents to yield Ar-CH3 products.
- Mankad, Neal P.,Toste, F. Dean
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- Dual-pathway chain-end modification of RAFT polymers using visible light and metal-free conditions
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We report a metal-free strategy for the chain-end modification of RAFT polymers utilizing visible light. By turning the light source on or off, the reaction pathway in one pot can be switched between either complete desulfurization (hydrogen chain-end) or simple cleavage (thiol chain-end), respectively. The versatility of this process is exemplified by application to a wide range of polymer backbones under mild, quantitative conditions using commercial reagents.
- Discekici, Emre H.,Shankel, Shelby L.,Anastasaki, Athina,Oschmann, Bernd,Lee, In-Hwan,Niu, Jia,McGrath, Alaina J.,Clark, Paul G.,Laitar, David S.,De Alaniz, Javier Read,Hawker, Craig J.,Lunn, David J.
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- Facile preparation of polymer-supported methyl sulfonate and its recyclable use for methylation of carboxylic acids and amines
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A simple and efficient one-pot procedure for the preparation of polymer-supported methyl sulfonate from the reaction of polymer-supported sulfonic acid with trimethyl orthoacetate was achieved, and it could be successfully used for efficient methylation of carboxylic acids, phosphonic acids, sulfinic acids, amines, thiol, and phenol. Moreover, the polymer reagent could be recovered, regenerated, and reused easily for the same reactions. Georg Thieme Verlag Stuttgart.
- Yoshino, Tomonori,Togo, Hideo
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- Substituent and Ring Size Dependence of the 4J(Me-C-C-H) Coupling Constant
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The magnitude of the 4J proton-proton coupling constant across the fragment CH3-C-C-H (a probe of the bond order between the central sp2-sp2 hybridized carbon atoms) has been found to be essentially independent of substitution on a toluene fragment and the size of the ring containing the ortho-allylic fragment.The coupling constant is sensitive to direct substitution on the ortho-allilyc fragment, especially where the substituent is placed α to methyl group.KEY WORDS - 4J proton-proton coupling constant ortho-benzylic coupling constant ring size dependence substituent dependence
- Collins, M. J.,Hatton, P. M.,Sternbell, S.,Tansey, C. W.
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- MERCURY IN ORGANIC CHEMISTRY. 19. RHODIUM PROMOTED METHYLATION OF ORGANOMERCURIALS
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Alkenyl-, alkynyl- and arylmercurials are methylated in excellent yield upon treatment with stoichiometric amounts of CH3RhI2(PPh3)2 (1).Catalytic methylation of these organomercurials is possible using 1 and methyliodide, but side reactions interfere.
- Larock, R. C.,Hershberger, S. S.
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- Molybdenum-Catalyzed Deoxygenation Coupling of Lignin-Derived Alcohols for Functionalized Bibenzyl Chemicals
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With the growing demand for sustainability and reducing CO2 footprint, lignocellulosic biomass has attracted much attention as a renewable, carbon-neutral and low-cost feedstock for the production of chemicals and fuels. To realize efficient utilization of biomass resource, it is essential to selectively alter the high degree of oxygen functionality of biomass-derivates. Herein, we introduced a novel procedure to transform renewable lignin-derived alcohols to various functionalized bibenzyl chemicals. This strategy relied on a short deoxygenation coupling pathway with economical molybdenum catalyst. A well-designed H-donor experiment was performed to investigate the mechanism of this Mo-catalyzed process. It was proven that benzyl carbon-radical was the most possible intermediate to form the bibenzyl products. It was also discovered that the para methoxy and phenolic hydroxyl groups could stabilize the corresponding radical intermediates and then facilitate to selectively obtain bibenzyl products. Our research provides a promising application to produce functionalized aromatics from biomass-derived materials.
- Jiang, Huifang,Lu, Rui,Luo, Xiaolin,Si, Xiaoqin,Xu, Jie,Lu, Fang
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- Arylation of aliphatic alcohols with tri-p-tolylbismuth and tri-p-tolylbismuth diacetate in the presence of a copper salt
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Tri-p-tolylbismuth diacetate in the presence of a catalytic amount of a copper(II) salt (1 : 0.02, mol/mol) and tri-p-tolylbismuth in the presence of copper diacetate (1 : 2) replace the hydrogen atom of the hydroxyl groups of methanol and butanol with a tolyl group at 80 deg C in up to 90percent yields. - Key words: tri-p-tolylbismuth, tri-p-tolylbismuth diacetate, arylation; copper diacetate; methanol, butanol; alkyl tolyl ethers.
- Dodonov, V. A.,Starostina, T. I.,Kuznetsova, Yu. L.,Gushchin, A. V.
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- Methylation with Dimethyl Carbonate/Dimethyl Sulfide Mixtures: An Integrated Process without Addition of Acid/Base and Formation of Residual Salts
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Dimethyl sulfide, a major byproduct of the Kraft pulping process, was used as an inexpensive and sustainable catalyst/co-reagent (methyl donor) for various methylations with dimethyl carbonate (as both reagent and solvent), which afforded excellent yields of O-methylated phenols and benzoic acids, and mono-C-methylated arylacetonitriles. Furthermore, these products could be isolated using a remarkably straightforward workup and purification procedure, realized by dimethyl sulfide‘s neutral and distillable nature and the absence of residual salts. The likely mechanisms of these methylations were elucidated using experimental and theoretical methods, which revealed that the key step involves the generation of a highly reactive trimethylsulfonium methylcarbonate intermediate. The phenol methylation process represents a rare example of a Williamson-type reaction that occurs without the addition of a Br?nsted base.
- Chan, Bun,Lui, Matthew Y.,Lui, Yuen Wai
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- A Mild, General, Metal-Free Method for Desulfurization of Thiols and Disulfides Induced by Visible-Light
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A visible-light-induced metal-free desulfurization method for thiols and disulfides has been explored. This radical desulfurization features mild conditions, robustness, and excellent functionality compatibility. It was successfully applied not only to the desulfurization of small molecules, but also to peptides.
- Qiu, Wenting,Shi, Shuai,Li, Ruining,Lin, Xianfeng,Rao, Liangming,Sun, Zhankui
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supporting information
p. 1255 - 1258
(2021/05/05)
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- Catalytic SNAr Hydroxylation and Alkoxylation of Aryl Fluorides
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Nucleophilic aromatic substitution (SNAr) is a powerful strategy for incorporating a heteroatom into an aromatic ring by displacement of a leaving group with a nucleophile, but this method is limited to electron-deficient arenes. We have now established a reliable method for accessing phenols and phenyl alkyl ethers via catalytic SNAr reactions. The method is applicable to a broad array of electron-rich and neutral aryl fluorides, which are inert under classical SNAr conditions. Although the mechanism of SNAr reactions involving metal arene complexes is hypothesized to involve a stepwise pathway (addition followed by elimination), experimental data that support this hypothesis is still under exploration. Mechanistic studies and DFT calculations suggest either a stepwise or stepwise-like energy profile. Notably, we isolated a rhodium η5-cyclohexadienyl complex intermediate with an sp3-hybridized carbon bearing both a nucleophile and a leaving group.
- Kang, Qi-Kai,Li, Ke,Li, Yuntong,Lin, Yunzhi,Shi, Hang,Xu, Lun
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supporting information
p. 20391 - 20399
(2021/08/13)
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- Metal-Organic Framework-Confined Single-Site Base-Metal Catalyst for Chemoselective Hydrodeoxygenation of Carbonyls and Alcohols
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Chemoselective deoxygenation of carbonyls and alcohols using hydrogen by heterogeneous base-metal catalysts is crucial for the sustainable production of fine chemicals and biofuels. We report an aluminum metal-organic framework (DUT-5) node support cobalt(II) hydride, which is a highly chemoselective and recyclable heterogeneous catalyst for deoxygenation of a range of aromatic and aliphatic ketones, aldehydes, and primary and secondary alcohols, including biomass-derived substrates under 1 bar H2. The single-site cobalt catalyst (DUT-5-CoH) was easily prepared by postsynthetic metalation of the secondary building units (SBUs) of DUT-5 with CoCl2 followed by the reaction of NaEt3BH. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy (XANES) indicated the presence of CoII and AlIII centers in DUT-5-CoH and DUT-5-Co after catalysis. The coordination environment of the cobalt center of DUT-5-Co before and after catalysis was established by extended X-ray fine structure spectroscopy (EXAFS) and density functional theory. The kinetic and computational data suggest reversible carbonyl coordination to cobalt preceding the turnover-limiting step, which involves 1,2-insertion of the coordinated carbonyl into the cobalt-hydride bond. The unique coordination environment of the cobalt ion ligated by oxo-nodes within the porous framework and the rate independency on the pressure of H2 allow the deoxygenation reactions chemoselectively under ambient hydrogen pressure.
- Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Manna, Kuntal
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supporting information
p. 9029 - 9039
(2021/06/28)
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- Dynamic Kinetic Cross-Electrophile Arylation of Benzyl Alcohols by Nickel Catalysis
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Catalytic transformation of alcohols via metal-catalyzed cross-coupling reactions is very important, but it typically relies on a multistep procedure. We here report a dynamic kinetic cross-coupling approach for the direct functionalization of alcohols. The feasibility of this strategy is demonstrated by a nickel-catalyzed cross-electrophile arylation reaction of benzyl alcohols with (hetero)aryl electrophiles. The reaction proceeds with a broad substrate scope of both coupling partners. The electron-rich, electron-poor, and ortho-/meta-/para-substituted (hetero)aryl electrophiles (e.g., Ar-OTf, Ar-I, Ar-Br, and inert Ar-Cl) all coupled well. Most of the functionalities, including aldehyde, ketone, amide, ester, nitrile, sulfone, furan, thiophene, benzothiophene, pyridine, quinolone, Ar-SiMe3, Ar-Bpin, and Ar-SnBu3, were tolerated. The dynamic nature of this method enables the direct arylation of benzylic alcohol in the presence of various nucleophilic groups, including nonactivated primary/secondary/tertiary alcohols, phenols, and free indoles. It thus offers a robust alternative to existing methods for the precise construction of diarylmethanes. The synthetic utility of the method was demonstrated by a concise synthesis of biologically active molecules and by its application to peptide modification and conjugation. Preliminary mechanistic studies revealed that the reaction of in situ formed benzyl oxalates with nickel, possibly via a radical process, is an initial step in the reaction with aryl electrophiles.
- Guo, Peng,Wang, Ke,Jin, Wen-Jie,Xie, Hao,Qi, Liangliang,Liu, Xue-Yuan,Shu, Xing-Zhong
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p. 513 - 523
(2021/01/12)
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- Boron carbonitride photocatalysts for direct decarboxylation: The construction of C(sp3)-N or C(sp3)-C(sp2) bonds with visible light
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A metal-free protocol is established for the decarboxylative N-H or C(sp2)-H functionalization of acidsviametal-free boron carbon nitride (BCN) photocatalysis, delivering the desired products under ambient conditions. This methodology is applicable to the late-stage modification of pharmaceutical molecules and gram-scale experiments as well as in the recovery and reuse of the photocatalysts without the loss of reactivity. The developed photochemical reaction system fulfills the requirements of green and sustainable chemistry.
- Shi, Jiale,Wang, Rong,Wang, Xinchen,Yuan, Tao,Zheng, Meifang
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supporting information
p. 3945 - 3949
(2021/06/17)
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- Photocatalytic Reductive C-O Bond Cleavage of Alkyl Aryl Ethers by Using Carbazole Catalysts with Cesium Carbonate
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Methods to activate the relatively stable ether C-O bonds and convert them to other functional groups are desirable. One-electron reduction of ethers is a potentially promising route to cleave the C-O bond. However, owing to the highly negative redox potential of alkyl aryl ethers (Ered -2.6 V vs SCE), this mode of ether C-O bond activation is challenging. Herein, we report the visible-light-induced photocatalytic cleavage of the alkyl aryl ether C-O bond using a carbazole-based organic photocatalyst (PC). Both benzylic and non-benzylic aryl ethers underwent C-O bond cleavage to form the corresponding phenol products. Addition of Cs2CO3 was beneficial, especially in reactions using a N-H carbazole PC. The reaction was proposed to occur via single-electron transfer (SET) from the excited-state carbazole to the substrate ether. Interaction of the N-H carbazole PC with Cs2CO3 via hydrogen bonding exists, which enables a deprotonation-assisted electron-transfer mechanism to operate. In addition, the Lewis acidic Cs cation interacts with the substrate alkyl aryl ether to activate it as an electron acceptor. The high reducing ability of the carbazole combined with the beneficial effects of Cs2CO3 made this otherwise formidable SET event possible.
- Yabuta, Tatsushi,Hayashi, Masahiko,Matsubara, Ryosuke
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p. 2545 - 2555
(2021/02/01)
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- Synthesis of Dibenzyls by Nickel-Catalyzed Homocoupling of Benzyl Alcohols
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Dibenzyls are essential building blocks that are widely used in organic synthesis, and they are typically prepared by the homocoupling of halides, organometallics, and ethers. Herein, we report an approach to this class of compounds using alcohols, which are more stable and readily available. The reaction proceeds via nickel-catalyzed and dimethyl oxalate assisted dynamic kinetic homocoupling of benzyl alcohols. Both primary and secondary alcohols are tolerated.
- Pan, Feng-Feng,Guo, Peng,Huang, Xiaochuang,Shu, Xing-Zhong
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supporting information
p. 3094 - 3100
(2021/04/23)
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- Iodine-catalyzed alcohol disproportionation method
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The invention relates to the technical field of catalysis, in particular to an iodine-catalyzed alcohol disproportionation method which comprises the following steps: sequentially adding alcohol, iodine and a solvent into a high-temperature and high-pressure reaction kettle, introducing a certain amount of nitrogen, conducting reacting for a certain time, collecting an organic phase after the reaction is ended, and conducting fractionating to obtain corresponding alkane and aldehyde/ketone. Alcohol disproportionation is efficient and atom-economical conversion without any additional oxidizing agent and reducing agent, and hydrocarbon and aldehyde/ketone molecules which are easy to separate can be formed at the same time. Meanwhile, the method has wide functional group tolerance, various substrate samples including aryl alcohol derivatives, heterocyclic alcohol derivatives, allyl alcohol derivatives and dihydric alcohol are tested, and the result shows that most of the substrate samples show good or extremely good yield.
- -
-
Paragraph 0040-0041
(2021/06/13)
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- Radical induced disproportionation of alcohols assisted by iodide under acidic conditions
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The disproportionation of alcohols without an additional reductant and oxidant to simultaneously form alkanes and aldehydes/ketones represents an atom-economical transformation. However, only limited methodologies have been reported, and they suffer from a narrow substrate scope or harsh reaction conditions. Herein, we report that alcohol disproportionation can proceed with high efficiency catalyzed by iodide under acidic conditions. This method exhibits high functional group tolerance including aryl alcohol derivatives with both electron-withdrawing and electron-donating groups, furan ring alcohol derivatives, allyl alcohol derivatives, and dihydric alcohols. Under the optimized reaction conditions, a 49% yield of 5-methyl furfural and a 49% yield of 2,5-diformylfuran were obtained simultaneously from 5-hydroxymethylfurfural. An initial mechanistic study suggested that the hydrogen transfer during this redox disproportionation occurred through the inter-transformation of HI and I2. Radical intermediates were involved during this reaction.
- Huang, Yang,Jiang, Haiwei,Li, Teng,Peng, Yang,Rong, Nianxin,Shi, Hexian,Yang, Weiran
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supporting information
p. 8108 - 8115
(2021/10/29)
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- Copper-Catalyzed Methoxylation of Aryl Bromides with 9-BBN-OMe
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A Cu-catalyzed cross-coupling reaction between aryl bromides and 9-BBN-OMe to provide aryl methyl ethers under mild conditions is reported. The oxalamide ligand BHMPO plays a key role in the transformation. Various functional groups on bromobenzenes are well tolerated, providing the desired anisole products in moderate to high yields.
- Li, Chen,Song, Zhi-Qiang,Wang, Dong-Hui,Wang, Jing-Ru
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supporting information
p. 8450 - 8454
(2021/11/17)
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- Decyanation method of nitrile organic compound
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The invention provides a decyanation method of a nitrile organic compound. The nitrile organic compound shown in a general formula (1), a sodium reagent, crown ether and a proton donor are subjected to decyanation reaction in an organic solvent I to generate an organic compound shown in a general formula (2). According to the method, a Na/15-crown-5/H2O system is adopted, so that nitrile organic matters can be converted into a decyanation product, and the generation of amine byproducts is inhibited. The new method does not need to use liquid ammonia as a solvent, and is safer and more convenient to operate. The required sodium dispersoid is low in price; and the 15-crown-5 can be recycled and repeatedly used. The method has the advantages of good chemical selectivity, wide substrate application range, good functional group compatibility and the like.
- -
-
Paragraph 0063-0066
(2020/02/10)
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- Reductive Amidation without an External Hydrogen Source Using Rhodium on Carbon Matrix as a Catalyst
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An efficient method for preparation of secondary amides from primary amides and aldehydes using rhodium on carbon matrix as catalyst was developed. The method does not require any external hydrogen source and carbon monoxide is used as a reducing agent. The most active rhodium catalysts were characterized by BET, TEM and XPS techniques. Unexpectedly, it was found that heterogeneous rhodium on carbon matrix works as precatalyst for homogenous active species due to leaching of rhodium to the solution. Various secondary amides were synthesized and checked for antifungal activity. 4-Methoxy-N-(4-methoxybenzyl)benzamide demonstrated promising activity against Rhizoctonia Solani.
- Tsygankov, Alexey A.,Makarova, Maria,Afanasyev, Oleg I.,Kashin, Alexey S.,Naumkin, Alexander V.,Loginov, Dmitry A.,Chusov, Denis
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p. 112 - 117
(2019/11/28)
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- Nickel catalyzed deoxygenative cross-coupling of benzyl alcohols with aryl-bromides
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A nickel-catalyzed cross-electrophile coupling of benzyl alcohols with aromatic bromides has been developed. This deoxygenative cross-coupling occurs under mild reaction conditions at ambient temperature affording diarylmethanes, or 1,3-diarylpropenes from benzyl allyl alcohols. The system demonstrated good chemoselectivity tolerating an assortment of reactive functional groups.
- Kumar Chenniappan, Vinoth,Peck, Devin,Rahaim, Ronald
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supporting information
(2020/03/03)
-
- Nickel/Photoredox-Catalyzed Methylation of (Hetero)aryl Chlorides Using Trimethyl Orthoformate as a Methyl Radical Source
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Methylation of organohalides represents a valuable transformation, but typically requires harsh reaction conditions or reagents. We report a radical approach for the methylation of (hetero)aryl chlorides using nickel/photoredox catalysis wherein trimethyl orthoformate, a common laboratory solvent, serves as a methyl source. This method permits methylation of (hetero)aryl chlorides and acyl chlorides at an early and late stage with broad functional group compatibility. Mechanistic investigations indicate that trimethyl orthoformate serves as a source of methyl radical via β-scission from a tertiary radical generated upon chlorine-mediated hydrogen atom transfer.
- Kariofillis, Stavros K.,Shields, Benjamin J.,Tekle-Smith, Makeda A.,Zacuto, Michael J.,Doyle, Abigail G.
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supporting information
p. 7683 - 7689
(2020/04/22)
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- A methylation platform of unconventional inert aryl electrophiles: Trimethylboroxine as a universal methylating reagent
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Methylation is one of the most fundamental conversions in medicinal and material chemistry. Extension of substrate types from aromatic halides to other unconventional aromatic electrophiles is a highly important yet challenging task in catalytic methylation. Disclosed herein is a series of transition metal-catalyzed methylations of unconventional inert aryl electrophiles using trimethylboroxine (TMB) as the methylating reagent. This transformation features a broad substrate type, including nitroarenes, benzoic amides, benzoic esters, aryl cyanides, phenol ethers, aryl pivalates and aryl fluorides. Another important merit of this work is that these widespread "inert"functionalities are capable of serving as directing or activating groups for selective functionalization of aromatic rings before methylation, which greatly expands the connotation of methylation chemistry.
- Feng, Boya,Yang, Yudong,You, Jingsong
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p. 6031 - 6035
(2020/07/10)
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- Efficient Pd-Catalyzed Direct Coupling of Aryl Chlorides with Alkyllithium Reagents
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Organolithium compounds are amongst the most important organometallic reagents and frequently used in difficult metallation reactions. However, their direct use in the formation of C?C bonds is less established. Although remarkable advances in the coupling of aryllithium compounds have been achieved, Csp2?Csp3 coupling reactions are very limited. Herein, we report the first general protocol for the coupling or aryl chlorides with alkyllithium reagents. Palladium catalysts based on ylide-substituted phosphines (YPhos) were found to be excellently suited for this transformation giving high selectivities at room temperature with a variety of aryl chlorides without the need for an additional transmetallation reagent. This is demonstrated in gram-scale synthesis including building blocks for materials chemistry and pharmaceutical industry. Furthermore, the direct coupling of aryllithiums as well as Grignard reagents with aryl chlorides was also easily accomplished at room temperature.
- Dilchert, Katharina,Gessner, Viktoria H.,Gro?johann, Angela,Rodstein, Ilja,Scherpf, Thorsten,Steinert, Henning,Tappen, Jens
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supporting information
p. 20596 - 20603
(2020/09/09)
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- Desulfurization method of organic compounds containing mercapto or disulfide bond
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The invention relates to a desulfurization method of organic compounds, in particular, organic compounds containing mercapto or a disulfide bond. The method comprises following steps: dissolving organic compounds containing mercapto or a disulfide bond by a solvent; adding a phosphine reagent and an initiator; and carrying out reactions in the presence of light to convert the substrate into corresponding desulfurization products. The organic compounds containing mercapto or a disulfide bond is R-SH or R-S-S-R; wherein R represents a primary carbon group, a secondary carbon group, a tertiary carbon group, an aryl group, or an acyl group. The reactions do not need any metal, and the reaction conditions are mild. Moreover, the desulfurization method has the advantages of high yield, wide substrate application range, and multiple suitable solvents, and is widely suitable for multiple kinds of mercapto-removing reactions and desulfurization reactions of disulfide.
- -
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Paragraph 0026
(2019/10/01)
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- Palladium oxide nanoparticles supported on graphene oxide: A convenient heterogeneous catalyst for reduction of various carbonyl compounds using triethylsilane
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Palladium oxide nanoparticles supported on graphene oxide - triethylsilane was found to be an effective reductive system for a broad range of reduction processes, including the reduction of various carbonyl compounds such as aromatic aldehydes to their corresponding alcohols or methyl arene compounds, aromatic ketones to their respective alcohols or saturated compounds, aromatic acyl chlorides to their reduced compounds. The desired products were obtained in good to excellent yields under mild conditions. The heterogeneous environmentally friendly catalyst can be easily separated from the reaction mixture through a simple filtration, facilitating purification of the prepared compounds.
- Mirza-Aghayan, Maryam,Kalantari, Meisam,Boukherroub, Rabah
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- Reductive Cleavage of Unactivated Carbon-Cyano Bonds under Ammonia-Free Birch Conditions
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A general protocol for the reductive cleavage of unactivated carbon-cyano bonds in aliphatic nitriles has been achieved under single-electron-transfer conditions using Na/15-crown-5/H2O. Electron is supplied by the electride derived from bench-stable sodium dispersions and recoverable 15-crown-5. H2O provides the proton source and suppresses the reduction of aromatic moieties. Compared with the Na/NH3 electride system generated under traditional Birch conditions, this ammonia-free electride system is more practical and features better reactivity and chemoselectivity for the decyanations of a broad range of aliphatic nitriles.
- An, Jie,Ding, Yuxuan,Luo, Shihui,Ma, Lifu
-
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- Chemoselective Hydrodeoxygenation of Carboxylic Acids to Hydrocarbons over Nitrogen-Doped Carbon-Alumina Hybrid Supported Iron Catalysts
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The establishment of catalyst systems for the chemoselective hydrodeoxygenation (HDO) of carboxylic acids to hydrocarbons, such as the HDO of long-chain fatty acids to alkanes, is important for biomass to biofuel conversion. As the most abundant and probably the cheapest transition metal on the earth, iron is a promising non-noble-metal alternative to precious metals for large-scale conversion of biomass. However, it usually suffers from unsatisfactory activity. In this work, a nitrogen-doped carbon-alumina hybrid supported iron (Fe-N-C@Al2O3) catalyst is established for chemoselective HDO of carboxylic acids to hydrocarbons. By using stearic acid HDO as the model reaction, n-octadecane and n-heptadecane are produced with yields of 91.9% and 6.0%, respectively. Triglycerides can also be converted into liquid alkanes with a total molar yield of >92%. In addition, the iron catalyst can chemoselectively catalyze the HDO of the carboxylic acid group in the presence of other functional groups such as an aromatic ring. This chemoselectivity has rarely been seen before because the aromatic ring is usually more easily hydrogenated in comparison to HDO of the carboxylic acid group. The characterization results showed that both the formation of a nitrogen-doped carbon-alumina hybrid and the iron loading are important for the Lewis basicity of these catalysts, in order to adsorb the acid substrates. The addition of melamine as the nitrogen precursor during pyrolysis eliminates undesired reactions between the iron precursor and alumina support to form an inactive hercynite phase, leading to the formation of an Fe3C active phase for the hydrogenation of -COOH to -CH2OH and the hybrid of N-C and alumina for the HDO of -CH2OH to -CH3.
- Li, Jiang,Zhang, Junjie,Wang, Shuai,Xu, Guangyue,Wang, Hao,Vlachos, Dionisios G.
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p. 1564 - 1577
(2019/02/03)
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- Iron-catalyzed cross coupling of aryl chlorides with alkyl Grignard reagents: Synthetic scope and FeII/FeIV mechanism supported by x-ray absorption spectroscopy and density functional theory calculations
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A combination of iron(III) fluoride and 1,3-bis(2,6-diiso-propylphenyl)imidazolin-2-ylidene (SIPr) catalyzes the high-yielding cross coupling of an electron-rich aryl chloride with an alkyl Grignard reagent, which cannot be attained using other iron catalysts. A variety of alkoxy-or amino-substituted aryl chlorides can be cross-coupled with various alkyl Grignard reagents regardless of the presence or absence of β-hydrogens in the alkyl group. A radical probe experiment using 1-(but-3-enyl)-2-chlorobenzene does not afford the corresponding cyclization product, therefore excluding the intermediacy of radical species. Solution-phase X-ray absorption spectroscopy (XAS) analysis, with the help of density functional theory (DFT) calculations, indicates the formation of a high-spin (S = 2) heteroleptic difluorido organoferrate(II), [MgX][FeIIF2(SIPr)-(Me/alkyl)], in the reaction mixture. DFT calculations also support a feasible reaction pathway, including the formation of a difluorido organoferrate(II) intermediate which undergoes a novel Lewis acid-assisted oxidative addition to form a neutral organoiron(IV) intermediate, which leads to an FeII/FeIV cata-lytic cycle, where the fluorido ligand and the magnesium ion play key roles.
- Agata, Ryosuke,Takaya, Hikaru,Matsuda, Hiroshi,Nakatani, Naoki,Takeuchi, Katsuhiko,Iwamoto, Takahiro,Hatakeyama, Takuji,Nakamura, Masaharu
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supporting information
p. 381 - 390
(2019/02/25)
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- Water and Sodium Chloride: Essential Ingredients for Robust and Fast Pd-Catalysed Cross-Coupling Reactions between Organolithium Reagents and (Hetero)aryl Halides
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Direct palladium-catalysed cross-couplings between organolithium reagents and (hetero)aryl halides (Br, Cl) proceed fast, cleanly and selectively at room temperature in air, with water as the only reaction medium and in the presence of NaCl as a cheap additive. Under optimised reaction conditions, a water-accelerated catalysis is responsible for furnishing C(sp3)–C(sp2), C(sp2)–C(sp2), and C(sp)–C(sp2) cross-coupled products, in competition with protonolysis, within a reaction time of 20 s, in yields of up to 99 %, and in the absence of undesired dehalogenated/homocoupling side products even when challenging secondary organolithiums serve as the starting material. It is worth noting that the proposed protocol is scalable and the catalyst and water can easily and successfully be recycled up to 10 times, with an E-factor as low as 7.35.
- Dilauro, Giuseppe,Quivelli, Andrea Francesca,Vitale, Paola,Capriati, Vito,Perna, Filippo Maria
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supporting information
p. 1799 - 1802
(2019/01/25)
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- Role of copper- or cerium-promoters on NiMo/Γ-Al2O3 catalysts in hydrodeoxygenation of guaiacol and bio-oil
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Effect of copper (Cu) or cerium (Ce) as promoters for nickel-molybdenum/γ-alumina (NiMo/γ-Al2O3) catalyst on the hydrodeoxygenation (HDO) of guaiacol (GUA), a model oxygenated compound found in a bio-oil derived from woody biomass, was comparatively investigated. The addition of Cu- or Ce-promoters affected the physicochemical properties of the NiMo catalyst. The NiMo catalyst promoted by Cu showed the higher reducibility, whilst the Ce-promoter (2–8 wt% based on γ-Al2O3 content) provided the NiMo catalyst with a higher distribution of active metals and induced a greater difficulty in the reduction under hydrogen (H2) atmosphere. For the HDO of GUA at a mild reaction condition (10 bar initial H2 pressure and 300 °C) in the absence of solvent, the Cu-promoter enhanced the hydrogenation activity of the NiMo catalyst to convert GUA to phenol and methylphenols, one-atomic oxygen species. Whereas, the addition of Ce obviously inhibited the formation of coke on the catalyst surface after a long reaction period (6 h) and gave a higher GUA conversion level with increasing yield of phenols. For the HDO of real bio-oil obtained from the fast pyrolysis of cassava rhizome, the NiMo catalysts promoted by Cu or Ce at 4 wt% based on the γ-Al2O3 content showed a higher performance at eliminating the oxygenated compounds in the bio-oil, reducing the oxygen/carbon (O/C) molar ratio by over seven-fold from 1.75 to 0.24–0.25. Moreover, the gross heating value of the bio-oil was improved from 21.5 to ca. 29.0 MJ/kg after the HDO process. However, the addition of the Cu or Ce promoter did not inhibit coke deposition, possibly due to the acidic properties of the bio-oil that deteriorated the catalyst performance by metal leaching.
- Sangnikul, Patiphat,Phanpa, Chanisara,Xiao, Rui,Zhang, Huiyan,Reubroycharoen, Prasert,Kuchonthara, Prapan,Vitidsant, Tharapong,Pattiya, Adisak,Hinchiranan, Napida
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p. 151 - 160
(2019/02/17)
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- Palladium-Catalyzed Difluoromethylation of Aryl Chlorides and Bromides with TMSCF2H
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A palladium-catalyzed cross-coupling of aryl chlorides/bromides with TMSCF2H is described. Two different catalysts, Pd(dba)2/BrettPhos and Pd(PtBu3)2, are demonstrated and provide a variety of difluoromethylated arenes in good yields.
- Ferguson, Devin M.,Malapit, Christian A.,Bour, James R.,Sanford, Melanie S.
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p. 3735 - 3740
(2019/04/11)
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- Synthesis of the isotopically labeled JAK1/3 inhibitor [D7]-R545 and its oxidative metabolite [D7]-R935: Protecting group-directed regioselective bromination to access 3,4,5-substituted anilines
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An extensive medicinal chemistry campaign and subsequent SAR studies led to the discovery of the highly potent and selective JAK1/3 inhibitor R545. To support advanced pre-clinical DMPK studies of R545, the isotopically labeled versions of the drug and its metabolite R935 were required. Herein, we describe the development of synthetic routes to deuterium-labeled [D7]-R545 and its oxidative metabolite [D7]-R935. Deuterium atoms were introduced at several sites in the target molecules by employing a convergent synthesis strategy. The desired regiochemistry at the right-hand side of [D7]-R935 was established via a newly discovered protecting group-directed bromination. The described synthetic approach gave rise to the desired deuterium-labeled target compounds and sufficient quantities were synthesized to enable pre-clinical DMPK studies.
- Heckrodt, Thilo J.,Chen, Yan,Singh, Rajinder
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p. 2385 - 2399
(2019/03/20)
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- Preparation method of 4-methylanisole
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The invention discloses a preparation method of 4-methylanisole. The method includes: using p-cresol and sodium hydroxide as the raw materials to prepare p-methylphenol sodium; allowing the p-methylphenol sodium and dimethyl sulfate to have methylation in a nonpolar solvent to prepare the 4-methylanisole and byproduct sodium methylsulfate; allowing the p-methylphenol sodium and the byproduct sodium methylsulfate to have reaction in a polar solvent to prepare the 4-methylanisole and sodium sulfate. The method has the advantages that the 4-methylanisole is prepared through the three-step reaction, the utilization rate of the dimethyl sulfate is increased, and wastewater zero discharge is achieved.
- -
-
Paragraph 0041-0043; 0044-0047; 0052-0058
(2019/08/20)
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- Nickel-catalyzed intelligent reductive transformation of the aldehyde group using hydrogen
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The selective transformation of the aldehyde group (-CHO) in multifunctional oxygenates is a key challenge in the development of sustainable biomass feedstock. Herein, a smart Ni-MFC catalyst was developed from a 2D Ni-based metal-organic framework (MOF), which efficiently promoted the transformation of -CHO in the presence of H2 to a methyl group (-CH3) via the reductive etherification and hydrogenolysis of the C-O ether bond in methanol. Moreover, the catalytic process could be controlled to directionally produce methyl ether (-CH2OR) using the reductive etherification protocol. For the catalytic reduction of vanillin, the Ni-MFC-700 catalyst guaranteed the full conversion of vanillin and 96.5% yield of the desired 2-methoxy-4-methylphenol (MMP), while the Ni-MFC-500 catalyst afforded about 82.7% yield of 4-(methoxymethyl)-2-methoxyphenol in methanol solvent. This is a novel and promising approach for the valorization of multifunctional oxygenates and biomass-derived platform compounds.
- Tong, Xinli,Guo, Pengfei,Liao, Shengyun,Xue, Song,Zhang, Haigang
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p. 5828 - 5840
(2019/11/11)
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- Nanolayered cobalt-molybdenum sulphides (Co-Mo-S) catalyse borrowing hydrogen C-S bond formation reactions of thiols or H2S with alcohols
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Nanolayered cobalt-molybdenum sulphide (Co-Mo-S) materials have been established as excellent catalysts for C-S bond construction. These catalysts allow for the preparation of a broad range of thioethers in good to excellent yields from structurally diverse thiols and readily available primary as well as secondary alcohols. Chemoselectivity in the presence of sensitive groups such as double bonds, nitriles, carboxylic esters and halogens has been demonstrated. It is also shown that the reaction takes place through a hydrogen-autotransfer (borrowing hydrogen) mechanism that involves Co-Mo-S-mediated dehydrogenation and hydrogenation reactions. A novel catalytic protocol based on the thioetherification of alcohols with hydrogen sulphide (H2S) to furnish symmetrical thioethers has also been developed using these earth-abundant metal-based sulphide catalysts.
- Corma, Avelino,Sorribes, Iván
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p. 3130 - 3142
(2019/03/13)
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- Efficient p-methyl anisole synthesis method
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The invention discloses an efficient p-methyl anisole synthesis method which comprises the following steps: firstly, preparing a ZrO2/mesoporous molecular sieve composite catalyst; by taking the composite catalyst as a catalyst, and carbonic ester and phenol as raw materials, performing a reaction at 200-400 DEG C so as to obtain methylphenol; mixing phenoxide and ammonium hydroxide, adding the methylphenol, and uniformly stirring and mixing so as to obtain a mixed solution; putting the prepared mixed solution into a reactor, adding dimethyl carbonate, performing stirring treatment for 3 minutes, and heating to 80-120 DEG C to implement a reaction; after the reaction is completed, adjusting the pH value of the reaction system to 2-5, leaving to stand and layer, collecting an oil phase, washing the oil phase with ammonium hydroxide, and collecting the oil phase, thereby obtaining p-methyl anisole. The method is simple to operate, gentle in reaction condition, rapid in reaction velocity,high in target product yield and high in purity.
- -
-
Paragraph 0026; 0031; 0032; 0039; 0046; 0053; 0060; 0067
(2018/04/03)
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- Application of Silicon-Initiated Water Splitting for the Reduction of Organic Substrates
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The use of water as a donor for hydrogen suitable for the reduction of several important classes of organic compounds is described. It is found that the reductive water splitting can be promoted by several metalloids among which silicon shows the best efficiency. The developed methodologies were applied for the reduction of nitro compounds, N-oxides, sulfoxides, alkenes, alkynes, hydrodehalogenation as well as for the gram-scale synthesis of several substrates of industrial importance.
- Gevorgyan, Ashot,Mkrtchyan, Satenik,Grigoryan, Tatevik,Iaroshenko, Viktor O.
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p. 375 - 382
(2018/06/04)
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- Hydrogenolysis of C?O Chemical Bonds of Broad Scope Mediated by a New Spherical Sol–Gel Catalyst
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The new spherical sol–gel hybrid material SiliaCat Pd0 selectively mediates the hydrogenolysis of aromatic alcohols, aldehydes, and ketones by using an ultralow catalytic amount (0.1 mol % Pd) under mild reaction conditions. The broad reaction scope as well as the catalyst's superior activity and pronounced stability open the route to green and convenient reductive deoxygenation processes of primary synthetic relevance in chemical research as well as in the fine chemical and petrochemical industries.
- Pandarus, Valerica,Ciriminna, Rosaria,Gingras, Geneviève,Béland, Fran?ois,Pagliaro, Mario,Kaliaguine, Serge
-
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- Improving Catalytic Hydrogenation Performance of Pd Nanoparticles by Electronic Modulation Using Phosphine Ligands
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Tuning the activity and selectivity of metal nanoparticles (NPs) is a long-term pursuit in the field of catalysis. Herein, we report successfully improving both the activity and chemoselectivity of Pd NPs (1.1 nm) with triphenylphosphine (PPh3) cross-linked in the nanopore of FDU-12. The electron-donating effect of PPh3 increases the surface electronic density of Pd NPs and weakens the Pd-H bond, as evidenced by the results of XPS, in situ FT-IR adsorption of CO, and H2-D2 exchange reactions. Consequently, Pd NPs modified with PPh3 obtain >99% selectivity to 1-phenylethanol in acetophenone hydrogenation and 94% selectivity to styrene in phenylacetylene hydrogenation. Furthermore, the activity of Pd NPs is enhanced and suppressed by PPh3, respectively, in the hydrogenation of electrophilic nitro compounds and nucleophilic carbonyl substrates. Our primary results shed some light on judiciously choosing organic ligands for modifying the catalytic performance of metal NPs toward specific chemical transformations.
- Guo, Miao,Li, He,Ren, Yiqi,Ren, Xiaomin,Yang, Qihua,Li, Can
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p. 6476 - 6485
(2018/06/18)
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- Ultra-Stable and High-Cobalt-Loaded Cobalt@Ordered Mesoporous Carbon Catalysts: All-in-One Deoxygenation of Ketone into Alkylbenzene
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Catalytic deoxygenation represents a straightforward and core methodology for fine-chemical production and biomass upgrading. Generally, the application of homogeneous metal complexes or heterogeneous noble-metal catalysts prevails in academia and the chemical industry. Herein, we introduce cobalt@ordered mesoporous carbon (Co@OMC) catalysts, which are constructed conveniently by a mechanochemical coordination self-assembly based on a renewable tannin precursor. Importantly, the Co@OMC catalysts with a high loading of in situ confined Co species promote the selective deoxygenation of various ketones, aldehydes, and alcohols efficiently into the corresponding alkanes under mild conditions. Therefore, a simple, inexpensive, and heterogeneous catalyst for selective deoxygenation can be expected, meanwhile the solid-state synthesis affords a green, rapid, and scalable pathway to Co@OMC catalysts.
- Zhang, Pengfei,Chen, Nanqing,Chen, Dong,Yang, Shize,Liu, Xiaofei,Wang, Li,Wu, Peiwen,Phillip, Nathan,Yang, Guang,Dai, Sheng
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p. 3299 - 3304
(2018/06/04)
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- Generation of Phosphoranyl Radicals via Photoredox Catalysis Enables Voltage-Independent Activation of Strong C-O Bonds
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Despite the prevalence of alcohols and carboxylic acids as functional groups in organic molecules and the potential to serve as radical precursors, C-O bonds remain difficult to activate. We report a synthetic strategy for direct access to both alkyl and acyl radicals from these ubiquitous functional groups via photoredox catalysis. This method exploits the unique reactivity of phosphoranyl radicals, generated from a polar/SET crossover between a phosphine radical cation and an oxygen-centered nucleophile. We show the desired reactivity in the reduction of benzylic alcohols to the corresponding benzyl radicals with terminal H atom trapping to afford the deoxygenated products. Using the same method, we demonstrate access to synthetically versatile acyl radicals, which enables the reduction of aromatic and aliphatic carboxylic acids to the corresponding aldehydes with exceptional chemoselectivity. This protocol also transforms carboxylic acids to heterocycles and cyclic ketones via intramolecular acyl radical cyclizations to forge C-O, C-N, and C-C bonds in a single step.
- Stache, Erin E.,Ertel, Alyssa B.,Rovis, Tomislav,Doyle, Abigail G.
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p. 11134 - 11139
(2018/11/21)
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- Selective Hydrogenations and Dechlorinations in Water Mediated by Anionic Surfactant-Stabilized Pd Nanoparticles
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We report a facile, inexpensive, and green method for the preparation of Pd nanoparticles in aqueous medium stabilized by anionic sulfonated surfactants sodium 1-dodecanesulfonate 1a, sodium dodecylbenzenesulfonate 1b, dioctyl sulfosuccinate sodium salt 1c, and poly(ethylene glycol) 4-nonylphenyl-3-sulfopropyl ether potassium salt 1d simply obtained by stirring aqueous solutions of Pd(OAc)2 with the commercial anionic surfactants further treated under hydrogen atmosphere for variable amounts of time. The aqueous Pd nanoparticle solutions were tested in the selective hydrogenation reactions of aryl-alcohols, -aldehydes, and -ketones, leading to complete conversion to the deoxygenated products even in the absence of strong Br?nsted acids in the reduction of aromatic aldehydes and ketones, in the controlled semihydrogenation of alkynes leading to alkenes, and in the efficient hydrodechlorination of aromatic substrates. In all cases, the micellar media were crucial for stabilizing the metal nanoparticles, dissolving substrates, steering product selectivity, and enabling recycling. What is interesting is also that a benchmark catalyst like Pd/C can often be surpassed in activity and/or selectivity in the reactions tested by simply switching to the appropriate commercially available surfactant, thereby providing an easy to use, flexible, and practical catalytic system capable of efficiently addressing a variety of synthetically significant hydrogenation reactions.
- La Sorella, Giorgio,Sperni, Laura,Canton, Patrizia,Coletti, Lisa,Fabris, Fabrizio,Strukul, Giorgio,Scarso, Alessandro
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supporting information
p. 7438 - 7446
(2018/05/29)
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- Solvent free facile room temperature reduction of aromatic carbonyl and nitro compounds by zn/Conc. HCl system - An experimental and DFT study
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This experimental and DFT studies involve a novel technique for the reduction of aromatic carbonyl/nitro compounds to the corresponding alcohols/amines, in high yield under laboratory conditions. The reducing species is the nascent hydrogen generated by the Zn/HCl system. The novelty of this work is that the comparison of yield with and without solvent. The yield is increased by many folds in the solvent free method compared to the solvent method reported earlier. The technique followed is to make a 'slurry' of the substrate with zinc dust (zinc slurry) and to add (in small portion of the dry slurry) to the optimized amount of conc. HCl, over a period of 3 to 4 h at room temperature. In this technique the substrate, adsorbed on zinc dust being very proximal to the site of generation nascent hydrogen, the reduction is very effective and the yield is high. The novelty is that zinc dust acts as catalyst (adsorbent role) and reactant (hydrogen generation role). The DFT study with B3LYP/6.311g ++ (d,p) basis set revealed that the stability of first formed free radical (energy factor) and the homo nuclear nature of carbonyl and nitro group (charge factor) decide the yield. The electrostatic potential calculated by DFT studies correlates well with Mullikan charges in deciding the charge factor. The free radical mechanism was confirmed by the formation of pinacol coupled product in one instance.
- Rajamathe,Bhuvaneswari
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p. 639 - 644
(2018/02/09)
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- Catalyst, preparation method thereof, and application of same in pyrolysis reduction of aryl ether compounds
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The invention belongs to the technical field of catalysts and particularly relates to: a catalyst, a preparation method thereof, and an application of same in pyrolysis reduction of aryl ether compounds. The catalyst employs nickel and nickel oxide as active sites and alumina as a carrier and is produced through high-temperature reduction with hydrogen. The catalyst can be used for catalyzing reactions of pyrolying aryl ether compounds with n-butanol, iso-propanol, benzyl alcohol, ethylene glycol and the like as hydrogen sources. The catalyst has simple preparation method and great stability,can be recycled for more than 16 times, and has excellent industrial application prospect.
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Paragraph 0058-0062
(2018/10/11)
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- Photoredox-Catalyzed Decarboxylative Alkylation of Silyl Enol Ethers to Synthesize Functionalized Aryl Alkyl Ketones
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Photoredox-catalyzed decarboxylative alkylation of silyl enol ethers has been developed. Diverse functionalized aryl alkyl ketones were afforded in modest to good yields using N-(acyloxy)phthalimide as an easy access alkyl radical source under mild and operationally simple conditions. The excellent performance of drug molecules such as fenbufen and indomethacin and naturally occurring carboxylic acids such as stearic acid and dehydrocholic acid further demonstrated the practicability of the reaction.
- Kong, Weiguang,Yu, Changjiang,An, Hejun,Song, Qiuling
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supporting information
p. 349 - 352
(2018/01/28)
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- An Additive-Free, Base-Catalyzed Protodesilylation of Organosilanes
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We report an additive-free, base-catalyzed C-, N-, O-, and S-Si bond cleavage of various organosilanes in mild conditions. The novel catalyst system exhibits high efficiency and good functional group compatibility, providing the corresponding products in good to excellent yields with low catalyst loadings. Overall, this transition-metal-free process may offer a convenient and general alternative to current employing excess bases, strong acids, or metal-catalyzed systems for the protodesilylation of organosilanes.
- Yao, Wubing,Li, Rongrong,Jiang, Huajiang,Han, Deman
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p. 2250 - 2255
(2018/02/23)
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- Nickel-catalyzed C-O bond reduction of aryl and benzyl 2-pyridyl ethers
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The reduction of aryl and benzyl 2-pyridyl ethers with sodium isopropoxide was carried out via nickel-catalyzed C-OPy bond cleavage, giving reductive products in reasonable to excellent yields. This method allowed the 2-pyridyloxy group to be directly rem
- Li, Jing,Wang, Zhong-Xia
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p. 2138 - 2141
(2018/03/06)
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- Ormetoprim synthesis method
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The invention provides an ormetoprim synthesis method. The method includes steps: subjecting p-cresol and dimethyl carbonate to phenolic hydroxymethylation to obtain a compound I; subjecting the compound I and potassium bromide to bromination reaction under an acetic anhydride-nitric acid system to obtain a compound II; taking cuprous chloride as a catalyst, and subjecting the compound II and sodium methylate methanol solution to methoxylation reaction to obtain a compound III; subjecting the compound III and a VHA reagent to formylation reaction to obtain a compound IV; subjecting the compound IV to reaction with sodium methylate and acrylonitrile methanol solution to obtain a compound V; after the compound V is subjected to alkali isomerization to obtain a vinyl ether structure, subjecting to addition reaction with methyl alcohol and direct condensation and cyclization with guanidine to finally obtain a compound VI which is a final product namely ormetoprim. Defects in the prior art are overcome, and the provided ormetoprim synthesis method has advantages of technical simplicity, easiness in acquisition of starting materials, high yield and low production cost.
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Paragraph 0031; 0032; 0044; 0045
(2017/11/16)
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- Synthesis method of environment-friendly p-methyl anisole
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The invention relates to a synthesis method of environment-friendly p-methyl anisole. The method includes: taking p-cresol as the raw material, using a polar solvent like water as the solvent, adopting an alkaline substance Y type zeolite as the catalyst, and adding a proper surfactant Turkey red oil as the emulsifier, and under a 130-180DEG C temperature range and other specific conditions, using environment-friendly dimethyl carbonate (DMC) as the methylation raw material to prepare p-methyl anisole. The yield is up to 96% or above, and the final product purity is up to 99% or more.
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Paragraph 0032; 0033; 0034; 0035; 0040; 0041; 0042-0045
(2017/08/30)
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