- Copper-nickel mixed oxide catalysts from layered double hydroxides for the hydrogen-transfer valorisation of lignin in organosolv pulping
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Copper and nickel mixed catalysts obtained by calcination of iron and aluminium hydrotalcites (layered double hydroxides, LDH) have been tested in the conversion of a lignin model dimer in subcritical methanol. Phase distribution and textural properties of the catalysts were characterized by X-ray diffraction Rietveld analysis and N2 physisorption. The presence of copper was critical for effective hydrogenation, both by direct hydrogen transfer from methanol to aldehyde groups and by reactivity of products from methanol reforming. TPR experiments showed that the hydrogenation activity was promoted by an enhanced reducibility of the Cu-catalysts, related to the presence of other oxide components. Characterisation of the catalysts after reaction indicated that metallic copper was formed by the reduction of CuO by methanol and that modifications of the oxide catalysts in the reaction medium played a major role in the formation of active sites.
- Albonetti, Stefania,Awan, Iqra Zubair,Beltrami, Giada,Bonincontro, Danilo,Cacciaguerra, Thomas,Cavani, Fabrizio,Di Renzo, Francesco,Gimello, Olinda,Martucci, Annalisa,Tanchoux, Nathalie
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- An alternative route for boron phenoxide preparation from arylboronic acid and its application for C[sbnd]O bond formation
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An efficient synthetic route to benzyl phenyl ether preparation has been successfully developed via a one-pot synthetic protocol utilizing a combination of arylboronic acids, hydrogen peroxide (H2O2), and benzyl halides. The whole procedure consists of two consecutive reactions, formation of boron phenoxide from arylboronic acids and its nucleophilic attack. A simple operation under mild conditions such as room-temperature ionic liquid (choline hydroxide), aerobic environment, and absence of metal- and base-catalysts has been employed. Expansion to utilize benzyl surrogates was also successfully accomplished.
- Joo, Seong-Ryu,Kim, Seung-Hoi,Lim, In-Kyun
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- α-Lithiobenzyloxy as a Directed Metalation Group in ortho-Lithiation Reactions
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The α-lithiobenzyloxy group, easily generated from aryl benzyl ethers by selective α-lithiation with t-BuLi at low temperature, behaves as a directed metalation group (DMG) providing a direct access to o-lithiophenyl α-lithiobenzyl ethers. This ortho-directing effect is reinforced in substrates bearing an additional methoxy group at the meta position. The generated dianions can be reacted with a selection of electrophiles including carboxylic esters and dihalosilanes or germanes, which afford interesting benzofuran, sila(germa)dihydrobenzofuran, and silachroman derivatives from simple aryl benzyl ethers.
- Sedano, Carlos,Velasco, Rocío,Feberero, Claudia,Suárez-Pantiga, Samuel,Sanz, Roberto
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supporting information
p. 6365 - 6369
(2020/08/24)
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- Oxidative cleavage of β-O-4 bonds in lignin model compounds with a single-atom Co catalyst
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Single-atom catalysts are emerging as primary catalysts for many reactions due to their 100% utilization of active metal centers leading to high catalytic efficiencies. Herein, we report the use of a single-atom Co catalyst for the oxidative cleavage of the β-O-4 bonds of lignin model compounds at a low oxygen pressure. Under the optimized reaction conditions, the conversion of 2-(2-methoxyphenoxy)-1-phenylethanol up to 95% with high selectivities was achieved with a variety of substrates investigated. The reusability of the Co catalyst with a high catalytic efficiency indicates its potential application in the oxidative cleavage of C-O bonds.
- Liu, Sijie,Bai, Lichen,Van Muyden, Antoine P.,Huang, Zhangjun,Cui, Xinjiang,Fei, Zhaofu,Li, Xuehui,Hu, Xile,Dyson, Paul J.
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p. 1974 - 1981
(2019/04/29)
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- Oxalic Diamides and tert-Butoxide: Two Types of Ligands Enabling Practical Access to Alkyl Aryl Ethers via Cu-Catalyzed Coupling Reaction
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A robust and practical protocol for preparing alkyl aryl ethers has been developed, which relies on using two types of ligands to promote Cu-catalyzed alkoxylation of (hetero)aryl halides. The reaction scope is very general for a variety of coupling partners, particularly for challenging secondary alcohols and (hetero)aryl chlorides. In case of coupling with aryl chlorides and bromides, two oxalic diamides serve as the powerful ligands. The tert-butoxide is first demonstrated as a ligand for Cu-catalyzed coupling reaction, leading to alkoxylation of aryl iodides complete at room temperature. Additionally, a number of carbohydrate derivatives are applicable for this coupling reaction, affording the corresponding carbohydrate-aryl ethers in 29-98% yields.
- Chen, Zhixiang,Jiang, Yongwen,Zhang, Li,Guo, Yinlong,Ma, Dawei
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supporting information
p. 3541 - 3549
(2019/02/26)
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- Exploring the Reactivity of α-Lithiated Aryl Benzyl Ethers: Inhibition of the [1,2]-Wittig Rearrangement and the Mechanistic Proposal Revisited
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By carefully controlling the reaction temperature, treatment of aryl benzyl ethers with tBuLi selectively leads to α-lithiation, generating stable organolithiums that can be directly trapped with a variety of selected electrophiles, before they can undergo the expected [1,2]-Wittig rearrangement. This rearrangement has been deeply studied, both experimentally and computationally, with aryl α-lithiated benzyl ethers bearing different substituents at the aryl ring. The obtained results support the competence of a concerted anionic intramolecular addition/elimination sequence and a radical dissociation/recombination sequence for explaining the tendency of migration for aryl groups. The more favored rearrangements are found for substrates with electron-poor aryl groups that favor the anionic pathway.
- Velasco, Rocío,Silva López, Carlos,Nieto Faza, Olalla,Sanz, Roberto
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supporting information
p. 15058 - 15068
(2016/10/11)
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- Highly efficient, NiAu-catalyzed hydrogenolysis of lignin into phenolic chemicals
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A highly efficient, stable NiAu catalyst that exhibits unprecedented low temperature activity in lignin hydrogenolysis was for the first time developed, leading to the formation of 14 wt% aromatic monomers from organosolv lignin at 170 °C in pure water. the Partner Organisations 2014.
- Zhang, Jiaguang,Asakura, Hiroyuki,Van Rijn, Jeaphianne,Yang, Jun,Duchesne, Paul,Zhang, Bin,Chen, Xi,Zhang, Peng,Saeys, Mark,Yan, Ning
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p. 2432 - 2437
(2014/05/06)
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- Tetrabutyl ammonium bromide-mediated benzylation of phenols in water under mild condition
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Benzylation of phenol was successfully achieved in water under room temperature mediated by tetrabutylammonium bromide (TBAB) for only 2 h affording the corresponding benzyl phenyl ether with good to excellent yields. This protocol is very efficient, simple, avoiding catalysts, easy to work-up after reaction, and especially 'green'.
- Wang, Hailei,Ma, Yuping,Tian, Heng,Yu, Ajuan,Chang, Junbiao,Wu, Yangjie
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p. 2669 - 2673
(2014/04/03)
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- PHENOLIC COMPOUNDS WITH ANTIOXIDANT AND ANTI-CANCER PROPERTIES, ANALOGS AND SYNTHESIS THEREOF
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The present document describes a phytochemical isolated from maple syrup and composition comprising the same. More specifically, the document describes an antioxidant phytochemical compound, derivates thereof, and composition comprising the same. The document also describes a process of synthesizing the antioxidant phytochemical compound.
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Page/Page column 54
(2013/02/27)
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- Counterattack mode differential acetylative deprotection of phenylmethyl ethers: Applications to solid phase organic reactions
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A counterattack protocol for differential acetylative cleavage of phenylmethyl ether has been developed. The phenylmethyl moiety is liberated as benzyl bromide that is isolated and reused providing advantages in terms of waste minimization/utilization and atom economy. The applicability of this methodology has been extended for solid phase organic reactions with the feasibility of reuse of the solid support.
- Chakraborti, Asit K.,Chankeshwara, Sunay V.
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supporting information; experimental part
p. 1367 - 1370
(2009/07/04)
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- Practical synthesis of aromatic ethers by SNAr of fluorobenzenes with alkoxides
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Aromatic fluorines have been substituted by alkoxides in a variety of activated and unactivated aromatic systems.
- Rodriguez, Juan R.,Agejas, Javier,Bueno, Ana B.
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p. 5661 - 5663
(2007/10/03)
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- Synergism of low energy microwave irradiation and solid-liquid phase transfer catalysis for selective alkylation of phenols to phenolic ethers
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A 100% selectivity with an order of magnitude rate enhancement is obtained in the synthesis of phenolic ethers when synergistic combination of solid-liquid phase transfer catalysis and low energy microwave irradiation (MISL-PTC) is employed. As against conventional microwave heating with 600 W power input, the current work demonstrates that a low input of 40 W leads to remarkable enhancement in rates without any destruction of the catalyst.
- Yadav, Ganapati D.,Bisht, Priyal M.
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p. 2885 - 2892
(2007/10/03)
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