13049-40-6Relevant articles and documents
Anionic porous polymers with tunable structures and catalytic properties
Zhao, Wuxue,Zhang, Fan,Yang, Lingyun,Bi, Shuai,Wu, Dongqing,Yao, Yefeng,Wagner, Manfred,Graf, Robert,Hansen, Michael Ryan,Zhuang, Xiaodong,Feng, Xinliang
, p. 15162 - 15168 (2016)
A series of boron-containing conjugated microporous polymers with hierarchical porous structures have been readily prepared via typical transition metal-catalyzed coupling reactions. The distribution of micro- and mesopores in the networks as well as the specific surface areas are tunable via tailoring the structures of the building blocks. The distinct capability of the resulting Lewis acid-based neutral porous polymers to selectively capture fluoride ions provides a high-efficiency conversion into stable anionic porous polymers. For the first time, fluoride anion binding to boron atoms in a solid sample was essentially characterized by solid-state 11B MAS NMR spectroscopy, clearly revealing such an efficient conversion from a neutral network to a negatively charged one only through Lewis acid-base adduct formation. Upon a simple ion-exchange process, various heavy metal cations were facile to be loaded into the networks of the anionic porous polymers. Furthermore, the cobalt(ii)-loaded porous polymers were shown to promote the stoichiometric homocoupling reactions of the different aryl Grignard regents, and exert distinct size selectivities for the homocoupling products, highly dependent on their porous structures. Such a successful loading strategy might be used for design and synthesis of new types of zeolite-like porous polymers with desirable catalytic properties for a certain organic transformation, as well as other functional materials.
Photocatalytic coupled redox cycle for two organic transformations over Pd/carbon nitride composites
Jia, Qiaohui,Zhang, Sufen,Jia, Xiaoxia,Dong, Xiaoyang,Gao, Ziwei,Gu, Quan
, p. 5077 - 5089 (2019)
Heterogeneous photocatalysis offers a means for "green" organic transformations. Generally, photogenerated electrons and holes are not utilized simultaneously and effectively. Here we report a coupling approach to promote simultaneously two organic transformations of the Ullmann C-C coupling reaction and the value-added aromatic alcohol oxidation reaction in inert solvent and under anaerobic conditions using a carbon nitride based composite (Pd/CN-450) prepared by loading Pd nanoparticles (NPs) on CN-450 (N defect and O dopant co-modified g-C3N4 with high crystallinity). Upon photo-excitation of the photocatalyst, the activation of carbon-halogen bonds of the adsorbed aryl halides can be promoted by the photogenerated electrons on Pd NPs and the aromatic alcohols undergo dissociation and dehydrogenation, and finally can be oxidized by the captured photogenerated holes from CN-450 in the presence of a Br?nsted base. N defects, O doping, and improved crystallinity, controlled by changing the post-annealing temperature in molten salts, enhance the visible light absorption and improve charger carrier separation of the functionalized carbon nitride. The smaller size and high dispersity of Pd NPs give the higher surface area-to-volume ratio resulting in efficient adsorption and activation of reactant molecules on Pd NPs and allow for the effective interfacial interaction of CN-450 with Pd NPs for promoting electron transfer from CN-450 to Pd NPs. As a result, Pd/CN-450 displays a superior photocatalytic activity of the coupled reaction compared to Pd/g-C3N4 (Pd NP supported pristine g-C3N4). Moreover, the coupled reaction system has general applicability for various substrates and shows reusability.
A Copper-Based Metal-Organic Framework Acts as a Bifunctional Catalyst for the Homocoupling of Arylboronic Acids and Epoxidation of Olefins
Parshamoni, Srinivasulu,Telangae, Jyothi,Sanda, Suresh,Konar, Sanjit
, p. 540 - 547 (2016)
A copper(I)-based metal-organic framework ({[Cu2Br2(pypz)]na.nH2O} (Cu-Br-MOF) [pypz=bis[3,5-dimethyl-4-(4'-pyridyl)pyrazol-1-yl] methane] has been synthesized by using an elongated and flexible bridging ligand. The structure analysis reveals that each pypz ligand acts as a tritopic ligand connected to two Cu2Br2 dimeric units, forming a one-dimensional zig-zag chain, and these chains further connected by a Cu2Br2 unit, give a two-dimensional framework on the bc-plane. In the Cu2Br2 dimeric unit, the copper ions are four coordinated, thereby possessing a tetrahedral geometry; this proves to be an excellent heterogeneous catalyst for the aerobic homocoupling of arylboronic acids under mild reaction conditions. This method requires only 3 mol % of catalyst and it does not require any base or oxidant-compared to other conventional (Cu, Pd, Fe, and Au) catalysts-for the transformation of arylboronic acids in very good yields (98 %). The shape and size selectivity of the catalyst in the homocoupling was investigated. The use of the catalyst was further extended to the epoxidation of olefins. Moreover, the catalyst can be easily separated by simple filtration and reused efficiently up to 5 cycles without major loss of reactivity.
Controlling selectivity in the Ullmann reaction on Cu(111)
Lewis,Marcinkowski,Murphy,Liriano,Therrien,Pronschinske,Sykes
, p. 7816 - 7819 (2017)
Using a surface science approach, the selectivity in the Ullmann cross-coupling of aryl halides on Cu(111) has been understood and controlled. The binding strength of the reactants and repulsion between them dictates which organometallic intermediates form, and hence the product distribution. Cross coupling can be maximized at low reactant concentrations.
In water homocoupling of arylboronic acids using nano-rod shaped and reusable copper oxide(II) catalyst at room temperature
Raul, Prasanta Kumar,Mahanta, Abhijit,Bora, Utpal,Thakur, Ashim Jyoti,Veer, Vijay
, p. 7069 - 7073 (2015)
The work describes a simple in situ soft chemical synthesis of rod shaped nano CuO, characterization and study of its catalytic performance in the aerobic homocoupling of arylboronic acids to synthesize symmetrical biphenyls. The catalyst is simple to prepare, environmentally benign, efficient, easy recovery, reusable, stable and heterogeneous in nature.
Synthesis, characterization and crystal structure of Cu(II) complex of trans-cyclohexane-1,2-diamine: Application in synthesis of symmetrical biaryls
Agrahari, Bhumika,Layek, Samaresh,Kumari, Shweta,Anuradha,Ganguly, Rakesh,Pathak, Devendra D.
, p. 85 - 90 (2017)
A new Cu(II) complex [Cu(cyhxn)2(H2O)2][OTf]2 was synthesised by the reaction of ligand cyhxn (cyhxn?=?trans-cyclohexane-1,2-diamine) with Cu(OTf)2 in methanol at room temperature. The complex was fully characterized by elemental analysis (CHN), FT-IR, UV–Vis and EPR spectroscopic techniques. The structure of the complex was confirmed by single crystal X-ray diffraction study. The EPR spectrum is isotropic type having giso?=?2.078, which indicates a distorted octahedral geometry of the complex. The complex was found to be an active homogeneous catalyst for the homocoupling reactions of arylboronic acid to obtain symmetrical biaryls at room temperature in methanol without the use of any additives such as a base and or an oxidant.
Cu(ii)-vitamin C-complex catalyzed photo-induced homocoupling reaction of aryl boronic acid in base-free and visible light conditions
Feizpour, Fahimeh,Jafarpour, Maasoumeh,Pourmorteza, Narges,Rezaeifard, Abdolreza
, p. 4931 - 4938 (2022/02/19)
In this work, the photocatalytic efficiency of Cu(ii)-vitamin C complex immobilized on titanium dioxide nanoparticles was exploited in the photo-assisted homocoupling reaction of aryl boronic acids under heterogeneous conditions. The homocoupling reaction affords the corresponding symmetrical biaryls in 50-97% yields at ambient temperature in the air under visible light irradiation without any need for any additive such as base or oxidant. This method tolerates various substituents on the aryl boronic acids such as halogen, carbonyl, and a nitro group. The light-dependent photocatalytic performance of the title catalyst evaluated by action spectra revealed a maximum apparent quantum efficiency (AQYs) at 410 nm demonstrating the visible-light-driven photocatalytic reaction. The as-prepared nano biophotocatalyst proved to be reusable at least six times without losing its activity. Thus this work exhibits a favorable method from the environmental and economic point of view which enables the industrially important reactions such as coupling reactions, to be carried out efficiently under photocatalytic and practically attainable conditions.
