4853-56-9Relevant academic research and scientific papers
Iridium-catalyzed coupling of simple primary or secondary amines, aldehydes and trimethylsilylacetylene: Preparation of propargylic amines
Sakaguchi, Satoshi,Mizuta, Tomoya,Furuwan, Masuyuki,Kubo, Takashi,Ishii, Yasutaka
, p. 1638 - 1639 (2004)
The coupling of amines, aldehydes and trimethylsilylacetylene was found to be promoted in the presence of a catalytic amount of [IrCl(cod)]2; 1:1:1 or 1:2:2 coupling products were obtained by allowing primary amine to react with aldehyde and trimethylsilylacetylene.
Synthesis, Characterization, and Photocatalytic Application of Type-II CdS/Bi2W2O9 Heterojunction Nanomaterials towards Aerobic Oxidation of Amines to Imines
Bhoi, Yagna Prakash,Mishra, Braja G.
, p. 2648 - 2658 (2018)
A series of new type-II CdS/Bi2W2O9 heterojunction nanomaterials is prepared by a two stage process. Initially, phase-pure Bi2W2O9, with orthorhombic crystalline structure, is prepared by a facile combustion-synthesis route. The combustion-synthesized Bi2W2O9 is subsequently modified by CdS nanoparticles using a hydrothermal route. The CdS/Bi2W2O9 heterojunctions are characterized using XRD, XPS, FTIR spectroscopy, UV/Vis DRS, PL, and FESEM and HRTEM studies. The occurrence of ultrafine CdS nanoparticles, with diameters of 8–15 nm, well-dispersed over BWO plates, is inferred from microscopic characterization studies. The two crystalline phases exhibit microscopic close contact across grain boundaries, facilitating the transfer of excitons. The heterojunction materials exhibit improved visible-light absorption, enhanced charge-carrier separation, and suitable band-alignment characteristics of a type-II heterojunction. The CdS/Bi2W2O9 heterojunctions are evaluated as visible-light-active photocatalysts for the aerobic oxidation of amines to imines. Structurally and functionally diverse amine molecules are oxidized to the corresponding imines, with excellent selectivity, in a short span of time.
Cyclometalated Half-Sandwich Iridium(III) Complexes: Synthesis, Structure, and Diverse Catalytic Activity in Imine Synthesis Using Air as the Oxidant
Li, Rong-Jian,Ling, Chun,Lv, Wen-Rui,Deng, Wei,Yao, Zi-Jian
, p. 5153 - 5162 (2021/05/04)
Four air-stable cyclometalated half-sandwich iridium complexes 1-4 with C,N-donor Schiff base ligands were prepared through C-H activation in moderate-to-good yields. These complexes have been well characterized, and their exact structure was elaborated on by single-crystal X-ray analysis. The iridium(III) complexes 1-4 showed good catalytic activity in the imine synthesis under open-flask conditions (air as the oxidant) from primary amine oxidative homocoupling, secondary amine dehydrogenation, and the cross-coupling reaction of amine and alcohol. Substituents bonded on the ligands of the iridium complexes displayed little effect on the catalytic efficiency. The stability and good catalytic efficiency of the iridium catalysts, mild reaction conditions, and substrate universality showed their potential application in industrial production.
Fe2Mn(μ3-O)(COO)6 Cluster Based Stable MOF for Oxidative Coupling of Amines via Heterometallic Synergy
Wang, Ying-Xia,Wang, Hui-Min,Meng, Pan,Song, Dong-Xia,Qi, Zhikai,Zhang, Xian-Ming
, p. 2983 - 2989 (2021/08/30)
The direct catalytic oxidative coupling of amines is one of the attracting methods for the synthesis of a variety of pharmaceutical or industrial needed imines. Numerous earth-abundant manganese based salts, oxides, and complexes have been applied in this reaction. However, these compounds suffered from difficult separation, large catalyst loading, complicated reactivation or indeterminate activity. Considering the facts that metal-organic frameworks (MOFs) with crystalline structure, precise composition, and enormous surface area have superior performance in heterogeneous catalytic reactions, herein, we introduced Mn into [Fe3(μ3-O)(CH3COO)6], one of the precursors for the preparation of stable MOFs, and got [Fe2Mn(μ3-O)(CH3COO)6] cluster. After ligand replacement with biphenyl-3,4’,5-tricarboxylic acid (BPTC), heterometallic cluster-based [Fe2Mn(μ3-O)(BPTC)2(DMF)2(H2O)] (1) was obtained. As expected, 1 is stable and able to catalyze the homo- or cross-coupling of amines effectively and selectively with 0.9 mol% catalyst loading at room temperature. Control experiments indicated that the catalytic activity of 1 mainly stems from Mn sites and that Fe synergistically contributes to the stability. Additionally, 1 is recyclable and can be reused easily for at least 8 runs without obvious decrease in catalytic ability. To our knowledge, 1 should be the first heterometallic cluster-based MOF with defined structure suitable for the synthesis of diverse imines from oxidative coupling of amines under mild conditions, which may shed light on the easy preparation of effective heterogeneous catalysts for organic synthesis.
Confined pyrolysis of a dye pollutant for two-dimensional F,N,S tri-doped nanocarbon as a high performance oxidative coupling reaction catalyst
Chen, Sian,Hu, Yajing,Li, Fang-Fang,Liu, Sijie,Peng, Ping,Wang, Haining,Yu, Ao,Yu, Bingzhe
, p. 7839 - 7847 (2020/11/30)
Nanocarbon materials as metal-free catalysts for the oxidative coupling of primary amines to imines suffer from high catalyst loading, low reaction rate and high oxygen demand. Doping heteroatoms in nanocarbons is realized as an effective strategy to improve the catalytic activity, however, the doping of fluorine has been rarely studied. Here we synthesized a F,N,S tri-doped hierarchical nanocarbon (FNSHC) by pyrolyzing a fluorine-containing azo-sulphonate dye (acid red-337, a pollutant in wastewater) confined in a layered double hydroxide (LDH). The LDH-confined synthetic method is beneficial to the formation of a two-dimensional porous structure with a large specific surface area (～1432 m2 g-1) and high fluorine content, enabling remarkable catalytic performance (98% yield in 4 h at 2 wt% catalyst loading under open-air conditions) and high recyclability, outcompeting current metal-free carbocatalysts. The conversion of environmental pollutants into heteroatom-doped carbon materials provides a new green strategy for the design and synthesis of functional carbon catalysts.
Air-Stable Half-Sandwich Iridium Complexes as Aerobic Oxidation Catalysts for Imine Synthesis
Deng, Wei,Fan, Xiao-Nan,Ou, Hui-Dan,Yao, Zi-Jian
supporting information, (2020/04/02)
Several N,O-coordinate half-sandwich iridium complexes, 1-5, containing constrained bulky β-enaminoketonato ligands were prepared and clearly characterized. Single-crystal X-ray diffraction characterization of these complexes indicates that the iridium center adopts a distorted octahedral geometry. Complexes 1-5 showed good catalytic efficiency in the oxidative homocoupling of primary amines, dehydrogenation of secondary amines, and the oxidative cross-coupling of amines and alcohols, which furnished various types of imines in good yields and high selectivities using O2 as an oxidant under mild conditions. No distinctive substituent effects of the iridium catalysts were observed in these reactions. The diverse catalytic activity, broad substrate scope, mild reaction conditions, and high yields of the products made this catalytic system attractive in industrial processes.
Uniform Cu/chitosan beads as a green and reusable catalyst for facile synthesis of iminesviaoxidative coupling reaction
Bunchuay, Thanthapatra,Chantiwas, Rattikan,Chutimasakul, Threeraphat,Intanin, Apichai,Na Nakhonpanom, Pakamon,Tantirungrotechai, Jonggol,Tirdtrakool, Warinda
, p. 21009 - 21018 (2020/06/22)
A nonprecious metal and biopolymer-based catalyst, Cu/chitosan beads, has been successfully prepared by using a software-controlled flow system. Uniform, spherical Cu/chitosan beads can be obtained with diameters in millimeter-scale and narrow size distribution (0.78 ± 0.04 mm). The size and morphology of the Cu/chitosan beads are reproducible due to high precision of the flow rate. In addition, the application of the Cu/chitosan beads as a green and reusable catalyst has been demonstrated using a convenient and efficient protocol for the direct synthesis of iminesviathe oxidative self- and cross-coupling of amines (24 examples) with moderate to excellent yields. Importantly, the beads are stable and could be reused more than ten times without loss of the catalytic performance. Furthermore, because of the bead morphology, the Cu/chitosan catalyst has greatly simplified recycling and workup procedures.
Site-specific catalytic activities to facilitate solvent-free aerobic oxidation of cyclohexylamine to cyclohexanone oxime over highly efficient Nb-modified SBA-15 catalysts
Ding, Wei,Mao, Liqiu,Peng, Haoyu,Yin, Dulin,Zhong, Wenzhou
, p. 3409 - 3422 (2020/06/09)
The development of highly active and selective heterogeneous catalysts for efficient oxidation of cyclohexylamine to cyclohexanone oxime is a challenge associated with the highly sensitive nitrogen center of cyclohexylamine. In this work, dispersed Nb oxide supported on SBA-15 catalysts are disclosed to efficiently catalyze the selective oxidation of cyclohexylamine with high conversion (>75%) and selectivity (>84%) to cyclohexanone oxime by O2without any addition of solvent (TOF = 469.8 h?1, based on the molar amount of Nb sites). The role of the active-site structure identity in dictating the site-specific catalytic activities is probed with the help of different reaction and control conditions and multiple spectroscopy methods. Complementary to the experimental results, further poisoning tests (with KSCN or dehydroxylation reagents) and DFT computational studies clearly unveil that the surface exposed active centers toward activation of the reactants are quite different: the surface -OH groups can catch the NH2group from cyclohexylamine by forming a hydrogen bond and lead to a more facile cyclohexylamine oxidation to desired products, while the monomeric or oligomeric Nb sites with a highly distorted structure play a key role in the dissociation of O2molecules beneficial for insertion of active oxygen species into cyclohexylamine. These catalysts exhibit not only satisfactory recyclability for cyclohexylamine oxidation but also efficiently catalyze the aerobic oxidation of a wide range of amines under solvent-free conditions.
Selective one-pot synthesis of asymmetric secondary amines via N-alkylation of nitriles with alcohols
Segobia,Trasarti,Apesteguía
, p. 178 - 185 (2019/11/13)
The synthesis of asymmetric secondary amines (ASA) is commonly achieved by N-alkylation of primary amines with alcohols. Here, we investigated the ASA synthesis via the direct amination of alcohols with nitriles, which avoids the synthesis, separation and purification of the primary amines in a first step. Specifically, the ASA synthesis via N-alkylation of butyronitrile (BN) with primary (n-propanol, iso-butanol and n-octanol) and secondary (2‐propanol, 2‐butanol and 2‐octanol) alcohols was studied on SiO2-supported Co, Ni and Ru catalysts. Competitive BN hydrogenation‐condensation reactions formed dibutylamine (the symmetric secondary amine) and tertiary amines as main secondary products. On Co/SiO2, the ASA selectivities for BN/primary alcohol reactions were between 49 and 58% at complete BN conversion, forming dibutylamine and tertiary amines as byproducts. For BN/secondary alcohol reactions, Co/SiO2 formed selectively (ASA + dibutylamine) mixtures containing 78–85% of ASA, thereby showing that the alcohol amination with nitriles is an attractive alternative route for the synthesis of valuable asymmetric secondary amines.
Rhodium complex containing ortho-carborane benzimidazole structure and preparation method and application thereof
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Paragraph 0049-0052, (2019/08/20)
The invention relates to a rhodium complex containing an ortho-carborane benzimidazole structure and a preparation method and application thereof. The preparation method of the rhodium complex includes the following steps that 1), an n-BuLi solution is added into an ortho-carborane solution for reaction at room temperature for 30-60 minutes; 2), benzimidazole bromide is added into the mixed solution for reaction at room temperature for 6-8 hours; 3), then [Cp*RhCl2]2 is added into the mixed solution for reaction at room temperature for 3-5 hours, and the rhodium complex is obtained after aftertreatment. The rhodium complex is used for catalyzing autoxidation coupling of primaryaliphaticamine to prepare imine compounds. Compared with the prior art, the synthesis process is simple and greenand has excellent selectivity and high yield, and the prepared rhodium complex has the advantages of stable physical and chemical properties and thermal stability, can catalyze the autoxidation coupling of primaryaliphaticamine to prepare the imine compounds under the condition of air as an oxidant, and has excellent catalytic activity.
