538-51-2Relevant articles and documents
'On-Water' Multicomponent Reaction for the Diastereoselective Synthesis of Functionalized Tetrahydropyridines and Mechanistic Insight
Parikh, Naisargee,Roy, Sudipta Raha,Seth, Kapileswar,Kumar, Asim,Chakraborti, Asit K.
, p. 547 - 556 (2016)
An ecofriendly approach for the synthesis of highly substituted tetrahydropyridines by an 'on-water' multicomponent reaction has been demonstrated. The use of water as the reaction medium is essential under the catalytic influence of a surfactant. The use of a variety of anionic, cationic, and non-ionic surfactants in water was examined and the reaction was successfully catalyzed by anionic surfactants sodium dioctyl sulfosuccinate (SDOSS) and sodium dodecyl sulfate (SDS), with the former being superior. The use of an organic solvent together with a catalytic amount of sodium dioctyl sulfosuccinate to form homogeneous conditions afforded inferior yields and highlighted the specific role of water through the creation of microreactors at the water surfactant interface. A mechanistic insight for the five-component reaction leading to the formation of tetrahydropyridines is provided invoking a tandem inter- and intramolecular Mannich reaction pathway.
MnOX supported on a TiO2@SBA-15 nanoreactor used as an efficient catalyst for one-pot synthesis of imine by oxidative coupling of benzyl alcohol and aniline under atmospheric air
Mandal, Sandip,Maity, Sudip,Saha, Sujan,Banerjee, Biplab
, p. 73906 - 73914 (2016)
In the present study, a mesoporous silica (SBA-15) encapsulated TiO2 nanoreactor is used as a support for MnOx and this MnOx/TiO2@SBA-15 acts as a catalyst for the one-pot synthesis of imine by oxidative coupling between benzyl alcohol and aniline in the presence of atmospheric air. To understand the properties, the catalysts were characterized by several analytical techniques, namely, N2 adsorption-desorption isotherm, small angle X-ray scattering (SAXS), wide angle X-ray diffraction, high resolution transmission electron microscopy (HRTEM), H2-temperature programmed reduction (H2-TPR), O2-temperature programmed oxidation (O2-TPO) and NH3-temperature programmed desorption (NH3-TPD). The pore encapsulation process by SBA-15 causes TiO2 to be in a highly dispersed state, and this highly dispersed TiO2 makes maximum contact with the MnOx species as well as the reactant molecules. The reaction was carried out at atmospheric pressure with equimolar amounts of substrates without additives in the presence of atmospheric air. The yield and selectivity of imines vary with the MnOx and TiO2 loading. The 7.5 wt% MnOx loaded TiO2@SBA-15 (5 wt% TiO2) nanoreactor showed the highest catalytic activity. With the increase in weak acid sites and the oxygen activation ability of the prepared catalyst, the conversion and selectivity of the desired product reached 96% and 97%, respectively. The investigation of the reaction mechanism suggests that there is a synergistic effect between highly dispersed TiO2 and MnOx, which improves the reactant conversion and the selectivity of the desired product (N-benzylideneaniline) and also the prepared catalyst shows excellent recyclability up to the 10th cycle. The recyclability and hot filtration study confirms the true heterogeneity of the prepared catalyst during imine synthesis. The heterogeneity of the prepared catalyst, the avoidance of any noble metal and the utilization of air as an oxidizing agent represent an efficient, green reaction pathway for imine synthesis.
Palladium-catalyzed tandem cyclization of fluorinated imidoyl chlorides with 2-bromophenylboronic acid: Synthesis of 6-fluoroalkyl-phenanthridines
Bao, Yinwei,Wang, Zhuo,Chen, Chen,Zhu, Bolin,Wang, Yuebo,Zhao, Jinghui,Gong, Jinyu,Han, Mengya,Liu, Chang
, p. 1450 - 1456 (2019)
An efficient method has been developed to synthesize 6-fluoroalkyl-phenanthridines via the palladium-catalyzed tandem cyclization of fluorinated imidoyl chlorides with 2-bromophenylboronic acid. This methodology facilitates the rapid synthesis of 6-fluoroalkyl-phenanthridines through dual C–C bond formation in an oxidant-free one-pot manner.
Postsynthetic modification of an imine-based microporous organic network
Kerneghan, Phillip A.,Halperin, Shira D.,Bryce, David L.,Maly, Kenneth E.
, p. 577 - 582 (2011)
A highly cross-linked microporous organic network with imine linkers was prepared by condensation of tetrakis(4-aminophenyl)methane with terephthaldehyde. Gas adsorption studies indicate that the material exhibits permanent microporosity, and guest exchan
High Catalytic Activity of C60Pdn Encapsulated in Metal–Organic Framework UiO-67, for Tandem Hydrogenation Reaction
Zheng, Deng-Yue,Zhou, Xue-Meng,Mutyala, Suresh,Huang, Xiao-Chun
, p. 19141 - 19145 (2018)
Metal nanoparticles (NPs) stabilized by MOFs are very promising for catalysis, whereas introduction of C60 into MOFs has been very rarely used, and there was no report for their cooperative catalysis in organic syntheses. In this work, C60@UiO-67 was synthesized by a one-pot method, so that C60 is uniformly distributed on UiO-67 in molecular form. Pd NPs coordinating with C60 have been successfully embedded into the framework. The obtained multifunctional C60Pdn@UiO-67 catalyst exhibits remarkable synergistic catalytic activity in cascade reactions under mild conditions, where UiO-67 affords Lewis acidity and C60Pdn offers higher hydrogenation activity relative to solely Pd NPs.
Catalytic stereoselective Mannich reaction under solvent-free conditions
Azizi, Najmadin,Baghi, Roya,Batebi, Elham,Bolourtchian, Seyed Mohammad
, p. 278 - 282 (2012)
Silicon tetrachloride catalyzed one-pot three-component Mannich reaction of cyclic ketones, aromatic aldehydes, and aromatic amine under solvent-free conditions affords the corresponding β-amino ketones with excellent yield and good to excellent anti-selectivity.
Simultaneous photocatalytic and catalytic activity of p–n junction NiO@anatase/rutile-TiO2 as a noble-metal free reusable nanoparticle for synthesis of organic compounds
Ziarati, Abolfazl,Badiei, Alireza,Mohammadi Ziarani, Ghodsi,Eskandarloo, Hamed
, p. 77 - 82 (2017)
Photocatalytic and catalytic activity of NiO loaded on mixture of anatase/rutile phases of TiO2 nanoparticles were investigated for some organic reactions including selective oxidation of alcohols, synthesis of benzimidazoles and preparation of imines at room temperature. The p–n junction formed between NiO and TiO2 as well as difference between band gaps in anatase/rutile phases facilitated electron transfer to TiO2 and successfully promoted synthesis of compounds. The use of a reusable photocatalyst without noble metal co-catalysts, along with the mild reaction conditions and use of light energy, make this method as an environmentally benign and energy saving chemical procedure.
MnO2/graphene oxide: A highly efficient catalyst for imine synthesis from alcohols and amines
Cheng, Shengxian,Ma, Xiaoxia,Hu, Yongke,Li, Bindong
, (2017)
α-MnO2 nanocrystals supported on graphene oxide (α-MnO2/GO) was prepared through a soft chemical route and evaluated for the first time as a novel, eco-friendly and efficient catalyst in the coupling reaction of alcohols and amines to imines. The well-organized α-MnO2/GO was characterized using various techniques. The results show that MnO2 nanocrystals are highly dispersed on the GO sheets and interconnected with each other, leading to large available surface area, which greatly enhances the catalytic performance of conventional MnO2. Under mild conditions, the catalyst exhibits excellent catalytic activity and selectivity with O2 serving as terminal oxidant. Various imines can be smoothly obtained in good to excellent yield. Importantly, the catalyst is easily recovered and can be reused six times with no significant loss of activity.
Large Dimensional CeO2 Nanoflakes by Microwave-Assisted Synthesis: Lamellar Nano-Channels and Surface Oxygen Vacancies Promote Catalytic Activity
Ding, Huihui,Yang, Jingxia,Ma, Shuyi,Yigit, Nevzat,Xu, Jingli,Rupprechter, Günther,Wang, JinJie
, p. 4100 - 4108 (2018)
Large nano-structured flakes of CeO2 (20–80 nm in thickness, up to 5.6 μm in diameter) were synthesized by a combination of microwave (MW), ultraviolet (UV) and ultrasound (US), with or without pressure (P). The CeO2 structures were systematically examined by XRD, SEM, N2 sorption, HRTEM, XPS, Raman and H2-TPR. The synthesized CeO2 nanoflakes were composed by 3.0–7.5 nm nanoparticles with the (111) surface exposed, and laminated to nanoflakes with 3.42–3.85 nm nano-channels in between. MW-assisting was beneficial to form a higher surface Ce3+/(Ce3++Ce4+) ratio and surface oxygen vacancies during short synthesis procedure. A Raman peak at 480 cm?1 correlating with bulk Ce3+ was detected. H2-TPR found MW and MW+P had more surface Ce3+ (surface oxygen vacancies). CO oxidation and imine conversion proved that MW+P was the optimum condition to produce highly active CeO2 nanoflakes. The much better catalytic performance than CeO2 from solvothermal preparation, due to the larger channel gap (3.85 nm),a higher Ce3+/(Ce3++Ce4+) ratio (32 %) and more surface oxygen vacancies on the particles of the organized flake structures.
Combined catalytic action of supported Cu and Au in imine production from coupled benzyl alcohol and nitrobenzene reactions
Li, Maoshuai,Cárdenas-Lizana, Fernando,Keane, Mark A.
, p. 145 - 153 (2018)
The feasibility of continuous gas phase coupling of benzyl alcohol dehydrogenation with nitrobenzene hydrogenation for imine (N-benzylideneaniline) synthesis over mixtures of Cu/SiO2 and (TiO2, MgO) supported Au catalysts has been established. The catalysts were characterised in terms of specific surface area, pore volume, TPR, H2 chemisorption, STEM, XPS and TGA-DSC analysis. Au/TiO2 prepared by deposition-precipitation exhibited a narrower particle size distribution (1–6 nm) and smaller mean (3.2 nm) than Au/MgO (1–15 nm, mean = 7.7 nm) prepared by impregnation. Dehydrogenation of benzyl alcohol (to benzaldehyde) over Cu/SiO2 delivered a (ten-fold) higher rate than supported Au and Au/TiO2 exhibited a higher H2 chemisorption capacity and greater (by a factor of ten) nitrobenzene hydrogenation rate than Cu/SiO2 and Au/MgO. Inefficient hydrogen utilisation is demonstrated for the cross-coupling reaction over Cu/SiO2 alone and a temporal activity loss is linked to carbonaceous (benzoate) deposition (on the basis of XPS and TGA-DSC analysis). Incorporation of Au/TiO2 (and Au/MgO) with Cu/SiO2 increased the imine formation rate and H2 utilisation efficiency. The combination of Au/TiO2 with Cu/SiO2 served to circumvent Cu/SiO2 deactivation, resulting in enhanced stability with a four-fold increase in imine production and full H2 utilisation at Cu/Au = 10.
