886-08-8Relevant academic research and scientific papers
Phenoxy imine substituted ruthenium complex as well as preparation and application thereof
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Paragraph 0076-0080, (2020/11/23)
The invention relates to a phenoxy imine substituted ruthenium complex as well as preparation and application thereof, and the chemical general formula of the ruthenium complex is shown in the specification, in the formula, R1 is C1-C20 alkyl with a linear, branched or cyclic structure, or C7-C30 mono-or polyaryl substituted alkyl; R2 - R5 are respectively and independently hydrogen, or nitro, orC1-C20 straight-chain and branched-chain alkyl, or C7-C30 monoaryl or polyaryl substituted alkyl, or C6-C18 aryl, or halogen. Compared with the prior art, the method has the advantages that the effectof double-component catalysis can be achieved, polymerization starting can be effectively controlled, industrial operation is facilitated. Meanwhile, the catalyst has the advantages of being resistant to water, oxygen and impurities. In addition, phenoxy imine ligands are easy to synthesize, steric hindrance and the electronic effect of ligand substituents are easy to adjust, and the method is suitable for industrial production. The catalytic activity of ruthenium in a metal center can be effectively regulated and controlled, so that the catalyst is effectively regulated and controlled.
Formaldehyde-Free Polybenzoxazines for High Performance Thermosets
Tavernier, Romain,Granado, Lérys,Foyer, Gabriel,David, Ghislain,Caillol, Sylvain
, p. 2557 - 2567 (2020/04/10)
We report the synthesis and ring-opening polymerization of new formaldehyde-free benzoxazines. The polybenzoxazines obtained displayed high thermal stability and high char yields. Data from the literature combined with our analyses by differential scanning calorimetry and thermogravimetric analyses gave deeper understanding about the use of aromatic aldehydes instead of formaldehyde for the generation of polybenzoxazines. Using pyrolysis coupled with gas chromatography/mass spectrometry (Py-GC/MS) at different temperatures, we provided qualitative data to propose some polymerization and degradation mechanisms associated with these new structures. A dialdehyde was also used for the first time in order to obtain difunctional monomers, instead of using diamines or bisphenols. Interestingly, we demonstrated that formaldehyde, which is a CMR (carcinogenic, mutagenic, and/or reprotoxic) substance, could be avoided for the synthesis of polybenzoxazines without any loss of thermal performance. Finally, some interesting structure-properties relationships are herein discussed. In particular, the use of benzyl amines, rather than aromatic amines, was found to significantly increase the char yields.
Inclusion of Peripheral Basic Groups Activates Dormant Cobalt-Based Molecular Complexes for Catalytic H2 Evolution in Water
Khandelwal, Shikha,Zamader, Afridi,Nagayach, Vivek,Dolui, Dependu,Mir, Ab Qayoom,Dutta, Arnab
, p. 2334 - 2344 (2019/02/27)
The protein scaffold plays a key role during the enzymatic catalysis for metalloenzymes. Here we have rationally designed an enzyme-inspired outer coordination sphere in the form of protic functionalities, such as natural amino acid derived carboxylic acid and phenolic -OH groups, on the fringe of the cobalt-salen like complexes. This inclusion has enabled electrocatalytic H2 evolution for an otherwise inactive cobalt-salen like core. The complexes containing peripheral carboxylic acid groups exhibited unique pH-switchable catalytic H2 production that is connected with the pKa of the carboxylic acid group (～4.0), suggesting the crucial involvement of the carboxylate group during the catalytic activity. The one- and two-dimensional NMR results of the complexes have indicated the presence of a possible hydrogen bonding network, generated by those protic groups in aqueous solution. These results highlight that an inactive metal complex can be activated for specific small molecule activation via rational inclusion of outer coordination sphere functionalities.
Dinuclear iminophenoxide copper complexes in rac-lactide polymerisation
Daneshmand, Pargol,Pinon, Leena,Schaper, Frank
, p. 10147 - 10161 (2018/08/09)
Dinuclear bis(R′-(R′′-iminomethyl)phenoxide) copper complexes L2Cu2(μ-OR)2 were prepared from the reaction of copper methoxide with ROH and LH (ROH = dimethylaminoethanol or pyridylmethanol, R′ = H, 4,6-tBu, 1,3-Cl, R′′ = benzyl, cyclohexyl, diphenylmethyl and 2,6-dimethylphenyl). Preparation was complicated by formation of homoleptic L2Cu and only 9 of the 24 possible combinations could be prepared. All complexes were characterized by single crystal X-ray diffraction studies and crystallized as dinuclear penta-coordinated complexes. Homoleptic complexes L2Cu were inactive in lactide polymerization at room temperature. Most heteroleptic complexes showed modest to good activities with full conversion in less than 6 h at room temperature. Complexes with R′ = H showed poor molecular weight control, complexes with R′ = Cl were inactive in polymerization. In pyridylmethoxide-containing complexes, only one alkoxide initiated chain growth. All complexes produced atactic polymer.
Syntheses, structures and catalytic properties of ruthenium(II) nitrosyl complexes with bidentate and tetradentate Schiff base ligands
Wu, Fule,Wang, Chang-Jiu,Lin, Hui,Jia, Ai-Quan,Zhang, Qian-Feng
, p. 718 - 723 (2017/12/26)
Treatment of Ru(NO)Cl3·xH2O with 1 equiv. bidentate Schiff bases in the presence of triethylamine in DMF/THF afforded a series of anionic ruthenium(II) nitrosyl complexes of the type [Et3NH][Ru(κ2-N,O-LR)(NO)Cl3] (HLR = 2-butyliminomethyl-phenol 1, 2-(benzylimino-methyl)-phenol 2, 2-[(4-chloro-phenylimino)-methyl]-phenol 3, 2-[(4-nitro-phenylimino)-methyl]-phenol 4, 2-[(2,6-diisopropyl-phenylimino)-methyl]-phenol 5). Interaction of Ru(NO)Cl3·xH2O and 1 equiv. tetradentate Schiff bases under the same condition led to isolation of an anionic complex [Et3NH][Ru(κ2-N,O-L-CH2CH2-NOH)-(NO)Cl3] (HL-CH2CH2-NOH = N,N′-disalicylidene-1,2-ethanediamine 6) and a neutral complex [Ru(salen-phn)(NO)Cl] (H2salen-phn = N,N′-disalicylidene-1,2-phenyldiamine 7). The molecular structures of 1·?C2H5OH, 2–6, and 7·CH2Cl2 have been determined by single-crystal X-ray crystallography. Investigation of the catalytic properties of ruthenium(II) nitrosyl complexes 1–7 showed that they are efficient catalytic precursors for the transfer hydrogenation of acetophenone.
Investigation of the dinuclear effect of aluminum complexes in the ring-opening polymerization of ε-caprolactone
Hsu, Chiao-Yin,Tseng, Hsi-Ching,Vandavasi, Jaya Kishore,Lu, Wei-Yi,Wang, Li-Fang,Chiang, Michael Y.,Lai, Yi-Chun,Chen, Hsing-Yin,Chen, Hsuan-Ying
, p. 18851 - 18860 (2017/04/10)
A series of aluminum (Al) complexes bearing hydrazine-bridging Schiff base and salen ligands were synthesized and investigated as catalysts for the ring-opening polymerization of ε-caprolactone (CL). The introduction of steric bulky groups increases the catalytic activity of the corresponding mononuclear aluminum complex. However, the opposite phenomenon was observed in dinuclear Al complexes bearing salen ligands because the steric repulsion reduced the cooperative activation mechanism in the dinuclear Al system. Among these Al complexes, LN2Bu-Al2Me4 bearing a hydrazine-bridging Schiff base ligand had the highest catalytic activity, approximately 3- to 11-fold higher than that of dinuclear Al complexes bearing salen ligands and mononuclear Al complexes bearing Schiff base ligands. Density functional theory calculations revealed that the mechanism of the coordination of CL to one Al center was initiated by the benzyl alkoxide of another Al center.
Synthesis, structure and catalytic activity of bis(phenoxyiminato)iron(III) complexes in coupling reaction of CO2 and epoxides
Al-Qaisi, Feda'a,Genjang, Nevil,Nieger, Martin,Repo, Timo
, p. 81 - 85 (2015/12/30)
Here we described the synthesis and characterization of a series of new bis(phenoxyiminato)Fe(III)-chloro complexes using a variety of techniques, including: elemental analysis, IR-, MS(EI), UV-Vis-spectroscopy, and X-ray diffraction. A solid-state structure of bis(N-salicylidene-3-phenylpropylamine)iron(III)chloride reveals a distorted square-pyramid coordination with crystallographic C2-symmetry wherein chloride occupies the axial position. Isolated complexes were also evaluated as catalysts for a coupling reaction of CO2 and various epoxides, including propylene, 1-hexene, cyclohexene and styrene oxides to form corresponding cyclic carbonates. Accordingly, the ligand structure and the solvent used influenced the catalytic activity and marked enhancement in the activity was observed using DMF as a solvent. Under optimized reaction conditions (145 °C and 10 bar of CO2) bis(N-salicylidene-2-phenylethylamine)iron(III)chloride gave cyclopropylene carbonate with considerable high TON value (1029) within 3 h.
Trans-Symmetric Dynamic Covalent Systems: Connected Transamination and Transimination Reactions
Schaufelberger, Fredrik,Hu, Lei,Ramstr?m, Olof
, p. 9776 - 9783 (2015/06/30)
The development of chemical transaminations as a new type of dynamic covalent reaction is described. The key 1,3-proton shift is under complete catalytic control and can be conducted orthogonally to, or simultaneous with, transimination in the presence of an amine to rapidly yield two-dimensional dynamic systems with a high degree of complexity evolution. The transamination-transimination systems are proven to be fully reversible, stable over several days, compatible with a range of functional groups, and highly tunable. Kinetic studies show transamination to be the rate-limiting reaction in the network. Furthermore, it was discovered that readily available quinuclidine is a highly potent catalyst for aldimine transaminations. This study demonstrates how connected dynamic reactions give rise to significantly larger systems than the unconnected counterparts, and shows how reversible isomerizations can be utilized as an effective diversity-generating element. Constant exchange: The development of chemical transaminations as a new type of dynamic covalent reactions is described (see figure). This study demonstrates how connected dynamic reactions give rise to significantly larger systems than the unconnected counterparts, and shows how reversible isomerizations can be utilized as an effective diversity-generating element.
Selective aerobic oxidation of alcohols to aldehydes, carboxylic acids, and imines catalyzed by a Ag-NHC complex
Han, Lei,Xing, Ping,Jiang, Biao
supporting information, p. 3428 - 3431 (2014/07/21)
Silver NHC catalysts have been developed for the selective oxidation of alcohols to aldehydes or carboxylic acids in the presence of BnMe3NOH or KOH under dry air. The aerobic oxidation conditions are mild, and the yield is excellent. Further tandem catalysis enables the one-pot synthesis of imines in excellent yield. Only 0.1 mol % of the catalyst is required.
Morphology-tuned exceptional catalytic activity of porous-polymer-supported Mn3O4 in aerobic sp3 C-H bond oxidation of aromatic hydrocarbons and alcohols
Mondal, John,Borah, Parijat,Sreejith, Sivaramapanicker,Nguyen, Kim Truc,Han, Xiguang,Ma, Xing,Zhao, Yanli
, p. 3518 - 3529 (2015/04/16)
Mn3O4 nanomaterials with different morphologies (sphere, nanowire, and octahedron) embedded into functionalized nanoporous polymers were developed by a facile one-pot solvothermal technique at different temperatures. These Mn3O4-based hybrid materials could behave as heterogeneous nanocatalysts to perform sp3 C-H bond oxidation of aromatic hydrocarbons and alcohols with molecular oxygen as an economic oxidant. Catalytic activity could be effectively tuned by changing the morphology of incorporated Mn3O4 in nanoporous polymer. These Mn3O4-based hybrid materials exhibited remarkable catalytic performance for sp3 C-H bond oxidation as compared with bare Mn3O4 nanoparticles. Mn3O4 with octahedral morphology in nanoporous polymer exhibited the highest catalytic activity on account of its more exposed crystallographic planes and edges. These Mn3O4-based nanocatalysts could be recycled and reused for consecutive catalytic cycles without a significant loss of catalytic activity. Exceptional crystal facets: Nanoporous-polymer-supported Mn3O4 nanocatalysts (Mn@DVTA, DVTA=divinyltriallyl) with different morphologies are developed to catalyze aerobic sp3 C-H bond oxidation of aromatic hydrocarbons and alcohols. Among the different nanocatalysts, those with octahedral crystallite morphology exhibit outstanding catalytic performance.
