621-82-9Relevant articles and documents
Spatially orthogonal chemical functionalization of a hierarchical pore network for catalytic cascade reactions
Parlett, Christopher M.A.,Isaacs, Mark A.,Beaumont, Simon K.,Bingham, Laura M.,Hondow, Nicole S.,Wilson, Karen,Lee, Adam F.
, p. 178 - 182 (2016)
The chemical functionality within porous architectures dictates their performance as heterogeneous catalysts; however, synthetic routes to control the spatial distribution of individual functions within porous solids are limited. Here we report the fabrication of spatially orthogonal bifunctional porous catalysts, through the stepwise template removal and chemical functionalization of an interconnected silica framework. Selective removal of polystyrene nanosphere templates from a lyotropic liquid crystal-templated silica sol-gel matrix, followed by extraction of the liquid crystal template, affords a hierarchical macroporous-mesoporous architecture. Decoupling of the individual template extractions allows independent functionalization of macropore and mesopore networks on the basis of chemical and/or size specificity. Spatial compartmentalization of, and directed molecular transport between, chemical functionalities affords control over the reaction sequence in catalytic cascades; herein illustrated by the Pd/Pt-catalysed oxidation of cinnamyl alcohol to cinnamic acid. We anticipate that our methodology will prompt further design of multifunctional materials comprising spatially compartmentalized functions.
Synthesis and Structures of Ti-Pd Heterobimetallic Complexes
Suzuki, Noriyuki,Haraga, Kenji,Shimamura, Tatsuki,Masuyama, Yoshiro
, p. 5480 - 5487 (2015)
Heterobimetallic complexes containing titanium and palladium were prepared from O,N,O-N,N multidentate ligands. The ligands each contained an O,N,O-tridentate part based on a 2,6-lutidine scaffold and an N,N-bidentate di(pyridin-2-yl) part. The O,N,O-moiety selectively coordinated to a titanium atom on treatment with titanium(tetraisopropoxide), although one of the di(pyridin-2-yl) groups in the N,N-moiety coordinated to the titanium atom. The N,N-bidentate di(pyridin-2-yl) moiety coordinated to the palladium atom on treatment with bis(benzonitrile)palladium(II) chloride to afford a heterobimetallic complex. The dynamic behavior of the complexes in solution was studied by NMR spectroscopy. Heterobimetallic complexes containing titanium and palladium were prepared from O,N,O-N,N multidentate ligands and structurally characterized.
Synthesis and characterization of two new molten acid salts: Safe and greener alternatives to sulfuric acid for the hydrolytic conversion of 1,1,1,3-tetrachloro-3-phenylpropane to cinnamic acid
Gorjian, Hayedeh,Johan, Mohd Rafie,Khaligh, Nader Ghaffari,Zaharani, Lia
, (2021)
Available online Two new acid salts were synthesized, and their chemical structures were characterized by various spectra data analyses. Although 1H NMR did not show acid proton of [HSO4]?, the FTIR spectra of molten acid salts act as key support to approve of their chemical structures. The structure elucidation of the molten acid salts demonstrated the existence of 4,4?-trimethylene-N,N?-dipiperidinium dication with sulfate and hydrogen sulfate anion(s). Thus, sulfuric acid can act as a diprotic or monoprotic Br?nsted acid when it is treated by a secondary amine regarding the initial mole ratio of sulfuric acid and amine. Also, the catalytic activity of these molten acid salts was investigated for the hydrolytic conversion of (1,3,3,3-tetrachloropropyl)benzene to cinnamic acid. The desired product was obtained in 88 ± 2.0% yield under optimal conditions. The molten acid salts were high recyclable and their chemical structure and catalytic efficiency showed no significant change even after the 5th run. Furthermore, TMDP-SA (1:1) showed a much weaker corrosive property compared with TMDP-SA (1:2) and SA (98%), and the surface of stainless steel was intact even after 24 h. This fact and the acidity of two molten acid salts also confirm the proposed chemical structures.
Synthesis, characterization and catalytic oxidation property of copper(I) complexes containing monodentate acylthiourea ligands and triphenylphosphine
Gunasekaran,Bhuvanesh,Karvembu
, p. 39 - 45 (2017)
The reactions between [CuCl2(PPh3)2] and 3,3-diphenyl-1-(2,4-dichlorobenzoyl)thiourea (HL1), 3,3-diisobutyl-1-(2,4-dichlorobenzoyl)thiourea (HL2) or 3,3-diethyl-1-(2,4-dichlorobenzoyl)thiourea (HL3) in benzene gave new four-coordinated tetrahedral copper(I) complexes of the type [CuCl(HL)(PPh3)2] (1–3) [HL = 3,3-dialkyl/aryl-1-(2,4-dichlorobenzoyl)thiourea derivatives]. These complexes were then characterized by analytical and spectroscopic (IR, UV/Vis,1H,13C and31P NMR) techniques. The molecular structure of a representative complex, [CuCl(HL1)(PPh3)2] (1), was determined by the single crystal X-ray diffraction method which reveals a distorted tetrahedral geometry around the Cu(I) ion. The complexes 1–3 (0.007 mmol) were found to be active catalysts for the oxidation of primary and secondary alcohols 5.0 mmol to their corresponding acids and ketones, respectively, in the presence of hydrogen peroxide (6.0 mmol) in 1-butyl-3-methylimidazolium hexafluorophosphate {[bmim][PF6]} (0.1 mL) without any additive and base, at 70 °C.
Robust Fe3O4/SiO2-Pt/Au/Pd magnetic nanocatalysts with multifunctional hyperbranched polyglycerol amplifiers
Zhou, Li,Gao, Chao,Xu, Weijian
, p. 11217 - 11225 (2010)
Here we report a facile approach to prepare multicarboxylic hyperbranched polyglycerol (HPG)-grafted SiO2-coated iron oxide (Fe 3O4/SiO2) magnetic hybrid support. This support combined the both features of Fe3O4 and HPG, facile magnetic separation, and favorable molecular structure with numerous functional groups. With the use of the grafted-HPGs as templates, various noble metal nanocatalysts such as Pt, Au, and Pd were directly grown on the surfaces of magnetic support with ultrasmall and nearly monodisperse sizes (e.g., the average sizes of Pt, Au, and Pd are 4.8 ± 0.5, 6.0 ± 0.6, and 4.0 ± 0.4 nm, respectively) and high coverage densities. Because of the amplification effect of HPG, high loading capacities of the nanocatalysts, around 0.296, 0.243, and 0.268 mmol/g for Pt, Au, and Pd, respectively, were achieved. Representative catalytic reactions including reduction of 4-nitrophenol, alcohol oxidation, and Heck reaction demonstrated the high catalytic activity of the noble metal nanocatalysts. Because of the stabilization of HPG templates, the nanocatalysts can be readily recycled by a magnet and reused for the next reactions with high efficiencies. The robust multifunctional magnetic hybrids will find important applications in catalysis and other fields such as drug delivery and bioseparations.
Amine grafting on coordinatively unsaturated metal centers of MOFs: Consequences for catalysis and metal encapsulation
Hwang, Young Kyu,Hong, Do-Young,Chang, Jong-San,Jhung, Sung Hwa,Seo, You-Kyong,Kim, Jinheung,Vimont, Alexandre,Daturi, Marco,Serre, Christian,Ferey, Gerard
, p. 4144 - 4148 (2008)
(Figure Presented) The coordinatively unsaturated sites in MIL-101, Cr 3(F,OH)(H2O)2O[(O2C)-C 6H4(CO2)]3·nH2O (n≈25), having zeotypic giant pores can be selectively functionalized in a way differing from that of mesoporous silica. Metal-organic frameworks, grafted with ethylenediamine or diethylenetriamine on the unsaturated CrIII sites of MIL-101, exhibit remarkably high activities in the Knoevenagel condensation relative to that of the mesophase.
Post-synthesis functionalization of MIL-101 using diethylenetriamine: A study on adsorption and catalysis
Kim, Se-Na,Yang, Seung-Tae,Kim, Jun,Park, Ji-Eun,Ahn, Wha-Seung
, p. 4142 - 4147 (2012)
An effective metal organic framework (MOF) catalyst (DETA-MIL-101) was prepared by grafting an electron-rich triamine functional group to the open metal sites in MIL-101. The samples were characterized via XRD, FT-IR, and N2 adsorption-desorption measurements, and their N content was measured using EA. The CO2 and H2O adsorption-desorption properties were measured and compared with those of non-functionalized MIL-101. Their catalytic performances in the Knoevenagel condensation between benzaldehyde and malononitrile were examined, and the catalyst stabilities were confirmed using recycling and hot filtering experiments. Finally, the Pd 2+ ions (0.5, 1.0, and 3.0 wt%) were immobilized onto the amine species that were grafted to the MIL-101 using PdCl2 and were tested for Heck reactions of the acrylic acid and iodobenzene in N,N-dimethylacetamide as a solvent with triethylamine additives as a function of time. The catalyst stability was re-established via recycling and hot filtering experiments.
Platinum catalysed aerobic selective oxidation of cinnamaldehyde to cinnamic acid
Durndell, Lee J.,Cucuzzella, Costanza,Parlett, Christopher M.A.,Isaacs, Mark A.,Wilson, Karen,Lee, Adam F.
, (2018)
Aerobic selective oxidation of allylic aldehydes offers an atom and energy efficient route to unsaturated carboxylic acids, however suitable heterogeneous catalysts offering high selectivity and productivity have to date proved elusive. Herein, we demonstrate the direct aerobic oxidation of cinnamaldehyde to cinnamic acid employing silica supported Pt nanoparticles under base-free, batch and continuous flow operation. Surface and bulk characterisation of four families of related Pt/silica catalysts by XRD, XPS, HRTEM, CO chemisorption and N2 porosimetry evidence surface PtO2 as the common active site for cinnamaldehyde oxidation, with a common turnover frequency of 49,000 ± 600 h-1; competing cinnamaldehyde hydrogenolysis is favoured over metallic Pt. High area mesoporous (SBA-15 or KIT-6) and macroporous-mesoporous SBA-15 silicas confer significant rate and cinnamic acid yield enhancements versus low area fumed silica, due to superior platinum dispersion. High oxygen partial pressures and continuous flow operation stabilise PtO2 active sites against in-situ reduction and concomitant deactivation, further enhancing cinnamic acid productivity.
Cascade Aerobic Selective Oxidation over Contiguous Dual-Catalyst Beds in Continuous Flow
Durndell, Lee J.,Isaacs, Mark A.,Li, Chao'En,Parlett, Christopher M. A.,Wilson, Karen,Lee, Adam F.
, p. 5345 - 5352 (2019)
Cascade reactions represent an atom-economical and energy-efficient technology by which to reduce the number of manipulations required for chemical manufacturing. Biocatalytic cascades are ubiquitous in nature; however, controlling the sequence of interactions between reactant, intermediate(s), and active sites remains a challenge for chemocatalysis. Here, we demonstrate an approach to achieve efficient cascades using chemical catalysts through flow chemistry. Close-coupling of Pd/SBA-15 and Pt/SBA-15 heterogeneous catalysts in a dual bed configuration under continuous flow operation affords a high single pass yield of 84% (a 20-fold enhancement over batch operation) and high stability for >14000 turnovers in the cascade oxidation of cinnamyl alcohol to cinnamic acid, despite both catalysts being individually inactive for this reaction. Judicious ordering of Pd (first bed) and Pt (second bed) catalysts is critical to promote cascade oxidation with respect to undesired hydrogenation and hydrogenolysis, the latter favored over the reverse-bed sequence or a single mixed PdPt reactor bed. The intrinsic catalytic performance of each bed is preserved in the optimal dual-bed configuration, enabling quantitative prediction of final product yields for reactants/intermediates whose individual oxidation behavior is established. Continuous processing using contiguous reactor beds enables plug-and-play design of cascades employing "simple" catalysts.
Coordinative Role of Alkali Cations in Organic Reactions.V. The Perkin Reaction
Poonia, Narinder S.,Sen, Swagata,Porwal, Prafulla K.,Jayakumar, A.
, p. 3338 - 3343 (1980)
The Perkin condensation of benzaldehyde (PhCHO) and acetic anhydride (Ac2O) in the presence of an alkali acetate (M+OAc-) involves extensive participation of M+ and take place best with K+OAc-.Employing an excess of meticulousy dehydrated K+OAc-, a record high yield of cinnamic acid (ca.75percent) can be obtained in a 60 min reaction.The product of the reaction before hydrolysis is not PhCH=CHCOOCOCH3 as usually believed but potassium cinnamate plus K+(OAc,HOAc)-.Conductometric solution stability studies on M+-ligand (M+=Na+ and K+; Ligand=PhCHO, o-NO2C6H4CHO,o-HOC6H4CHO) systems in 2-propanol show that stabilty sequences for PhCHO and o-NO2C6H4CHO are NaOAc+OAc- in 2-propanol.
