7029-48-3Relevant articles and documents
Mechanically Strong Heterogeneous Catalysts via Immobilization of Powderous Catalysts to Porous Plastic Tablets
Li, Tingting,Xu, Bo
supporting information, p. 2673 - 2678 (2021/08/03)
Main observation and conclusion: We describe a practical and general protocol for immobilization of heterogeneous catalysts to mechanically robust porous ultra-high molecular weight polyethylene tablets using inter-facial Lifshitz-van der Waals Interactions. Diverse types of powderous catalysts, including Cu, Pd/C, Pd/Al2O3, Pt/C, and Rh/C have been immobilized successfully. The immobilized catalysts are mechanistically robust towards stirring in solutions, and they worked well in diverse synthetic reactions. The immobilized catalyst tablets are easy to handle and reused. Moreover, the metal leaching of immobilized catalysts was reduced significantly.
Easy-handling and low-leaching heterogeneous palladium and platinum catalysts via coating with a silicone elastomer
Zhou, Mi,Li, Tingting,Xu, Bo
supporting information, p. 948 - 952 (2019/03/08)
We have developed a practical protocol for coating of commercial Pd/Al2O3 and Pt/Al2O3 catalysts in micro-powders with a silicone elastomer. Compared to original catalysts, the treated catalysts are easier to weight and transfer, and they are easier to recover by simple filtration. More importantly, the metal leaching of treated catalysts was significantly reduced. The treated catalysts worked very well in diverse hydrogenation reactions.
Iodine-catalyzed transformation of aryl-substituted alcohols under solvent-free and highly concentrated reaction conditions
Jereb, Marjan,Vra?i?, Dejan
, p. 747 - 762 (2018/01/17)
Iodine-catalyzed transformations of alcohols under solvent-free reaction conditions (SFRC) and under highly concentrated reaction conditions (HCRC) in the presence of various solvents were studied in order to gain insight into the behavior of the reaction intermediates under these conditions. Dimerization, dehydration and substitution were the three types of transformations observed with benzylic alcohols. Dimerization and substitution reactions were predominant in the case of primary- and secondary alcohols, whereas dehydration prevailed in the case of tertiary alcohols. The relative reactivity of substituted 1-phenylethanols in I2-catalyzed dimerization under SFRC provided a good Hammett plot ρ+ = -2.8 (r2 = 0.98), suggesting the presence of electron-deficient intermediates with a certain degree of developed charge in the rate-determining step.
Radical reactivity of Aza[60]fullerene: Preparation of monoadducts and limitations
Vougioukalakis, Georgios C.,Roubelakis, Manolis M.,Orfanopoulos, Michael
experimental part, p. 4124 - 4130 (2010/10/02)
Six aza[60]fullerene monoadducts were synthesized by the thermal reaction between the azafullerene radical C59N· and 9-alkyl-substituted fluorenes, 9,10-dihydroanthracene, or xanthene. Unlike fluorenes, dihydroanthracene, and xanthene, the structurally related substituted diphenylmethanes, ethylbenzene, cumene, 1,2-diphenylethane, 5,6,11,12-tetrahydrodibenzo[a,e]cyclooctene, 10,11-dihydro-5H-dibenzo[a,d] cycloheptene, 9-methylanthracene, and 9-benzylanthracene do not lead to the isolation of azafullerene monoadducts. Moreover, 1,2-dichlorobenzene, the most commonly utilized solvent for azafullerene reactions, reacts slowly with the azafullerenyl radical C59N· affording the corresponding aza[60]fullerene monoadduct.
Partial hydrogenation of alkynes to cis-olefins by using a novel Pd 0-polyethyleneimine catalyst
Sajiki, Hironao,Mori, Shigeki,Ohkubo, Tomoyuki,Ikawa, Takashi,Kume, Akira,Maegawa, Tomohiro,Monguchi, Yasunari
supporting information; experimental part, p. 5109 - 5111 (2009/05/07)
The creation and application of a new Pd0-polyethyleneimine complex catalyst (Pd0-PEI) was investigated. The 55 Pd 0-PEI catalyst was prepared by introduction of Pd(OAc)2 directly in the MeOH solution of deaerated PEI under Ar atmosphere. Reactions were carried out using 10 weight % versus substrate of 5% Pd0-PEI in 2mL solvent under H2 atmosphere at room temperature. The generality of the process was shown by disubstituting alkynes. Even for the substrate bearing a conjugated ketone on the alkyne, the serious over-reduction was not observed while significant cistrans isomerization of methyl styryl ketone accompanied the partial hydrogenation on the basis of keto-enol tautomerism. Pd0-PEI catalyst is also applicable to the partial hydrogenation of monosubstituted alkynes to monosubstituted olefins.
Tricyclic aromatic and bis-phenyl sulfinyl derivatives
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Page/Page column 17, (2010/02/14)
The present invention provides compounds of the structure: wherein the constituent members are defined herein, including pharmaceutical compositions thereof and methods of treating diseases therewith.
Functionalization of azafullerene C59N. Radical reactions with 9-substituted fluorenes
Vougioukalakis, Georgios C.,Orfanopoulos, Michael
, p. 8649 - 8652 (2008/04/18)
An efficient reaction between the azafullerene dimer, (C 59N)2 and 9-substituted fluorenes leads to the formation of four new azafullerene monoadducts.
Synthesis of a 9-fluorenone derived β-amino alcohol ligand depicting high catalytic activity and pronounced non-linear stereochemical effects
Reddy, Katamreddy Subba,Sola, Lluis,Moyano, Albert,Pericas, Miquel A.,Riera, Antoni
, p. 165 - 176 (2007/10/03)
The Jacobsen epoxidation of 9-alkylidenefluorenes 4a (ethylidene), 4b (benzylidene) and 4c (1-naphtylmethylene) with standard (R,R)-manganese salen catalyst has been studied. Both conversion and enantioselectivity depend on the steric bulk of the olefin substituent, best results being recorded with 4b (96% yield, 99% ee). The stereochemical course of the epoxidation of 4a is highly dependent on temperature and solvent, the ee of the resulting epoxide (S)-5a varying from 22% (-18°C, CH2Cl2) to 49% (55°C, MTBE). The lithium perchlorate induced ring-opening of 5a with piperidine in MeCN affords a mixture of regioisomeric amino alcohols 3a/2a arising from the amine attack at the more substituted and less substituted carbons, respectively. The 3a/2a ratio can be modulated by the LiClO4 concentration and the reaction temperature, and varies from 44:56 to 91:9. An independent, completely regiocontrolled synthesis of 3a has been developed involving ring-opening by the more substituted carbon of epoxide 5a with diisopropoxytitanium diazide, reduction of azidoalcohol 10a (H2, Pd/C) and cycloalkylation (1,5- dibromopentane, K2CO3) of the amino alcohol 11a. The amino alcohol 3a exhibits a positive nonlinear stereochemical effect in its action as a ligand for the enantioselective addition of Et2Zn to benzaldehyde. The use of regiochemically pure 3a of >99% ee has been studied in the addition of Et2Zn to a representative family of aldehydes [19 examples, 93.6% mean ee]. The use of the directly available 9:1 mixture of 3a and 2a derived from 46-47% ee 5a as a ligand system for the enantioselective addition of Et2Zn to aldehydes [8 examples, 93.1% mean ee] is also reported.
Phase-Transfer Permanganate Oxidation of Unfunctionalized Benzylic Positions
Gannon, Sharon M.,Krause, Josef G.
, p. 915 - 917 (2007/10/02)
The utility of potassium permanganate in a biphasic medium employing a phase-transfer catalyst is described for the selective oxidations of doubly-benzylic secondary carbons to ketones and doubly-benzylic tertiary carbons to alcohols as well as of singly-benzylic secondary alcohols to ketones.
Proton-Transfer Reactions between 9-Alkylfluorene and (9-Alkylfluorenyl)lithium in Ether
Murdoch, J. R.,Bryson, J.A.,McMillen, D.F.,Brauman, J.I.
, p. 600 - 610 (2007/10/02)
The rates of proton-transfer reactions between 9-substituted fluorenes and 9-substituted fluorenyllithium have been examined in ether at 25 and 71 deg C.A high primary isotope effect (kH/kD = 9.5) and substantial secondary kinetic (1.11 +/- 0.04) and equilibrium (1.19 +/- 0.04) isotope effects are observed for fluorene.Surprisingly, intermolecular steric effects seem to play only a minor role in spite of the fact that the alkyl groups are located directly at the carbon involved in the proton transfer.The barriers for the endergonic cross reactions (i.e., those involving different alkyl groups in the anion and hydrocarbon) are half of the sum of the barriers for the two corresponding identity reactions (i.e., those involving the same alkyl groups in the anion and hydrocarbon).This leads to Broensted slopes which vary from 0.7 for reactions of fluorenyl anion to 1.8 for reactions of 9-(tert-butyl)fluorenyl anion.The rates of the identity and cross reactions give approximate linear correlations with each other and with ΔpK and are dominated by an effect which correlates with ?*.The substituent effect correlated by ?* is inconsistent with a classical field or repulsive steric effect and may originate from solvatation effects.The thermodynamic and kinetic relationships between the identity and cross reactions show that the transition states for the cross reac tions are only responding to half of the substituent effect on the identity reactions and that the substituent effect on the equilibria appears absent from the cross-reaction transition states.The results can be consistent with Marcus' theory only if the substituent effect on the equilibria appears in steps separate from proton transfer.The results suggest that changes in solvation and proton transfer occur as discrete kinetic steps.
