5779-94-2Relevant articles and documents
A green approach for aerobic oxidation of benzylic alcohols catalysed by CuI-Y zeolite/TEMPO in ethanol without additional additives
Senthilkumar, Samuthirarajan,Zhong, Wei,Natarajan, Mookan,Lu, Chunxin,Xu, Binyu,Liu, Xiaoming
, p. 705 - 713 (2021/01/25)
An efficient and green protocol for aerobic oxidation of benzylic alcohols in ethanol using CuI-Y zeolite catalysts assisted by TEMPO (TEMPO = 2,2,6,6-tetramethyl-1-piperidine-N-oxyl) as the radical co-catalyst in the presence of atmospheric air under mild conditions is reported. The CuI-Y zeolite prepared via ion exchange between CuCl and HY zeolite was fully characterized by a variety of spectroscopic techniques including XRD, XPS, SEM, EDX and HRTEM. The incorporation of Cu(i) into the 3D-framework of the zeolite rendered the catalyst with good durability. The results of repetitive runs revealed that in the first three runs, there was hardly a decline in activity and a more substantial decrease in yield was observed afterwards, while the selectivity remained almost unchanged. The loss in activity was attributed to both the formation of CuO and the bleaching of copper into the liquid phase during the catalysis, of which the formation of CuO was believed to be the major contributor since the bleaching loss for each run was negligible (2%). In this catalytic system, except TEMPO, no other additives were needed, either a base or a ligand, which was essential in some reported catalytic systems for the oxidation of alcohols. The aerobic oxidation proceeded under mild conditions (60 °C, and 18 hours) to quantitatively and selectively convert a wide range of benzylic alcohols to corresponding aldehydes, which shows great potential in developing green and environmentally benign catalysts for aerobic oxidation of alcohols. The system demonstrated excellent tolerance against electron-withdrawing groups on the phenyl ring of the alcohols and showed sensitivity to steric hindrance of the substrates, which is due to the confinement of the pores of the zeolite in which the oxidation occurred. Based on the mechanism reported in the literature for homogenous oxidation, a mechanism was analogously proposed for the aerobic oxidation of benzylic alcohols catalysed by this Cu(i)-containing zeolite catalyst. This journal is
Synthesis and Immobilization of Metal Nanoparticles Using Photoactive Polymer-Decorated Zeolite L Crystals and Their Application in Catalysis
Wissing, Maren,Niehues, Maximilian,Ravoo, Bart Jan,Studer, Armido
supporting information, p. 2245 - 2253 (2020/05/05)
A facile route to generate Au and Pd nanoparticles (NPs) on zeolite L crystals decorated with photoactive polymer brushes is described. The polymers used in this approach serve a dual role: Upon irradiation with UV light, they release highly reducing ketyl radicals in a Norrish-Type-I reaction. These radicals serve as one electron donors to reduce metal salts to the corresponding metal NPs. At the same time the polymer shell stabilizes the in situ generated metal NPs. It is shown that the zeolite-polymer-NP composites can be used as recyclable catalysts for the oxidation of benzylic alcohols to aldehydes and the stereoselective semihydrogenation of alkynes to Z-alkenes. The polymer shell in these hybrid catalysts protects the NPs from aggregation and also alters their catalytic properties. (Figure presented.).
Production and testing of technical catalysts based on MnO2 for the abatement of aromatic volatile compounds at the laboratory and pilot plant scales
Baldovino-Medrano, Víctor Gabriel,Kartheuser, Beno?t,Gaigneaux, Eric M.
, p. 81 - 92 (2019/04/25)
Shaping is a crucial step to produce technical catalysts that remains as some sort of dark art for catalytic researchers in academia. This contribution discusses aspects concerning the fabrication of technical catalysts based on MnO2 powders ai
Novel oxidative aromatic alkene cleavage with sodium nitrite under mild conditions
Yin, Bo,Peng, Xiangjun,Huang, Panpan,Huang, Qing,Liu, Liangxian
supporting information, p. 2189 - 2194 (2017/11/15)
We have developed a simple and practical process for the oxidation of aromatic alkene to the corresponding carbonyl compounds using NaNO2 as an oxidant. The practical utility of this oxidative process has been demonstrated in the gram-scale oxidation of 1-(tert-butyl)-4-vinylbenzene.
Simple formylation of aromatic compounds using a sodium formate/triphenylphosphine ditriflate system
Khodaei, Mohammad M.,Alizadeh, Abdolhamid,Hezarkhani, Hadis Afshar
supporting information, p. 840 - 843 (2017/06/13)
A new procedure was developed for formylation of arenes to produce aromatic aldehydes using a sodium formate/triphenylphosphine ditriflate system in ethanol at room temperature in good yields. The simplicity of the procedure, short reaction times, and mild reaction conditions are the other advantages of this metal- and carbon monoxide-free protocol.
A Copper-Benzotriazole-Based Coordination Polymer Catalyzes the Efficient One-Pot Synthesis of (N′-Substituted)-hydrazo-4-aryl-1,4-dihydropyridines from Azines
Kallitsakis, Michael,Loukopoulos, Edward,Abdul-Sada, Alaa,Tizzard, Graham J.,Coles, Simon J.,Kostakis, George E.,Lykakis, Ioannis N.
supporting information, p. 138 - 145 (2017/01/14)
A series of new (N′-substituted)-hydrazo-4-aryl-1,4-dihydropyridines was successfully synthesized via a facile one-pot catalytic pathway utilizing azines and propiolate esters as starting materials and a one-dimensional copper benzotriazole-based coordination polymer as catalyst. In the absence of catalyst, the corresponding 5-substituted 4,5-dihydropyrazoles were formed in moderate to high yields. Fine-tuning of the catalysts allowed us to gain more insights regarding the plausible reaction mechanism. (Figure presented.).
Oxygenation of Methylarenes to Benzaldehyde Derivatives by a Polyoxometalate Mediated Electron Transfer-Oxygen Transfer Reaction in Aqueous Sulfuric Acid
Sarma, Bidyut Bikash,Efremenko, Irena,Neumann, Ronny
, p. 5916 - 5922 (2015/05/27)
The synthesis of benzaldehyde derivatives by oxygenation of methylarenes is of significant conceptual and practical interest because these compounds are important chemical intermediates whose synthesis is still carried out by nonsustainable methods with very low atom economy and formation of copious amounts of waste. Now an oxygenation reaction with a 100% theoretical atom economy using a polyoxometalate oxygen donor has been found. The product yield is typically above 95% with no "overoxidation" to benzoic acids; H2 is released by electrolysis, enabling additional reaction cycles. An electrocatalytic cycle is also feasible. This reaction is possible through the use of an aqueous sulfuric acid solvent, in an aqueous biphasic reaction mode that also allows simple catalyst recycling and recovery. The solvent plays a key role in the reaction mechanism by protonating the polyoxometalate thereby enabling the activation of the methylarenes by an electron transfer process. After additional proton transfer and oxygen transfer steps, benzylic alcohols are formed that further react by an electron transfer-proton transfer sequence forming benzaldehyde derivatives. (Chemical Equation Presented).
Formylation of electron-rich aromatic rings mediated by dichloromethyl methyl ether and TiCl4: Scope and limitations
Ramos-Tomillero, Iván,Paradís-Bas, Marta,De Pinho Ribeiro Moreira, Ibério,Bofill, Josep María,Nicolás, Ernesto,Albericio, Fernando
supporting information, p. 5409 - 5422 (2015/05/13)
Here the aromatic formylation mediated by TiCl4 and dichloromethyl methyl ether previously described by our group has been explored for a wide range of aromatic rings, including phenols, methoxy- and methylbenzenes, as an excellent way to produce aromatic aldehydes. Here we determine that the regioselectivity of this process is highly promoted by the coordination between the atoms present in the aromatic moiety and those in the metal core.
An improved protocol for the oxidative cleavage of alkynes, alkenes, and diols with recyclable Ru/C
Vijay Kumar,Prakash Reddy,Sridhar,Srinivas,Rama Rao
experimental part, p. 739 - 742 (2009/07/18)
Efficient synthesis of carboxylic acids from alkynes; aldehydes from alkenes and diols employing Ru/C-based recyclable catalytic system is reported with good to excellent yields. Georg Thieme Verlag Stuttgart.
