scholarly journals Pd-Based Polysaccharide Hydrogels as Heterogeneous Catalysts for Oxidation of Aromatic Alcohols

Organics ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 50-56
Author(s):  
Oshrat Levy-Ontman ◽  
Eliraz Stamker ◽  
Vital Mor ◽  
Adi Wolfson
Keyword(s):  
Calcium Chloride ◽  
Heterogeneous Catalysts ◽  
Aerobic Oxidation ◽  
Benzylic Alcohol ◽  
Aromatic Alcohols ◽  
First Time

Immobilization of Pd(OAc)2(TPPTS)2 in various renewable polysaccharides hydrogels, yielded heterogeneous catalysts that were successfully used, for the first time, in the aerobic oxidation of benzylic alcohol. The new catalysts were easily removed from the reaction mixture and recycled with some loss of activity. Among all tested polysaccharides, iota-carrageenan was found to be the most suitable support, using calcium chloride as a gelation agent.

Highly efficient Cu(ii)-pyrazoledicarboxylate heterogeneous catalysts for a base-free aerobic oxidation of benzylic alcohol to benzaldehyde with hydrogen peroxide as the oxidant

2020 ◽  
Vol 49 (23) ◽  
pp. 7758-7765
Author(s):  
Mei-Ling Cheng ◽  
Meng-Na Qin ◽  
Lin Sun ◽  
Lu Liu ◽  
Qi Liu ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
High Activity ◽  
Benzyl Alcohol ◽  
Heterogeneous Catalysts ◽  
Aerobic Oxidation ◽  
Highly Efficient ◽  
Oxidation Of Benzyl Alcohol ◽  
Benzylic Alcohol ◽  
Free Oxidation

A Cu(ii)-pyrazoledicarboxylate MOF displayed high activity and selectivity in the base-free oxidation of benzyl alcohol to benzaldehyde combined with H2O2.

Dissolution and Performing Homogeneous Photocatalysis of Polymeric Carbon Nitride

2018 ◽  
Author(s):  
Chaofeng Huang ◽  
Jing Wen ◽  
Yanfei Shen ◽  
Fei He ◽  
Li Mi ◽  
...  
Keyword(s):  
Conjugated Polymer ◽  
Carbon Nitride ◽  
Heterogeneous Catalysts ◽  
Methane Sulfonic Acid ◽  
Environment Friendly ◽  
The Poor ◽  
Catalytic Sites ◽  
Homogeneous Photocatalysis ◽  
Polymeric Carbon ◽  
First Time

<a></a><a>As a metal-free conjugated polymer, carbon nitride (CN) has attracted tremendous attention as heterogeneous (photo)catalysts. </a><a></a><a>By following prototype of enzymes, making all catalytic sites of accessible via homogeneous reactions is a promising approach toward maximizing CN activity, but hindered due to </a><a></a><a>the poor insolubility of CN</a>. Herein, we report the dissolution of CN in environment-friendly methane sulfonic acid and the homogeneous photocatalysis driven by CN for the first time with the activity boosted up to 10-times, comparing to the heterogeneous counterparts. Moreover, facile recycling and reusability, the <a>hallmark</a> of heterogeneous catalysts, were kept for the homogeneous CN photocatalyst via reversible precipitation using poor solvents. It opens new vista of CN in homogeneous catalysis and offers a successful example of polymeric catalysts in bridging gaps of homo/heterogeneous catalysis.

Green photocatalytic organic transformations by polyoxometalates vs. mesoporous TiO2 nanoparticles: selective aerobic oxidation of alcohols

2015 ◽  
Vol 14 (3) ◽  
pp. 563-568 ◽  
Author(s):  
Theodoros S. Symeonidis ◽  
Ioannis Tamiolakis ◽  
Gerasimos S. Armatas ◽  
Ioannis N. Lykakis
Keyword(s):  
Electron Transfer ◽  
Tio2 Nanoparticles ◽  
Aerobic Oxidation ◽  
Mesoporous Tio2 ◽  
Transfer Mechanism ◽  
Organic Transformations ◽  
Electron Transfer Mechanism ◽  
Nanoparticle Assemblies ◽  
Oxidation Of Alcohols ◽  
Aromatic Alcohols

Decatungstate supported on mesoporous TiO2 nanoparticle assemblies catalyze the selective and efficient oxidation of aromatic alcohols under “green” oxidation conditions. An electron transfer mechanism was predominated under UV-vis irradiation.

Direct dehydrogenation of isobutane to isobutene over Zn-doped ZrO2 metal oxide heterogeneous catalysts

2018 ◽  
Vol 8 (19) ◽  
pp. 4916-4924 ◽  
Author(s):  
Yang Liu ◽  
Chengjie Xia ◽  
Qi Wang ◽  
Lei Zhang ◽  
Ao Huang ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Heterogeneous Catalysts ◽  
First Time

A series of unconventional nano-sized Zn-doped ZnZrO-x catalysts are applied for the first time to the direct dehydrogenation of isobutane to isobutene.

scholarly journals Second-Generation Manganese(III) Porphyrins Bearing 3,5-Dichloropyridyl Units: Innovative Homogeneous and Heterogeneous Catalysts for the Epoxidation of Alkenes

Catalysts ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 967 ◽  
Author(s):  
Neves ◽  
Rebelo ◽  
Faustino ◽  
Neves ◽  
Simões
Keyword(s):  
Heterogeneous Catalysts ◽  
Second Generation ◽  
Supported Catalyst ◽  
Catalytic Efficiency ◽  
Major Product ◽  
Aqueous Hydrogen Peroxide ◽  
Tert Butyl Hydroperoxide ◽  
Merrifield Resin ◽  
Catalytic Cycles ◽  
First Time

The synthesis, characterisation and homogeneous catalytic oxidation results of two manganese(III) porphyrins of the so-called second-generation of metalloporphyrin catalysts, containing one or four 3,5-dichloropyridyl substituents at the meso positions are reported for the first time. The catalytic efficiency of these novel manganese(III) porphyrins was evaluated in the oxidation of cyclooctene and styrene using aqueous hydrogen peroxide as the oxidant, under homogeneous conditions. High conversions were obtained in the presence of both catalysts, obtaining the corresponding epoxide as the major product. The asymmetric metalloporphyrin, chloro[5,10,15-tris(2,6-dichlorophenyl)-20-(3,5-dichloropyridin-4-yl)porphyrinate]manganese(III), CAT-4, evidences a similar activity to that obtained with the well-known and highly efficient second-generation metalloporphyrin catalyst, chloro[5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrinate]manganese(III), CAT-2. CAT-4 was covalently attached onto Merrifield resin and 3-bromopropylsilica supports. The solid materials obtained were characterized by several techniques including diffuse reflectance, UV—VIS spectrophotometry, SEM and XPS. The catalytic results for the oxidation of cyclooctene and styrene using the immobilized catalysts are also presented. The Merrifield-supported catalyst showed to be very efficient, leading to five catalytic cycles in the oxidation of cyclooctene, using tert-butyl hydroperoxide as the oxidant.

AIBN/NaBr-promoted aerobic oxidation of benzylic alcohols via a radical process

2016 ◽  
Vol 14 (2) ◽  
pp. 577-581 ◽  
Author(s):  
Chengkou Liu ◽  
Zheng Fang ◽  
Zhao Yang ◽  
Qingwen Li ◽  
Shiyu Guo ◽  
...  
Keyword(s):  
Aerobic Oxidation ◽  
Alcohol Oxidation ◽  
Radical Mechanism ◽  
Radical Process ◽  
Benzylic Alcohols ◽  
First Time ◽  
Oxidation System

A new aerobic alcohol oxidation system of AIBN/NaBr was described for the first time. Moreover, a radical mechanism was assumed and confirmed.

Investigation of Phthalocyanine Catalysts for the Aerobic Synthesis of meso-Substituted Porphyrins

1997 ◽  
Vol 01 (04) ◽  
pp. 385-394 ◽  
Author(s):  
M. RAVIKANTH ◽  
CATALINA ACHIM ◽  
JOHN S. TYHONAS ◽  
ECKARD MÜNCK ◽  
JONATHAN S. LINDSEY
Keyword(s):  
Trifluoroacetic Acid ◽  
Room Temperature ◽  
Heterogeneous Catalysts ◽  
Mossbauer Spectroscopy ◽  
Oxidation Process ◽  
Aerobic Oxidation ◽  
Heterogeneous Reactions ◽  
High Concentration ◽  
Neutral Conditions ◽  
Homogeneous Reactions

The aerobic oxidation process for the synthesis of porphyrins, previously performed using 5 mol % p-chloranil (TCQ), 5 mol % iron(II) phthalocyanine ( FePc ) and stoichiometric amounts of O 2, has been refined using new phthalocyanine catalysts. Four phthalocyanine catalysts have been prepared, characterized by Mössbauer spectroscopy and examined for efficacy in the high concentration (0.1 M) synthesis of tetraphenylporphyrin at room temperature. Each phthalocyanine has been identified to be a μ-oxo dimer. Two catalysts are soluble (the μ-oxo dimers [(t-butyl)4 FePc ]2 O and [(n- C 6 H 13 O )4 FePc ]2 O ) and enable homogeneous reactions, while two are insoluble (the μ-oxo(1) and μ-oxo(2) dimers of FePc , ( FePc )2 O ) and give heterogeneous reactions. These four phthalocyanine compounds provide efficient catalysis at the 0.3–1 mol % level using only 1 mol % quinone or hydroquinone ( TCQ , DDQ , TCQH 2 or DDQH 2), affording ~25% yields of tetraphenylporphyrin in 60 min of oxidation. There are no discernible advantages of the homogeneous versus heterogeneous catalysts. The μ-oxo dimers are active, but FePc is inactive, at the 0.3 mol % level. The activity of the FePc sample at the 5 mol % level is attributed to residual μ-oxo dimer impurity. This aerobic oxidation process is superior to stoichiometric oxidation with TCQ or DDQ , and can be performed in the presence of BF 3· O ( Et )2, trifluoroacetic acid, or under neutral conditions.

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