scholarly journals Dehydrogenative Transformation of Alcoholic Substrates in Aqueous Media Catalyzed by an Iridium Complex Having a Functional Ligand with α-Hydroxypyridine and 4,5-Dihydro-1H-imidazol-2-yl Moieties

Catalysts ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 312 ◽  
Author(s):  
Masato Yoshida ◽  
Han Wang ◽  
Takuya Shimbayashi ◽  
Ken-ichi Fujita
Keyword(s):  
Catalytic System ◽  
Aqueous Media ◽  
Catalytic Performance ◽  
Water Soluble ◽  
Iridium Complex ◽  
Similar Reaction ◽  
Reaction Conditions ◽  
System A ◽  
Iridium Catalyst ◽  
Oxidation Of Alcohols

A new catalytic system that employs water as an environmentally friendly solvent for the dehydrogenative oxidation of alcohols and lactonization of diols has been developed. In this catalytic system, a water-soluble dicationic iridium complex having a functional ligand that comprises α-hydroxypyridine and 4,5-dihydro-1H-imidazol-2-yl moieties exhibits high catalytic performance. For example, the catalytic dehydrogenative oxidation of 1-phenylethanol in the presence of 0.25 mol % of the iridium catalyst and base under reflux in water proceeded to give acetophenone in 92% yield. Additionally, under similar reaction conditions, the iridium-catalyzed dehydrogenative lactonization of 1,2-benzenedimethanol gave phthalide in 98% yield.

Dehydrogenative Oxidation of Alcohols in Aqueous Media Catalyzed by a Water-Soluble Dicationic Iridium Complex Bearing a Functional N-Heterocyclic Carbene Ligand without Using Base

ACS Catalysis ◽  
2017 ◽  
Vol 7 (10) ◽  
pp. 7226-7230 ◽  
Author(s):  
Ken-ichi Fujita ◽  
Ryuichi Tamura ◽  
Yuhi Tanaka ◽  
Masato Yoshida ◽  
Mitsuki Onoda ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Water Soluble ◽  
Iridium Complex ◽  
Oxidation Of Alcohols

scholarly journals Iridium Complex Catalyzed Hydrogen Production from Glucose and Various Monosaccharides

Catalysts ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 891
Author(s):  
Ken-ichi Fujita ◽  
Takayoshi Inoue ◽  
Toshiki Tanaka ◽  
Jaeyoung Jeong ◽  
Shohichi Furukawa ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Catalytic System ◽  
Catalytic Reaction ◽  
Hydrogen Gas ◽  
Water Soluble ◽  
Starting Material ◽  
Iridium Complex ◽  
Production Of Hydrogen ◽  
Bipyridine Ligand

A new catalytic system has been developed for hydrogen production from various monosaccharides, mainly glucose, as a starting material under reflux conditions in water in the presence of a water-soluble dicationic iridium complex bearing a functional bipyridine ligand. For example, the reaction of D-glucose in water under reflux for 20 h in the presence of [Cp*Ir(6,6′-dihydroxy-2,2′-bipyridine)(H2O)][OTf]2 (1.0 mol %) (Cp*: pentamethylcyclopentadienyl, OTf: trifluoromethanesulfonate) resulted in the production of hydrogen gas in 95% yield. In the present catalytic reaction, it was experimentally suggested that dehydrogenation of the alcoholic moiety at 1-position of glucose proceeded.

scholarly journals Figures of Merit for Photocatalysis: Comparison of NiO/La-NaTaO3 and Synechocystis sp. PCC 6803 as a Semiconductor and a Bio-Photocatalyst for Water Splitting

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1415
Author(s):  
Eike S. Welter ◽  
Sebastian Kött ◽  
Fabian Brandenburg ◽  
Jens Krömer ◽  
Michael Goepel ◽  
...  
Keyword(s):  
Water Splitting ◽  
Critical Evaluation ◽  
Catalytic Performance ◽  
Similar Reaction ◽  
Apparent Quantum Yield ◽  
Reaction Conditions ◽  
Figures Of Merit ◽  
Space Time Yield ◽  
Synechocystis Sp ◽  
Pcc 6803

While photocatalysis is considered a promising sustainable technology in the field of heterogeneous catalysis as well as biocatalysis, figures of merit (FOM) for comparing catalytic performance, especially between disciplines, are not well established. Here, photocatalytic water splitting was conducted using a semiconductor (NiO/La-NaTaO3) and a bio-photocatalyst (Synechocystis sp. PCC 6803) in the same setup under similar reaction conditions, eliminating the often ill-defined influence of the setup on the FOMs obtained. Comparing the results enables the critical evaluation of existing FOMs and a quantitative comparison of both photocatalytic systems. A single FOM is insufficient to compare the photocatalysts, instead a combination of multiple FOMs (reaction rate, photocatalytic space time yield and a redefined apparent quantum yield) is superior for assessing a variety of photocatalytic systems.

scholarly journals Bio-assisted synthesized Ag(0) nanoparticles stabilized on hybrid of sepiolite and chitin: efficient catalytic system for xanthene synthesis

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Fatemeh Ghoreyshi Kahangi ◽  
Morteza Mehrdad ◽  
Majid M. Heravi ◽  
Samahe Sadjadi
Keyword(s):  
Silver Nanoparticles ◽  
Catalytic Activity ◽  
Specific Surface ◽  
Catalytic System ◽  
Synergistic Effects ◽  
Aqueous Media ◽  
Catalytic Performance ◽  
High Catalytic Activity ◽  
Mean Diameter ◽  
High Yields

Abstract In this work, with the use of two natural compounds, chitin and sepiolite clay, a novel covalent hybrid is fabricated and applied as a support for the stabilization of silver nanoparticles with the aid of Kombucha extract as a natural reducing agent. The resultant catalytic system, Ag@Sep-N–CH, was characterized via XRD, TEM, FTIR, ICP, SEM, TGA, UV–Vis and BET. It was found that fine Ag(0) nanoparticles with mean diameter of 6.1 ± 1.8 nm were formed on the support and the specific surface area of the catalyst was 130 m2 g−1. The study of the catalytic performance of Ag@Sep-N–CH for catalyzing synthesis of xanthenes in aqueous media under mild reaction condition confirmed that Ag@Sep-N–CH exhibited high catalytic activity and could promote the reaction of various substrates to furnish the corresponding products in high yields. Moreover, the contribution of both chitin and sepiolite to the catalysis has been affirmed. It was found that hybridization of these two components led to synergistic effects and consequently improved the observed catalytic activity. Notably, the catalyst was recyclable up to several reaction runs.

Tandem Hydroformylation–Acetalization Using a Water-Soluble Catalytic System: a Promising Procedure for Preparing Valuable Oxygen-Containing Compounds from Olefins and Polyols

2018 ◽  
Vol 91 (6) ◽  
pp. 990-995 ◽  
Author(s):  
D. N. Gorbunov ◽  
M. V. Nenasheva ◽  
N. A. Sinikova ◽  
Yu. S. Kardasheva ◽  
A. L. Maksimov ◽  
...  
Keyword(s):  
Catalytic System ◽  
Water Soluble ◽  
System A

Pd/ZrO2: An Efficient Catalyst for Liquid Phase Oxidation of Toluene in Solvent Free Conditions

2017 ◽  
Vol 15 (2) ◽  
Author(s):  
Mohsin Siddique ◽  
Muhammad Saeed ◽  
Mohammad Ilyas ◽  
Hussain Gulab
Keyword(s):  
Batch Reactor ◽  
Catalytic Efficiency ◽  
Catalytic Performance ◽  
Solvent Free ◽  
Catalyst Loading ◽  
Similar Reaction ◽  
Reaction Conditions ◽  
Efficient Catalyst ◽  
Solvent Free Conditions ◽  
Free Oxidation

Abstract 0.1 % Pd/ZrO2 was synthesized and characterized by various physicochemical techniques and was successfully used as catalyst for solvent free oxidation of toluene in the presence of molecular oxygen using batch reactor. The catalytic performance of Pd/ZrO2 was explored in terms of effect of catalyst loading, reaction time, temperature and partial pressure of oxygen on oxidation of toluene in solvent free conditions. Pd/ZrO2 was found as a stable catalyst under the reaction conditions. Used catalyst exhibited the same catalytic efficiency as fresh catalyst under similar reaction conditions. Reaction was taking place according to Langmuir-Hinshelwood type of mechanism.

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