Nature of vanadium species on vanadium silicalite-1 zeolite and their stability in hydroxylation reaction of benzene to phenol

2011 ◽  
Vol 1 (6) ◽  
pp. 1060 ◽  
Author(s):  
Bin Guo ◽  
Liangfang Zhu ◽  
Xiaoke Hu ◽  
Qian Zhang ◽  
Dongmei Tong ◽  
...  
Keyword(s):  
Hydroxylation Reaction ◽  
Vanadium Species

scholarly journals Cerium promoted V-g-C 3 N 4 as highly efficient heterogeneous catalysts for the direct benzene hydroxylation

2018 ◽  
Vol 5 (6) ◽  
pp. 180371 ◽  
Author(s):  
Cheng Wang ◽  
Liya Hu ◽  
Meiyin Wang ◽  
Bin Yue ◽  
Heyong He
Keyword(s):  
Heterogeneous Catalysts ◽  
High Dispersion ◽  
Adsorption Ability ◽  
Cerium Content ◽  
Assembly Method ◽  
Benzene Hydroxylation ◽  
Hydroxylation Reaction ◽  
Catalytic Stability ◽  
Vanadium Species ◽  
Active Centres

A series of Ce x -V-g-C 3 N 4 catalysts with different cerium content were synthesized by a facile co-assembly method. Compared with pure V-g-C 3 N 4 catalyst, the addition of cerium facilitated the high dispersion of vanadium species as well as the benzene adsorption ability of the corresponding catalysts. Also, the existence of cerium promoted the partial reduction of vanadium species, which improved the redox property of vanadium species as the active centres. The Ce x -V-g-C 3 N 4 catalysts showed considerably improved activity in the benzene hydroxylation reaction compared with V-g-C 3 N 4 catalyst. Among the catalysts studied, Ce 0.07 -0.07 V-g-C 3 N 4 exhibited the best catalytic activity with a benzene conversion of 33.7% and a phenol yield of 32.3% with good structural and catalytic stability, while only 24.7% of benzene conversion and phenol yield of 24.2% were obtained over 0.07 V-g-C 3 N 4 .

Diastereoselective Synthesis of (3R,5R)-γ-Hydroxypiperazic Acid

Synlett ◽  
2021 ◽  
Author(s):  
Juan R. Del Valle ◽  
Taylor A. Gerrein ◽  
Yassin M. Elbatrawi
Keyword(s):  
Asymmetric Synthesis ◽  
Late Stage ◽  
Ring Formation ◽  
Peptide Chain ◽  
Nonribosomal Peptides ◽  
Diastereoselective Synthesis ◽  
Hydroxylation Reaction ◽  
Enolate Hydroxylation

AbstractWe report an asymmetric synthesis of the (3R,5R)-γ-hydroxypiperazic acid (γ-OHPiz) residue encountered in several bioactive nonribosomal peptides. Our strategy relies on a diastereoselective enolate hydroxylation reaction and electrophilic N-amination to provide the acyclic γ-OHPiz precursor. This orthogonally protected α-hydrazino acid intermediate is amenable to late-stage diazinane ring formation following incorporation into a peptide chain. We determined the N-terminal amide rotamer propensity of the γ-OHPiz residue and showed that the γ-OH substituent enhances trans-amide bias relative to piperazic acid.

scholarly journals Multienzymatic in situ hydrogen peroxide generation cascade for peroxygenase-catalysed oxyfunctionalisation reactions

2019 ◽  
Vol 74 (3-4) ◽  
pp. 101-104 ◽  
Author(s):  
Milja Pesic ◽  
Sébastien Jean-Paul Willot ◽  
Elena Fernández-Fueyo ◽  
Florian Tieves ◽  
Miguel Alcalde ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Formate Dehydrogenase ◽  
Flavin Mononucleotide ◽  
Candida Boidinii ◽  
Reaction Parameters ◽  
Old Yellow Enzyme ◽  
Hydroxylation Reaction ◽  
In Situ Generation ◽  
Hydrogen Peroxide Generation

Abstract There is an increasing interest in the application of peroxygenases in biocatalysis, because of their ability to catalyse the oxyfunctionalisation reaction in a stereoselective fashion and with high catalytic efficiencies, while using hydrogen peroxide or organic peroxides as oxidant. However, enzymes belonging to this class exhibit a very low stability in the presence of peroxides. With the aim of bypassing this fast and irreversible inactivation, we study the use of a gradual supply of hydrogen peroxide to maintain its concentration at stoichiometric levels. In this contribution, we report a multienzymatic cascade for in situ generation of hydrogen peroxide. In the first step, in the presence of NAD+ cofactor, formate dehydrogenase from Candida boidinii (FDH) catalysed the oxidation of formate yielding CO2. Reduced NADH was reoxidised by the reduction of the flavin mononucleotide cofactor bound to an old yellow enzyme homologue from Bacillus subtilis (YqjM), which subsequently reacts with molecular oxygen yielding hydrogen peroxide. Finally, this system was coupled to the hydroxylation of ethylbenzene reaction catalysed by an evolved peroxygenase from Agrocybe aegerita (rAaeUPO). Additionally, we studied the influence of different reaction parameters on the performance of the cascade with the aim of improving the turnover of the hydroxylation reaction.

The role of vanadium species during SO2 removal over a V2O5/AC catalyst

2020 ◽  
Vol 10 (1) ◽  
pp. 231-239 ◽  
Author(s):  
Qianqian Guo ◽  
Wen Jing ◽  
Yaqin Hou ◽  
Yulin Li ◽  
Fenghai Li ◽  
...  
Keyword(s):  
So2 Removal ◽  
Vanadium Species

Mechanism of SO2 removal over a V2O5/AC catalyst.

scholarly journals Synthesis of 1,4-Dioxaspiro[4.4] and 1,4-Dioxaspiro[4.5] Novel Compounds from Oleic Acid as Potential Biolubricant

2017 ◽  
Vol 17 (2) ◽  
pp. 301
Author(s):  
Yehezkiel Steven Kurniawan ◽  
Yudha Ramanda ◽  
Kevin Thomas ◽  
Hendra Hendra ◽  
Tutik Dwi Wahyuningsih
Keyword(s):  
Oleic Acid ◽  
Viscous Liquid ◽  
Acid Number ◽  
The Other ◽  
Esterification Reaction ◽  
Base Number ◽  
Sonochemical Method ◽  
Total Acid ◽  
Hydroxylation Reaction ◽  
Total Base

Two 1,4-dioxaspiro novel compounds which derivated from methyl 9,10-dihydroxyoctadecanoate (MDHO) with cyclopentanone and cyclohexanone had been synthesized by a sonochemical method in the presence of montmorillonite KSF catalyst. The MDHO compound had been prepared from 9,10-dihydroxyoctadecanoic acid (DHOA) and methanol. Meanwhile, DHOA was synthesized by hydroxylation of oleic acid with the solution of 1% KMnO4 under basic condition. The structures of the products were confirmed by FTIR, GC-MS, 1H-NMR, and 13C-NMR spectrometers. Hydroxylation reaction of oleic acid gave DHOA as a white solid powder in 46.52% yield (m.p. 131-132 °C). On the other side, esterification reaction via sonochemical method between DHOA and methanol gave MDHO as a white powder in 93.80% yield (m.p. 80-81 °C). The use of cyclopentanone in 45 min sonochemical method gave methyl 8-(3-octyl-1,4-dioxaspiro[4.4]nonan-2-yl)octanoate as a yellow viscous liquid in 50.51% yield. The other compound, methyl 8-(3-octyl-1,4-dioxaspiro[4.5]decan-2-yl)octanoate as yellow viscous liquid had been synthesized by similar method with cyclohexanone via the sonochemical method in 45.12% yield. From physicochemical properties, i.e. density, total acid number, total base number, and iodine value, gave the conclusion that these novel compounds are potential biolubricant candidates to be developed.

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