Dioxygen dissociation over man-made system at room temperature to form the active α-oxygen for methane oxidation

Activation of dioxygen attracts enormous attention due to its potential for utilization of methane and applications in other selective oxidation reactions. We report a cleavage of dioxygen at room temperature over distant binuclear Fe(II) species stabilized in an aluminosilicate matrix. A pair of formed distant α-oxygen species [i.e., (Fe(IV)═O)2+] exhibits unique oxidation properties reflected in an outstanding activity in the oxidation of methane to methanol at room temperature. Designing a man-made system that mimicks the enzyme functionality in the dioxygen activation using both a different mechanism and structure of the active site represents a breakthrough in catalysis. Our system has an enormous practical importance as a potential industrial catalyst for methane utilization because (i) the Fe(II)/Fe(IV) cycle is reversible, (ii) the active Fe centers are stable under the reaction conditions, and (iii) methanol can be released to gas phase without the necessity of water or water-organic medium extraction.

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One-pot Synthesis of Pyrazolone Sulfones by Iodine-catalyzed Sulfenylation of Pyrazolones with Aryl Sulfonyl Hydrazides Followed by Oxidation in Water

Current Organic Synthesis ◽

10.2174/1570179414666171020113745 ◽

2018 ◽

Vol 15 (3) ◽

pp. 380-387

Author(s):

Xia Zhao ◽

Xiaoyu Lu ◽

Lipeng Zhang ◽

Tianjiao Li ◽

Kui Lu

Keyword(s):

Double Bond ◽

Efficient Method ◽

Room Temperature ◽

Sulfonyl Chloride ◽

Antibacterial Activities ◽

Oxidation Reactions ◽

Reaction Conditions ◽

One Pot ◽

X Ray ◽

Amide Form

Aim and Objective: Pyrazolone sulfones have been reported to exhibit herbicidal and antibacterial activities. In spite of their good bioactivities, only a few methods have been developed to prepare pyrazolone sulfones. However, the substrate scope of these methods is limited. Moreover, the direct sulfonylation of pyrazolone by aryl sulfonyl chloride failed to give pyrazolone sulfones. Thus, developing a more efficient method to synthesize pyrazolone sulfones is very important. Materials and Method: Pyrazolone, aryl sulphonyl hydrazide, iodine, p-toluenesulphonic acid and water were mixed in a sealed tube, which was heated to 100°C for 12 hours. The mixture was cooled to 0°C and m-CPBA was added in batches. The mixture was allowed to stir for 30 min at room temperature. The crude product was purified by silica gel column chromatography to afford sulfuryl pyrazolone. Results: In all cases, the sulfenylation products were formed smoothly under the optimized reaction conditions, and were then oxidized to the corresponding sulfones in good yields by 3-chloroperoxybenzoic acid (m-CPBA) in water. Single crystal X-ray analysis of pyrazolone sulfone 4aa showed that the major tautomer of pyrazolone sulfones was the amide form instead of the enol form observed for pyrazolone thioethers. Moreover, the C=N double bond isomerized to form an α,β-unsaturated C=C double bond. Conclusion: An efficient method to synthesize pyrazolone thioethers by iodine-catalyzed sulfenylation of pyrazolones with aryl sulfonyl hydrazides in water was developed. Moreover, this method was employed to synthesize pyrazolone sulfones in one-pot by subsequent sulfenylation and oxidation reactions.

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Selective Nitration of Chlorobenzene by NO2 in the Alkali Zeolite NaZSM-5

ISRN Physical Chemistry ◽

10.1155/2013/616532 ◽

2013 ◽

Vol 2013 ◽

pp. 1-5

Author(s):

Scott J. Kirkby

Keyword(s):

Gas Phase ◽

Room Temperature ◽

Temperature Dependent ◽

Reaction Conditions ◽

Cation Site ◽

Zeolite Lattice ◽

Reaction Proceeds ◽

Ft Ir ◽

Electron Donation

Chlorobenzene was reacted with NO2, in the initially acid-free zeolite NaZSM-5, to yield para-chloronitrobenzene exclusively. The precursors were loaded sequentially into self-supporting pellets of the zeolite, contained within a stainless steel cell, from the gas phase. The reaction proceeds spontaneously at room temperature. It is, however, very temperature dependent and effectively ceases at zero degrees Celsius. The reaction was monitored in situ using FT-IR. The active nitrating agent is formed from the partial electron donation by the NO2 to the Na+ cations present in the zeolite lattice. Under the reaction conditions, chlorobenzene is not readily mobile through the pore system; thus, only the molecules adsorbed near a cation site react to form para-chloronitrobenzene.

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Cobalt-Copper Nanoparticles Catalyzed Selective Oxidation Reactions: Efficient Catalysis at Room Temperature

ChemistrySelect ◽

10.1002/slct.201801140 ◽

2018 ◽

Vol 3 (34) ◽

pp. 9826-9832 ◽

Cited By ~ 4

Author(s):

Biraj Jyoti Borah ◽

Abhijit Mahanta ◽

Manoj Mondal ◽

Hemen Gogoi ◽

Yusuke Yamada ◽

...

Keyword(s):

Selective Oxidation ◽

Copper Nanoparticles ◽

Room Temperature ◽

Oxidation Reactions ◽

Selective Oxidation Reactions ◽

Cobalt Copper

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Naturally Occurring Organic Acid-catalyzed Facile Diastereoselective Synthesis of Biologically Active (E)-3-(arylimino)indolin-2-one Derivatives in Water at Room Temperature

Current Organic Chemistry ◽

10.2174/1385272822666190924182538 ◽

2019 ◽

Vol 23 (16) ◽

pp. 1778-1788 ◽

Cited By ~ 5

Author(s):

Gurpreet Kaur ◽

Arvind Singh ◽

Kiran Bala ◽

Mamta Devi ◽

Anjana Kumari ◽

...

Keyword(s):

Room Temperature ◽

Biologically Active ◽

Environmentally Benign ◽

Diastereoselective Synthesis ◽

Substituted Anilines ◽

Reaction Conditions ◽

Naturally Occurring ◽

Acid Catalyzed ◽

Reaction Media ◽

Column Chromatographic

A simple, straightforward and efficient method has been developed for the synthesis of (E)-3-(arylimino)indolin-2-one derivatives and (E)-2-((4-methoxyphenyl)imino)- acenaphthylen-1(2H)-one. The synthesis of these biologically-significant scaffolds was achieved from the reactions of various substituted anilines and isatins or acenaphthaquinone, respectively, using commercially available, environmentally benign and naturally occurring organic acids such as mandelic acid or itaconic acid as catalyst in aqueous medium at room temperature. Mild reaction conditions, energy efficiency, good to excellent yields, environmentally benign conditions, easy isolation of products, no need of column chromatographic separation and the reusability of reaction media are some of the significant features of the present protocol.

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A Facile, Efficient and Selective Deprotection of P - Methoxy Benzyl Ethers Using Zinc (II) Trifluoromethanesulfonate

Letters in Organic Chemistry ◽

10.2174/1570178616666190222151934 ◽

2019 ◽

Vol 16 (12) ◽

pp. 955-958

Author(s):

Reddymasu Sireesha ◽

Reddymasu Sreenivasulu ◽

Choragudi Chandrasekhar ◽

Mannam Subba Rao

Keyword(s):

Room Temperature ◽

Protecting Groups ◽

Side Reactions ◽

Reaction Conditions ◽

Acid Sensitivity ◽

Time Period ◽

Protective Groups ◽

Benzyl Ethers ◽

Last Stage ◽

Zinc Triflate

: Deprotection is significant and conducted over mild reaction conditions, in order to restrict any more side reactions with sensitive functional groups as well as racemization or epimerization of stereo center because the protective groups are often cleaved at last stage in the synthesis. P - Methoxy benzyl (PMB) ether appears unique due to its easy introduction and removal than the other benzyl ether protecting groups. A facile, efficient and highly selective cleavage of P - methoxy benzyl ethers was reported by using 20 mole% Zinc (II) Trifluoromethanesulfonate at room temperature in acetonitrile solvent over 15-120 min. time period. To study the generality of this methodology, several PMB ethers were prepared from a variety of substrates having different protecting groups and subjected to deprotection of PMB ethers using Zn(OTf)2 in acetonitrile. In this methodology, zinc triflate cleaves only PMB ethers without affecting acid sensitivity, base sensitivity and also chiral epoxide groups.

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Rh(III)-Catalyzed Olefination and Alkylation of Arenes with Maleimides: A Tunable Strategy for C(sp2)–H Functionalization

Synthesis ◽

10.1055/s-0037-1610765 ◽

2021 ◽

Author(s):

Hongji Li ◽

Wenjie Zhang ◽

Xueyan Liu ◽

Zhenfeng Tian

Keyword(s):

Room Temperature ◽

Functional Group ◽

Reaction Conditions ◽

Bond Functionalization ◽

Alkylation Process ◽

Coupling Partner

AbstractWe herein report a new nitrogen-directed Rh(III)-catalyzed C(sp2)–H bond functionalization of N-nitrosoanilines and azoxybenzenes with maleimides as a coupling partner, in which the olefination/alkylation process can be finely controlled at room temperature by variation of the reaction conditions. This method shows excellent functional group tolerance, and presents a mild access to the resulting olefination/alkylation products in moderate to good yields.

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Reaction Mechanism for Methane-to-Methanol in Cu-SSZ-13: First-Principles Study of the Z2[Cu2O] and Z2[Cu2OH] Motifs

Catalysts ◽

10.3390/catal11010017 ◽

2020 ◽

Vol 11 (1) ◽

pp. 17

Author(s):

Unni Engedahl ◽

Adam A. Arvidsson ◽

Henrik Grönbeck ◽

Anders Hellman

Keyword(s):

Liquid Fuel ◽

Density Functional ◽

Reaction Pathway ◽

Direct Conversion ◽

Reaction Conditions ◽

Oxidation Of Methane ◽

Small Pore ◽

Desorption Step ◽

Solution Gas ◽

Stable Motif

As transportation continues to increase world-wide, there is a need for more efficient utilization of fossil fuel. One possibility is direct conversion of the solution gas bi-product CH4 into an energy-rich, easily usable liquid fuel such as CH3OH. However, new catalytic materials to facilitate the methane-to-methanol reaction are needed. Using density functional calculations, the partial oxidation of methane is investigated over the small-pore copper-exchanged zeolite SSZ-13. The reaction pathway is identified and the energy landscape elucidated over the proposed motifs Z2[Cu2O] and Z2[Cu2OH]. It is shown that the Z2[Cu2O] motif has an exergonic reaction path, provided water is added as a solvent for the desorption step. However, a micro-kinetic model shows that neither Z2[Cu2O] nor Z2[Cu2OH] has any notable activity under the reaction conditions. These findings highlight the importance of the detailed structure of the active site and that the most stable motif is not necessarily the most active.

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Dioxygen splitting at room temperature over distant binuclear transition metal centers in zeolites for direct oxidation of methane to methanol

Chemical Communications ◽

10.1039/d1cc00909e ◽

2021 ◽

Author(s):

Kinga Mlekodaj ◽

Mariia Lemishka ◽

Stepan Sklenak ◽

Jiri Dedecek ◽

Edyta Tabor

Keyword(s):

Transition Metal ◽

Room Temperature ◽

Direct Oxidation ◽

Metal Centers ◽

Oxidation Of Methane ◽

First Time

Here we demonstrate for the first time the splitting of dioxygen at RT over distant binuclear transition metal (M = Ni, Mn, and Co) centers stabilized in ferrierite zeolite. Cleaved...

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Process intensification for enzyme assisted turmeric starch hydrolysis in hydrotropic and supercritical conditions

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2020-0161 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Yogita P. Labrath ◽

Prafulla V. Belge ◽

Uma G. Kulkarni ◽

Vilas G. Gaikar

Keyword(s):

Residence Time ◽

Filtration Rate ◽

Room Temperature ◽

Curcuma Longa ◽

Process Intensification ◽

Enzyme Treatment ◽

Starch Hydrolysis ◽

Reaction Conditions ◽

Natural Form ◽

Hydrolysis Of

Abstract The turmeric rhizome (Curcuma longa) contains curcuminoids embedded in the starch matrix. It is thus important to target starch hydrolysis to enhance extraction of curcuminoids. In the case of starch hydrolysis, α-amylase is more efficient when the starch is in a gelatinised form than when it is in its natural form. The present work includes hydrolysis of turmeric starch in its natural and gelatinised forms using α-amylase in hydrotrope solution (HS) and scCO2. The optimum rate of starch hydrolysis was obtained using 200 IU cm−3 of α-amylase, at reaction conditions of 6.5 pH at 328 K when 10% w/w of turmeric powder was stirred at 900 rpm in HSs. The hydrolysis in 15 MPa scCO2 at room temperature required a phase modifier and 40 min of residence time (RT). The enzyme treatment of turmeric powder in HSs increased the filtration rate for curcuminoid extraction (gelatinised and native) compared to untreated turmeric powder.

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