scholarly journals Heterocyclic bismuth(iii) compounds with transannular N→Bi interactions as catalysts for the oxidation of thiophenol to diphenyldisulfide

2017 ◽  
Vol 7 (22) ◽  
pp. 5343-5353 ◽  
Author(s):  
Ana M. Toma ◽  
Ciprian I. Raţ ◽  
Octavian D. Pavel ◽  
Christopher Hardacre ◽  
Tobias Rüffer ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Reaction Rates ◽  
Total Conversion ◽  
High Reaction ◽  
Diphenyl Disulfide ◽  
Aerial Oxidation

Aerial oxidation of thiophenol to diphenyl disulfide proceeds with high reaction rates, total conversion and selectivity in ionic liquids by using diorganobismuth(iii) catalysts.

Synthesis of 1,8-dioxo-octahydro-xanthene and tetrahydrobenzo[b]pyran derivatives promoted by two bis-imidazolium-based ionic liquids

2021 ◽  
Vol 08 ◽  
Author(s):  
Maryam Shirzad ◽  
Mitra Nasiri ◽  
Nader Daneshvar ◽  
Farhad Shirini ◽  
Hassan Tajik
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Knoevenagel Condensation ◽  
Reaction Rates ◽  
Xanthene Derivatives ◽  
Acidic Ionic Liquids ◽  
Dicationic Ionic Liquids ◽  
Acidic Nature ◽  
Work Up ◽  
Reaction Media

Aim and objective: In this work, we have prepared two bis-dicationic ionic liquids with the same cationic core (Bis-imidazole) and different counter-anions using sulfuric acid and perchloric acids. After that, the efficiency and ability of these compounds as catalysts were investigated and compared in the promotion of Knoevenagel condensation and synthesis of benzo[b]pyran derivatives to see the effect of the anionic counter-part in the reaction. Material and method: In a 25 mL round-bottomed flask, a mixture of aldehyde (1.0 mmol), 1,3-cyclodicarbonyl (2.0 mmol) and the desired amount of the mentioned acidic ionic liquids was heated at 90°C in the absence of solvent (Reaction A) or In a 25 mL round-bottomed flask, a mixture of aldehyde (1.0 mmol), 1,3-cyclodicarbonyl (1.0 mmol), malononitrile, (1.1 mmol) and optimized amounts of the ionic liquid in water (3.0 mL) was heated at 80°C (Reaction B) for the appropriated time. After the completion of the reactions which were monitored by TLC (n-hexane: EtOAc; 3:1), 10 mL of water was added and the mixture was stirred for 2 minutes. Then, the products were separated by filtration and were washed several times with water. After drying, the pure products were obtained while there was no need to further. Results: Comparison of the obtained results from both of the ionic liquids revealed that [H2-Bisim][HSO4]2 because of its more acidic structure had a more catalytic activity for the preparation of 1,8-dioxo-octahydro-xanthene derivatives but [H2-Bisim][ClO4]2 was relatively more efficient for the synthesis of tetrahydrobenzo[b]pyran derivatives since the stronger acidic nature of [H2-Bisim][HSO4]2 may prevent the simple activation of malononitrile in the reaction media. Conclusion: In this study, we have introduced efficient methods for the synthesis of 1,8-dioxo-octahydro-xanthene and tetrahydrobenzo[b]pyran derivatives in the presence of catalytic amounts of [H2-Bisim][ClO4]2 and [H2-Bisim][HSO4]2 These methods have several advantages such as ease of preparation and handling of the catalysts, high reaction rates, excellent yields, eco-friendly procedures and simple work-up.

scholarly journals Effects of Pretreatment with Ionic Liquids on Cellulose Hydrolysis under Hydrothermal Conditions

Molecules ◽  
2019 ◽  
Vol 24 (19) ◽  
pp. 3572 ◽  
Author(s):  
Toshitaka Funazukuri ◽  
Shingo Ozawa
Keyword(s):  
Ionic Liquids ◽  
Filter Paper ◽  
Biomass Conversion ◽  
Batch Reactor ◽  
Cellulose Hydrolysis ◽  
Reaction Rates ◽  
Crystalline Cellulose ◽  
Hydrothermal Conditions ◽  
Imidazolium Chloride ◽  
Product Yields

Hydrothermal hydrolysis in hot pressurized liquid water (HPLW) is attractive for biomass conversion into valuable products because it achieves high reaction rates without catalysts and additives. The hydrothermal hydrolysis of high crystalline cellulose requires higher reaction temperature than polysaccharides having low crystallinity. It can be expected to increase the reaction rate or decrease temperature by decreasing the crystallinity. In the present study ashless filter paper as a fibrous pure cellulose sample was pretreated with ionic liquids (ILs) such as imidazolium chloride ILs containing alkyl side chains ranging from two to six carbons, and with an aqueous solution of bis(ethylenediamine ammonium) copper (BEDC). Herein, the pretreatment with ILs was to regenerate filter paper: dissolving in ILs at 373 K for 120 min or in an aqueous BEDC solution at room temperature, precipitating by adding water, washing the solid, and then drying. Subsequently, the pretreated filter paper samples were hydrolyzed at 533 K and 5.0 MPa in HPLW in a small semi-batch reactor, and the effects of the pretreatment with ILs or BEDC on reaction rates and product yields were examined. While the crystallinity indexes with all ILs and BEDC after the pretreatments decreased to 44 to 47 from the original sample of 87, the reaction rates and product yields were significantly affected by the IL species. At 533 K and 5.0 MPa, the dissolution rate with [AMIM][Cl] was nine times as fast as that for untreated sample.

Bimolecular Electron Transfer in Ionic Liquids: Are Reaction Rates Anomalously High?

2012 ◽  
Vol 116 (4) ◽  
pp. 1370-1384 ◽  
Author(s):  
Min Liang ◽  
Anne Kaintz ◽  
Gary A. Baker ◽  
Mark Maroncelli
Keyword(s):  
Electron Transfer ◽  
Ionic Liquids ◽  
Reaction Rates

scholarly journals Surface-active ionic liquids in micellar catalysis: impact of anion selection on reaction rates in nucleophilic substitutions

2016 ◽  
Vol 18 (19) ◽  
pp. 13375-13384 ◽  
Author(s):  
Alice Cognigni ◽  
Peter Gaertner ◽  
Ronald Zirbs ◽  
Herwig Peterlik ◽  
Katharina Prochazka ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Reaction Rates ◽  
Micellar Catalysis ◽  
Nucleophilic Substitutions ◽  
Surface Active

A series of surface-active ionic liquids based on the 1-dodecyl-3-methylimidazolium cation and different anions was synthesized and applied for micellar catalysis of nucleophilic substitutions.

Surface-Active Ionic Liquids in Catalytic Water Splitting

2019 ◽  
Vol 72 (2) ◽  
pp. 34 ◽  
Author(s):  
Alice Cognigni ◽  
Ádám Márk Palvögyi ◽  
Christian Schröder ◽  
Herwig Peterlik ◽  
Alexander R. M. Müllner ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Water Splitting ◽  
External Surface ◽  
Reaction Rates ◽  
Initial Reaction ◽  
Surface Active Ionic Liquid ◽  
Surface Active ◽  
Turn Over ◽  
Catalytic Cycles ◽  
Reaction Media

We report the application of surface-active ionic liquids as ligands and optional reaction media in iridium-catalyzed water oxidations. Three novel catalysts with N,N-dialkylimidazolidin-2-ylidene ligands based on amphiphilic imidazolium ionic liquids were synthesized and characterized. Excellent turn-over frequencies of up to 0.92s−1 were obtained in catalytic water splitting, and activity was maintained for five consecutive catalytic cycles, with an overall turn-over number of 8967. The addition of external surface-active ionic liquid showed unexpected behaviour, because strongly enhanced initial reaction rates were observed.

Morphology and Phase Metastability in the Al/Cu Thin Film Reaction.

1993 ◽  
Vol 311 ◽  
Author(s):  
E. D. McCarty ◽  
S. A. Hackney
Keyword(s):  
Average Diameter ◽  
Reaction Rates ◽  
Growth Interface ◽  
Plan View ◽  
Cu Films ◽  
High Reaction ◽  
Transmission Electron ◽  
Interdiffusion Process ◽  
Sputter Deposited ◽  
Cu Thin Film

ABSTRACTThe initial stages of the reaction between thin Al grains with an average diameter of 2 × 10−5mand sputter deposited, nanocrystalline Cu films has been studied in plan view using in situ transmission electron microscopy. At high reaction rates, the phase transformation in the Al grain resulting from the interdiffusion process is found to exhibit metastable growth morphologies characterized by negative curvature at the growth interface. The crystal structure of the initial phase formed in the Al grain under relatively high reaction rates is a metastable, orthorhombic distortion of the equilibrium body centered tetragonal θ phase. The distortion is found to vary with Al grain surface orientation. The degree of metastability can be experimentally correlated with the kinetics of the interdiffusion process as controlled by diffusion barrier thickness.

THE EFFECT OF VISCOSITY ON THE PHASE SEPARATION DYNAMICS OF BINARY IMMISCIBLE MIXTURE COUPLED WITH REVERSIBLE REACTION

2010 ◽  
Vol 21 (12) ◽  
pp. 1479-1488 ◽  
Author(s):  
HUI LI ◽  
HONG LIU ◽  
ZHONG-YUAN LU ◽  
QIN WANG ◽  
CHIA-CHUNG SUN
Keyword(s):  
Phase Separation ◽  
Reaction Rate ◽  
Domain Size ◽  
Reaction Rates ◽  
Two Dimensions ◽  
Domain Growth ◽  
Reversible Reaction ◽  
Growth Exponent ◽  
High Reaction ◽  
Immiscible Mixture

The phase-separating system coupled with a simple reversible reaction A ⇌ B in a binary immiscible mixture due to critical quench is investigated with Lowe-Andersen temperature controlling method in two dimensions. The system viscosity strongly influences the asymptotic relationship between the excess energy (characterizing the domain growth) and the reaction rate. The competition between different dynamic factors results in the steady states with characteristic domain sizes. For low viscosities, the domain growth exponent approximates to 0.4 in the cases of low reaction rates and to 0.25 in the cases of high reaction rates, which shows the suppressing effects of high reversible reaction rates on the phase separation. However, in the cases of high viscosities, we find a 0.25 scaling with low reaction rates but a 0.5 scaling with high reaction rates. In these cases, high viscosities prevent mass transport in the binary mixture, consequently result in much smaller steady state domain sizes. Therefore the domain sizes with high viscosities and low reaction rates are very similar to those with low viscosities and high reaction rates, and the dependence of domain sizes on the reaction rates are similar. For the high-viscosity systems with high reaction rates, the domain sizes are predominantly controlled by the reaction rates, therefore we can observe stronger dependence of domain size on the reaction rate.

Spectroscopic determination of relative Brønsted acidity as a predictor of reactivity in aprotic ionic liquids

2015 ◽  
Vol 51 (30) ◽  
pp. 6651-6654 ◽  
Author(s):  
Ariel I. Horowitz ◽  
Paola Arias ◽  
Matthew J. Panzer
Keyword(s):  
Ionic Liquids ◽  
Reaction Rates ◽  
Spectroscopic Determination ◽  
Bronsted Acids ◽  
Brønsted Acidity ◽  
Brönsted Acidity ◽  
Relative Acidity

FTIR-enabled titration of pyridine with Brønsted acids in aprotic ionic liquids successfully predicts relative acidity and reaction rates.

Sustainable vanadium(V)-catalyzed oxybromination of styrene: Two-phase system versus ionic liquids

2005 ◽  
Vol 77 (9) ◽  
pp. 1575-1581 ◽  
Author(s):  
Valeria Conte ◽  
Barbara Floris ◽  
Pierluca Galloni ◽  
Adriano Silvagni
Keyword(s):  
Ionic Liquids ◽  
Aqueous Phase ◽  
Chlorinated Solvents ◽  
Reaction Rates ◽  
Point Of View ◽  
Metal Catalyst ◽  
Phase System ◽  
Two Phase ◽  
System Versus ◽  
Bromide Ion

Oxybromination reaction of styrene was performed in a two-phase system of water/ionic liquids (ILs). The aim of the work was to make the mild and efficient two-phase system previously developed for the vanadium(V)-catalyzed oxybromination of alkenes, inspired by the activity of haloperoxidase enzymes, even more interesting from a sustainable point of view. As in that case, a brominating intermediate was formed from the metal catalyst, H2O2, and bromide ion in the acid aqueous phase, but chlorinated solvents were replaced with ILs.[bmim+][PF6-], [bm2im+][PF6-], [bmim+][BF4-], [bmim+][CF3SO3-], and [bmim+][(CF3SO2)2N-] were tested. We report on interesting results in terms of reaction rates and selectivities.

scholarly journals Ionic liquids as (co)solvents for enzymatic reactions

2006 ◽  
Vol 12 (3) ◽  
pp. 181-186 ◽  
Author(s):  
Muzafera Paljevac ◽  
Maja Habulin ◽  
Zeljko Knez
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Immobilized Lipase ◽  
Rhizomucor Miehei ◽  
Reaction Rates ◽  
Synthetic Activity ◽  
Enzymatic Reactions ◽  
Lipozyme Rm Im ◽  
Catalyzed Reactions ◽  
Enzyme Catalyzed Reactions

Ionic liquids are low melting point salts that represent an exciting new class of reaction solvents. Many reactions show advantages when carried out in ionic liquids, either with regard to enhanced reaction rates, improved selectivity, or easier reuse of catalysts. To ascertain the influence of ionic liquids on the enzyme activity, three different ionic liquids 1-butyl-3-methylimidazolium chloride ([bmim] [CI]) 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim] [PF6]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) were synthesized and investigated as potential media for the hydrolysis of carboxymethyl cellulose, catalyzed by non-immobilized cellulase from Humicola insolens (Celluzyme 0,7T) and for ester synthesis, catalyzed by immobilized lipase from Rhizomucor miehei (Lipozyme RM IM). Enzyme-catalyzed reactions were performed in a batch stirred reactor at atmospheric pressure. Celluzyme 0,7T showed better activity in hydrophobic ionic liquid ([bmim] [PF6]), as compared to hydrophilic ionic liquid ([bmim] [BF4]). In the case of Lipozyme RM IM, the synthetic activity of the enzyme was strongly reduced by incubating the enzyme in ionic liquids.

Sign in / Sign up

Export Citation Format

Share Document