scholarly journals Developing principles for predicting ionic liquid effects on reaction outcome. The importance of the anion in controlling microscopic interactions

2015 ◽  
Vol 13 (12) ◽  
pp. 3771-3780 ◽  
Author(s):  
Sinead T. Keaveney ◽  
Ronald S. Haines ◽  
Jason B. Harper
Keyword(s):  
Ionic Liquid ◽  
Rate Constant ◽  
Condensation Reaction ◽  
Activation Parameters ◽  
Solvent Composition ◽  
Microscopic Interactions

Predictable changes in the rate constant of a condensation reaction were seen as the solvent composition was varied. The cation–nucleophile interaction could be controlled in a predictable manner; activation parameters varied linearly with the H-bond acceptor ability of the anions used.

Controlling the reactions of 1-bromogalactose acetate in methanol using ionic liquids as co-solvents

2020 ◽  
Vol 18 (28) ◽  
pp. 5442-5452 ◽  
Author(s):  
Alyssa Gilbert ◽  
Ronald S. Haines ◽  
Jason B. Harper
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Rate Constant ◽  
Solvent Mixture ◽  
Solvent Composition ◽  
Composition Changes

Using an ionic liquid in the solvent mixture for the reaction of a galactose substrate leads to changes in both the rate constant and the products as the solvent composition changes.

Effect of Modifying the Anion of an Ionic Liquid on the Outcome of an SN2 Process

2015 ◽  
Vol 68 (1) ◽  
pp. 31 ◽  
Author(s):  
Sinead T. Keaveney ◽  
Dominic V. Francis ◽  
Winnie Cao ◽  
Ronald S. Haines ◽  
Jason B. Harper
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Rate Constant ◽  
Kinetic Data ◽  
Activation Parameters ◽  
Temperature Dependent ◽  
Substitution Process

The effect of a series of ionic liquids containing different anions (bis(trifluoromethanesulfonyl)imide, dicyanimide, hexafluorophosphate, tetrafluoroborate, and bromide) on the rate constant of a bimolecular substitution process was investigated. A general ionic liquid effect was noted, with increases in the rate constant observed in all ionic liquids used when compared with that in acetonitrile. Temperature-dependent kinetic data allowed calculation of activation parameters in each of the reaction mixtures considered; these parameters showed that the microscopic origins of the rate enhancements observed were not the same for all of the ionic liquids used, demonstrating the importance of the nature of the anion.

Solvolysis of isopropyl bromide in ethanol–water mixtures. Dissection into initial state and transition state contributions

1976 ◽  
Vol 54 (24) ◽  
pp. 3944-3948 ◽  
Author(s):  
Wiendelt Drenth ◽  
Michael Cocivera
Keyword(s):  
Vapor Pressure ◽  
Transition State ◽  
Thermodynamic Parameters ◽  
Activation Parameters ◽  
Solvent Composition ◽  
Initial State ◽  
Partial Vapor Pressure ◽  
State Variation

Rates were determined for the solvolysis of isopropyl bromide in ethanol–water mixtures (20 to 80% by volume of ethanol) at 50 and 75 °C and the corresponding activation parameters calculated. From the partial vapor pressure of isopropyl bromide over the various solutions at 50 and 75 °C, the variations in its initial state thermodynamic parameters were calculated. Thus, the variation in the activation parameters with solvent composition could be analyzed in terms of initial and transition state contributions. The initial state variation dominates according to a unimolecular as well as to a bimolecular treatment of data.

Ionic Liquid 4-(3-Methyl-1-imidazolio)-1-butanesulfonic Acid Hydrogen Sulfate-catalyzed Synthesis of Phthalazinetrione Derivatives

2012 ◽  
Vol 67 (7) ◽  
pp. 717-724
Author(s):  
Shihua Song ◽  
Xiang Deng ◽  
Zhi Guan ◽  
Yanhong He
Keyword(s):  
Ionic Liquid ◽  
Polyethylene Glycol ◽  
Condensation Reaction ◽  
Reaction Times ◽  
Solvent System ◽  
Environmentally Benign ◽  
Hydrogen Sulfate ◽  
One Pot ◽  
Simple Method ◽  
Peg 600

A simple method for the synthesis of phthalazinetrione derivatives by a one-pot three-component condensation reaction of phthalhydrazide, 1,3-dicarbonyl compounds and aldehydes catalyzed by the ionic liquid 4-(3-methyl-1-imidazolio)-1-butanesulfonic acid hydrogen sulfate ([BSO3HmIm]HSO4) is reported. Good to excellent yields were obtained in short reaction times in the solvent PEG 600 (polyethylene glycol 600) at 120 °C. The strategy proved to be efficient and environmentally benign. The catalyst/solvent system could easily be recovered and reused for at least 5 times without noticeable loss of activity

Solvent effects in the metal interchange of crown ether – alkali metal cation complexes. Transition from an associative exchange in nitromethane to a dissociative exchange in acetonitrile studied by 23Na nuclear magnetic resonance

1992 ◽  
Vol 70 (10) ◽  
pp. 2536-2543 ◽  
Author(s):  
Kathleen M. Brière ◽  
Christian Detellier
Keyword(s):  
Rate Constant ◽  
Conformational Changes ◽  
Alkali Metal Cation ◽  
Molar Fraction ◽  
Activation Parameters ◽  
Sodium Cation ◽  
Dissociation Kinetics ◽  
Dissociative Mechanism ◽  
Recombination Mechanism ◽  
Cationic Exchange

The role of the solvent in the dissociation kinetics and cation exchange mechanisms of the complex sodium–monobenzo-15-crown-5 (Na: B15C5)+ was examined by 23Na NMR. In nitromethane (NM), the cationic exchange between the complexes takes place via an associative metal interchange mechanism, 1M. In acetonitrile (AN), it takes place via a dissociative (dissociation/recombination) mechanism. In AN–NM binary mixtures, the rate constant of the dissociative exchange (k−1) increases with the AN molar fraction, XAN, from 1.1 × 10−2 s−1 for XAN = 0 to 89 × 10−2 s−1 for XAN = 0.400 (corresponding to a decrease of the free energy of activation, ΔGdi≠ from 62.1 to 51.1 kJ mol−1 respectively, at 301.5 K). The activation parameters were ΔHdi≠ = 48 kJ mol−1 and ΔSdi≠ = −20 J K−1, mol−1 for XAN = 0.200. This rate increase was related to the concentration increase in solution of the AN monosolvated complex (AN: Na: B15C5)+. In the whole range of AN mole fractions studied, the rate constant of the associative exchange, k2, was not dependent upon XAN in the error limits: k2 ≈ 9 × 104 M−1 s−1 at 301.5 K (ΔGas≠ = 45 kJ mol−1). The activation parameters were determined to be ΔHas≠ = 23 kJ mol−1 and ΔHas≠ = −75 J K−1 mol−1. These findings are in good agreement with an associative exchange controlled mainly by the conformational changes of the ligand during the concerted partial decomplexation of a sodium cation and partial complexation of a second one, while solvation of the complexed cation plays a major role in the dissociative mechanism.

First Application of Ionic Liquid to Reactions Involving Organotellurium Compounds as Intermediates

2005 ◽  
Vol 2005 (7) ◽  
pp. 446-448 ◽  
Author(s):  
Lei Wang ◽  
Zhizhen Huang
Keyword(s):  
Ionic Liquid ◽  
High Purity ◽  
Stereoselective Synthesis ◽  
Condensation Reaction ◽  
Unsaturated Compounds ◽  
Novel Method ◽  
Ionic Solvent ◽  
Organotellurium Compounds ◽  
High Stereoselectivity

The condensation reaction of telluronium salts 1 with aldehydes and dibutyl telluride 4, bromide 5 with aldehyde 2 proceeded smoothly in the ionic solvent [bmim][BF4], affording a novel method for the stereoselective synthesis of (E)-α,β-unsaturated compounds 3 in high purity, excellent yields and high stereoselectivity.

Enhanced Emission from Single Component Organic Core–Shell Nanoparticles

2007 ◽  
Vol 7 (12) ◽  
pp. 4311-4317 ◽  
Author(s):  
Koushik Dhara ◽  
Krishanu Sarkar ◽  
Partha Roy ◽  
Asim Bhaumik ◽  
Pradyot Banerjee
Keyword(s):  
Rate Constant ◽  
Mixed Solvent ◽  
Condensation Reaction ◽  
Single Component ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Remarkable Feature ◽  
Packing Factor ◽  
The Core ◽  
Core Shell Nanoparticles

By one-step mixed-solvent mediated approach, we have prepared fluorescent organic core–shell nanoparticles with an oligomer (1) derived from the Schiff base condensation reaction of 2,6-diformyl-4-methylphenol and o-phenylenediamine at room temperature. The core and shell structures are generated by the same oligomer (1) featuring the aggregation structure in core different from that in shell. The radial packing factor distribution of oligomer cluster depending on the solvent interaction in the time of nucleation is mainly responsible for the single component core–shell formation. Different morphologies of the core–shell nanospheres (CSNS) and core–shell nanohemispheres (CSNHS) were generated simply by changing the concentration of 1 in chloroform-methanol mixed solvent (1:2). We observed that fluorescent emission from those core–shell nanoparticles is intense whereas as-synthesized oligomer (1) itself is non-fluorescent in dilute solution. The enhanced emission in the core–shell form with more than 50 times increase in fluorescent quantum yield vis-à-vis 1 is a remarkable feature of the study. As UV absorption spectra of nanoparticles are blue-shifted relative to their properties in solution, the observed strong emission in the solid state makes the oligomer an outstanding exception to a well-established rule based on the molecular exciton model. The core–shell nanoparticles have been characterized by FE-SEM, TEM, XRD, nanosecond (ns) time-resolved fluorescence dynamics, UV-Vis and fluorescence spectroscopy. The longer fluorescence lifetimes (τ) of core–shell nanoparticles (3.50 ns and 3.52 ns for CSNS and CSNHS respectively) than 1 as-synthesized (1.28 ns) implies that the formation of the nanoparticles restricts the rotation and vibration of the groups in the molecules. The factor that induces fluorescent enhancement of nanoparticles is mainly ascribed to the increase of radiative rate constant (kr) and simultaneous decrease of nonradiative rate constant (knr).

scholarly journals Estimation of activation parameters for the propagation rate constant of styrene

1996 ◽  
Vol 34 (12) ◽  
pp. 2473-2479 ◽  
Author(s):  
Bart G. Manders ◽  
Gr�gory Chambard ◽  
Wieb J. Kingma ◽  
Bert Klumperman ◽  
Alex M. Van Herk ◽  
...  
Keyword(s):  
Rate Constant ◽  
Activation Parameters ◽  
Propagation Rate ◽  
Propagation Rate Constant
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