1
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Hsieh AY, Haines RS, Harper JB. The effects of ionic liquids on the ethanolysis of a chloroacenaphthene. Evaluation of the effectiveness of nucleofugality data to predict reaction outcome. RSC Adv 2023; 13:21036-21043. [PMID: 37448642 PMCID: PMC10336772 DOI: 10.1039/d3ra04302a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 06/30/2023] [Indexed: 07/15/2023] Open
Abstract
The reaction of a chlorobenzene in mixtures containing ethanol and eight different ionic liquids was investigated in order to understand the effects of varying proportions and constituent ions of an ionic liquid on the rate constant of the process. The results were found to be generally consistent with previously studied reactions of the same type, with small proportions of an ionic liquid resulting in a rate constant increase compared to ethanol and large proportions causing a rate constant decrease. Temperature dependent kinetic studies were used to interpret the changes in reaction outcome, particularly noting an entropic cost on moving to high proportions of ionic liquid, consistent with organisation of solvent around the transition state. While attempts to use empirical solvent parameters to correlate outcome with the ionic liquid used were unsuccessful, use of recently acquired nucleofugality data for chloride and estimations for the electrofuge allowed for excellent prediction of the effects of ionic liquids, with rate constants quantitatively predicted in systems containing both different proportions of ionic liquid (mean absolute error (MAE) log(k1) = 0.11) and different ionic liquids (MAE log(k1) = 0.33). Importantly, this demonstrates the ready application of these quantitative reactivity parameters.
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Affiliation(s)
- Andrew Y Hsieh
- School of Chemistry, University of New South Wales UNSW Sydney NSW 2052 Australia +61 2 9385 6141 +61 2 9385 4692
| | - Ronald S Haines
- School of Chemistry, University of New South Wales UNSW Sydney NSW 2052 Australia +61 2 9385 6141 +61 2 9385 4692
| | - Jason B Harper
- School of Chemistry, University of New South Wales UNSW Sydney NSW 2052 Australia +61 2 9385 6141 +61 2 9385 4692
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2
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Morris DC, Prescott SW, Harper JB. Rapid relaxation NMR measurements to predict rate coefficients in ionic liquid mixtures. An examination of reaction outcome changes in a homologous series of ionic liquids. Phys Chem Chem Phys 2021; 23:9878-9888. [PMID: 33908419 DOI: 10.1039/d0cp06066f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of ionic liquids based on the 1-alkyl-3-methylimidazolium cations were examined as components of the solvent mixture for a bimolecular substitution process. The effects on both the rate coefficient of the process and the NMR spin-spin relaxation of the solvent components of changing either the alkyl chain length or the amount of ionic liquid in the reaction mixture were determined. At a constant mole fraction, a shorter alkyl chain length resulted in a greater rate coefficient enhancement and a longer relaxation time, with the opposite effects for a longer alkyl chain length. For a given ionic liquid, increasing the proportion of salt in the reaction mixture resulted in a greater rate coefficient and a shorter relaxation time. The microscopic origins of the rate coefficient enhancement were determined and a step change found in the activation parameters on increasing the alkyl chain length from hexyl to octyl, suggesting notable structuring in solution. Across a range of ionic liquids and solvent compositions, the relaxation time from NMR measurements was shown to relate to the reaction rate coefficient. The approach of using fast and simple NMR relaxation measurements to predict reaction outcomes was exemplified using a morpholinium-based ionic liquid.
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Affiliation(s)
- Daniel C Morris
- School of Chemical Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
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3
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Greaves TL, Schaffarczyk McHale KS, Burkart-Radke RF, Harper JB, Le TC. Machine learning approaches to understand and predict rate constants for organic processes in mixtures containing ionic liquids. Phys Chem Chem Phys 2021; 23:2742-2752. [PMID: 33496292 DOI: 10.1039/d0cp04227g] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The ability to tailor the constituent ions in ionic liquids (ILs) is highly advantageous as it provides access to solvents with a range of physicochemical properties. However, this benefit also leads to large compositional spaces that need to be explored to optimise systems, often involving time consuming experimental work. The use of machine learning methods is an effective way to gain insight based on existing data, to develop structure-property relationships and to allow the prediction of ionic liquid properties. Here we have applied machine learning models to experimentally determined rate constants of a representative organic process (the reaction of pyridine with benzyl bromide) in IL-acetonitrile mixtures. Multiple linear regression (MLREM) and artificial neural networks (BRANNLP) were both able to model the data well. The MLREM model was able to identify the structural features on the cations and anions that had the greatest effect on the rate constant. Secondly, predictive MLREM and BRANNLP models were developed from the full initial set of rate constant data. From these models, a large number of predictions (>9000) of rate constant were made for mixtures of different ionic liquids, at different proportions of ionic liquid and molecular solvent, at different temperatures. A selection of these predictions were tested experimentally, including through the preparation of novel ionic liquids, with overall good agreement between the predicted and experimental data. This study highlights the benefits of using machine learning methods on kinetic data in ionic liquid mixtures to enable the development of rigorous structure-property relationships across multiple variables simultaneously, and to predict properties of new ILs and experimental conditions.
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Affiliation(s)
- Tamar L Greaves
- College of Science Engineering and Health, RMIT University, Melbourne, VIC 3001, Australia.
| | | | | | - Jason B Harper
- School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia.
| | - Tu C Le
- College of Science Engineering and Health, RMIT University, Melbourne, VIC 3001, Australia.
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4
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Liu KTC, Haines RS, Harper JB. The effect of bisimidazolium-based ionic liquids on a bimolecular substitution process. Are two head(group)s better than one? Org Biomol Chem 2020; 18:7388-7395. [PMID: 32930294 DOI: 10.1039/d0ob01500h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A homologous series of biscationic ionic liquids based on two imidazolium centres, separated by alkyl chains of varying length, were examined as solvents for a bimolecular substitution reaction across a range of proportions of ionic liquid in the reaction mixture. Their effects on the rate constant of the process were compared to monocationic ionic liquids, with generally a greater rate constant increase observed. Importantly, it was observed that the magnitude of the effect was shown to vary with the length of the linking chain. To investigate the origins of these solvent effects, temperature dependent kinetic studies were performed to obtain activation parameters at high and low mole fractions of ionic liquid. The observed activation parameters showed the rate constant enhancement was due to interaction of the ionic liquid with the starting materials, consistent with previous results. Significantly, however, these data also showed that the balance of enthalpic and entropic effects varied dramatically with the length of the alkyl chain between the cationic centres.
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Affiliation(s)
- Kenny T-C Liu
- School of Chemistry, University of New South Wales, UNSW Sydney, NSW, 2052, Australia.
| | - Ronald S Haines
- School of Chemistry, University of New South Wales, UNSW Sydney, NSW, 2052, Australia.
| | - Jason B Harper
- School of Chemistry, University of New South Wales, UNSW Sydney, NSW, 2052, Australia.
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5
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Gao F, Ji P, Cheng JP. Unexpected Strong Acidity Enhancing the Effect in Protic Ionic Liquids Quantified by Equilibrium Acidity Studies: A Crucial Role of Cation Structures on Dictating the Solvation Properties. J Org Chem 2020; 85:3041-3049. [PMID: 32027506 DOI: 10.1021/acs.joc.9b02946] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The equilibrium acidities for several series of structural and electronic different organic acids were measured in 3-pyrrolidinium-based aprotic and protic ionic liquid (IL) analogues, that is, [Bmpy][NTf2], [BpyH][NTf2], and [PyH2][NTf2], by the UV-Vis method. The acidities of neutral acids are found to be much stronger in the protic ILs (PILs) than aprotic ILs (AILs), and the acidifying effect in the two PILs roughly increases proportionally to the number of protons in the cation of the PIL. On the other hand, interestingly, the cationic N+-H acids exhibit similar acidities in [Bmpy][NTf2] and [BpyH][NTf2] but much weaker than those in [PyH2][NTf2]. The Hammett ρ values for the acidic dissociation of para-substituted benzoic acids in two PILs are about the same as that in water (1.00) but significantly smaller than that in the AIL [Bmpy][NTf2] (2.66). The correlations between the acidities in the PILs and water show double-linear relationships with different slopes and intercepts for the neutral and cationic acids. These, together with previous observations in the PILs [DBUH][OTf] (DBU = 1,5-diazabicyclo(5.4.0)-5-undecene) and EAN (ethylammonium nitrate), clearly indicate that the structure of the cation plays a subtle but a crucial role on sensing the electronic nature of solutes and strongly affects the solvation behaviors of PILs.
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Affiliation(s)
- Feixiang Gao
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Pengju Ji
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Jin-Pei Cheng
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing 100084, China.,State Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation Center of Chemical Science and Engineering, Nankai University, Tianjin 300071, China
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6
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Schaffarczyk McHale KS, Haines RS, Harper JB. Ionic Liquids as Solvents for S N 2 Processes. Demonstration of the Complex Interplay of Interactions Resulting in the Observed Solvent Effects. Chempluschem 2020; 83:1162-1168. [PMID: 31950706 DOI: 10.1002/cplu.201800510] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Revised: 11/03/2018] [Indexed: 11/11/2022]
Abstract
Bimolecular nucleophilic substitution reactions between triphenylphosphine and benzylic electrophiles have been examined in an ionic liquid to probe interactions with species along the reaction coordinate. Trends in the rate constant were found on both varying the leaving group and the electronic nature of the aromatic ring. In all the cases considered, interactions between the components of the ionic liquid and the transition state were shown to be more significant in determining reaction outcome than previously observed for this class of reaction. This demonstrates the importance of considering interactions of the ionic liquid components with all species along the reaction coordinate when investigating the origin of ionic liquid solvent effects, along with how such effects might be exploited.
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Affiliation(s)
| | - Ronald S Haines
- School of Chemistry, University of New South Wales UNSW, Sydney, NSW 2052, Australia
| | - Jason B Harper
- School of Chemistry, University of New South Wales UNSW, Sydney, NSW 2052, Australia
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7
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Schaffarczyk McHale KS, Haines RS, Harper JB. Investigating Variation of the Pnicogen Nucleophilic Heteroatom on Ionic Liquid Solvent Effects in Bimolecular Nucleophilic Substitution Processes. Chempluschem 2020; 84:534-539. [PMID: 31943899 DOI: 10.1002/cplu.201900188] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 05/03/2019] [Indexed: 01/22/2023]
Abstract
A series of nucleophiles containing Group 15 nucleophilic heteroatoms has been used to expand and develop the current understanding of ionic liquid solvent effects on bimolecular nucleophilic substitution processes. It was found that when using arsenic-, antimony- and bismuth-based nucleophiles, rate constant enhancement was observed for all solvent compositions containing ionic liquids. This rate constant enhancement was driven by ionic liquid/transition state interactions, which contrasts with previous studies on earlier Group 15 nucleophiles. This study provides a holistic understanding and augments the predictive framework for the effects of ionic liquids on bimolecular nucleophilic substitution processes, with the potential for these periodic trends to be broadly applied.
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Affiliation(s)
| | - Ronald S Haines
- School of Chemistry, University of New South Wales, UNSW Sydney, NSW 2052, Australia
| | - Jason B Harper
- School of Chemistry, University of New South Wales, UNSW Sydney, NSW 2052, Australia
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8
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Schindl A, Hawker RR, Schaffarczyk McHale KS, Liu KTC, Morris DC, Hsieh AY, Gilbert A, Prescott SW, Haines RS, Croft AK, Harper JB, Jäger CM. Controlling the outcome of S N2 reactions in ionic liquids: from rational data set design to predictive linear regression models. Phys Chem Chem Phys 2020; 22:23009-23018. [PMID: 33043942 DOI: 10.1039/d0cp04224b] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Rate constants for a bimolecular nucleophilic substitution (SN2) process in a range of ionic liquids are correlated with calculated parameters associated with the charge localisation on the cation of the ionic liquid (including the molecular electrostatic potential). Simple linear regression models proved effective, though the interdependency of the descriptors needs to be taken into account when considering generality. A series of ionic liquids were then prepared and evaluated as solvents for the same process; this data set was rationally chosen to incorporate homologous series (to evaluate systematic variation) and functionalities not available in the original data set. These new data were used to evaluate and refine the original models, which were expanded to include simple artificial neural networks. Along with showing the importance of an appropriate data set and the perils of overfitting, the work demonstrates that such models can be used to reliably predict ionic liquid solvent effects on an organic process, within the limits of the data set.
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Affiliation(s)
- Alexandra Schindl
- Department of Chemical and Environmental Engineering, University of Nottingham, Nottingham NG7 2RD, UK.
| | - Rebecca R Hawker
- School of Chemistry, University of New South Wales, UNSW Sydney, 2052, Australia.
| | | | - Kenny T-C Liu
- School of Chemistry, University of New South Wales, UNSW Sydney, 2052, Australia.
| | - Daniel C Morris
- School of Chemistry, University of New South Wales, UNSW Sydney, 2052, Australia. and School of Chemical Engineering, University of New South Wales, UNSW Sydney, 2052, Australia
| | - Andrew Y Hsieh
- School of Chemistry, University of New South Wales, UNSW Sydney, 2052, Australia.
| | - Alyssa Gilbert
- School of Chemistry, University of New South Wales, UNSW Sydney, 2052, Australia.
| | - Stuart W Prescott
- School of Chemical Engineering, University of New South Wales, UNSW Sydney, 2052, Australia
| | - Ronald S Haines
- School of Chemistry, University of New South Wales, UNSW Sydney, 2052, Australia.
| | - Anna K Croft
- Department of Chemical and Environmental Engineering, University of Nottingham, Nottingham NG7 2RD, UK.
| | - Jason B Harper
- School of Chemistry, University of New South Wales, UNSW Sydney, 2052, Australia.
| | - Christof M Jäger
- Department of Chemical and Environmental Engineering, University of Nottingham, Nottingham NG7 2RD, UK.
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9
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Gilbert A, Bucher G, Haines RS, Harper JB. Correlating ionic liquid solvent effects with solvent parameters for a reaction that proceeds through a xanthylium intermediate. Org Biomol Chem 2019; 17:9336-9342. [PMID: 31612896 DOI: 10.1039/c9ob01807g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A unimolecular nucleophilic substitution reaction that proceeds through a xanthylium carbocation was studied in seven ionic liquid solvents. It was found that the general trend in the rate constant with changing proportion of ionic liquid in the reaction mixture was different to that seen for other unimolecular processes, with the rate constant increasing as more ionic liquid was added to the reaction mixture. A significant correlation was found between the natural logarithm of the rate constant and a combination of the Kamlet-Taft solvent parameters. This relationship indicated that the principal interaction involved hydrogen bonding between the ionic liquid and some species along the reaction coordinate. Further, this correlation enables prediction of the effects that other ionic liquids will have on this, and other, reactions that proceed through a similar intermediate.
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Affiliation(s)
- Alyssa Gilbert
- School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia.
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10
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Schaffarczyk McHale KS, Wong MJ, Evans AK, Gilbert A, Haines RS, Harper JB. Understanding the effects of solvate ionic liquids as solvents on substitution processes. Org Biomol Chem 2019; 17:9243-9250. [PMID: 31599321 DOI: 10.1039/c9ob01753d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effects of solvate ionic liquids as solvents have been considered for two substitution processes where the solvent effects of typical ionic liquids have been extensively investigated previously; the bimolecular nucleophilic substitution (SN2) reaction between pyridine and benzyl bromide and the nucleophilic aromatic substitution (SNAr) reaction between ethanol and 1-fluoro-2,4-dinitrobenzene. It was found that use of solvate ionic liquids gave rise to similar trends in the activation parameters for both substitution processes as typical ionic liquids, implying the microscopic interactions responsible for the effects were the same. However, different effects on the rate constants compared to typical ionic liquids were observed due to the changes in the balance of enthalpic and entropic contributions to the observed rate constants. From these data it is clear that the reaction outcome for both of these substitution reactions fall within the 'predictive framework' established in previous studies with a cautionary tale or two of their own to add to the general knowledge of ionic liquid solvent effects for these processes, particularly with respect to potential reactivity of the solvate ionic liquids themselves.
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11
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Schindl A, Hagen ML, Muzammal S, Gunasekera HAD, Croft AK. Proteins in Ionic Liquids: Reactions, Applications, and Futures. Front Chem 2019; 7:347. [PMID: 31179267 PMCID: PMC6543490 DOI: 10.3389/fchem.2019.00347] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 04/26/2019] [Indexed: 01/01/2023] Open
Abstract
Biopolymer processing and handling is greatly facilitated by the use of ionic liquids, given the increased solubility, and in some cases, structural stability imparted to these molecules. Focussing on proteins, we highlight here not just the key drivers behind protein-ionic liquid interactions that facilitate these functionalities, but address relevant current and potential applications of protein-ionic liquid interactions, including areas of future interest.
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Affiliation(s)
- Alexandra Schindl
- Department of Chemical and Environmental Engineering, Faculty of Engineering, University of Nottingham, Nottingham, United Kingdom
- Faculty of Medicine & Health Sciences, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
- Faculty of Science, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
| | - Matthew L. Hagen
- Department of Chemical and Environmental Engineering, Faculty of Engineering, University of Nottingham, Nottingham, United Kingdom
- Centre for Additive Manufacturing, Faculty of Engineering, University of Nottingham, Nottingham, United Kingdom
| | - Shafaq Muzammal
- Department of Chemical and Environmental Engineering, Faculty of Engineering, University of Nottingham, Nottingham, United Kingdom
| | - Henadira A. D. Gunasekera
- Department of Chemical and Environmental Engineering, Faculty of Engineering, University of Nottingham, Nottingham, United Kingdom
- Centre for Additive Manufacturing, Faculty of Engineering, University of Nottingham, Nottingham, United Kingdom
| | - Anna K. Croft
- Department of Chemical and Environmental Engineering, Faculty of Engineering, University of Nottingham, Nottingham, United Kingdom
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12
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Kostić M, Verdía P, Fernández‐Stefanuto V, Puchta R, Tojo E. A mild and efficient procedure for alkenols oxyselenocyclization by using ionic liquids. J PHYS ORG CHEM 2019. [DOI: 10.1002/poc.3928] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Marina Kostić
- Faculty of Science, Department of ChemistryUniversity of Kragujevac Kragujevac Serbia
| | - Pedro Verdía
- Department of Organic ChemistryUniversidade de Vigo, Marcosende Vigo Spain
| | | | - Ralph Puchta
- Inorganic Chemistry, Department of Chemistry and PharmacyUniversity of Erlangen‐Nürnberg Erlangen Germany
- Computer Chemistry Center, Department of Chemistry and PharmacyUniversity of Erlangen‐Nuremberg Erlangen Germany
- Central Instituite for Scientific Computing (ZISC)Friedrich‐Alexander University Erlangen‐Nürnberg Martensstrasse 5a Erlangen Germany
| | - Emilia Tojo
- Department of Organic ChemistryUniversidade de Vigo, Marcosende Vigo Spain
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13
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Gilbert A, Haines RS, Harper JB. Understanding the effects of ionic liquids on a unimolecular substitution process: correlating solvent parameters with reaction outcome. Org Biomol Chem 2019; 17:675-682. [DOI: 10.1039/c8ob02460j] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The polarisability of an ionic liquid is key in determining the rate constant of a unimolecular substitution process.
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Affiliation(s)
- Alyssa Gilbert
- School of Chemistry
- University of New South Wales
- Sydney
- Australia
| | | | - Jason B. Harper
- School of Chemistry
- University of New South Wales
- Sydney
- Australia
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14
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Hawker RR, Haines RS, Harper JB. Predicting solvent effects in ionic liquids:
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xtension of a nucleophilic aromatic substitution reaction on a benzene to a pyridine. J PHYS ORG CHEM 2018. [DOI: 10.1002/poc.3862] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Rebecca R. Hawker
- School of Chemistry University of New South Wales UNSW Sydney Australia
| | - Ronald S. Haines
- School of Chemistry University of New South Wales UNSW Sydney Australia
| | - Jason B. Harper
- School of Chemistry University of New South Wales UNSW Sydney Australia
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15
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Butler BJ, Harper JB. The effect of the structure of the anion of an ionic liquid on the rate of reaction at a phosphorus centre. J PHYS ORG CHEM 2018. [DOI: 10.1002/poc.3819] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Bradley J. Butler
- School of Chemistry; University of New South Wales, UNSW; Sydney Australia
| | - Jason B. Harper
- School of Chemistry; University of New South Wales, UNSW; Sydney Australia
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16
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Hawker RR, Haines RS, Harper JB. Rational selection of the cation of an ionic liquid to control the reaction outcome of a substitution reaction. Chem Commun (Camb) 2018; 54:2296-2299. [DOI: 10.1039/c8cc00241j] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Rational selection of ionic liquids to get the rate constant you want in a substitution process.
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Affiliation(s)
| | | | - Jason B. Harper
- School of Chemistry
- University of New South Wales
- Sydney
- Australia
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17
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Hawker RR, Haines RS, Harper JB. The effect of varying the anion of an ionic liquid on the solvent effects on a nucleophilic aromatic substitution reaction. Org Biomol Chem 2018; 16:3453-3463. [DOI: 10.1039/c8ob00651b] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Variety of ionic liquids with different anions used as solvents for a nucleophilic aromatic substitution reaction.
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Affiliation(s)
| | | | - Jason B. Harper
- School of Chemistry
- University of New South Wales
- Sydney
- Australia
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18
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19
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Keaveney ST, Haines RS, Harper JB. Ionic liquid solvents: the importance of microscopic interactions in predicting organic reaction outcomes. PURE APPL CHEM 2017. [DOI: 10.1515/pac-2016-1008] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractIonic liquids are attractive alternatives to molecular solvents as they have many favourable physical properties and can produce different organic reaction outcomes compared to molecular solvents. Thus far, interactions between the ionic liquid components and specific sites (such as charged centres, lone pairs and π systems) on the reagents and transition state have been identified as affecting reaction outcome; a comprehensive understanding of these interactions is necessary to allow prediction of ionic liquid solvent effects. This manuscript summarises our recent progress in the development of a framework for predicting the effect of an ionic liquid solvent on the outcome of organic processes. There will be a particular focus on the importance of the different interactions between the ionic liquid components and the species along the reaction coordinate that are responsible for the changes in reaction outcome observed in the cases described.
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Affiliation(s)
- Sinead T. Keaveney
- School of Chemistry, University of New South Wales, UNSW Sydney 2052, Australia
| | - Ronald S. Haines
- School of Chemistry, University of New South Wales, UNSW Sydney 2052, Australia
| | - Jason B. Harper
- School of Chemistry, University of New South Wales, UNSW Sydney 2052, Australia
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20
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Keaveney ST, Haines RS, Harper JB. Investigating Solvent Effects of an Ionic Liquid on Pericyclic Reactions through Kinetic Analyses of Simple Rearrangements. Chempluschem 2017; 82:449-457. [DOI: 10.1002/cplu.201600585] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 01/02/2017] [Indexed: 11/12/2022]
Affiliation(s)
- Sinead T. Keaveney
- School of Chemistry University of New South Wales Sydney NSW 2052 Australia
| | - Ronald S. Haines
- School of Chemistry University of New South Wales Sydney NSW 2052 Australia
| | - Jason B. Harper
- School of Chemistry University of New South Wales Sydney NSW 2052 Australia
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21
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Hawker RR, Wong MJ, Haines RS, Harper JB. Rationalising the effects of ionic liquids on a nucleophilic aromatic substitution reaction. Org Biomol Chem 2017; 15:6433-6440. [DOI: 10.1039/c7ob01476g] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The nucleophilic aromatic substitution reaction between 1-fluoro-2,4-dinitrobenzene and ethanol was examined in a series of ionic liquids across a range of mole fractions.
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Affiliation(s)
| | | | | | - Jason B. Harper
- School of Chemistry
- University of New South Wales
- Sydney
- Australia
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22
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Keaveney ST, Greaves TL, Kennedy DF, Harper JB. Understanding the Effect of Solvent Structure on Organic Reaction Outcomes When Using Ionic Liquid/Acetonitrile Mixtures. J Phys Chem B 2016; 120:12687-12699. [PMID: 27973829 DOI: 10.1021/acs.jpcb.6b11090] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The rate constant for the reaction between hexan-1-amine and 4-methoxybenzaldehyde was determined in ionic liquids containing an imidazolium cation. The effect on the rate constant of increasing the length of the alkyl substituent on the cation was examined in a number of ionic liquid/acetonitrile mixtures. In general it was found that there was no significant effect of changing the alkyl substituent on the rate constant of this process, suggesting that any nanodomains in these mixtures do not have a significant effect on the outcome of this process. A series of small-angle X-ray scattering and wide-angle X-ray scattering experiments were performed on mixtures of the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Bmim][N(CF3SO2)2]) and acetonitrile; this work indicated that the main structural changes in the mixtures occur by about a 0.2 mole fraction of ionic liquid in the mixture (χIL). This region at which the main changes in the solvent structuring occurs corresponds to the region at which the main changes in the rate constant and activation parameters occur for SN2 and condensation reactions examined previously; this is the first time that such a correlation has been observed. To examine the ordering of the solvent about the nucleophile hexan-1-amine, WAXS experiments were performed on a number of [Bmim][N(CF3SO2)2]/acetonitrile/hexan-1-amine mixtures, where it was found that some of the patterns featured asymmetric peaks as well as additional peaks not observed in the [Bmim][N(CF3SO2)2]/acetonitrile mixtures; this suggests that the addition of hexan-1-amine to the mixture affects the bulk structure of the liquid. The SAXS/WAXS patterns of mixtures of 1-butyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide ([Bm2im][N(CF3SO2)2]) and acetonitrile were also determined, with the results suggesting that [Bm2im][N(CF3SO2)2] is more ordered than [Bmim][N(CF3SO2)2] due to an enhancement in the short-range interactions.
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Affiliation(s)
- Sinead T Keaveney
- School of Chemistry, University of New South Wales , Sydney, NSW 2052, Australia
| | - Tamar L Greaves
- School of Science, College of Science, Engineering and Health, RMIT University , Melbourne, VIC 3001, Australia
| | | | - Jason B Harper
- School of Chemistry, University of New South Wales , Sydney, NSW 2052, Australia
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Keaveney ST, Schaffarczyk McHale KS, Stranger JW, Ganbold B, Price WS, Harper JB. NMR Diffusion Measurements as a Simple Method to Examine Solvent-Solvent and Solvent-Solute Interactions in Mixtures of the Ionic Liquid [Bmim][N(SO2CF3)2] and Acetonitrile. Chemphyschem 2016; 17:3853-3862. [DOI: 10.1002/cphc.201600927] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Indexed: 11/09/2022]
Affiliation(s)
- Sinead T. Keaveney
- School of Chemistry; University of New South Wales, UNSW; Sydney NSW 2052 Australia
| | | | - James W. Stranger
- Nanoscale Organisation and Dynamics Group; Western Sydney University; Locked Bag 1797, Penrith NSW 2751 Australia
| | - Batchimeg Ganbold
- Nanoscale Organisation and Dynamics Group; Western Sydney University; Locked Bag 1797, Penrith NSW 2751 Australia
| | - William S. Price
- Nanoscale Organisation and Dynamics Group; Western Sydney University; Locked Bag 1797, Penrith NSW 2751 Australia
| | - Jason B. Harper
- School of Chemistry; University of New South Wales, UNSW; Sydney NSW 2052 Australia
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24
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Butler BJ, Thomas DS, Hook JM, Harper JB. NMR spectroscopy to follow reaction progress in ionic liquids. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2016; 54:423-428. [PMID: 25287592 DOI: 10.1002/mrc.4161] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 09/05/2014] [Accepted: 09/15/2014] [Indexed: 06/03/2023]
Abstract
In order to understand reaction outcomes in ionic liquids, it is crucial to be able to follow the progress of these reactions. This review highlights the advantages of NMR spectroscopy over other analytical techniques in following reaction progress in ionic liquids, particularly addressing the practical aspects of the methodology and highlighting the range of processes that can be readily followed. Copyright © 2014 John Wiley & Sons, Ltd.
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Affiliation(s)
- Bradley J Butler
- School of Chemistry, University of New South Wales (UNSW), Sydney, NSW, 2052, Australia
| | - Donald S Thomas
- Nuclear Magnetic Resonance Facility, Mark Wainwright Analytical Centre, University of New South Wales (UNSW), Sydney, NSW, 2052, Australia
| | - James M Hook
- Nuclear Magnetic Resonance Facility, Mark Wainwright Analytical Centre, University of New South Wales (UNSW), Sydney, NSW, 2052, Australia
| | - Jason B Harper
- School of Chemistry, University of New South Wales (UNSW), Sydney, NSW, 2052, Australia
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25
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Hawker RR, Panchompoo J, Aldous L, Harper JB. Novel Chloroimidazolium‐Based Ionic Liquids: Synthesis, Characterisation and Behaviour as Solvents to Control Reaction Outcome. Chempluschem 2016; 81:574-583. [DOI: 10.1002/cplu.201600099] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Revised: 04/06/2016] [Indexed: 11/10/2022]
Affiliation(s)
- Rebecca R. Hawker
- School of Chemistry University of New South Wales Sydney NSW 2052 Australia
| | - Janjira Panchompoo
- School of Chemistry University of New South Wales Sydney NSW 2052 Australia
| | - Leigh Aldous
- School of Chemistry University of New South Wales Sydney NSW 2052 Australia
| | - Jason B. Harper
- School of Chemistry University of New South Wales Sydney NSW 2052 Australia
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26
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Butler BJ, Harper JB. The effect of the structure of the cation of an ionic liquid on the rate of reaction at a phosphorus centre. J PHYS ORG CHEM 2016. [DOI: 10.1002/poc.3554] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Bradley J. Butler
- School of Chemistry University of New South Wales, UNSW Sydney 2052 Australia
| | - Jason B. Harper
- School of Chemistry University of New South Wales, UNSW Sydney 2052 Australia
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27
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Unimolecular Solvolyses in Ionic Liquid: Alcohol Dual Solvent Systems. Molecules 2016; 21:60. [PMID: 26751434 PMCID: PMC6273061 DOI: 10.3390/molecules21010060] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 12/12/2015] [Accepted: 12/24/2015] [Indexed: 11/17/2022] Open
Abstract
A study was undertaken of the solvolysis of pivaloyl triflate in a variety of ionic liquid:alcohol solvent mixtures. The solvolysis is a kΔ process (i.e., a process in which ionization occurs with rearrangement), and the resulting rearranged carbocation intermediate reacts with the alcohol cosolvent via two competing pathways: nucleophilic attack or elimination of a proton. Five different ionic liquids and three different alcohol cosolvents were investigated to give a total of fifteen dual solvent systems. ¹H-NMR analysis was used to determine relative amounts of elimination and substitution products. It was found, not surprisingly, that increasing the bulkiness of alcohol cosolvent led to increased elimination product. The change in the amount of elimination product with increasing ionic liquid concentration, however, varied greatly between ionic liquids. These differences correlate strongly, though not completely, to the Kamlet-Taft solvatochromic parameters of the hydrogen bond donating and accepting ability of the solvent systems. An additional factor playing into these differences is the bulkiness of the ionic liquid anion.
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Schaffarczyk McHale KS, Hawker RR, Harper JB. Nitrogen versus phosphorus nucleophiles – how changing the nucleophilic heteroatom affects ionic liquid solvent effects in bimolecular nucleophilic substitution processes. NEW J CHEM 2016. [DOI: 10.1039/c6nj00721j] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Changing the nucleophile gave different ionic liquid effects, showing the importance of interactions with all species along the reaction coordinate.
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Affiliation(s)
| | | | - Jason B. Harper
- School of Chemistry
- University of New South Wales
- Sydney
- Australia
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29
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Keaveney ST, White BP, Haines RS, Harper JB. The effects of an ionic liquid on unimolecular substitution processes: the importance of the extent of transition state solvation. Org Biomol Chem 2016; 14:2572-80. [DOI: 10.1039/c5ob02598b] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An ionic liquid significantly increases benzylic carbocation formation due to favourable ionic liquid–transition state interactions. The magnitude of transition state solvation was shown to be critical, explaining the difference between this and previous cases.
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Affiliation(s)
| | | | | | - Jason B. Harper
- School of Chemistry
- University of New South Wales
- Sydney
- Australia
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30
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Kulchat S, Lehn JM. Dynamic Covalent Chemistry of Nucleophilic Substitution Component Exchange of Quaternary Ammonium Salts. Chem Asian J 2015. [DOI: 10.1002/asia.201500604] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Sirinan Kulchat
- Laboratoire de Chimie Supramoléculaire, ISIS; Université de Strasbourg; 8 allée Gaspard Monge 67000 Strasbourg France
| | - Jean-Marie Lehn
- Laboratoire de Chimie Supramoléculaire, ISIS; Université de Strasbourg; 8 allée Gaspard Monge 67000 Strasbourg France
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31
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Keaveney ST, Haines RS, Harper JB. Ionic liquid effects on a multistep process. Increased product formation due to enhancement of all steps. Org Biomol Chem 2015. [DOI: 10.1039/c5ob01214g] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
An ionic liquid is shown to increase the rate of all three steps in this imine formation and the microscopic origins of such are investigated. The magnitude of this enhancement varies with the nature of the substituent, though in all cases the rate of imine formation is increased.
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Affiliation(s)
| | | | - Jason B. Harper
- School of Chemistry
- University of New South Wales
- Sydney
- Australia
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32
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Keaveney ST, Haines RS, Harper JB. Developing principles for predicting ionic liquid effects on reaction outcome. The importance of the anion in controlling microscopic interactions. Org Biomol Chem 2015; 13:3771-80. [DOI: 10.1039/c4ob02482f] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
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.
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Affiliation(s)
| | | | - Jason B. Harper
- School of Chemistry
- University of New South Wales
- Sydney
- Australia
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33
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Butler BJ, Harper JB. The effect of an ionic liquid on the rate of reaction at a phosphorus centre. NEW J CHEM 2015. [DOI: 10.1039/c4nj01224k] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Rate constant of a substitution at phosphorus varies with amount of ionic liquid present; enthalpic benefit offsets entropic cost.
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Affiliation(s)
- Bradley J. Butler
- School of Chemistry
- University of New South Wales
- UNSW Sydney 2052
- Australia
| | - Jason B. Harper
- School of Chemistry
- University of New South Wales
- UNSW Sydney 2052
- Australia
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34
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Keaveney ST, Harper JB, Croft AK. Computational approaches to understanding reaction outcomes of organic processes in ionic liquids. RSC Adv 2015. [DOI: 10.1039/c4ra14676j] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The utility of using a combined experimental and computational approach for understanding ionic liquid media, and their effect on reaction outcome, is highlighted through a number of case studies.
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Affiliation(s)
| | - Jason B. Harper
- School of Chemistry
- University of New South Wales
- Sydney
- Australia
| | - Anna K. Croft
- Department of Chemical and Environmental Engineering
- University of Nottingham
- University Park
- Nottingham
- UK
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35
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Pavez P, Millán D, Cocq C, Santos JG, Nome F. Ionic liquids: anion effect on the reaction of O,O-diethyl O-(2,4-dinitrophenyl) phosphate triester with piperidine. NEW J CHEM 2015. [DOI: 10.1039/c4nj02121e] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The ionic liquids can be considered as designer solvents in the titled reaction because by an appropriate choice of the anion it is possible to steer the selectivity of this reaction.
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Affiliation(s)
- Paulina Pavez
- Facultad de Química
- Pontificia Universidad Católica de Chile
- Santiago 6094411
- Chile
| | - Daniela Millán
- Facultad de Química
- Pontificia Universidad Católica de Chile
- Santiago 6094411
- Chile
| | - Cristian Cocq
- Facultad de Química
- Pontificia Universidad Católica de Chile
- Santiago 6094411
- Chile
| | - José G. Santos
- Facultad de Química
- Pontificia Universidad Católica de Chile
- Santiago 6094411
- Chile
| | - Faruk Nome
- INCT-Catálise, Departamento de Química
- Universidade Federal de Santa Catarina
- Florianópolis
- Brasil
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36
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Anthofer MH, Wilhelm ME, Cokoja M, Markovits IIE, Pöthig A, Mink J, Herrmann WA, Kühn FE. Cycloaddition of CO2 and epoxides catalyzed by imidazolium bromides under mild conditions: influence of the cation on catalyst activity. Catal Sci Technol 2014. [DOI: 10.1039/c3cy01024d] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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37
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Keaveney ST, Schaffarczyk McHale KS, Haines RS, Harper JB. Developing principles for predicting ionic liquid effects on reaction outcome. A demonstration using a simple condensation reaction. Org Biomol Chem 2014; 12:7092-9. [DOI: 10.1039/c4ob01070a] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Predictions of the effects of the proportion and the components of an ionic liquid on the reaction rate are shown to correlate well with experimental results.
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Affiliation(s)
| | | | - Ronald S. Haines
- School of Chemistry
- University of New South Wales
- Sydney, Australia
| | - Jason B. Harper
- School of Chemistry
- University of New South Wales
- Sydney, Australia
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38
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Wang Z, Deng H, Li X, Ji P, Cheng JP. Standard and Absolute pKa Scales of Substituted Benzoic Acids in Room Temperature Ionic Liquids. J Org Chem 2013; 78:12487-93. [DOI: 10.1021/jo4021858] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Zhen Wang
- State
Key Laboratory on Elemento-organic Chemistry, Collaborative Innovation
Center of Chemical Science and Engineering, Department of Chemistry, Nankai University, Tianjin 300071, China
| | - Hui Deng
- State
Key Laboratory on Elemento-organic Chemistry, Collaborative Innovation
Center of Chemical Science and Engineering, Department of Chemistry, Nankai University, Tianjin 300071, China
| | - Xin Li
- State
Key Laboratory on Elemento-organic Chemistry, Collaborative Innovation
Center of Chemical Science and Engineering, Department of Chemistry, Nankai University, Tianjin 300071, China
| | - Pengju Ji
- Center
of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100083, China
| | - Jin-Pei Cheng
- State
Key Laboratory on Elemento-organic Chemistry, Collaborative Innovation
Center of Chemical Science and Engineering, Department of Chemistry, Nankai University, Tianjin 300071, China
- Center
of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100083, China
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39
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Tanner EEL, Hawker RR, Yau HM, Croft AK, Harper JB. Probing the importance of ionic liquid structure: a general ionic liquid effect on an SNAr process. Org Biomol Chem 2013; 11:7516-21. [DOI: 10.1039/c3ob41634h] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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