The Effect of Hydrogen Bonding on Allylic Alkylation and Isomerization Reactions in Ionic Liquids (original) (raw)
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Ligand Effects in Palladium-Catalyzed Allylic Alkylation in Ionic Liquids
Organometallics, 2001
Palladium-catalyzed allylic alkylation with a variety of active methylene compounds has been carried out in the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]-[BF 4 ]). Phosphine ligands are found to exert a profound effect on the active palladium species, with the more electron-donating ones such as PCy 3 affording faster rates and the strong electron acceptors such as P(OPh) 3 affording extremely low conversions. In the most commonly used molecular solvent, THF, the reaction is slower and the choice of ligands is more limited. These observations may be accounted for by the allylpalladium intermediate existing in different forms in the two solvents.
Hydrogen Bonding in 1-Butyl- and 1-Ethyl-3-methylimidazolium Chloride Ionic Liquids B
The Journal of Physical Chemistry, 2012
A detailed investigation of hydrogen bonding in the pure ionic liquids [C 4 C 1 im]Cl and [C 2 C 1 im]Cl has been carried out using primarily molecular dynamics techniques. Analyses of the individual atom−atom pair radial distribution functions, and in particular those for C•••Cl − , have revealed that hydrogen bonding to the first methylene or methyl units of the substituent groups is important. Multiple geometric criteria for defining a hydrogen bond have been applied, and in particular the choice of the cutoff angle has been carefully examined. The interpretation of hydrogen bonding within these ionic liquids is highly angle dependent, and justification is provided for why it may be appropriate to employ a wider angle criteria than the 30°used for water or alcohol systems. The different types of hydrogen bond formed are characterized, and "top" conformations where the Cl anion resides above (or below) the imidazolium ring are investigated. The number of hydrogen bonds undertaken by each hydrogen atom (and the chloride anion) is quantified, and the propensity to form zero, one, or two hydrogen bonds is established. The effects of an increase in temperature on the static hydrogen bonding are also briefly examined.
ChemInform, 2004
Supporting information Experimental and Characterization of Compounds: General. All reagents were obtained commercially and were used without further purification unless otherwise noted. Microwave assisted reaction was performed in a domestic microwave oven (Panasonic Model NN-S562WF, 1200 W, 2450 MHz). 1 H NMR and 13 C NMR spectra were recorded on Varian Mercury-300 (300 MHz) or Mercury-400 (400 MHz) at 20 ºC. Chemical shifts for protons are reported in parts per million and referenced to residual protium in deuterated chloroform (δ 7.26), deuterium oxide (δ 4.60) or acetone (δ 2.06). Carbon chemical shifts are reported in parts per million relative to the carbon resonance of the methyl group of chloroformd 1 (δ 77.0) or acetone-d 6 (δ 29.8, 206). Mass spectroscopic data were obtained at the McGill University Mass Spectrometry Facility. Proparation of 1-(2-hydroxyethyl)-3-methylimidazolium bromide 1 : A mixture of 1methylimidazole (3.28g, 0.04 mol) and 1-bromoethanol (5.0g, 0.04 mol) in a 25 ml round bottom flask equipped with a drying tube was placed in a 100 ml beaker containing 30 ml of water. The reaction mixture was heated intermittently (360W 60s + 50s + 30s) in the microwave oven and mixed occasionally by swirling between intervals. 2 The temperature of the water bath was below 70 ºC during the course of the reaction. The pale brown oil solidified on cooling and was washed by ether (10ml×3) and dried at 70 ºC under vacuum. The product was obtained as a pale yellow
Hydrogen Bonding in 1-Butyl- and 1-Ethyl-3-methylimidazolium Chloride Ionic Liquids
Journal of Physical Chemistry B, 2012
A detailed investigation of hydrogen bonding in the pure ionic liquids [C 4 C 1 im]Cl and [C 2 C 1 im]Cl has been carried out using primarily molecular dynamics techniques. Analyses of the individual atom−atom pair radial distribution functions, and in particular those for C•••Cl − , have revealed that hydrogen bonding to the first methylene or methyl units of the substituent groups is important. Multiple geometric criteria for defining a hydrogen bond have been applied, and in particular the choice of the cutoff angle has been carefully examined. The interpretation of hydrogen bonding within these ionic liquids is highly angle dependent, and justification is provided for why it may be appropriate to employ a wider angle criteria than the 30°used for water or alcohol systems. The different types of hydrogen bond formed are characterized, and "top" conformations where the Cl anion resides above (or below) the imidazolium ring are investigated. The number of hydrogen bonds undertaken by each hydrogen atom (and the chloride anion) is quantified, and the propensity to form zero, one, or two hydrogen bonds is established. The effects of an increase in temperature on the static hydrogen bonding are also briefly examined.
II. Ionic Liquids 3669 A. Overview 3669
2002
IX. Allylation Reactions 3685 X. Olefin Metathesis 3685 XI. Miscellaneous Reactions 3686 XII. Mechanistic Aspects of the Reactions in Ionic Liquids 3687 XII. Conclusions and Perspectives 3687 XIII. Acknowledgments 3688 XIV. References 3688
Ruthenium-catalyzed allylation reaction in ionic liquid
Journal of Molecular Catalysis A: Chemical, 2005
Ruthenium-catalyzed allylic substitution reactions from unsymmetrical allylic carbonates have been demonstrated to proceed in the ionic liquid 1-hexyl-2,3-dimethylimidazolium hexafluorophosphate ([hdmim][PF 6 ]) under neutral conditions with very good conversion and regioselectivity, and high level of recyclability of the solvent/catalyst system.