A NMR Study on the Interactions of 1-Alkyl-3-Methylimidazolium Ionic Liquids with Acetone

Abstract

Summary 1H and 13C NMR chemical shifts have been determined to investigate the interactions of acetone with room temperature ionic liquids ([C4mim][PF6], [C6mim][PF6], [C8mim][PF6] and [C6mim][BF4]) at various acetone mole fractions. Changes in the chemical shifts of hydrogen and carbon atoms of the above systems indicated that hydrogen bonds were formed between the ring protons, the methyl and methylene next to the nitrogen of the ionic liquids and the carbonyl oxygen of the acetone molecules. The strength of hydrogen bond was found to be influenced not only by the type of the anion but also by the length of alkyl chain on the imidazolium ring of cations. At the same time, ab initio calculations have been performed to support the NMR results.

Ionic liquid mediated technology for synthesis of cellulose acetates using different co-solvents

“…There are reports of ILs that are miscible with acetone in the literature (Ruiz, Ferro, Palomar, Ortega, & Rodriguez, 2013;Zhai, Wang, Zhao, Tang, & Wang, 2006). [HDBN][OAc] is polar; possess a high dipolarity/polarizability, relatively strong basicity due mainly to the acetate ion and moderate acidity mainly influenced by the [DBNH] + cation.…”

Probing structural patterns of ion association and solvation in mixtures of imidazolium ionic liquids with acetonitrile by means of relative1H and13C NMR chemical shifts

“…27,38 Indeed, interpretation of the variations in 13 C chemical shifts is not that straight forward since they are not involved explicitly in the intermolecular interactions even though the observed variations are close in magnitude to those found for 1 H chemical shifts. 27,30,31,38,55 Another difficulty in the interpretation of the 13 C chemical shift variations for carbon nuclei is that the changes in microenvironment of the carbon atoms stem 24 from both hydrogen bonding effects at the adjacent hydrogen atoms and from the electron density redistribution along the skeleton of Rmim + cation. 28 As the observed chemical shift change reflects only the net effect of electron density gain/loss at a given atom, it is rather challenging to track all the pathways of electron density redistribution and to assign it to distinct intermolecular…”

“…The reference concentration can be chosen arbitrarily. So far the following options were proposed in the literature: a virtually intermediate concentration,25 the lowest employed concentration,36,68 or the highest one 14,16,27,38,69. However, from the point of view of interpretation, the most relevant reference concentration is that of the corresponding neat compound, and it is the most frequently used approach.…”

“…exhibit more significant deshielding than the terminal methyl ones, i.e., positive relative chemical shift variations are observed: EmimTFSI-Ac-d 6 ,25 RmimPF 6 /BF 4 -Ac-d6 ,27 EmimTFSIMeOH/DMSO/H 2 O 28,51,54. For some systems, however, there was no appreciable difference in chemical shift variation for the ring hydrogen atoms and the terminal methyl which resulted in roughly zero values of the relative chemical shift variations like in BmimBF 4 -H 2 O (note that there is a number of reports for this system concerning negative values of the relative chemical shift variation),75,76 and RmimBF 4 -ethylene glycol 79.…”

A Cobalt (II) Complex [Co(VIM)4](NCS)2 Based on 1-vinylimidazole (VIM) and SCN–

“…The coordination geometry of Co1 can be described as a distorted octahedral. The bond distances of Co (1) [23]. Molecules of the complex are packed in an interdigitated bilayer fashion with the layer thickness of 10.3 Å.…”