Synthesis and Properties of Alkoxy‐ and Alkenyl‐Substituted Peralkylated Imidazolium Ionic Liquids

Abstract

Novel peralkylated imidazolium ionic liquids bearing alkoxy and/or alkenyl side chains have been synthesized and studied. Different synthetic routes towards the imidazoles and the ionic liquids comprising bromide, iodide, methanesulfonate, bis(trifluoromethylsulfonyl)imide ([NTf2](-)), and dicyanamide {[N(CN)2](-)} as the anion were evaluated, and this led to a library of analogues, for which the melting points, viscosities, and electrochemical windows were determined. Incorporation of alkenyl moieties hindered solidification, except for cations with high symmetry. The alkoxy-derivatized ionic liquids are often crystalline; however, room-temperature ionic liquids (RTILs) were obtained with the weakly coordinating anions [NTf2](-) and [N(CN)2](-). For the viscosities of the peralkylated RTILs, an opposite trend was found, that is, the alkoxy derivatives are less viscous than their alkenyl-substituted analogues. Of the crystalline compounds, X-ray diffraction data were recorded and related to their molecular properties. Upon alkoxy substitution, the electrochemical cathodic limit potential was found to be more positive, whereas the complete electrochemical window of the alkenyl-substituted imidazolium salts was shifted to somewhat more positive potentials.

Halogen-free synthesis of symmetrical 1,3-dialkylimidazolium ionic liquids using non-enolisable starting materials

“…1 H NMR: (300 MHz, DMSO-d6, δ/ppm): 9.76 (s, 1H, CH), 7.86 (s, 2H, 2 CH), 4.19 (m, 4H, 2 CH2-N), 1.79 (m, 4H, 2 CH2), 1.76 (s, 3H, CH3), 1.23 (m, 28H, 14 CH2), 0.85 (m, 6H, 2 CH3). 13…”

“…The 1 H NMR and 13 C NMR spectra were recorded on a Bruker Avance 300 spectrometer (operating at 300 MHz for 1 H, 75 MHz for 13 C). The chemical shis are noted in parts per million (ppm), referenced to tetramethylsilane for 1 H and 13 C. All solutions were made in CDCl 3 or DMSO-d 6 . The spectra were analyzed with SpinWorks soware.…”

“…Maton et al have described the synthesis of highly substituted imidazolium ionic liquids from readily available molecules, at 120 °C in pressure vials, yet the products were obtained in low yields. 12,13 In the literature on imidazole synthesis, phenyl is the most often used substituent. For instance, the oldest synthetic route to obtain imidazole is the Debus-Radziszewski method where a benzil (1,2-diphenylethane-1,2-dione) molecule reacts with formaldehyde and two ammonia equivalents to form an imidazole ring.…”

Study of an Environmentally Friendly Method for the Dissolution of Precious Metal with Ionic Liquid and Iodoalkane

“…Combining the above characterization and analysis results, the possible reaction mechanism is shown in Scheme 2 and Figure 8: Light induces the formation of iodine free radicals in CHI 3 (step (3)), then I captures the electrons on Au 0 to form Au + (step (4)), which then combines with N(CN) 2 − to form AuN(CN) 2 (step ( 5)). Subsequently, the imidazole cation of the ionic liquid forms a stable [Bmim]•[Au(N(CN) 2 ) 2 ] ion pair through various intermolecular forces such as electrostatic attraction, hydrogen bonding, and cation-π bonding with AuN(CN) 2 [34][35][36] (step ( 6)).The ion-pair structure makes the metal shed from the particle surface exist in the ionic liquid in a stable form, and shifts the balance of the oxidation (step (4)) to the right, which further promotes the dissolution reaction and finally promotes the continuous dissolving of the gold particles into the ionic liquid system. In addition, the new ionic liquid BmimI obtained by ion exchange is partially precipitated in the form of crystals.…”