scholarly journals Time-Resolved Characterization of Dynamic Tribochemical Processes for Dicationic Imidazolium Ionic Liquid

2017 ◽  
Author(s):  
Roman Nevshupa ◽  
Marcello Conte ◽  
Silvia Guerra ◽  
Elisa Roman
Keyword(s):  
Ionic Liquid ◽  
Imidazolium Ionic Liquid ◽  
Imidazolium Cation ◽  
Water Desorption ◽  
Time Resolved ◽  
Head Groups ◽  
Volatile Products ◽  
Tribochemical Processes ◽  
Dicationic Ionic Liquid ◽  
Poly Ethylene

Dynamic tribochemical processes for dicationic ionic liquid containing a germinal imidazolium cation head groups bridged by a poly(ethylene glycol) and bis(trifluoromethylsulfonyl)imide anion were studied using time-resolved Mechanically Stimulated Gas Emission Mass-Spectrometry (MSGE-MS). In comparison with similar monocationic imidazolium ionic liquids with short alkylic or long polyether side chains the dicationic ionic liquid had lower coefficient of friction on Ti6Al4V alloy and smoother behaviour. The analysis of volatile decomposition products suggested multiple tribochemical reactions in which both anionic and cationic moieties are involved. Tribochemical degradation of cations was mainly through detachment of the side and bridging chains from the imidazolium head groups. Absence of volatile products containing nitrogen implies that imidazole group remained unchanged. Hydrogen and water desorption were attributed to the reactions of hydrogen fluoride being a product of anion degradation with titanium and titanium oxide.

scholarly journals Time-Resolved Characterization of Dynamic Tribochemical Processes for Dicationic Imidazolium Ionic Liquid

Lubricants ◽  
2017 ◽  
Vol 5 (3) ◽  
pp. 27 ◽  
Author(s):  
Roman Nevshupa ◽  
Marcello Conte ◽  
Silvia Guerra ◽  
Elisa Roman
Keyword(s):  
Ionic Liquid ◽  
Imidazolium Ionic Liquid ◽  
Time Resolved ◽  
Tribochemical Processes

Long-term preservation of α-amylase activity in highly concentrated aqueous solutions of imidazolium ionic liquid

2018 ◽  
Vol 7 (2) ◽  
pp. 106-113 ◽  
Author(s):  
Konstantza Tonova
Keyword(s):  
Ionic Liquid ◽  
Aqueous Solutions ◽  
Free Water ◽  
Potassium Acetate ◽  
Acetate Anion ◽  
High Concentration ◽  
Imidazolium Ionic Liquid ◽  
Imidazolium Cation ◽  
Long Term Preservation

AbstractThe activity of the α-amylase enzyme incubated in aqueous solutions with a high concentration (80.2% w/v) of imidazolium ionic liquid, [C4C1im]Br, has been studied. Contrary to the complete deactivation hitherto reported in the literature, a way is found to preserve the enzyme, by adding the appropriate salt, so that the activity is saved for a long grace period. Different salts are studied and the concentration is optimized in view of the enzyme hydration. Due to the limited amount of free water available to the enzyme at higher salt concentrations, the activity decreases. The best results are obtained by adding potassium acetate, 0.200 mol dm−3. Some 90% of the activity is saved in a 2-week incubation, and a half activity remains in a month. Precipitates are observed in the samples of the solution without salt. No precipitation is noticed when acetate is present. Regardless of the fluorescence quenching, the activity is saved. The effect of the acetate on the α-amylase preservation is probably related to the ability of the acetate anion to interact with the imidazolium cation thus shielding the enzyme from being salted out and precipitated. Compared with potassium bromide, which does not interact with [C4C1im]Br, precipitation and fast inactivation are observed.

Effect of spacer chain length on the liquid structure of aqueous dicationic ionic liquid solutions: molecular dynamics studies

2015 ◽  
Vol 17 (17) ◽  
pp. 11627-11637 ◽  
Author(s):  
Sourav Palchowdhury ◽  
B. L. Bhargava
Keyword(s):  
Molecular Dynamics ◽  
Ionic Liquid ◽  
Liquid Structure ◽  
Hydrophilic Surface ◽  
Hydrophobic Core ◽  
Alkyl Chains ◽  
Head Groups ◽  
Liquid Solutions ◽  
Dicationic Ionic Liquid ◽  
Spacer Chain Length

Cations in an aqueous [C16(MIm)2][2Br] solution aggregate spontaneously to form micelles, with a hydrophobic core composed of spacer alkyl chains and a hydrophilic surface composed of imidazolium head groups.

Synthesis of a Novel Diol-Functionalized Poly(ethylene glycol)-Bridged Dicationic Ionic Liquid and its Application in Copper-Catalyzed Amination of Aryl Halides

2013 ◽  
Vol 66 (5) ◽  
pp. 586 ◽  
Author(s):  
Yinglei Wang ◽  
Jun Luo ◽  
Tianjiao Hou ◽  
Zuliang Liu
Keyword(s):  
Ionic Liquid ◽  
Ethylene Glycol ◽  
Tetrabutylammonium Bromide ◽  
Primary Amines ◽  
Poly Ethylene Glycol ◽  
Strong Electron ◽  
Aryl Bromides ◽  
Dicationic Ionic Liquid ◽  
Electron Withdrawing Group ◽  
Poly Ethylene

A novel diol-functionalized poly(ethylene glycol)-bridged dicationic ionic liquid ([diol-PEG1000-DIL][PF6]) is prepared and used as an efficient and reusable ligand for copper-catalyzed amination. A variety of aryl iodides and aryl bromides reacted smoothly with aqueous ammonia to afford the corresponding aromatic primary amines in good to excellent yields. It is remarkable that aryl chlorides with a strong electron-withdrawing group exhibited a dramatically elevated activity in the presence of tetrabutylammonium bromide. Furthermore, the catalyst could be easily recovered and reused without obvious loss of catalytic activity after five recycling runs.

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