Search results for "ionic"
showing 10 items of 2016 documents
Ionic liquids as solvents for the Knoevenagel condensation: understanding the role of solvent–solute interactions
2015
The Knoevenagel condensation in ionic liquids has been demonstrated as a strongly solvent-dependent process. The objective of this study was to establish a simple and descriptive trend of solvent–solute interactions that favour the Knoevenagel condensation in ionic liquid media. The reaction between 4-(dimethylamino)benzaldehyde and ethyl cyanoacetate in several imidazolium- and pyrrolidinium-based ionic liquids and one ionic liquid mixture was studied. The rate constants were rationalised by studying the change in the 1H NMR chemical shift of representative starting materials in the ionic liquids and the measurement and consideration of the Kamlet–Taft descriptors for each solvent. The hyd…
Lewis acid-catalyzed Beckmann rearrangement of ketoximes in ionic liquids
2009
Abstract The Beckmann rearrangement of five ketoximes was done in 17 different ionic liquids by using four Lewis acids. The effect of the type of cation and the type of anion in the ionic liquid on the rate of the rearrangement reaction and product composition is compared and discussed. The effects of the hydrophobicity and the hydrogen bonding ability of ionic liquids on the rearrangement of ketoximes were investigated, as well as the catalytical activity of the Lewis acids.
Structure and vibrational features of the protic ionic liquid 1,8-diazabicyclo[5.4.0]-undec-7-ene-8-ium bis(trifluoromethanesulfonyl)amide, [DBUH][TF…
2022
Abstract The Protic Ionic Liquid (PIL) formed by neutralization of the super-strong base 1,7-diazabicyclo[5.4.0]undec-7-ene (DBU) with the super-strong acid bis(trifluoromethanesulfonyl)-imide (TFSI), indicated as [DBUH][TFSI], has been investigated. Its chemical physical properties and structural features have been explored using a synergy of experimental and computational tools. Molecular Dynamics-rationalised X-ray diffraction patterns highlight the major role played by hydrogen bonding (HB) in affecting morphology in this PIL. A comparison between HB features in this and in related PILs has been presented, on the base of far-IR experiments and DFT analysis. Indications of a weaker HB in…
ESI-FTICR investigation of triethylammonium ion-driven resorcin[4]arene dimer formation and structure
2002
In the course of mass spectrometric measurements a self-assembled hydrogen bonded resorcinarene dimer was observed, the formation of which was driven by the binding of triethylammonium ion as a guest and as an ionic label.
Bio-based 1,3-diisobutyl imidazolium hydrogen oxalate [iBu 2 IM](HC 2 O 4 ) as CO 2 shuttle
2017
International audience; This manuscript describes the using of biosourced L-valine, oxalic acid and glyoxal to produce a biobased imidazolium hydrogen oxalate [iBu(2)IM](HC2O4) which is converted to its related hydrogen carbonate salt by a simple electrolysis without using strong base. The addition of weak protic acids to the latter compound leads to a rapid and quantitative CO2 release with formation of the starting hydrogen oxalate salt or a new halide free bio-based ionic liquid [iBu(2)IM](AcO) which is able to adsorb reversibly the CO2 at room temperature. The protonation reactions, combined with electrolysis, could then be a promising alternative solution for storage and transport of C…
Hydrogen-bonded dimers of a thiacalixarene substituted by carbamoylmethylphosphineoxide groups at the wide rim.
2006
A thiacalix[4]arene derivative bearing four carbamoylmethylphosphineoxide groups at the wide rim forms hydrogen-bonded, dimeric capsules with S8 symmetry in the crystalline state and in apolar solvents, where the inclusion of cationic guests could be proved by 1H NMR and ESI mass spectra.
Hydrolysis of methyltin(IV) trichloride in aqueous NaCl and NaNO3 solutions at different ionic strengths and temperatures
1999
The hydrolysis of methyltin(IV) trichloride (CH 3 SnCl 3 ) has been studied in aqueous NaCl and NaNO 3 solutions (0 < l/mol dm -3 ≤1), at different temperatures (15 ≤ T/°C ≤ 45) by potentiometric measurements (H + -glass electrode). By considering the generic hydrolytic reaction pCH 3 Sn 3+ + qH 2 O = (CH 3 Sn) p (OH) q 3p-q +qH + (logβ pq ), we have the formation of five species and logβ 12 = -3.36, logβ 13 = -8.99, logβ 14 = -20.27 and logβ 25 = -7.61. The first hydrolysis step is measurable only at very low pH values and was not determined: a rough estimate of the hydrolysis constant is logβ 11 = -1.5 (± 0.5). The dependence on ionic strength of logβ pq is quite different in NaNO 3 and N…
ChemInform Abstract: Transition Metal Derivatives of Low Oxidation State Phosphorus Oxoacids: Synthetic Pathways and Structural Studies
2010
Abstract A general synthetic approach intended to rationalize the solution preparative chemistry of transition metal phosphites and hypophosphites is presented. As previously shown for other derivatives containing also tetrahedral or pseudotetrahedral oxoanions, the hydrolytic processes affecting the cationic moieties play a determinant role on the very nature of the final solid. In fact, despite the limited number of donor atoms in the anions, the crystal chemistry of these compounds is quite intricate because of both the variety of possible cationic aggregates and the many ways to interconnect them through pseudotetrahedral anionic groups.
Über den angriff des carboniumions am monomeren styrol bei der kationischen copolymerisation von trioxane und styrol. 19. Mitt. über polyoxymethylene
1962
Bei der Saure-katalysierten Hydrolyse von kationisch dargestellten Copolymeren aus Trioxan und Styrol entsteht 4-Phenyl-1,3-Dioxan. Das last sich nur so erklaren, das in Analogie zur radikalischen und zur anionischen Polymerisation der Angriff des Carboniumions ebenfalls am β-Kohlenstoffatom des Styrols erfolgt. Formation of 4-phenyl-1,3-dioxan occurs during the acid catalyzed hydrolysis of cationically produced copolymers of trioxane and styrene. The only possible explanation involves an attack of the carboniumion at the β-carbonatom of styrene analogous to the radical and anionic polymerization.
Some new examples of cationic polymerization
1986
Preparation, proprietes et polymerisation cationique de cis et trans-methoxyvinylchlorure. Le polymere trans est surtout threodiisotactique. Copolymerisation du cis avec le trans ou le styrene ou le dioxolanene-1,3. Polymerisation de la phenyl-2 oxazoline et de la conidine