6309-30-4Relevant articles and documents
Phonon-like Hydrogen-Bond Modes in Protic Ionic Liquids
Reichenbach, Judith,Ruddell, Stuart A.,González-Jiménez, Mario,Lemes, Julio,Turton, David A.,France, David J.,Wynne, Klaas
, p. 7160 - 7163 (2017)
Gigahertz- to terahertz-frequency infrared and Raman spectra contain a wealth of information concerning the structure, intermolecular forces, and dynamics of ionic liquids. However, these spectra generally have a large number of contributions ranging from slow diffusional modes to underdamped librations and intramolecular vibrational modes. This makes it difficult to isolate effects such as the role of Coulombic and hydrogen-bonding interactions. We have applied far-infrared and ultrafast optical Kerr effect spectroscopies on carefully selected ions with a greater or lesser degree of symmetry in order to isolate spectral signals of interest. This has allowed us to demonstrate the presence of longitudinal and transverse optical phonon modes and a great similarity of alkylammonium-based protic ionic liquids to liquid water. The data show that such phonon modes will be present in all ionic liquids, requiring a reinterpretation of their spectra.
Exploring the acid-catalyzed substitution mechanism of [Fe4S4Cl4]2??
Al-Rammahi, Thaer M.M.,Henderson, Richard A.
, p. 307 - 314 (2019/05/17)
Kinetic studies on the acid-catalyzed substitution reactions of the teminal chloro-ligands in [Fe4S4Cl4]2? by PhS? in the presence of the acids NHR3+ (R = Me, Prn or Bun) are reported. Although these acids have very similar pKas (17.6-18.4) the reactions show a variety of different kinetics, some of which are inconsistent with a mechanism involving simple protonation of the cluster followed by substitution of a terminal ligand. The observed behaviour is more consistent with the recently proposed mechanism in which Fe-(μ3-SH) bond elongation/cleavage occurs upon protonation of a μ3-S, and suggests that both the acidity and bulk of the acid is important in the protonation step. Other studies have determined the activation parameters (ΔH? and ΔS?) for both the protonation and substitution steps of the acid-catalyzed substitution reactions of [Fe4S4X4]2? (X = Cl or SEt). A significantly negative ΔS? is observed for the substitution steps of both clusters indicating associative pathways. This is inconsistent with earlier interpretation of the kinetics of these reactions (based exclusively on the dependence of the rate on the concentration of nucleophile) and indicates that there is no dissociative substitution mechanism and the pathway associated with a zero order dependence on the concentration of PhS? involves associative substitution with the solvent (MeCN) being the nucleophile.
EFFECT OF THE STRUCTURE OF THE SUBSTRATE AND NUCLEOPHILE ON THE REACTION RATES OF ARYLSULFONYLVINYLTRIALKYLAMMONIUM SALTS WITH AMINES
Popov, A. F.,Kravchenko, V. V.,Kostenko, L. I.,Kotenko, A. A.,Kovach, N. A.
, p. 1915 - 1917 (2007/10/02)
The kinetics of the reactions of arylsulfonylvinyltrialkylammonium salts with primary and secondary aliphatic amines in acetonitrile at 25 deg C were studied.On the basis of the low sensitivity of the reaction of β-(p-nitrophenylsulfonyl)vinyltriethylammonium chloride with alkylamines to the effect of the electronic and steric factors in the structure of the amines it was concluded that the transition state of the process is "looser" than in the reactions of the analogous substrates with a halogen as leaving group.The effect of the structure of the leaving trialkylammonium group on the rate of its substitution by the amino group was studied for the reaction of β-(p-nitrophenylsulfonyl)vinyltrialkylammonium chlorides with piperidine.The obtained data indicate that the process take place by an addition-elimination mechanism.