Liquid ion-pair

Keywords Asymmetric synthesis, Chiral ionic liquids, Ion pairing, Local structure. Nuclear Overhauser effect. Task-specific ionic liquids... 

In contrast with the previous method, Gao et al. [35] reported a GC-MS method which did not require prior derivatization for the analysis of rocuronium bromide and 17-desacetylrocuronium in biological samples. To prevent hydrolysis of rocuronium, solutions containing 1 M NaH2P04 was added to plasma samples, which were then stored at 20 °C prior to analysis. Similar with the previously described method, the internal standard was 3-desacetylvecuronium. The extraction process employed here also involved liquid-liquid ion pair extraction with saturated... 

Reversed-phase liquid-liquid ion-pair chromatography has been used to separate some tertiary 15... 

Normal phase liquid-liquid ion-pair chromatography... 

By analogy with liquid-liquid ion-pair extraction, a more hydrophobic counter-ion X (higher (hax)) higher concentration will increase the distribution to... 

The special role of ionic liquids at the interfacial boundary between gas-liquid and solid-liquid phases lies in their enhancement or mediation of chemical processes by creating a stabilizing interfacial environment. The objective of the present chapter is to give a concise description of the mechanisms of ionic liquid interaction with the interfacial layers that should help identify the most suitable ionic liquid ion pairs for a particular process (Figure 7.1) [1, 2]. 

Ion pairing agents in liquid-liquid systems in reversed-phase mode have included dihydrogenphos-phate for separation of tricyclic amines, octyl sulfate for catecholamines, and tetrabutylammonium for aromatic carboxylates and anions of sulfonamides, to exemplify some of the comparatively few applications. Liquid stationary phases coated on the alkyl-bonded phase include 1-pentanol, butyronitrile, and tributylphosphate. In normal-phase liquid-liquid ion pair chromatography aqueous perchlorate solution has been coated on to silica particles for ion pair separation of catecholamines and related compovmds and tetrabutylammonium ion at neutral pH for carboxylates and anions of sulfonamides. The organic mobile phase often contained dichloromethane and butanol. In the normal-phase mode on silica alternative separation systems have been described with aqueous perchloric acid in methanol added to dichloromethane as mobile phase for separation of amines such as drug substances. This is not an extensively utilized, but quite useful, kind of separation, which has been named ion pair adsorption chromatography. 

Fraser, K.J., Izgorodina, E.I., Forsyth, M., Scott, J.L. and MacFarlane, D.R., Liquids intermediate between molecular and ionic liquids liquid ion pairs Chem. Commun. 37, 3817-3819 (2007). 

PHOTOMETRIC DETERMINATION OF ACIDIC IMPURITIES IN OILS AND ORGANIC LIQUIDS WITH THE USE OF THE ION PAIR OF TRINONYLOCTADECYLAMMONIUM AND BROMOTHYMOL BLUE AS THE COLORED REAGENT... 

K. Yamashita, M. Motohaslii and T. Yashiki, Sensitive high-performance liquid cliro-matographic determination of propranolol in human plasma with ultraviolet detection using column switcliing combined with ion-pair cliromatography , J. Chromatogr. 527 196-200(1990). 

R. El Hairak, M. Calull, R. M. Marce and R Boirull, Determination of naphthalene-sulphonates in water by on-line ion-pair solid-phase exti action and ion-pair liquid cliro-matography with diode-airay UV detection , Int. J. Environ Anal. Chem. 69 295-305 (1998). 

E. Pocumll, C. Aguilar, M. C. Alonso, D. Barcelo, E. Bonnll and R. M. Marce, On-line solid-phase extraction-ion-pair liquid cliromatography-electi ospray mass spectrometry for the ti ace determination of naphthalene monosulphonates in water ,... 

The behavior of ionic liquids as electrolytes is strongly influenced by the transport properties of their ionic constituents. These transport properties relate to the rate of ion movement and to the manner in which the ions move (as individual ions, ion-pairs, or ion aggregates). Conductivity, for example, depends on the number and mobility of charge carriers. If an ionic liquid is dominated by highly mobile but neutral ion-pairs it will have a small number of available charge carriers and thus a low conductivity. The two quantities often used to evaluate the transport properties of electrolytes are the ion-diffusion coefficients and the ion-transport numbers. The diffusion coefficient is a measure of the rate of movement of an ion in a solution, and the transport number is a measure of the fraction of charge carried by that ion in the presence of an electric field. 

Typically, the ionic liquid is best considered as an ion-pair (or ion, on an individual basis). The main forces of attraction between the ions are the electrostatic forces and dispersion (van der Waals) forces. At intermediate distances, there is a slight... 

Another ionic liquid, containing a nonyl-rather than a butyl-side chain, is shown in Figure 4.2-2. There is little difference between the basic structures of these two ion-pairs (Figures 4.2-1 and 4.2-2) with respect to the non-bonded interactions (hydrogen bonds) occurring between the F atoms on the anion and the C-H moieties on the imidazolium cation. 

EC = ion exchange chromatography IPC = ion pair chromatography LSC = liquid—solid chromatography... 

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