Reverse micelle supercritical fluid chromatography

Gale, Robert W.; Fulton, John L.; Smith, Richard D.

doi:10.1021/ac00142a017

Cited by 35 publications

(6 citation statements)

References 30 publications

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“…The cosolvent reduces the interfacial tension between the droplets and the continuous phase . Microemulsions are good solvents for both hydrophilic and hydrophobic reactants and have been utilized as media for catalytic and enzymatic reactions, for enhanced oil recovery, and as a mobile phase in chromatographic solutions …”

Section: Introductionmentioning

confidence: 99%

Organic Synthesis in Water/Carbon Dioxide Microemulsions

1999

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Nucleophilic substitution reactions were performed in H2O/CO2 (w/c) microemulsions formed with an anionic perfluoropolyether ammonium carboxylate (PFPE COO-NH4 +) surfactant. These reactions between hydrophilic nucleophiles and hydrophobic substrates were accomplished in an environmentally benign microemulsion without requiring toxic organic solvents or phase transfer catalysts. For the synthesis of benzyl bromide from benzyl chloride and KBr, the yield was an order of magnitude higher in w/c microemulsions versus conventional water-in-oil (w/o) microemulsions. Benzoyl chloride and p-nitrophenyl chloroformate were hydrolyzed in w/c microemulsions with rate constants an order of magnitude faster than those in w/o microemulsions.

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Section: Introductionmentioning

confidence: 99%

Organic Synthesis in Water/Carbon Dioxide Microemulsions

1999

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“…Also an on-line solvent extraction technique was combined with the reversed micellar-mediated CL detection. [20][21][22][23] There are several reports concerning the application of reversed micellar media as mobile phases in liquid chromatography, 24,25 TLC, 26,27 and SFC; 28 certain problems related to the adsorption of the surfactants were also reported. 25 The adsorption of cationic surfactants at solid/liquid interface is dependent on the nature of substrate and conditions of the medium, e.g., concentration of the surfactant, pH, ionic strength, and electrostatic as well as hydrophobic interactions are significant in it.…”

Section: Introductionmentioning

confidence: 99%

Adsorption Behavior of the Cetyltrimethylammonium Chloride Reverse Micelles on Porous Silica Gels

et al. 2009

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The adsorption behavior of reverse micelles of cetyltrimethylammonium chloride (CTAC) onto porous silica gels of various pore sizes has been investigated. A decrease in the amount of CTAC in the reversed micellar bulk solution in chloroform/water added to the silica gel in a column was observed, indicating the CTAC adsorption onto the silica surface. The adsorption profile obtained showed a maximum of the adsorbed surfactant amount, where the point of surface saturation may be reached, beyond which the adsorption amount remained unchanged. The adsorption of CTAC was also dependent on the specific surface area of the silica gel used. These results suggest that a CTAC monolayer may be formed and completed on the silica surface. The adsorbed CTAC amount slightly decreased with increasing the water to surfactant molar ratio, R, in the reversed micellar bulk solution, although at R < 2 the CTAC adsorption remained constant with silica gels having larger pore diameters. Even in the presence of traces of water moisture in the bulk solution used for the CTAC adsorption, the adsorption of water on silica gel was also observed and the molar ratios, RG, of the water to surfactant adsorbed on different silica gels were almost unity, implying that the silica gel may tend to hold some of water molecules originally adsorbed on its surface. The adsorption of CTAC molecules appears to occur through the adsorbed water molecules, probably polarized at the silica surface, and a CTAC-water-silica nanointerface seems to be formed. The adsorbed water amount or RG also increased with an increase in R and on silica gels with larger pore diameters and a plateau was observed in the R range of 3 -4, beyond which an increase in RG occurred again. The water molecules present in the vicinity of the adsorbed CTAC and the silica surface may possess different properties at different R and RG values.

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“…Microemulsions are often good solvents for both hydrophilic and hydrophobic substances 1–3. Therefore, they have been used as media for enhanced oil recovery,4, 5 organic6, 7 and enzymatic reactions,8, 9 and as a mobile phase in chromatographic solutions 10, 11. The surfactant‐covered water pools in the water–oil microemulsions offer a unique microenvironment for the formation of nanoparticles 12–18.…”

Section: Introductionmentioning

confidence: 99%

Organic Reactions and Nanoparticle Preparation in CO₂‐Induced Water/P104/p‐Xylene Microemulsions

Zhang

Han

et al. 2003

Chemistry A European J

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Nanometer-sized gold particles are synthesized by the reduction of HAuCl(4) with KBH(4) in the CO(2)-induced microemulsion of (EO)(27)(PO)(61)(EO)(27) (P104; EO=ethylene oxide, PO=propylene oxide)/p-xylene/CO(2)/H(2)O. The recovery of gold particles from the microemulsion can be easily accomplished by the venting of CO(2), while the surfactant remains in the organic phase. The effect of the molar ratio of the reductant to HAuCl(4), the concentration of the reactants, and the molar ratio of water to EO segments (W(0)) in the reverse micelles on the size of the gold particles is studied. The hydrolysis of benzoyl chloride (BzCl) and p-nitrophenyl chloroformate (NPhCl) has also been carried out in the microemulsion. The results show that the observed rate constants k(obs) of both substrates increase significantly with W(0), and that W(0) has a larger influence on the hydrolysis of BzCl. The different extents of the influence of W(0) on the two reactions can be ascribed to the different reaction mechanisms and the expected changes in nucleophilicity and polarity of water in the reverse micelles.

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Reverse micelle supercritical fluid chromatography

Cited by 35 publications

References 30 publications

Organic Synthesis in Water/Carbon Dioxide Microemulsions

Organic Synthesis in Water/Carbon Dioxide Microemulsions

Adsorption Behavior of the Cetyltrimethylammonium Chloride Reverse Micelles on Porous Silica Gels

Organic Reactions and Nanoparticle Preparation in CO₂‐Induced Water/P104/p‐Xylene Microemulsions

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Reverse micelle supercritical fluid chromatography

Cited by 35 publications

References 30 publications

Organic Synthesis in Water/Carbon Dioxide Microemulsions

Organic Synthesis in Water/Carbon Dioxide Microemulsions

Adsorption Behavior of the Cetyltrimethylammonium Chloride Reverse Micelles on Porous Silica Gels

Organic Reactions and Nanoparticle Preparation in CO2‐Induced Water/P104/p‐Xylene Microemulsions

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Organic Reactions and Nanoparticle Preparation in CO₂‐Induced Water/P104/p‐Xylene Microemulsions