Triflic Acid and Sodium Triflate as Chaotropic Mobile Phase Additives in RP-LC

Loeser, Eric; Babiak, Stanislaw; DelaCruz, Marilyn; Karpinski, Peter

doi:10.1093/chrsci/49.1.57

Cited by 4 publications

(4 citation statements)

References 23 publications

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“…Both TFA and perchloric acids are chaotropic agents, which are highly polarizable anions with a low degree of hydration that typically aide in the approach of the analyte to the stationary phase . Formation of an ion pair between the chaotropic anion and analyte increases its hydrophobicity . This facilitates the adsorption of analyte to the hydrophobic portion of a stationary phase .…”

Section: Resultsmentioning

confidence: 99%

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Comparison of Chiral Separations of Aminophosphonic Acids and Their Aminocarboxylic Acid Analogs Using a Crown Ether Column

et al. 2013

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Crown ethers are capable of complexing with primary amines and have been utilized in chromatography to separate amino acid racemates. This application has been extended to resolve (1-amino-1-phenylmethyl)phosphonic acid and (1-aminoethyl)phosphonic acid racemates, along with their aminocarboxylic acid analogs (2-phenylglycine and alanine, respectively), via a ChiroSil RCA crown ether based chiral stationary phase. Effects of the organic modifier, temperature, and acid type and concentration on retention and selectivity were also investigated. Trends in retention and selectivity varied between aminophosponic acids and their aminocarboxylic analogs. Computer modeling and (1)H NMR analyses were performed to potentially gain a better understanding of interactions of the aforementioned molecules with the ChiroSil RCA chiral stationary phase. Theoretical predictions of the most stable conformations for (R)- and (S)-enantiomers were compared to elution order; it was found that the elution order agreed with molecular modeling such that the longest retention correlated with the predicted most stable complex between the enantiomer and crown ether. (1)H NMR demonstrated interactions of aminophosphonic and aminocarboxylic racemates with (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid in solution and was utilized to determine enantiomeric excess of (1-amino-1-phenylmethyl)phosphonic acid after its enantioenrichment via crystallization through diastereomeric salt formation with the crown ether followed by filtration.

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Section: Resultsmentioning

confidence: 99%

“…Formation of an ion pair between the chaotropic anion and analyte increases its hydrophobicity . This facilitates the adsorption of analyte to the hydrophobic portion of a stationary phase . The chaotropic nature of TFA and perchloric acid may explain why

k_{1}^{'}

increases for 2‐Phg with increasing acid concentrations.…”

Section: Resultsmentioning

confidence: 99%

Comparison of Chiral Separations of Aminophosphonic Acids and Their Aminocarboxylic Acid Analogs Using a Crown Ether Column

et al. 2013

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“…This means that triflic acid would not be expected to be liberated from the copper(II) triflate and this is confirmed by the much higher decomposition point of triflic acid (380˚C) [40]. Pure sodium triflate decomposes between 253°C and 256°C [41] and therefore, the formed species must not be sodium triflate either. Therefore, it seems reasonable that what actually happens when copper(II) triflate is added to our support is that the place of sodium cation is taken up by an ion par such as [CuNa(OTf) 2 ] + .…”

Section: Preparation and Characterization Of Cu-al-mcm41mentioning

confidence: 96%

Improved methodology for non-covalent immobilization of tert-butyl-azabis(oxazoline)–copper complex on Al-MCM41

Feldman

Fraile

2015

Applied Catalysis A: General

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Please cite this article as: Robert A.Feldman, José M.Fraile, Improved methodology for non-covalent immobilization of tert-butyl-azabis(oxazoline)-copper complex on Al-MCM41, Applied Catalysis A, General http://dx. Highlights-Chiral azabox-copper complex was immobilized on Al-MCM41 in a non-covalent way.-Cu(OTf) 2 was first impregnated by incipient wetness and then treated at 450ºC.-Final modification with azabox leads to stable immobilized complexes.-Better results in enantioselective cyclopropanation are obtained at high temperature. AbstractCopper sites are supported on Al-MCM41 by thermally treating copper(II) triflate that was deposited using the incipient wetness method. The change of the chemical state of the triflate anions following thermal treatment is monitored using TGA and SEM-EDX.Thermal treatment yields copper sites that then can be modified with chiral tert-butylazabis(oxazoline) by adding a solution of this ligand to the support using incipient wetness. The catalyst produced in this way is efficient and stable with good enantioselectivity, and can be used in the cyclopropanation of styrene with ethyl diazoacetate under conditions employing an elevated temperature. The use of thermal treatment in the catalyst preparation method produces catalysts that are superior to the solids prepared by cation exchange or incipient wetness of the pre-formed complex.

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“…stationary phase, leading to slow column-equilibration and difficulty in recovering the initial column properties [10][11][12][13]. Nowadays, chaotropic salts are usually used in the analysis of active ingredients and impurities in pharmaceutical formulations [11,[14][15][16]. In the meanwhile, attempts to understand the fundamentals behind the applications are still ongoing (see Ref.…”

Section: Introductionmentioning

confidence: 99%

Liquid chromatographic method for toxic biogenic amines in foods using a chaotropic salt

Zhong

Liao

Ding

et al. 2015

Journal of Chromatography A

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Triflic Acid and Sodium Triflate as Chaotropic Mobile Phase Additives in RP-LC

Cited by 4 publications

References 23 publications

Comparison of Chiral Separations of Aminophosphonic Acids and Their Aminocarboxylic Acid Analogs Using a Crown Ether Column

Comparison of Chiral Separations of Aminophosphonic Acids and Their Aminocarboxylic Acid Analogs Using a Crown Ether Column

Improved methodology for non-covalent immobilization of tert-butyl-azabis(oxazoline)–copper complex on Al-MCM41

Liquid chromatographic method for toxic biogenic amines in foods using a chaotropic salt

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