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• 74928-54-4 3,5-(NO2)2C6H3CONHCH(CH2CH(CH3)2)COOH 
• 4328-13-6 tetrahexylammonium bromide 
• 5922-92-9 tetrahexylammonium chloride 
• 70-11-1 α-bromoacetophenone 
• 77-78-1 dimethyl sulfate 
• 328-39-2 LEUCINE 
• 99-33-2 3,5-dinitrobenoyl chloride 
• 99-73-0 para-bromophenacyl bromide 

Relevant academic research and scientific papers

Proof of concept for continuous enantioselective liquid-liquid extraction in capillary microreactors using 1-octanol as a sustainable solvent

The use of capillary microreactors for enantioselective liquid-liquid extraction (ELLE) was successfully demonstrated using a model system consisting of a buffered aqueous amino acid derivative (3,5-dinitrobenzoyl-(R,S)-leucine) solution (phosphate buffer, pH 6.58) and a chiral cinchona alkaloid (CA) host in an organic solvent. It was shown that 1-octanol is a suitable replacement for the commonly used chlorinated solvents like 1,2-dichloroethane. Experiments were conducted in a capillary microreactor set-up (0.8 mm internal diameter) operated in the slug flow regime at 294 K (residence times between 12 and 900 s, 1:1 flow ratio of the aqueous to organic phases, 1 mM of host and 1 mM of amino acid derivative). The enantiomeric excess (ee) was shown to be a function of the solvent and residence time and varied between 37% and 49% in 1,2-DCE and 28 and 46% in 1-octanol in the organic phase. The ee values in the organic phase at shorter residence times were higher than the independently determined equilibrium ee values (41% in 1,2-DCE and 31% in 1-octanol at a host concentration of 1 mM). This is an unprecedented observation with large implications for ELLE, as it implies that operation in the kinetic regime may lead to improved enantioseparation performance.

Uridine, thymidine and inosine used as chiral stationary phases in HPLC

In this paper, we present the first enantioseparations research using thymidine, uridine and inosine as chiral stationary phase bonded to silica gel via 3-(triethoxysilyl)propyl isocyanate in HPLC. Thymidine and uridine chiral stationary phases possess enantioseparation selectivity for alcohols, amines, ketones and carboxylic acids to some degree in normal-phase and reversed-phase mode. This work indicates that nucleoside or deoxynucleoside can be useful for the separation of enantiomers in the liquid phase as a new kind of chiral stationary phase.

COMPOSITIONS AND METHODS FOR CYCLOFRUCTANS AS SEPARATION AGENTS

The present invention relates to derivatized cyclofructan compounds, compositions comprising derivatized cyclofructan compounds, and methods of using compositions comprising derivatized cyclofructan compounds for chromatographic separations of chemical species, including enantiomers. Said compositions may comprise a solid support and/or polymers comprising derivatized cyclofructan compounds.

Continuous separation of racemic 3,5-dinitrobenzoyl-amino acids in a centrifugal contact separator with the aid of cinchona-based chiral host compounds

The resolution of racemates is mostly performed by crystallisation of diastereomeric salts. Direct physical separation could be much more efficient, but so far most concepts, with the exception of SMB, have proven to be non-scaleable. Here we report the f

Scalable enantioseparation of amino acid derivatives using continuous liquid-liquid extraction in a cascade of centrifugal contactor separators

Using a cascade of six centrifugal contactor separators in a countercurrent liquid-liquid extraction mode allowed the separation of one of the enantiomers of 3,5-dinitrobenzoyl-leucine in 55% yield and 98% ee using a catalytic amount of a chiral host comp

Development of new HPLC chiral stationary phases based on native and derivatized cyclofructans

An unusual class of chiral selectors, cyclofructans, is introduced for the first time as bonded chiral stationary phases. Compared to native cyclofructans (CFs), which have rather limited capabilities as chiral selectors, aliphatic-and aromatic-functionalized CF6s possess unique and very different enantiomeric selectivities. Indeed, they are shown to separate a very broad range of racemic compounds. In particular, aliphatic-derivatized CF6s with a low substitution degree baseline separate all tested chiral primary amines. It appears that partial derivatization on the CF6 molecule disrupts the molecular internal hydrogen bonding, thereby making the core of the molecule more accessible. In contrast, highly aromaticfunctionalized CF6 stationary phases lose most of the enantioselective capabilities toward primary amines, however they gain broad selectivity for most other types of analytes. This class of stationary phases also demonstrates high "loadability" and therefore has great potential for preparative separations. The variations in enantiomeric selectivity often can be correlated with distinct structural features of the selector. The separations occur predominantly in the presence of organic solvents.

Biphasic enantioselective partitioning studies using small-molecule chiral selectors

Enantioselective partitioning of racemic N-3,5-(dinitrobenzoyl)leucine or racemic naproxen was studied using a two-component chiral phase transfer approach. A combination of an achiral ion-pairing reagent and a chiral complexing agent (selector) is necessary to effect enantioselective partitioning between an aqueous bicarbonate solution and a nonpolar organic solvent. In these biphasic resolutions, the interplay between the ion-pairing reagent and the selector is essential for maximizing enantioselectivities. Furthermore, the lipophilicity of the ion-pairing reagent, the concentration of the ion-pairing reagent and selector, and the polarity of the organic solvent all exert a considerable influence on the biphasic process. In this manuscript, we conduct optimization studies through analysis of solvent, concentration and ion-pairing effects. Conclusions concerning the mechanistic rationale behind enantioselective partitioning are given.

Enantioselective hydrolysis of N-acylated α-amino esters at a biphasic interface: Tandem reaction kinetic resolution using a chiral complexing agent

equation presented Highly enantioselective hydrolytic kinetic resolutions of esters derived from N-acylated α-amino acids proceed rapidly at hydrocarbon/water interfaces in the presence of a proline-derived chiral selector. When performed in tandem with an enantioselective biphasic esterification reaction, esters of 100% enantiomeric excess are obtained.

Enantiomer separation by countercurrent chromatography using cinchona alkaloid derivatives as chiral selectors

Cinchona-derived anion-exchange type chiral selectors were used in countercurrent chromatography (CCC) for the separation of enantiomers of N-derivatized amino acids and 2-aryloxypropionicacids. The accurate optimization of the enantioseparation in terms of solvent system composition, pH values, ionic strength, and CCC operating conditions was carried out. Successful resolutions were obtained in systems such as ammonium acetate buffer/tert-amyl alcohol/methanol/heptane and ammonium acetate buffer/methyl isobutyl ketone (MIBK) or diisopropyl ether (DIPE). Different α values were obtained in CCC and HPLC for a given pair of selector/racemate. For n-(3,5-dinitrobenzoyl)-(±)-leucine and N-(3,5-dinitrobenzyloxycarbonyl)-(±)-neopentylglycine, enantioselectivity factors were lower in CCC, while for N-(3,5-dinitrobenzyloxycarbonyl)-(±)-β-phenylalan ine, α values slightly increased. No significant separation was observed for any of the of the aryloxypropionic acid derivatives tested in system containing (MIBK). In contrast, some discriminations for the enantiomers of these compounds was detected when DIPE was used in the binary system. The results exhibited the high potential of CCC as a separative separation technique.

Two-component chiral phase transfer catalysts: enantioselective esterification of an N-acylated amino acid.

[see reaction]. The first example of a two-component chiral phase transfer catalyst is described which, operating in a biphasic solvent system, preferentially esterifies one enantiomer of a racemic N-acylated amino acid. The two-component catalyst is comprised of an achiral quaternary ammonium ion and a proline-derived chiral selector initially developed for the liquid chromatographic separation of enantiomers.