Chiral derivatization reagent

Table 1. Analyte Functional Groups and Chiral Derivatizing Reagents...

Based on gasliquidchromatography (GLPC) amides, formed from various enantiomeric amines and the chiral-derivatizing reagent ( S)-(—)-JV-pentafluorobenzoylprolyl-l-imidazole, could be detected at nanogram levels [43],[44]... 

Butyl oleate, 10 492 y-Butyloxycarbonyl-L-leucine anhydride, chiral derivatizing reagent, 6 76t Butylparaben, antimicrobial used in cosmetics, 7 831t terl-Butyl peroxyacetate, 13 484 terl-Butyl peroxybenzoate, 13 486 2-sec-Butylphenol (OSBP), 2 221-222 health and safety data, 2 220t physical properties of, 2 205t o-sec-Butylphenol. See 2-sec-Butylphenol (OSBP)... 

Dibenzoyltartaric anhydride, chiral derivatizing reagent, 6 76t Dibenzylamine, 3 595 Dibenzyl carbonate, molecular formula, 6 305t... 

Menthone glycerol acetal, 24 525 (—)-Menthoxy acid chloride, chiral derivatizing reagent, 6 76t Menthyl anthranilate, cosmetic uv absorber, 7 846t... 

Menthyl chloroformate, chiral derivatizing reagent, 6 76t Menthyl esters, 24 524 Menthyl pyrrolidone carboxylate, 24 525 Menthyl salicylate, 24 524 physical properties of, 22 14t Menthyl valerate, 24 524 Mentoring, of technical service personnel, 24 346-347... 

Methoxyacrylates, insecticidal, 14 348 a-Methoxy-a-trifluoromethylphenylacetyl chloride, chiral derivatizing reagent,... 

Methyl isovalerate, azeotropic mixtures with butyl alcohols, 4 395t Methyl ketones, acetic anhydride used in synthesis, 1 148 Methyllithium, 14 249 15 147 Methylmagnesium chloride, 16 319 (R)-(—)-Methylmandelic acid chloride, chiral derivatizing reagent, 6 76t Methyl mercaptan production, 15 17 3-Methylmercaptopropionaldehyde (MMP), intermediate in methionine synthesis, 1 268, 269, 276... 

Naphthyl)ethyl isocyanate, chiral derivatizing reagent, 6 76t 1-Naphthyl-Al-methylcarbamate, 17 84 Napierian absorbance, 23 126 Naples yellow, 14 792 Napping, of staple-fiber non woven fabrics, 17 515... 

Phthalazinone, 19 332 o-Phthaldialdehyde-2-mercaptoethanol, chiral derivatizing reagent, 6 76t Phthalein dyes, 19 304-305 Phthalic acid, 19 332... 

Chiral resolution by HPLC can by divided into three categories (1) a direct resolution using a chiral stationary phase (CSP) (2) addition of a chiral agent to the mobile phase, which reacts with the enantiomeric analytes (chiral mobile phase additive method (CMPA)) (3) an indirect method that utilizes a precolumn diastereomer formation with a chiral derivatization reagent (Misl anova and Hutta, 2003). 

Toyo oka T. 2002. Resolution of chiral drugs by liquid chromatography based upon diastereomer formation with chiral derivatization reagents. J Biochem Biophys Methods 54 25-56. 

Lactols derived from camphor, such as CT 6 0-octahydro-7,8,8-trimethyl-4,7-methanobenzo-furan-2-ol and its dimer are in many cases advantageous as chiral derivatizing reagents. It is described in the following section as (+)- and (-)-MBF-OH or in accordance with Mosher s reagent as Noe s lactol (Figure 8). 

TAB1.E I. ANALYTE FUNCTIONAL GROUPS AND CHIRAL DERIVATIZING REAGENTS... 

N Nimura, T. Kinoshita. o-Phthalaldehyde-A -acetyl-t.-cystcine as a chiral derivatization reagent for liquid chromatographic optical resolution of amino acid enantiomers and its application to conventional amino acid analysis. J Chromatogr 352 169-177, 1986. 

There are several types of chiral derivatizing reagents commonly used depending on the functional group involved. For amines, the formation of an amide from reaction with an acyl halide [147,148], chloroformate reaction to form a carbamate [149], and reaction with isocyanate to form the corresponding urea are common reactions [150]. Carboxyl groups can be effectively esterified with chiral alcohols [151-153]. Isocynates have been used as reagents for enantiomer separation of amino acids, iV-methylamino acids, and 3-hydroxy acids [154]. In addition to the above-mentioned reactions, many others have been used in the formation of derivatives for use on a variety of packed and capillary columns. For a more comprehensive list, refer to References 155-159. 

Enantiomers are derivatized with an optically pure chiral derivatization reagent to form a pair of diastereomers. The ability to resolve the diastereomeric derivatives on an achiral sorbent is enhanced when the chiral centers of the enantiomers and the derivatives are in close proximity [181]. Two different separation mechanisms have been proposed. One postulates that the diastereomers are separated by differences in molecular structure and polarity [182], The other possible mechanism is based on differences in the diastereomer energies of adsorption [183]. Table 5.7 lists the chiral reagents that have been used for separation of enantiomers as diastereomers. 

Table 5.7 Chiral Derivatization Reagents for Separation of Enantiomers...

Although these chiral derivatization reagents have demonstrated their utility for indirect chiral separation, the arguments against them include length of time involved for derivatization, possibilty of racemization, and presence of optically active contaminants, variability of the formation rate of the diasteromers [184]. 

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