Chiral stationary phases cellulose

Chiral stationary phases in tic have been primarily limited to phases based on normal or microcrystalline cellulose (44,45), triacetylceUulose sorbents or siHca-based sorbents that have been chemically modified (46) or physically coated to incorporate chiral selectors such as amino acids (47,48) or macrocyclic antibiotics (49) into the stationary phase. 

The potential for use of chiral natural materials such as cellulose for separation of enantiomers has long been recognized, but development of efficient materials occurred relatively recently. Several acylated derivatives of cellulose are effective chiral stationary phases. Benzoate esters and aryl carbamates are particularly useful. These materials are commercially available on a silica support and imder the trademark Chiralcel. Figure 2.4 shows the resolution of y-phenyl-y-butyrolactone with the use of acetylated cellulose as the adsorbent material. 

There is a wide variety of commercially available chiral stationary phases and mobile phase additives.32 34 Preparative scale separations have been performed on the gram scale.32 Many stationary phases are based on chiral polymers such as cellulose or methacrylate, proteins such as human serum albumin or acid glycoprotein, Pirkle-type phases (often based on amino acids), or cyclodextrins. A typical application of a Pirkle phase column was the use of a N-(3,5-dinitrobenzyl)-a-amino phosphonate to synthesize several functionalized chiral stationary phases to separate enantiomers of... 

Ichihara, H., Fukushima, T., Imai, K. (1999).. Enantiomeric determination of d- and L-lactate in rat serum using high-performance liquid chromatography with a cellulose-type chiral stationary phase and fluorescence detection. Anal. Biochem. 269, 379-385. 

Tanaka, M., Yamazaki, H. (1996). Direct determination of pantoprazole enantiomers in human serum by reverse-phase high-performance liquid chromatography using a cellulose-based chiral stationary phase and column-switching system as a sample cleanup procedure. Anal. Chem. 68, 1513-16. 

In this study, Ali and Aboul-Enein [80] used cellulose tr is (3,5-d ich Ioropheny 1 carbamate) chiral stationary phase for the enantioseparation of miconazole and other clinically used drugs by high performance liquid chromatography. The mobile... 

Okamoto et al [85] performed the optical resolution of primaquine and other racemic drugs by high performance liquid chromatography using cellulose and amylose tris-(phenylcarbamate) derivatives as chiral stationary phases. Primaquine and other compounds were effectively resolved by cellulose and/or amylose derivatives having substituents such as methyl, tertiary butyl, or halogen, on the phenyl groups. 

For the preparation of the chiral stationary phase (3-methylbenzoyl cellulose) and of the analytical HPLC columns, see ref1421. The preparative column (glass column 5 cm i.d. x 75 cm Btichi AG, Flawil, Switzerland) was slurry-packed with a suspension of 3-methylbenzoyl-cellulose beads (550 g) in hexane/ iPrOH (9 l). The glass column was topped with a column of the same dimension as a reservoir. After decantation of the material in the column, the reservoir was taken away and the stationary phase washed by pumping the eluent through the column equipped with an inlet plunger, at a flow rate of 60 mL-min 1... 

Enantiomeric purity (% ee) of (i )-41 as determined by HPLC using cellulose triacetate as a chiral stationary phase. 

Okamoto, Y., Aburatani, R., and Hatada, K. (1987) Cellulose tribenzoate derivatives as chiral stationary phases for high-performance liquid chromatography, J. Chromatogr. 389, 95-102. 

Kubota, T., Yamamoto, C., and Okamoto, Y. (2000) Tris(cyclohexylcarbamate)s of cellulose amylose as potential chiral stationary phases for high-performance liquid chromatography and thin-layer chromatography, /. Am. Chem. Soc. 122, 4056-4059. 

Ishikawa, A. and Shibata, T. (1993) Cellulosic chiral stationary phase under reversed-phase condition, J. Liq. Chromatogr. 16, 859-878. 

Franco, P., Senso, A., Minguillon, C., and Oliveros, L. (1998) 3,5-Dimethylphenylcarbamates of amylose, chitosan and cellulose bonded on silica gel. Comparison of their chiral recognition abilities as high-performance liquid chromatography chiral stationary phases, J. Chromatogr. A 796, 265-272. 

H. Y. Aboul-Enein and M. R. Islam, Direct separation and optimization of timolol enantiomers on a cellulose tris-3,5-dimethyl-phenylcarbamate high-performance liquid chromatographic chiral stationary phase, J. Chromatogr., 55 109 (1990). 

L. Miller and R. Bergeron, Analytical and preparative resolution of enantiomers of verapamil and norverapamil using a cellulose-based chiral stationary phase in the reversed-phase mode, J. Chromatogr., 648 36(1993)... 

A simple, isocratic chromatographic method for the separation, identification, and measurement of etodolac enantiomers without derivitization using chiral stationary phase columns has been reported [25]. A chiral stationary phase column packed with Chiracel OD (cellulose tris-3,5-dimethylphenylcarbamate coated on 10 pm silica gel) was used as the stationary phase. The mobile phase (85 15 v/v, n-hexane/2-propanol (containing 0.1% trifluoroacetic acid)) was pumped at 0.7 mL/min and the UV detection was set at 230 nm. The (-)-(/ )-etodolac enantiomer eluted first, indicating its stronger interaction between the stationary phase relative to the (+)-(S)-etodolac enantiomer. 

The majority of preparative separations undertaken at Ultrafine have used chiral stationary phases based on either cellulose or amylose derivatives. In one project 500 mg of salts of both the (R,R)- and (S,S)-Formoterol (6) enantiomers were prepared using an OJ column with a resulting ee of >97%.45 A loading of 200 mg/mL on a semipreparative column was achievable without loss of resolution or purity relative to the racemate. 

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