Chiral stationary phases cellulose triacetate

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

Resolution of chiral tetraorganotin compounds has been achieved, using chiral auxiliary groups (equation 35), as well as the use of chromatography on chiral stationary phases, e.g. cellulose triacetate for Me(PhCMe2CH2)Ph(Ph3C)Sn. 

Only cellulose, cellulose triacetate, and silanized sihca gel impregnated with the copper(II) salt of derivatized L-hydroxyproline have been used as chiral stationary phases for the separation of enantiomeric solutes. 

X Chen, H Zou, L Yang, H Wang, O Zhang. Optical resolution of alpha-alkyl phenyl acetonitriles by HPLC on cellulose triacetate chiral stationary phases coated on underivatized silica gel. Chirality 12 599-605, 2000. 

Chiral stationary phases can exist in different forms [10] (see Fig. 8). Some selectors can be used as particulate phase materials, such as polymeric cellulose triacetate. Polymeric cellulose and amylose derivatives are often coated onto silica carrier particles so that only 20% of the CSP consists of the chiral selector. This combination of stationary phase and chiral polymer combines good chromatographic properties (due to the homogeneous particle size distribution) with a high density of chiral adsorption sites in the polysaccharide derivatives. Another approach is selected for the so-called brush-type CSPs. In these, the chiral selector is covalently bound to the surface of the silica particles. These phases show high chemical inertness and allow the use of a multitude of different mobile phases. 

Francotte, E. et ah. Chromatographic resolution of racemates on chiral stationary phases I. Influence of the supramolecular structure of cellulose triacetate, J. Chromatogr., 347, 25, 1985. 

The second system studied was the separation of the chiral epoxide enantiomers (la,2,7,7a-tetrahydro-3-methoxynaphth-(2,3b)-oxirane Sandoz Pharma) used as an intermediate in the enantioselective synthesis of optically active drugs. The SMB has been used to carry out this chiral separation [27, 34, 35]. The separation can be performed using microcrystalline cellulose triacetate as stationary phase with an average particle diameter greater than 45 )tm. The eluent used was pure methanol. A... 

For example, cyclodextrins form chiral cavities which adsorb the corresponding enantiomers with different affinity while cellulose triacetate crystallizes in the form of helical substructures in which the enantiomers may be incorporated with different rates. For amino acid derived stationary phases there are two types of enantiomer differentiating interactions a brush-like hydrogen bond and dipole interaction plus a /[-complex donor or acceptor interaction with the aromatic residues in the amino acid. 

However, only few stationary phases (i.e., cellulose and cellulose triacetate) have been commercialized as preeoated plates because of the high cost of most chiral adsorbents and the difficulty to detect analytes on stationary phases showing a strong adsorbance during exposition to UV lights. 

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