Enantiomers visual resolution

In general, however, the occurence of spontaneous resolution of racemate is rare. Moreover cases in which the crystals of the enantiomers have visually distinct hemihedral face are extremely rare. 

X-ray crystal structures were used for the production of computer projected images of inclusion complexes of structural isomers, enantiomers and dlastereomers with a- or B-cyclodextrin. These projections allow for a visual evaluation of the interaction that occurs between various molecules and cyclodextrin, and an understanding of the mechanism for chromatographic resolution of these agents with bonded phase chromatography. 

FIGURE 4.4 Chromatograms showing chiral resolution of racemic compounds on (a) Microcrystalline cellulose frw(3,5-dimethylphenyl)carbamate of cellulose in the 1 1 (w/w) ratio as stationary phase. Eluent n-hexane/propan-2-ol (80 20, v/v). Visualization anisaldehyde reagent. Migration distance = 6 cm at room temperature. Enantiomers and racemic propranolol [36]. (b) Microcrystalline cellulose tris(2,3-dimethylphenyl)carbamate of cellulose in the 1 1 (w/w) ratio as stationary phase. Eluent n-hexane/propan-2-ol (90 10, w/w). Enantiomers and racemic bupranolol [36]. (c) Amino-propyl sUanized sihca gel (3 g) coated with rnj(cyclohexyl)carbamates of amylose (0.75 g) as stationary phase. Eluent n-hexane/propan-2-ol (90 10, v/v). Racemates (a) 2,2,2-trifluoro-(9-antryl)ethanol, (b) Troger s base, and (c) benzoin ethyl ether. Visualization UV (254 nm). Migration distance = 6.2 cm at room temperature [37]. 

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