Cyclodextrin octakis

VII = Heptakis (2,6-di-0-methyl-3-0-pentyl)--P--cyclodextrin + Octakis (2,6-di--0-methyl-3-0-trifluoroacetyl)-y-cyclodextrin... 

Polytosylated cyclodextrins (octakis[6-0-tosyl]-2-0-tosyl-y-cyclodextrin and octakis- and heptakis[6-0-tosyl]-7-cyclodextrin) were separated on an aminopropyl column (A = 220 nm) using a 50-min 100/0 70/30 acetonitrile/water gradient... 

VIII = Octakis (2,3-di-0-acetyl-6-0-tert-butyldimethylsilyl)--y--cyclodextrin... 

It had been reported that fullerene Cgo forms a water-soluble complex with y-cyclodextrin by heating with an excess amount of y-cyclodextrin in water [10] or in a mixture of refluxing water and toluene for a long time, such as 30 h [ 11]. The isolated complex is considered to have the Cgo structure bicapped with y-cyclodextrin in a molar ratio of 1 2 [11], and the complex dissolved in water to give a solution of C o with a concentration of nearly 10 mol L 410,11 ]. Fullerene Qo was also solubilized in water by complexation with a sulfocalix[8] arene, i.e., calix-[8]aryloxy-49,50,51,52,53,54,55,56-octakis(propane-3-sulfonate). The concentration of this complex in water is estimated as 5x10 mol L [12]. Complex formation between fullerene and various calixarenes has also been reported [8]. 

Figure 19. Enantiomer separation of Q 2,4-dimcthyl-l-hcptcnc. (Z)-3,3,8,8-tetramethylcyclooctene. tricarbony](t/4-2-mcthylene-l,3-butanediyl)iron(0) and (a)-1,2,3,4,5.6-hexachlorocyclohexane on octakis(2.3,6-tri-0-pentyl)-y-cyclodextrin (50 m x 0.25 mm glass capillary column, at 60, 95, 80 and 190 °C, respectively. 1 bar hydrogen)175 176.

Fused silica column (30 m X 0.32 mm i.d. film thickness 0.32 pun) coated with octakis (2,3-di-0-butyryl-6-0-tertbutyldimethylsilyl)-y-cyclodextrin (50% in OV-1701 vinyl)... 

Lipodex E [octakis(3-0-butanoyl-2,6-di-0- -pentyl)-y-cyclodextrin] dissolved in a polysiloxane matrix (SE-54) was used as a chiral receptor. The binding strength of the analyte molecules depends on the interaction mech-... 

Enantioselective SMB-GC has been realized adapting the results previously obtained in the batch processes described above. Preliminary studies involved racemic enflurane with a separation factor of a 2 (Juza et al., 1998a Juza et al., 1998b Biressi et al., 2000) and isoflurane (Biressi et al., 2002a) which were separated on unpurified octakis(3-0-butanoyl-2,6-di-0-n-pentyl)-7-cyclodextrin, Lipodex E, in polysiloxane SE-54 and coated on Chromosorb P (AW, DMCS, 80-100 mesh). 

Konig, W. A., Krebber, R., and Mischnick, P. (1989) Cyclodextrins as chiral stationary phases in capillary gas chromatography. Part V octakis(3-0-butyryl-2,6-di-0-pentyl)-7-cyclo-dextrin. J. High Resol. Chromatogr. 12, 732-738,... 

Octakis (2,3,6-tri-0-methyl-gamma-cyclodextrin) was used to separate enantiomers of methyl esters of deltametrinic acid and permetrinic acid the positional isomers of nitrotoluene were also separated on the same column [17,18]. Various alkyl- and dialkyl-benzenes have been separated on beta- and gamma-cyclodextrin [19]. A complete review of the use of cyclodextrins in chromatography has been published by Hinze [20]. Cyclo-dextrins have been analyzed by packed-column gas chromatography as their dimethylsilyl ethers [21]. 

The extent of stereoselectivity in the chiral synthesis can be checked by determining the enantiomeric excess of the optically active olefins in the products. The optical purity was determined by gas chromatographic resolution of enantiomers by means of an optically active column. Thermostable substituted cyclodextrins are well suited as asymmetric phases (206). The trimer, 2,4-dimethyl-l-heptene, was resolved into its enantiomers by capillary gas chromatography with an octakis(6-0-methyl-2,3-r/-0-pentyl-)-7-cyclodextrine phase. 

Fig. 24. Asymmetric oligomerization of propylene at various temperatures gas-chromatographic separation of 2,4-dimethyl-2-heptene (trimer) in a capillary column coated with octakis(6-0-methyl-2,3-di-0-pentyl)cyclodextrin) (204).

Although enantiomer separation of amino adds has always been a domain of chiral diamide phases such as Chirasil-val (1] or XE-60-L-val- S)-a-phenylethylamide [2], the development of hydrophobic cyclodextrm derivatives has affected even this field of applications of enantioselective gas chromatography. Octakis(3-O-butyryl-2,6-di-0-pentyI)-7-cyclodextrin [Lipodex E , (32) (see footnote on p. 115)] is highly selective for amino acid enantiomers. Since hydrogen bonding is not necessary for a determination of the enantiomers, some unusual amino adds can be separated that could not be resolved before, including p-amino adds, a-alkylated, and N-alkyl-ated amino adds. 

Figure 7 Enantiomer separation of trifluoroacetylated tocainide on a 10 m fused silica capillary with 3-bu-2,6-pe--y-CD [= octakis(3-0-butyryl-2,6-di-Opentyl)-y-cyclodextrin] (60 40, w/w, mixture with polysiloxane OV1701).

Figure 11 Enantiomer separation of (rans-sobrerol (TFA derivative). 25 m Fused silica capillary on Pyrex glass capillary with 6-me-2,3-pe -CD [= octakis(6-0-methyl-2,3-di-0-pentyl)-y-cyclodextrin] at 75 C, (Irifluoroacetylation as in Fig. 9.)...

Likewise, chiral 5-lactones are known as characteristic flavouring compounds of fruits and dairy products /74y.Their stereodifferentiation was achieved with modified y-cyclodextrin by Konig et al. [84] and their chromatographic behaviour interpreted by coinjection with enantiopure references, as described by Palm et al. [36]. Using enantio-MDGC and the column combination OV 1701/octakis(3-O-butyryl-2,6-di-O-pentyl)-y-cyclodextrin the simultaneous stereodifferentiation of all aroma-relevant 4(5) alkylsubstituted y(5)-lactones has been reported recently [42, 85] (Fig. 6.30). 

W.A. Kbnig, R. Krebber and P. Mischnick. Cyclodextrins as Chiral Stationary Phases in Capillary Gas Chromatography. Part V Octakis (3-0-butyryl-2,6-di-0-pentyl)-y-cyclodextrin. J. High Reso-lut. Chromatogr., 12, 732-738 (1989). 

The derivative corresponds to the octakis (2,6 di O pentyl-3-O trifluoroacetyl) -y-cyclodextrine... 

A. Suing, O. Beakers, J. H. Beijnen, W. J. M. Underberg, T. Tanimoto, K. Koizumi, and M. Otagiri, Stabilization of daunorubicin and 4-demethoxydaunorubicin on complexation with octakis(2,6-di-0-methyl)-y-cyclodextrin in acidic aqueous solution, Int. J. Pharm. 82, 29-37(1992). 

Cyclodextrin Ethers. - Octakis 6-0-Tbdms-Y -CD underwent selective 2-... 

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