Carbohydrates, acetals, chromatography

The Gas-Liquid Partition Chromatography of Carbohydrate Derivatives. Part III. The Separation of Amino Glycose Derivatives and of Carbohydrate Acetal and Ketal Derivatives, H. G. Jones, J. K. N. Jones, and M. B. Perry, Can.]. Chem., 40 (1962) 1559 -1563. 

The only other carbohydrate acetates that have been examined by gas-liquid chromatography are the fully acetylated 2-amino-2-deoxy-D-glucose... 

Jones and coworkers were the first to report a separation of carbohydrate acetals by gas-liquid chromatography. They employed a column (117 x 0.5 cm inside diameter) packed with 40 cm of an intimate 1 1 (v/v) mixture of 20% (wt./wt.) Apiezon M grease on Chromosorb W and 20% (wt./wt.) of butanediol succinate polyester on Chromosorb W, on top of 77 cm of 1% (wt./wt.) of SE-30 medium on glass beads. The temperature of the column was kept at 206°. With... 

Figure 12.1. Thin layer chromatography of the separation of carbohydrates A, chromatography of mono-, di-, and trisaccharides on Whatman K5 silica gel, using four ascents of acetonitrile/H20 (85 15, v/v) (1 16), standards, (2), D-ribose, (3) D-xylose, (4) D-fruc-tose, (5) D-xylose, (6) D-galactose, (7) sucrose, (8) turanose, (9) maltose, (10) cellobiose, (11) lactose, (12) a,a-trehalose, (13) melibiose, (14) melezitose, (15) raffinose B, chromatography of maltodextrins (d.p. 1-13) on Whatman K5, using three ascents of acetoni-trile/ethyl acetate/propanol-l/H20 (85 20 50 50) C, chromatography of isomaltodextrins (d.p. 1-11) on Whatman K5, using acetonitrile/ethyl acetate/propanol-l/H20 (85 20 50 90).

Separation and quantitation of carbohydrate mixtures may be achieved using HPLC, a method that does not necessitate the formation of a volatile derivative as in GLC. Both partition and ion-exchange techniques have been used with either ultraviolet or refractive index detectors. Partition chromatography is usually performed in the reverse phase mode using a chemically bonded stationary phase and acetonitrile (80 20) in 0.1 mol U1 acetic acid as the mobile phase. Anion- and cation-exchange resins have both been used. Carbohydrates... 

Most carbohydrates are not sufficiently volatile to be used for gas-liquid chromatography, and they must therefore be converted into volatile compounds. The most usual derivatives for this purpose are trimethylsilyl (Me3Si) ethers, acetates, and trifluoroacetates. An extensive review on the trimethylsilylation of organic compounds has been written by Pierce.107... 

Steinberg, R, and Fox, A. (1999), Automated derivatization instrument Preparation of alditol acetates for analysis of bacterial carbohydrates using gas chromatography-mass spectrometry, Anal. Chem.,11,1914-1917. 

There is much current interest in the development of simple and effective methods for the conversion of selectively functionalised carbohydrates into stereodefined cyclopentanols, and South African chemists have reported an excellent samarium diiodide-based process. Thus, dropwise addition of the iodoglucoside 1 to a refluxing solution of excess of samarium diiodide in THF/HMPA, and heating of the mixture under reflux for 2 hours followed by cooling, dilution with 1 1 hexane/ethyl acetate and quenching with 5% aqueous citric acid gave the pure cyclopentanol 2 in 70% yield after flash chromatography. 

B. A. Dmitriev, L. V. Backinowsky, O. S. Chizhov, B. M. Zolotarev, and N. K. Kochetkov, Gas-liquid chromatography and mass spectrometry of aldononitrile acetates and partially methylated aldononitrile acetates, Carbohydr. Res., 19 (1971) 432 135. 

---