Glucose methyl ethers, separation

This particular trimethylglucose is unique in that it was separated in crystalline form from the hydrolyzates of the methyl ethers of several naturally-occurring glucose polymers almost two decades before it was synthesized from glucose. These natural sources, which still furnish the most convenient routes for the preparation of 2,3,6-trimethyl-D-glucose, include maltose,124-128 cellobiose,127,128 lactose,122-181 starch,71,182 glycogen,188,184 cellulose,185-187 and lichenin. 188,189 The literature pub-... 

Gee and Walker reported the separation of such methylated glucose and fructose derivatives, mainly tetra- and tri-methyl ethers, as would arise from methylated sucrose derivatives. At the same time, they showed that fully methylated di- and tri-saccharides could be separated by gas chromatography. In a study on sucrose lactate, Percival and Young showed that the isomeric methyl 1,3,4-, 1,3,6-, and 1,4,6-tri-O-methyl-D-fructosides have similar retention times on 15% butanediol succinate, but are resolved on IM polyphenyl ether or 10 ethylene glycol adipate. 

The separation of those methyl ethers of n-glucose likely to be encountered in research on cellulose derivatives has also been studied. ... 

Vanillin is the second largest food additive used each year. As a consequence of limited natural sources of this ubiquitous flavor and fragrance, the bulk of commercial vanillin is synthesized from phenol (19). A two-step synthesis of vanillin from glucose via DHS intermediacy was recently reported (Figure 3) (17). DHS dehydratase-catalyzed conversion of DHS into PCA is followed by formation of the methyl ether, catalyzed by catechol-O-methyltransferase, an enzyme not native to E. coli but for which the gene (comt) has been cloned from rat liver (20). In a separate step, incubation of the resulting vanillic acid with aryl-aldehyde dehydrogenase (21) affords vanillin. 

Kircher [399] also described the GC analysis of acetals, in addition to the above-mentioned derivatives (see p. 166). He demonstrated the analysis of 4,6-O-ethylidene-D-glucose in the form of the 1,2,3-triacetate on a column packed with completely methylated hydroxyethylcellulose. The diisopropylidene derivative of glucose (retention time ca. 50 min at 200°C) was sufficiently volatile for the analysis and its methyl, ethyl and vinyl ether in the 3-position was even more volatile (retention time 16 min). Mutual separations of these derivatives have not been achieved, however, on this column. 

The first, satisfactory methylation appears to have been effected by Bourne and his colleagues,48 who prepared 6-O-methyl-D-glucose in high yield from the l,2 3,5-bis(phenylboronate), using diazomethane and boron trifluoride etherate in dichloromethane for methylation, and a final separation on a column of cellulose powder. It is this procedure which the same group used for structural analysis of triol phenylboron-ates43 (see Section 111,1) others80 have attempted to use it, but without success. 

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