Heptitols analysis

Attempts to use 4,5,7-tri-0-acetyl-2,6-anhydro-l,3-dideoxy-l-iodo-D-giuco-heptitol for x-ray analysis were unsuccessful, because only twinned crystals could be prepared. Use of die deacetylated p-toluenesulfonate, namely, 2,6-anhydro-3-deoxy-l-0-p-tolylsulfonyl-D-gl co-heptitol, and of the parent alditol, 2,6-anhydro-3-deoxy-D-glaco-hepti-tol, was unsuccessful because no atom of sufficient electron density was present. 

An isolated example of the use of x-ray diflraction analysis is provided by the work of Camerman and coworkers. Hydroformyl-ation of 3,4,6-tri-O-acetyl-D-glucal gave 4,5,7-tri-0-acetyl-2,6-anhydro-3-deoxy-D-gIuco- and -D-manno-heptitols, which were converted into the corresponding 1-p-bromobenzenesulfonates. One of these sulfonates was shown hy x-ray analysis to have the CJ(d) conformation in which all of the substituents are oriented equatorially hence, this sulfonate was the D-gluco isomer. 

Improved procedures for the preparation and g.c. analysis of peracetylated aldoses have been developed. Acetylation (AcjO-l-raethylimidazole) can be performed directly on acid hydrolysates, and factors influencing the ratios of isomers produced have been studied. This method was compared with the alditol acetate procedure for the quantitative analysis of four plant materials. G.l.c.-m.s. data have been reported for partially methylated and acetylated derivatives of L-gfycero-n-manno- and n-gfycero-D-manno-heptoses and -heptitols. ... 

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