DL-Idaric acid

The optically inactive carbohydrate bio-inonose, QH10O5, reduces Benedict s solution, but does not react with bromine water. It is reduced to R and S, of formula C6H12O6. Compounds R and S are oxidized by HIO4 to six moles of HCOOH, and react with acetic anhydride to yield products of formula CigH240i2. Vigorous oxidation of bio-inonose yields DL-idaric acid (the dicarboxylic acid from idose) as the only six-carbon fragment. 

Postemak, on the other hand, applied the alkaline permanganate oxidation to scyllo-myo-inosose (bioinosose) and obtained DL-idaric acid (4 ). This evidence simultaneously establishes the configurations of the inosose, m o-inositol, and scj/Zto-inositol. The only configuration compatible with the recovery of DL-idaric acid from the inosose is ... 

This oxidation, as employed by Posternak, was very useful in elucidating the configuration of the inositols (see above). From mj/o-inositol, S. and T. Posternak obtained DL-talaric and DL-glucaric acids. From myo-inosose-2, T. Posternak obtained DL-idaric acid. In these instances, the ring was opened to form dibasic acids. d-Quercitol was oxidized by Posternak (6S) to 3-deoxy-D-galactaric acid. In all these oxidations, it was necessary to maintain low temperatures. 

It was converted into its crystalline bis(phenylhydrazone), bis[(p-nitrophenyl)hydrazone], and bis[(dinitrophenyl)hydrazone]. It was oxidized with peroxyacetic acid and esterified with diazoethane, yielding a crystalline product identical with diethyl tetra-O-acetyl-DL-idarate prepared by another method. 

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