Galactometasaccharinic acids

Deoxy-D-xy/o-hexonic acid (a-D-galactometasaccharinic acid, 111) can be prepared from D-galactose 289 the / -(d-lyxo) isomer can be isolated in smaller amounts from the mother liquors. 

Deoxy-D-a 2/io-hexonic acid ( a -D-galactometasaccharinic acid) was first detected as a product of the prolonged action of lime-water on lactose... 

Deoxy-D-l2/a o-hexonic acid ( /3 -D-galactometasaccharinic acid) was discovered by Kiliani and Sanda as a minor product of the n-galactose-al-kali reaction. Kiliani believed that this product was a new type of branched-chain saccharinic acid, and referred to it throughout subsequent publications as parasaccharinic acid. The evidence, provided both by his own work and that of Nef, that Kiliani s parasaccharinic acid contained, in fact, the epimer of a -D-galactometasaccharinic acid, is outlined on page 56. 

S) fi"-D-Galactometasaccharinic Acid.—Kiliani and Sanda reduced their parasaccharinic acid in the usual manner with hydriodic acid and red phosphorus. The product was a hexanoic lactone whose boiling point (217.5°) was precisely intermediate between that (220°) of the n-hexanoic 1,4-lactone obtained by a similar reduction of a -D-galactometasaccharinic acid and that (215°) reported for 2-ethylbutyro-l, 4-lactone. Kiliani, however, chose the latter structure for his lactone, since the corresponding acid, like DL-(2-ethyl-4-hydroxybutyric acid) and unlike either the enantiomor-... 

It is interesting that Nef assigned the correct configurations to the D-galactometasaccharinic acids, as well as to the D-glucometasaccharinic acids, on the basis of analogies between the optical rotations of n-tartaric acid, the 2,4-dihydroxyglutaric acids (obtained by oxidation of the five-carbon metasaccharinic acids), and the 2,3,5-trihydroxyadipic acids (obtained by oxidation of the six-carbon metasaccharinic acids). 

Crystalline calcium, copper, lead, and strontium salts have also been reported for a -D-galactometasaccharinic acid. 

L-lyxo-fbrm. L-Parasaccharinic acid. fi-L-Galactometasaccharinic acid... 

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