Amides of glucuronic, galacturonic, and mannuronic acids.

Heretofore the amides of glucuronic, galacturonic, and mannuronic acid were not known, and methods were not available for their preparation. It has now been found possible to obtain the amides of uronic acids from the corresponding 1-amino-uronamides by selective hydrolysis of the glycosylamino group. An aqueous solution of the 1-amino-uronamide is treated with an acid or a suitable cation exchange resin that replaces the glycosylamino group by a hydroxyl, forming the free amide. The new compounds, like the sugars, have a free reducing group, and hence they are capable of existing in the pyranose, furanose, and open-chain forms and of displaying mutarotation. D-Glucuronamide, D-mannuronamide, and D-galacturonamide were separated in the alpha pyranose form. The beta pyranose modification of D-galacturonamide was also obtained. The amides are stable crystalline substances, that should prove to.be useful representatives of a new class of carbohydrate derivatives.