D-Threose diacetamide

D-Threose diacetamide. (Aqua ammonia.) Thirty grams of tetraacetyl-o-xylononitrile was mixed with 300 ml. of concentrated aqua ammonia (28-29 %) and warmed on a water bath until the solid was all dissolved, and then allowed to stand for three hours. The solution was concentrated in vacuo to a thick sirup, which was dissolved in aqua ammonia and reconcentrated. The final thick sirup was dissolved in absolute ethanol and ether added to the point of turbidity. After forty-eight hours in a refrigerator the crystals which had formed were collected yield, 16.5 g. (78%). They were recrystallized by dissolution in two volumes of warm 75 % ethanol, filtration through carbon and the addition of an equal volume of absolute ethanol. The compound crystallized slowly, forming clear, sharp needles or prisms in resets, m. p. 165-167. ... 

D-Xylose. Maquenne obtained tetraacetyl-D-xylononitrile in 41% 3deld from the D-xylose employed, by treatment of the oxime with sodium acetate-acetic anhydride. From the nitrile, D-threose diacetamide was obtained in 30 % yield by the action of ammonia and it was hydrolyzed... 

Maquenne s method was improved by Hockett, who obtained the nitrile in 48% yield and the D-threose diacetamide in 78% yield the latter product was hydrolyzed with 0.1 sulfuric acid. Tetraacetyl-D-xylononitrile has been degraded by Deulofeu with sodium methoxide and also by hydrolysis of the acetyl groups with sulfuric acid. 

The rate of hydrolysis of D-threose diaoetamide by 0.1 sulfuric acid has been studied by Hockett by titration with iodine, and the rate was found to correspond approximately to that of a unimolecular reaction. The same results were obtained with D-erjrthrose diacetamide by Hockett and Majmard on following the change of rotatory power during the hydrolysis. 

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