Diacetamide

In a diacetamide, one acetamide is easily cleaved by hydrolysis with NaOMe and MeOH, which is consistent with the use of A,A-diacetyl-aminoquinazoUne, 2-trifluoromethyl-A, A-diacetylanihne, and A-methoxydi-acetamide as amidating agents. ... 

Purex process, 6,940 Barium, pentakis(diacetamide)-stereochemistry, 1, 99 Barium alkoxides synthesis, 2,336 Barium complexes cryptands, 3,53 phthalocyanines, 2, 863 porphyrins, 2,820 pyridine oxide, 3,9 urea, 3,9... 

Strontium, aquatetrakis(diacetamide)-structure, 1,98 Strontium, heptaaqua-dodecaiodide structure, 1, 72 Strontium, octaaqua-structure, 1, 84 Strontium alkoxides synthesis, 2,336 Strontium complexes porphyrins, 2, 820 pyridine oxide, 3, 9 Structure... 

Gentile and Shankoff (28) isolated several adducts, or complexes, of simple salts with monodentate ligands. They also found that diacetamide, CH3CONHCOCH3, formed 1 2 complexes with some but not all MX,... 

The Wohl degradation can be considered to consist of two steps (a) the elimination of the acetyl and nitrile groups by the action of ammonia or ammoniacal silver oxide, and (b) the formation of the diacetamide compound. The formation of the latter was explained by Wohl on the basis of the intermediate formation of oIde%do-D-arabinose... 

XXXV), whose free aldehyde group condensed with acetamide, formed during the first step of the reaction, and gave D-arabinose diacetamide... 

Examples of the condensation of amides with aldehydes were also known at this time. Roth and Schuster, working in Strecker s laboratory, had prepared benzylidene diacetamide and anisylidene diacetamide by heating the aldehydes with acetamide. Von Richter in 1872 reported that Tawildarow obtained ethylidene diacetamide by heating acetaldehyde and acetamide, and Nencki obtained ethylidene dibenzamide by carrying out a similar reaction in the presence of hydrochloric acid. 

Evidence that the aldose diacetamides are derived from the union of preformed amides with the aldehydo form of the aldose was obtained many years later. Brigl, Miihlschlegel and Schinle, obtained n-glucose dibenzamide (XXXVIII) by the action of methanolic ammonia on penta-benzoyl-oWe%do-D-glucose (XXXVII). They studied the same reaction... 

In the case of the above mentioned benzoyl-D-glucose derivatives a correlation was found between the formation of D-glucose dibenzamide and the permanent or transitory existence of a free aldehyde group. The same behavior was noted for triacetyl-oZdehydc-L-erythrose (XLI), which by the action of ammonia produces L-erjrthrose diacetamide (XLII). Isbell and Frush have obtained a similar result in the case of tetraacetyl-oWe/it/do-L-arabinose which, when treated with methanolic ammonia, gave L-arabinose diacetamide in 53 % yield. 

Hockett and Chandler were unable to combine pentaacetyl-aZdchydo-D-glucose (XLVIII) with acetamide or to obtain n-xylose diacetamide by the action of ammonia on tetraacetyl-oZde%do-n-xylose (XLVIIIa), in spite of the existence of a free aldehyde group in both substances. 

The diacetamide compounds were regularly obtained in all degradations employing ammonia with or without silver oxide until Hockett and Chandler applied the method to hexaacetyl-D-gluco-D-flruZo-heptono-nitrile (XLIX) and obtained a monoacetamide derivative that was identified as iV-acetyl-D-glucofuranosylamine (L). The furanose structure of L was established by lead tetraacetate oxidation. They... 

According to Hockett and Chandler, the hydrolysis of an acetylated nitrile (LIII) results in the formation of an acetylated aldehydo sugar (LIV). If this compound then undergoes ammonolysis at carbon atoms 2 or 3, the formation of diacetamides is to be expected, since hemiacetal formation involving the C2 or C3 hydroxyl group is unknown. The... 

On the other hand, if ammonolysis first occurred at carbon atoms 4 or 5, the formation of a cyclic hemiacetal would be favored, and the possibility of obtaining a diacetamide would be correspondingly decreased. Such an explanation accounts for the formation of iV-acetyl-D-gluco-furanosylamine reported by Hockett and Chandler. Here, the first product of the reaction is a D-glucofuranose, which then condenses with acetamide. A similar explanation accounts for the results obtained by Brigl, Miihlschleger and Schinle with 2-thioethyl-3,4,5,6-tetrabenzoyl-oZde%do-D-glucose. 

When a Wohl degradation is carried out in the laboratory, hydrolysis of the acyl and nitrile groups begins immediately upon addition of ammonia. The rate of hydrolysis of each of the groups present in the molecule is probably different and at the present time we have no knowledge of these rates of hydrolysis. As Hockett and Chandler have pointed out, the diacetamides are obviously formed as a result of a delicate balance among the rates of several concurrent reactions. ... 

An indication of the sensitivity of the reaction to changes in the structure of the acylated nitrile is furnished by the work of Neuberg and Wolff, who obtained hydrocyanic acid from the Wohl degradation of pentaacetyl-D-glucosaminonitrile, but could not obtain a diacetamide compound. 

Recently Isbell and Frush have given an interpretation of the reactions leading to the formation of the diacetamide compounds. They admit that an aldehyde group is necessary. 

The formation of the diacetamide derivatives requires, in this theory, the existence of two acetyl groups so located in the molecule, that they can react, through the ammonia, with the aldehyde carbon. 

D-Lyxose diacetamide. Ammonia-silver oxide.y Ten grams of pentaaoetyl-n-galactononitrile was dissolved in 30 ml. of ethanol, and a solution of silver oxide (from 5 g. of silver nitrate) in 50 ml. of 30 % ammonia added. After two days at room temperature, the precipitated silver cyanide was removed by filtration and the solution evaporated in vacuo at 40° imtil all ammonia was eliminated. The residue was diluted with water and the soluble silver eliminated by treatment with hydrogen sulfide and filtration. The filtrate was treated with decolorizing carbon, filtered and evaporated to dryness. When the residue crystallized, it was suspended in warm ethanol and filtered yield, 2.5 g. (40%). After recrystallization from 60% ethanol, the product had a melting point of 230-231°. 

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. ... 

Hydrolysis of the diacetamides is effected by acids. Dilute hydrochloric, sulfuric and nitric acid have been used. An aldose with one carbon atom less than the original nitrile is then liberated from the combination. Only exceptionally can this aldose be isolated in pure condition without transforming it into an insoluble derivative in these instances, the method has been employed for preparative work. In most cases the sugar has been characterized as an osazone. The aldose, without great purification, has been employed successfully for reduction - or oxidation experiments. ... 

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. 

Diacetamides are oxidized by lead tetraacetate, and Hockett and coworkers have studied the behavior of a number of these compounds. 

The aldose dipropionamides prepared by Gim6nez have properties similar to the diacetamides, although their solubility in water is lower. 

D-Ardbinoae. Tetraacetyl-D-arabononitrile was prepared by Deu-lofeu and degraded to triacetyl-D-erythrose and D-erythrose diacetamide by ammonia-silver oxide. Hockett and Maynard improved the yield of the nitrile and by hydrolysis of D-erythrose diacetamide with 0.6 N sulfuric acid obtained D-erythrose as a sirup from which methyl D-ery-throside was prepared. 

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. 

---