Pentaacetyl glucose

FIGURE 16.5 Hydrophilic bleach activators. TAGU = tetraacetyl glycolurils DADHT = diacetyl dioxo-hexahydrotriazine PAG = pentaacetyl glucose. 

Figure 3 Structures of activators (a) TAED (tetraacetyl ethylene diamine) (b) TAGU (tetraacetyl glycoluril) (c) SNOBS (sodium nonanoyloxybenzene sulfonate) (d) iso-NOBS (isononanoyloxy-benzene sulfonate) (e) BOBS (sodium benzoyloxybenzene sulfonate) (f) DADHT (diacetyldioxo-hexahydrotriazine) (g) PAG (pentaacetyl glucose), Ac = acetyl.

The above method for preparing glucose oxime is the modification of that of Jacobi1 developed by Wohl,2 who first converted the oxime into the pentaacetyl glucononitrile by means of acetic anhydride. The latter reaction was later employed for the same purpose by Zemplen and Kiss.3... 

Die in einer Nebenreaktion gebildete Pentaacetyl-P-D-glucose wurde nicht beriicksichtigt. 

In his first paper Wohl reported the conversion of D-glucose oxime (I) into pentaacetyl-D-glucononitrile (II). 

In the case of the oximes of the aldose sugars, the situation is more complicated because of the possibility of both open-chain and cyclic structures. That aldose oximes can react in the open-chain form follows from the formation of the nitriles and from the isolation of acylated open-chain aldose oximes as secondary products in preparation of nitriles. For example, Wolfrom and Thompson, by the action of sodium acetate-acetic anhydride on n-glucose oxime, not only obtained pentaacetyl-D-glucononitrile, in 40% yield, but also isolated a small amount of hexaacetyl-oWeAydo-D-glucose oxime (V) identical with that prepared by mild acetylation of pentaacetyl-aWe%do-D-glucose oxime (IV) whose structure was assured by its formation from pentaacetyl-aldehydo-D-glucoae (III). 

Wohl isolated a hexaacetyl-D-glucose oxime from the mother liquor obtained during the preparation of pentaacetyl-D-glucononitrile. The same acetylated oxime was prepared by Behrend. Wolfrom and Thompson studied it further, and showed conclusively that it possessed a ring structure XI, for it could not be transformed into a nitrile. Because of its low specific rotation, it was assigned to the jS-d series. 

Preparation of nitrile acetates from oximes with sodium acetate and acetic anhydride. Pentaacetyl-v-glucononitrile. If only the nitrile is needed, isolation of the oxime can be avoided. One hundred grams of anhydijous n-glucose was dissolved in 50 ml. of warm water, and maintaining the temperature at 60°, a solution of 28 g. of hydro-xylamine in 700 ml. of ethanol was added sufficiently slowly that no precipitation took place. After one hour at 65°, the reaction mixture was concentrated under reduced pressure to a thick sirup. The residue was mixed with absolute ethanol, the ethanol evaporated and the operation repeated in order to eliminate all water. One hundred and twenty grams of anhydrous sodium acetate and 700 ml. of acetic anhydride were added to the sirup, and the mixture was slowly and cautiously warmed in a water bath to 95°. It was advisable to agitate the flask continuously and to watch the... 

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. 

An alternative explanation for the formation of monoacetamides has also been suggested by Hockett and Chandler, who point out that the monoamide could have been formed from the diamide by the loss of acetamide. However, this explanation seems unlikely in view of the fact that Niemann and Hays have reported the preparation of AT-acetyl-D-glucofuranosylamine by the action of ammonia on pentaacetyl-/3-D-glucose, a reaction which involves the conversion of a pyranose to a furanose ring. 

D-Glucose. WohP obtained pentaacetyl-n-glucononitrile in 40% yield by the action of sodium acetate-acetic anhydride. The nitrile when treated with ammonia-silver oxide gave a 47 % yield of n-arabinose diacetamide. Hydrolysis of the diacetamide derivative with 6 N sulfuric acid produced crystalline n-arabinose in 50-60 % yield. The process was improved by Neuberg and Wohlgemuth, who obtained n-arabinose in an over-all yield of 34.7 % of the n-glucose employed. 

Concerning the mechanism of the rearrangement of sugar acetates by aluminum chloride, there is very little to be added at the present time. The reaction proceeds equally as well with the a-octaacetate of cellobiose as it does with the /3-octaacetate of lactose.Under the most favorable conditions so far discovered, it appears that octaacetyl-lactose is converted to about equal amounts of acetochlorolactose and acetochloroneolactose similar results were obtained with octaacetyl-cellobiose. Although Kunz and Hudson believed acetochlorolactose to be the primary reaction product, which was transformed subsequently to the isomeric neolactose derivative, later experiments by Richtmyer and Hudson did not substantiate this view. In an uncompleted study of the action of a mixture of aluminum and phosphorus chlorides upon pentaacetyl-D-glucose, Richtmyer and Hudson have demon.strated that both D-altrose and n-mannose derivatives are formed by rearrangement of the D-glucose molecule. 

Since acid hydrolysis of methyl a-D-altroside leads principally to D-altrosan, it became necessary to resort to other devices in order to complete the transformation to the free sugar. The pioneer work of Robertson and his collaborators had established a clear route from D-glucose to many D-altrose derivatives. The final steps, as described by Richtmyer and Hudson, are the acetolysis of methyl o-o-altroside (XXXVIII), or more simply of its benzylidene derivative (XXXVII), followed by catalytic deacetylation of the pentaacetyl-a-D-altrose thus produced. In this way crystalline D-altrose becomes readily available. 

Problem 34.22 (-f-)-Glucose reacts with acetic anhydride to give two isomeric pentaacetyl derivatives neither of which reduces Fehling s or Tollens reagent. Account for these facts. 

Nitrous acid cleaves the pentaacetyl oximes and semicarbazones of glucose and galactose to give the aldehyde pentaacetates." The reagent cleaves benzaldehyde semicarbazone, phenylosazones, " and 4-cinnolinecarboxaldehyde hydrazone. CH=NNH2 cho... 

Displacement of bromine. Bonner treated tetracetyl-a-D-glu< t>syl bromide in chloroform with thiolacetic acid and KOH (both in 10% excess) and obtained pentaacetyl-l-thio-/8-D-glucose in good yield. 

AGLU a-form of 1,2,3,4,6-Pentaacetyl-D-glucose BGLU /f-form of 1,2,3,4,6-Pentaacetyl-D-glucose Synonyms o-Glucose pentaacetate D-Glucopyranose pentaacetate Source Raveendran, P Wallen, S. L. J. Am. Chem. Soc. (2002), 124(25), 7274-7275. 

Acetohalo- -D-glucose Pentaacetyl-/ -D-glucose Acetohalo-a-D-glucose ac = CH3CO or C6H5CO. 

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