2.3.4.5.6- Penta-O-acetyl-d-gluconic

B. 2,3,4,5,6-Penta-O-acetyl-v-gluconic acid. Tetra-O-acetyl-D-gluconic acid monohydrate (50 g., 0.13 mole) is slowly added to a chilled (0-5°) solution of 18 g. of fused zinc chloride in 190 ml. of acetic anhydride contained in a 1-1. Erlenmeyer flask. The solution is kept in an ice bath for an hour and then allowed to stand at room temperature for 24 hours. After dilution with 1 1. of water, the solution is extracted with four 100-ml. portions of chloroform. In order to remove the chloroform, 200 ml. is distilled, 250 ml. of toluene is added, and 250 ml. of this solution is distilled. Another 250 ml. of toluene is then added and the volume is reduced to 300 ml. The product crystallizes on standing at 0° (Note 2). The solid is removed by filtration, washed with toluene and then with petroleum ether (b.p. 35-55°). A yield of 44-45 g. (83-84%) of anhydrous 2,3,4,5,6-penta-O-acetyl-D-gluconic acid, melting at 110-111°, is obtained [o ]d + 11.5° (c = 4.0 in ethanol-free chloroform). 

C. 2,3,4,5,6-Penta-O-acetyl-o-gluconyl chloride. Anhydrous 2,3,4,5,6-penta-O-acetyl-D-gluconic acid (25 g., 0.062 mole) is shaken with 185 ml. of anhydrous ethyl ether in a 1-1. round-bottomed flask until most of the solid dissolves. Then 15 g. (0.072 mole) of phosphorus pentachloride is added with shaking. The flask is fitted with a calcium chloride drying tube and stored overnight at room temperature. Any solid material is removed by filtration through a fritted-glass funnel into a 1-1. round-... 

Ether is used as solvent in a procedure by Braun and Cook for the conversion of 2,3,4,5,6-penta-O-acetyl-D-gluconic acid into the acid chloride. The acid (25 g.) was shaken with 185 ml. of ether until most of it was dissolved, and phosphorus... 

Penta-Ac 2,3,4,5,6-Penta-O-acetyl-D-gluconic acid C16H22O12 406.343... 

Methyl 2,3,4,5,6-penta-O-acetyl-D-gluconate, G-250 Methyl 2,3,4,6,7-penta-O-acetyl-L-g/yccro -a. D galacto -heptopyranoside, H-38... 

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