Of D-galactose

The structure of compound A was established in part by converting it to known compounds Treat ment of A with excess methyl iodide in the presence of silver oxide followed by hydrolysis with dilute hydrochlonc acid gave a tnmethyl ether of D galactose Companng this trimethyl ether with known trimethyl ethers of D galactose allowed the structure of compound A to be deduced... 

How many tnmethyl ethers of D galactose are there Which one is the same as the product derived from compound A" ... 

Although the pronounced reactivity at the C-4 position is evident, examples of the formation of polychlorinated sugars are available. Thus treatment of D-galactose (85) with sulfuryl chloride in pyridine followed... 

Problem 25.17 I Reduction of D-glucose leads to an optically active alditol (D-glucitol), whereas reduc-I tion of D-galactose leads to an optically inactive alditol. Explain. 

Deoxy-sugars. Part XVI. A Study of the Stabilities of Some Phosphoric Acid Derivatives of D-Galactose and 2-Deoxy-D-Gaiactose, A. B. Foster, W. G. Overend, and M. Stacey, /. Chem. Soc., (1951) 987-991. 

The hypothesis could also account for differences in the relative sweetness of sugars by simple consideration of the way in which configurational differences might affect hydrogen bonding. The sweetness of D-galactose... 

The disaccharide derivatives 196 and 197 of N-tosyl-L-serine, of interest for the study of D-galactose-binding lectins, were prepared by Kaifu and Osawa148 from 194 and 195, respectively, by protection of 0-4 and -6 with a benzylidene group, condensation of the acetal with tetra-O-acetyl-a-D-galactopyranosyl bromide (110) under Koenigs-Knorr conditions, and deprotection. 

The product retains, however, the configuration of D-galactose and is in fact methyl trimethyl-D-galactopyranoside (LII). The intermediate formation of a 1,3-anhydro ring is postulated. 

The only other araban which has hitherto been examined from the point of view of its chemical structure is the one present in gum traga-canth.38 This araban has properties similar to those of the araban just described, but in addition to L-arabinose it contains a small amount of D-galactose. 

The sirup and the crystalline acid (VIII), when oxidized with sodium periodate, gave the same aldehydes as those produced by the oxidation of the ester from D-glucose (II) and its saponification product (XXX), respectively. Hence, the mechanism of the reaction of D-galactose is the same as that of D-glucose and D-mannose. Moreover, the approximate yield from... 

Recently,14 the acid VIII (from the condensation of D-galactose with ethyl acetoacetate) was dehydrated by heating its aqueous solution, but no crystalline product was isolated. Nevertheless, the changes in the optical rotation of the sirup and its reaction with periodic acid indicated that anhydride formation had occurred. Up to the present, efforts to isolate the dialdehyde... 

A mixture of 10 g. of D-galactose, 10 ml. of ethyl acetoaeetate, 10 ml. of ethanol, and 5 g. of zinc chloride is heated on a steam bath during 75 minutes. The mixture is cooled, 45 ml. of water is added, and the solution is extracted with two 30-ml. portions of benzene. The aqueous layer is then extracted with nine 15-ml. portions of ethyl acetate. The united extracts are washed successively with an aqueous solution of sodium bisulfite and with an aqueous solution of sodium bicarbonate, dried with anhydrous sodium sulfate, filtered, and the filtrate evaporated to dryness, affording 4.5 g. of a sirup. This is saponified with 12.5 ml. of 10% sodium hydroxide solution, and then acidified (to Congo Red) with phosphoric acid. The aqueous solution is extracted with successive 30-ml. portions of ethyl acetate, and these are dried with anhydrous sodium sulfate, and individually evaporated to dryness. Extracts after the fourth yield a solid product m. p., 130°. Recrystallized from petroleum ether plus acetic acid, the compound has m. p. 132-134° yield, variable, ca. 2%.54... 

Maher, George G., The Methyl Ethers of the Aldopentoses and of Rhamnose and Fucose, X, 257-272 Maher, George G., The Methyl Ethers of D-Galactose, X, 273-282 McColloch, R. J. See Kertesz, Z. I. McDonald, Emma J., The Polyfructo-sans and Difructose Anhydrides, II, 253-277... 

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