The simple carbohydrates and the glucosides / by E. Frankland Armstrong.

  • Edward Frankland Armstrong
Date:
1910
Catalogue details

Licence: In copyright

Credit: The simple carbohydrates and the glucosides / by E. Frankland Armstrong. Source: Wellcome Collection.

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    opened a scheme identical with that just described as subsequently advocated by Lowry. , , . . The first product of the action of dry methyl alcohol containing 1 per cent, of hydrogen chloride on glucose at the ordinary temperature is a syrup differing from either glucoside. This could not be analysed, but was regarded by Fischer as glucose dimethylacetal.1 On heating this, it is in part converted into a mixture of the two glucosides in unequal quantities. A similar mixture is obtained when either gluco- side is heated with the acidified alcohol. MeOC—H CH(OMe)2 1 HC-OMe CH . OH chToiL^-^ yO CH.OH CH . OH | CH.OH CH 1 CH.OH CH/^ CH.OH CH . OH CH . OH ch2.oh ch2. OH CH2. OH a-Methyl glucoside. Glucose dimethylacetal. 0-Methyl glucoside. On the other hand, measurements of the velocity of their trans- formation made by Jungius led him to the conclusion that the two glucosides are directly convertible into each other, and that it is very improbable that an acetal is formed. Further, the reversible conver- sion of the a- and /3-tetramethyl methyl glucosides takes place at tem- peratures of 11 o°-150° independently of the nature of the solvent used : a result which excludes the intermediate formation of a compound of an acetal type. The isomeric change of one series of glucose derivatives into the other has been formulated in the foregoing on the hypothesis that additive oxonium compounds are formed in which the lactonic oxygen displays quadrivalency. Indeed no other explanation is applicable to all the transformations observed in the glucose series. Such additive oxonium compounds are well known to be formed in other cases, such as dimethylpyrone (Collie and Tickle). Recently Irvine and Moodie have brought forward evidence to show that tetramethyl glucose forms an oxonium derivative with isopropyl iodide. The presence of the etheric groups in the alkylated sugar apparently increases the basicity of the ry-oxidic oxygen atom, and so makes the identification of the oxonium compound possible. From the biological point of view, the fact that glucose exists in 1 A compound analogous to the acetal is obtained by the interaction of ethylmercaptan and glucose in presence of much hydrochloric acid. This is termed glucose ethylmercaptal, CHo(OH) . [CH(OH)]4. CH(SEt)a. It crystallises well, but cannot be converted into compounds analogous to the glucosides. 2 *
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