Dibenzoylglucoxlose : a natural benzoyl derivate of a new disaccharide / by Frederick Belding Power and Arthur Henry Salway.

  • Power, Frederick B. (Frederick Belding), 1853-1927
Date:
1914.]
Catalogue details

Licence: Public Domain Mark

Credit: Dibenzoylglucoxlose : a natural benzoyl derivate of a new disaccharide / by Frederick Belding Power and Arthur Henry Salway. Source: Wellcome Collection.

    7/8 (page 1068)
    Inversion of Glucoxylose.—As already stated, aqueous solutions of glucoxylose are laevorotatory, but on heating with mineral acids they become dextrorotatory, owing to the formation of dextrose and xylose. This change, being analogous to that produced when sucrose is inverted, may be termed the inversion of glucoxylose, although the optical rotations of the two primary sugars and their products of inversion are in opposite directions. Preliminary experiments showed that the change of rotation is rapidly completed by heating the glucoxylose for ten minutes at a temperature of 80° with mineral acids of 5 per cent, strength. The following experiments were according conducted: (1) 1'2780 Grams* of dibenzoylglucoxylose ( = O'7668 gram of glucoxylose) were converted into the disaccharide, as previously described, and the latter was dissolved in 100 c.c. of water. This solution gave aD —0°33/ in a 2-dcm. tube. It was then inverted by the addition of 10 c.c. of concentrated hydrochloric acid and heat- ing for ten minutes, when the rotation in a 2-dcm. tube became aD + 0°29'. (2) 1T050 Grams* of dibenzoylglucoxylose ( = 0‘6630 gram of glucoxylose) were converted into the disaccharide, and the latter was dissolved in 100 c.c. of water. This solution gave aD — 0°29/ in a 2-dcm. tube, and after inversion the rotation was aD +0°26/. With the assumption that the hydrolytic products of the disaccharide are dextrose ([a]D + 52'5°) and xylose ([o]D + 18T°), it is possible to calculate the rotation after inversion by means of the equation: a ,^(180^ + 150 B), D P 312x100 where Z = the length in decimetres of the tube in which the rotation is observed, p the weight of glucoxylose (M.W. = 312) represented by 100 c.c. of the final liquid after inversion, and A and B the specific rotations of dextrose (M.W. = 180) and xylose (M.W. = 150) respectively. Applying this equation to the experiments noted above, the calculated rotations are: (1) aD + 0°33/, and (2) aD + 0°28/, whilst the rotations found by experiment were aD-fO°29/ and aD + 0°26/ respectively. It is thus seen that the rotation of the hydrolytic products of glucoxylose is in agreement, within the limits of experimental error, with the calculated results. Since pure glucoxylose has no reducing action on Fehling’s solution, it is to be concluded that it does not contain a carbonyl