710 CARBOHYDRATES Two moles of periodic acid per mole of glycoside are required. One mole of formic acid is produced (d) There are two independent vicinal diol functions in this glycoside. Two moles of periodic acid are required per mole of substrate CHOH HO-HO OCH CHO 2HIOA HCH CH HC H OH 25.18 (a) The structure shown in Figure 25. 2 is D-(+)-xylose: therefore(-)-xylose must be its mirror image and has the L-configuration at C-4 CHO CHO D-(+)-Xylose L-(-)-Xylose (b) Alditols are the reduction products of carbohydrates; D-xylitol is derived from D-xylose by conversion of the terminal -CHO to-CH,OH CH,OH CHOH (c) Redraw the Fischer projection of D-xylose in its eclipsed conformation H CH,O H OH CHO HOH Eclipsed conformation B-D-xylopyranose Back Forward Main Menu TOC Study Guide Toc Student OLC MHHE WebsiteTwo moles of periodic acid per mole of glycoside are required. One mole of formic acid is produced. (d) There are two independent vicinal diol functions in this glycoside. Two moles of periodic acid are required per mole of substrate. 25.18 (a) The structure shown in Figure 25.2 is D-()-xylose; therefore ()-xylose must be its mirror image and has the L-configuration at C-4. (b) Alditols are the reduction products of carbohydrates; D-xylitol is derived from D-xylose by conversion of the terminal GCHO to GCH2OH. (c) Redraw the Fischer projection of D-xylose in its eclipsed conformation. HO H H OH CHO H OH CH2OH d-Xylose Eclipsed conformation of d-xylose Haworth formula of -d-xylopyranose redrawn as H H HO OH H H OH H HO OH H H H OH OH CH2O CHO O d-Xylitol H OH HO H CH2OH CH2OH H OH d-()-Xylose H OH HO H CHO CH2OH H OH l-()-Xylose HO H H OH CHO CH2OH HO H 2HIO4 H CH CH HC O O OCH3 HCH H O O  O H CH2OH OCH3 H OH HO H H H OH O 710 CARBOHYDRATES Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website