716 CARBOHYDRATES (c) Branched-chain sugars have a carbon substituent attached to the main chain; the carbohydrate in Problem 2520c fits this description H,C HO H CHOH (d) Only the sugar in Problem 2520d is a ketose ← Ketone carbonyl HOCH, O CH,OH CH,OH (e) A furanose ring is a five-membered cyclic hemiacetal. Only the compound in Problem 25.20 is a furanose form CHOH H (f) In D sugars, the a configuration corresponds to the condition in which the hydroxyl group at he anomeric carbon is down. The a-D sugar is that in Problem 2520d HOCH Ho→Q CHOH Anomeric hydroxyl ae-Pyranose form of a D-ketose In the a-L series the anomeric hydroxyl is up. Neither of the L sugars--namely, those of Problem 25 20a and c-is a; both are B. Back Forward Main Menu TOC Study Guide Toc Student OLC MHHE Website(c) Branched-chain sugars have a carbon substituent attached to the main chain; the carbohydrate in Problem 25.20c fits this description. (d) Only the sugar in Problem 25.20d is a ketose. (e) A furanose ring is a five-membered cyclic hemiacetal. Only the compound in Problem 25.20b is a furanose form. ( f ) In D sugars, the configuration corresponds to the condition in which the hydroxyl group at the anomeric carbon is down. The -D sugar is that in Problem 25.20d. In the -L series the anomeric hydroxyl is up. Neither of the L sugars—namely, those of Problem 25.20a and c—is ; both are . -Pyranose form of a d-ketose Anomeric hydroxyl is down. HOCH2 CH2OH HO HO HO OH O H CH2OH OH H H H H H HO OH O Ketone carbonyl in Fischer projection H OH H OH CH2OH O CH2OH C H OH H OH HOCH2 CH2OH HO HO HO OH O OH H3C OH CHO CH2OH H HO H Methyl group attached H3C to main chain OH HO HO HO O 716 CARBOHYDRATES Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website