(f)Amylose is a polysaccharide. Its glycoside linkages are inert to Benedict’s reagent, but the ter-minal glucose residues at the ends of the chain and its branches are hemiacetals in equilibriumwith open-chain structures. A positive test is expected.25.15Because the groups at both ends of the carbohydrate chain are oxidized to carboxylic acid functions,two combinations of one CH2OH with one CHO group are possible.L-Gulose yields the same aldaric acid on oxidation as does D-glucose.25.16In analogy with the D-fructose -D-glucose interconversion, dihydroxyacetone phosphate andD-glyceraldehyde 3-phosphate can equilibrate by way of an enediol intermediate.25.17(b)The points of cleavage of D-ribose on treatment with periodic acid are as indicated.Four moles of periodic acid per mole of D-ribose are required. Four moles of formic acid and
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