Question

b. Draw the product obtained when D-tagatose reacts with H₂ and Pt.

            c. D-tagatose is a reducing sugar. Explain how this can be the case.

            d. Draw the monosaccharide derivative(s) formed when D-tagatose reacts with      Benedict’s reagent.

            e. Draw and name the enantiomer of D-tagatose.

            f. Draw a diastereomer of D-tagatose that is a D-sugar, but is not D-fructose.

            g. Draw a-D-tagatofuranose.

            h. Draw b-D-tagatofuranose.

            i. Is a-D-tagatofuranose a reducing sugar? Why or why not?

            j. Draw a disaccharide that consists of two D-tagatofuranose residues joined by

            an a, b (2↔2) glycosidic bond.

            k. Is the disaccharide a reducing sugar? Why or why not?

Answer 1

b. Shown below is the structure of product formed by the catalytic reduction of D-Tagatose.

c. D-tagatose like other monosaccharides has a free keto group in its structure. The reducing sugars have either an aldehyde or a keto group in its structure which designates it as redcing sugar.

d. Shown below is the monosaccharide derrivative of D-tagatose when it reacts with Benedict's reagent.

e. The enantiomer of D-tagatose is L-tagatose. the structure of L-tagatose is shown below.

f. the diastereomer D-sorbose of D-Tagatose is shown below.

g. Drawn below the structure for alpha-D-Tagatofuranose

h. Drawn below is the structure of beta-D-Tagatofuranose

i. alpha-D-Tagatofuranose is not a reducing sigar, since it does not have an hemiacetal linkage.

j. Drawn below is the dissacaride for a,b-D-Tagatofuranose units.

k. The dissacahride is a non-reducing sugar. It foes not have a free OH group at the 4-position.