Disaccharide - Online Tutor, Practice Problems & Exam Prep

Is the following mechanism correct for the reaction between α-glucose and β-glucose in dilute HCl that forms α-maltose?

Lactose is a sugar molecule made up of two subunits: D-glucopyranose and D-galactopyranose. These subunits are connected by a β-1,4′-glycosidic linkage. In an experiment, lactose was treated with two chemical processes: first with methyl iodide (CH₃I) in excess with silver oxide (Ag₂O), then with HCl/H₂O. After these treatments, it was observed that the D-galactopyranose part had only one hydroxyl (OH) group that wasn't converted to a methoxy group, while the D-glucopyranose part had two such groups. Draw the structure of α-lactose based on this information.

For the disaccharide depicted: (i) determine its reducing end, (ii) specify the monosaccharides that constitute it, and (iii) describe the type of its glycosidic bond.

For the disaccharide below: (i) determine its reducing end, (ii) specify the monosaccharides that constitute it, and (iii) describe the type of its glycosidic bond.

Isomaltose (as shown below), like maltose, is also comprised of two glucose units. Contrast the two. (Note: The image shown below is isomaltose.)

Provide the reaction equation that represents how Tollen's reagent gets reduced by the α-anomer lactose.

Show the structures of the sugar derivatives given below.

4-O-(β-D-glucopyranosyl)-D-galactopyranose

Propose the plausible structures of the mutarotating α and β forms of the disaccharide lactose.

(i) Does D-cellobiose mutarotate? (ii) Can we classify D-cellobiose as a non-reducing or reducing disaccharide? (iii) Provide the structure of its anomers.

Consider a theoretical nonreducing sugar with a molecular formula of C₁₂H₂₂O₁₁, which forms only D-galactose when hydrolyzed by the enzyme maltase. When it is treated with excess CH₃I in the presence of Ag₂O and then hydrolyzed, only 2,3,4,6-tetra-O-methyl-D-galactose is formed. Draw the structure of the described sugar.