Question

For each of the following, give the monosaccharide units produced by hydrolysis, the type of glycosidic bond, and the name of the disaccharide including $\alpha$or $\beta$:

Short answer

(Part a) The name of the given disaccharide is $\beta$-maltose

(Part b) The name of the disaccharide is sucrose

Step-by-step solution

Given Information of (Part a)

The disaccharide is

Explanation for (Part a)

Monosaccharide is a polyhydroxy compound that contains an aldehyde or a ketone group.

It is composed of only one unit.

When the $-OH$group on the carbon atom 1 is downward, then that isomer is called an $\alpha$isomer, and when the $-OH$group on the carbon atom 1 is upward, then that isomer is called an $\beta$isomer.

The structure of disaccharide is given below

Disaccharide on hydrolysis gives two monosaccharide units as follows:

In the given disaccharide structure, a glycosidic bond is formed between the C1 carbon atom of a glucose molecule and the C4 carbon atom of another glucose molecule.

Therefore, the glycosidic link in the given structure is $\alpha -1,4-$glycosidic bond.

The name of given disaccharide is $\beta$-maltose .

Given Information (b)

The disaccharide is

Explanation for (b)

The structure of disaccharide is given below

Disaccharide on hydrolysis gives two monosaccharide units as follows:

In the given disaccharide structure, a glycosidic bond is formed between the C1 carbon atom of a $\alpha$-D-glucose molecule and the C2 carbon atom of the $\beta$- D-fructose molecule.

Therefore, the glycosidic link in the given structure is $\alpha ,\beta -1,2-$glycosidic bond.

The name of the disaccharide is sucrose.