Chapter 28, Problem 28.72P

Interpretation Introduction

(a)

Interpretation: The glycosidic linkages of the stachyose are to be labeled.

Concept introduction: Monosaccharides are the small units of simple sugars. Polysaccharides are made up of small units of monosaccharides. These small units are joined together by glycoside linkage.

Interpretation Introduction

(b)

Interpretation: Each glycosidic linkages of the stachyose are to be classified as $\text{α}$ or $\text{β}$ and the numbers are to be used to designate the locations between two rings.

Concept introduction: Monosaccharides are the small units of simple sugars. Polysaccharides are made up of small units of monosaccharides. These small units are joined together by glycoside linkage.

Interpretation Introduction

(c)

Interpretation: The products formed on hydrolysis of stachyose are to be predicted.

Concept introduction: Glycosidic linkages are hydrolyzed in presence of acid to form cyclic hemiacetal and corresponding alcohol. Acetals in the presence of acid undergo hydrolysis to form cyclic hemiacetals.

Interpretation Introduction

(d)

Interpretation: The validation to the corresponding fact that whether stachyose is reducing sugar or not is to be stated.

Concept introduction: The reducing sugars contain hemiacetal and they undergo mutarotation. These sugars are in equilibrium with cyclic monosaccharide forms.

Interpretation Introduction

(e)

Interpretation: The product formed on treatment of stachyose with excess ${\text{CH}}_{\text{3}}\text{I}$, ${\text{Ag}}_{\text{2}}\text{O}$ is to be determined.

Concept introduction: The hydroxyl groups of monosaccharides are converted into the ether groups in presence of base and alkyl halide. Glycosidic linkages are hydrolyzed in presence of acid to form cyclic hemiacetal and corresponding alcohol.

Interpretation Introduction

(f)

Interpretation: The product formed on treatment of product in (e) with ${\text{H}}_3{\text{O}}^{+}$ is to be determined.

Concept introduction: Glycosidic linkages are hydrolyzed in presence of acid to form cyclic hemiacetal and corresponding alcohol. Acetals in the presence of acid undergo hydrolysis to form cyclic hemiacetals.