Chapter 18, Problem 18.125EP

(a)

Interpretation Introduction

Interpretation: The configuration of the given disaccharide has to be specified.

Concept introduction: In a cyclic monosaccharide, the replacement of an $-\text{OH}$ group of the hemiacetal carbon by an $-\text{OR}$ group results in the formation of an acetal.  The acetal formed is known as a glycoside.  If both the $-{\text{CH}}_{\text{2}}\text{OH}$ group and $-\text{OR}$ group points in the same direction, then the configuration is $\beta$.  If both the $-{\text{CH}}_{\text{2}}\text{OH}$ group and $-\text{OR}$ group points in different direction, then the configuration is $\alpha$.

(b)

Interpretation Introduction

Interpretation: The configuration of the given disaccharide has to be specified.

Concept introduction: In a cyclic monosaccharide, the replacement of an $-\text{OH}$ group of the hemiacetal carbon by an $-\text{OR}$ group results in the formation of an acetal.  The acetal formed is known as a glycoside.  If both the $-{\text{CH}}_{\text{2}}\text{OH}$ group and $-\text{OR}$ group points in the same direction, then the configuration is $\beta$.  If both the $-{\text{CH}}_{\text{2}}\text{OH}$ group and $-\text{OR}$ group points in different direction, then the configuration is $\alpha$.

(c)

Interpretation Introduction

Interpretation: The configuration of the given disaccharide has to be specified.

Concept introduction: In a cyclic monosaccharide, the replacement of an $-\text{OH}$ group of the hemiacetal carbon by an $-\text{OR}$ group results in the formation of an acetal.  The acetal formed is known as a glycoside.  If both the $-{\text{CH}}_{\text{2}}\text{OH}$ group and $-\text{OR}$ group points in the same direction, then the configuration is $\beta$.  If both the $-{\text{CH}}_{\text{2}}\text{OH}$ group and $-\text{OR}$ group points in different direction, then the configuration is $\alpha$.

(d)

Interpretation Introduction

Interpretation: The configuration of the given disaccharide has to be specified.

Concept introduction: In a cyclic monosaccharide, the replacement of an $-\text{OH}$ group of the hemiacetal carbon by an $-\text{OR}$ group results in the formation of an acetal.  The acetal formed is known as a glycoside.  If both the $-{\text{CH}}_{\text{2}}\text{OH}$ group and $-\text{OR}$ group points in the same direction, then the configuration is $\beta$.  If both the $-{\text{CH}}_{\text{2}}\text{OH}$ group and $-\text{OR}$ group points in different direction, then the configuration is $\alpha$.