Chapter 23, Problem 23.52SP

(a)

Interpretation Introduction

To determine: The product when D-galactose reacts with ${\text{Br}}_{\text{2}}$ and ${\text{H}}_{\text{2}}\text{O}$.

Interpretation: The product when D-galactose reacts with ${\text{Br}}_{\text{2}}$ and ${\text{H}}_{\text{2}}\text{O}$ is to be predicted.

Concept introduction: The reaction of aldose with bromine water gives aldonic acid. It is an oxidation reaction. Bromine water is used for this oxidation because it does not oxidize the alcohols group.

Galactose is a monosaccharide which contains six carbons and aldehyde group. It exists in D and L forms. It is formed from dietary lactose.

D-galactose is a sugar which is found in milk products.

(b)

Interpretation Introduction

To determine: The product when D-galactose reacts with $\text{NaOH,}{\text{H}}_{\text{2}}\text{O}$.

Interpretation: The product when D-galactose reacts with $\text{NaOH,}{\text{H}}_{\text{2}}\text{O}$ is to be predicted.

Concept introduction: Galactose is a monosaccharide which contains six carbons and aldehyde group. It exists in D and L forms. It is formed from dietary lactose.

D-galactose is a sugar which is found in milk products.

(c)

Interpretation Introduction

To determine: The products when D-galactose reacts with ${\text{CH}}_{\text{3}}\text{OH,}{\text{H}}^{+}$.

Interpretation: The products when D-galactose reacts with ${\text{CH}}_{\text{3}}\text{OH,}{\text{H}}^{+}$ are to be predicted.

Concept introduction: The reaction of aldose with ${\text{CH}}_{\text{3}}\text{OH,}{\text{H}}^{+}$ gives the methyl glycosides that are more stable.

Galactose is a monosaccharide which contains six carbons and aldehyde group. It exists in D and L forms. It is formed from dietary lactose.

D-galactose is a sugar which is found in milk products.

(d)

Interpretation Introduction

To determine: The product when D-galactose reacts with $\text{Ag}{\left({\text{NH}}_{\text{3}}\right)}_2^{+}{\text{OH}}^{-}$.

Interpretation: The product when D-galactose reacts with $\text{Ag}{\left({\text{NH}}_{\text{3}}\right)}_2^{+}{\text{OH}}^{-}$ is to be predicted.

Concept introduction: Galactose is a monosaccharide which contains six carbons and aldehyde group. It exists in D and L forms. It is formed from dietary lactose.

D-galactose is a sugar which is found in milk products.

The reaction of Tollens reagent $\text{Ag}{\left({\text{NH}}_{\text{3}}\right)}_2^{+}{\text{OH}}^{-}$ with aldose gives aldonic acid and silver. Tollens test is a test for reducing sugar.

(e)

Interpretation Introduction

To determine: The product when D-galactose reacts with ${\text{H}}_{\text{2}}\text{,}\text{Ni}$.

Interpretation: The product when D-galactose reacts with ${\text{H}}_{\text{2}}\text{,}\text{Ni}$ is to be predicted.

Concept introduction: The reaction of aldose with reducing agents ${\text{H}}_{\text{2}}\text{,}\text{Ni}$ gives alditol.

Reductions of aldose give a new asymmetric carbon atom formed in either two configurations, resulting in two epimers.

(f)

Interpretation Introduction

To determine: The product when D-galactose reacts with excess ${\text{Ac}}_{\text{2}}\text{O}$ and pyridine.

Interpretation: The product when D-galactose reacts with excess ${\text{Ac}}_{\text{2}}\text{O}$ and pyridine is to be predicted.

Concept introduction: Galactose is a monosaccharide which contains six carbons and aldehyde group. It exists in D and L forms. It is formed from dietary lactose.

D-galactose is a sugar which is found in milk products.

The reaction of aldose with excess ${\text{Ac}}_{\text{2}}\text{O}$ and pyridine to give esters is known as acylation.

(g)

Interpretation Introduction

To determine: The product when D-galactose reacts with excess ${\text{CH}}_{\text{3}}\text{I,}{\text{Ag}}_{\text{2}}\text{O}$.

Interpretation: The product when D-galactose reacts with excess ${\text{CH}}_{\text{3}}\text{I,}{\text{Ag}}_{\text{2}}\text{O}$ is to be predicted.

Concept introduction: Galactose is a monosaccharide which contains six carbons and aldehyde group. It exists in D and L forms. It is formed from dietary lactose.

D-galactose is a sugar which is found in milk products.

The reaction of aldose with excess ${\text{CH}}_{\text{3}}\text{I,}{\text{Ag}}_{\text{2}}\text{O}$ to give ether is known as alkylation.

(h)

Interpretation Introduction

To determine: The product when D-galactose reacts with ${\text{NaBH}}_{\text{4}}$.

Interpretation: The product when D-galactose reacts with ${\text{NaBH}}_{\text{4}}$ is to be predicted.

Concept introduction: The reaction of aldose with reducing agents ${\text{H}}_{\text{2}}\text{,}\text{Ni}$ and ${\text{NaBH}}_{\text{4}}$ gives alditol. Reductions of aldose give a new asymmetric carbon atom formed in either two configurations, resulting in two epimers.

Galactose is a monosaccharide which contains six carbons and aldehyde group. It exists in D and L forms. It is formed from dietary lactose.

D-galactose is a sugar which is found in milk products.

(i)

Interpretation Introduction

To determine: The product when D-galactose reacts with given reagents.

Interpretation: The product when D-galactose reacts with given reagents is to be predicted.

Concept introduction: Ruff degradation is a method which is used to shorten sugar chain. It is a two step process which starts with a bromine-water oxidation of the aldose to its aldonic acid. Then in the second step treatment of aldonic acid with hydrogen peroxide and ferric sulfate oxidizes the carbonyl group to ${\text{CO}}_{\text{2}}$ and give aldose with one fewer carbon atom. It is used primarily for the determination of structure and synthesis of new sugar.

(j)

Interpretation Introduction

To determine: The products when D-galactose reacts with given reagents.

Interpretation: The products when D-galactose reacts given reagents are to be predicted.

Concept introduction: The Kiliani Fischer synthesis is a method of lengthening an aldose carbon chain buy adding one carbon atom to the aldehyde end of the aldose.

In Kiliani Fischer synthesis, the first step involves the aldehyde carbon atom is made asymmetric with the formation of cyanohydrin. Then in the second step the hydrogenation of the following cyanohydrin gives two imines, which hydrolyzes to give aldehyde.

(k)

Interpretation Introduction

To determine: The products when D-galactose reacts with excess ${\text{HIO}}_{\text{4}}$.

Interpretation: The products when D-galactose reacts with excess ${\text{HIO}}_{\text{4}}$ are to be predicted.

Concept introduction: Galactose is a monosaccharide which contains six carbons and aldehyde group. It exists in D and L forms. It is formed from dietary lactose.

D-galactose is a sugar which is found in milk products.