20. Carbohydrates

Write common names for the reduction and oxidation products of D-allose.

Complete the following reduction/oxidation reaction of D-idose.

In solution, glucose exists predominantly in the cyclic hemiacetal form, which does not contain an aldehyde group. How is it possible for mild oxidizing agents to oxidize glucose?

Treatment of an aldose with an oxidizing agent such as Tollens’ reagent (Section 15.5) yields a carboxylic acid. Gluconic acid, the product of glucose oxidation, is used as its magnesium salt for the treatment of magnesium deficiency. Draw the structure of gluconic acid.

Oxidation of the aldehyde group of ribose yields a carboxylic acid. Draw the structure of ribonic acid.

Draw the Fischer projection for the oxidation and the reduction products of D-xylose. What are the names of the sugar acid and the sugar alcohol produced? <IMAGE>

Draw the Fischer projection for the oxidation and the reduction products of D-mannose. What are the names of the sugar acid and the sugar alcohol produced?

Draw the Fischer projection for the oxidation and the reduction products of D-arabinose. What are the names of the sugar acid and the sugar alcohol produced? <IMAGE>

Use the Fischer projection for d-gulose in problem 13.69 to answer each of the following: (13.3, 13.5)

b. Draw the Fischer projection and name the product formed by the oxidation of d-gulose.

d-Erythritol is 70% as sweet as sucrose and contains only hydroxyl functional groups. When d-erythritol is oxidized it forms d-erythrose. Draw the Fischer projection for d-erythritol. (13.3, 13.5)

Draw the Fischer projection of the product of the oxidation of d-galactose at C1.

Will the following carbohydrates produce a positive Benedict’s test?

(a) d-glucose

Will the following carbohydrates produce a positive Benedict’s test?

(b) lactose