Chapter 21, Problem 28A

Interpretation Introduction

Interpretation:

Sugar can be referred as polyhydroxy carbonyl compounds. This terminology must be explained.

Concept Introduction:

Polyhydroxy carbonyl compounds are those which contains more than one alcoholic -OH groups along with aldehyde or ketone group.

Answer to Problem 28A

Carbohydrates have either aldehyde or ketone functional group along with hydroxyl groups.

Thus sugar can be termed as polyhydroxy carbonyl compounds.

Explanation of Solution

Sugar are two types which are aldoses and ketoses. Aldoses contain aldehyde group along with many hydroxyl groups. On the otherhand ketoses have ketone group along with many hydroxyl groups. Depending on number of carbon atoms there are many sugar like aldotriose (D-Glyceraldehyde), aldotetrose (D-Erythrose), aldopentose (D-Ribose) and aldohexose (D-Glucose). Similarly there are many ketoses depending on number of carbon atoms. One of the examples is D-Fructose which is a ketohexose.