Chapter 22, Problem 27P

Interpretation Introduction

Interpretation:

The names and structures of the aldohexoses based on the results of the products obtained through the reaction of these aldohexoses with phenyl hydrazine and hydrogen (in presence of catalyst) are to be given.

Concept introduction:

舧 A carbohydrate is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen-oxygen atom ratio of 2:1

舧 ${\text{HNO}}_{\text{3}}$ is an oxidizing agent.

舧 Carbohydrates are oxidized by ${\text{HNO}}_{\text{3}}$ to give aldaric acid as a product.

舧 Aldaric acids are carbohydrates having two carboxylic acids. They are formed due to oxidation reaction of aldoses with dilute ${\text{HNO}}_{\text{3}}$ and their general reaction can be represented as:

舧 Monosaccharides containing six carbon atoms and an aldehyde group are called aldohexoses.

舧 Alditols are compounds produced from aldoses or ketoses on reduction with certain reagents such as sodium borohydride (${\text{NaBH}}_{\text{4}}$) and hydrogen along with a catalyst.

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Compounds formed by the reaction of reducing sugars with excess of phenyl hydrazine are called osazones. Osazones are products of oxidation and are produced by all reducing sugars.

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Fischer projection is a way of representing the structural formulae of compounds through cross formulation of their open chain structures.