Chapter 22, Problem 7PP

Interpretation Introduction

Interpretation:

The optical activity for the given compounds is to be deduced and open-chain structure for the aldaric acid is to be written. Fischer projection formulas for D-threose and its nitric acid oxidation product is to be written and name of aldaric acids produced from D-erythrose and D-threose is to be deduced.

The structural formulas of the given compounds are to be represented and the true or false nature of the statements based on the optical activity for the given compounds, is to be deduced.

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

The molecules that are nonsuperimposable or not identical with their mirror images are known as chiral molecules.

舧 A pair of two mirror images that are nonidentical is known as enantiomers, which are optically active.

舧 The stereoisomers that are nonsuperimposable on each other and not mirror images of each other are known as diastereomers.

舧 The achiral compounds in which plane of symmetry is present internally and consists of chiral centres are known as meso compounds, but they are optically inactive.

舧 Compounds that have a plane of symmetry tend to exist in meso forms. A meso form arises when the two stereoisomers produce superimposable images, and hence, compounds having meso forms are optically inactive.

舧 When the order of progression from the group of highest priority to that of the next highest priority is clockwise, it is said to be the $\left(R\right)$ configuration

舧 When the order of progression from the group of highest priority to that of the next highest priority is anticlockwise, then it is said to be the $\left(S\right)$ configuration.