Chapter 5, Problem 67P

Interpretation Introduction

(a)

Interpretation: The relation between given pair of compounds is to be determined.

Concept introduction: The stereogenic centers with $R,S$ configuration are assigned according to Cahn-Ingold-Prelog rules. According to these rules, the substituents attached to stereogenic centers are given priority. On moving from higher priority to lower priority substituent in clockwise direction, the compound is assigned with $R$ configuration. On moving from higher priority to lower priority substituent in anticlockwise direction, the compound is assigned with $S$ configuration.

Enantiomer of a compound has opposite configuration at stereogenic centers. Diastereomers of a compound have at least one stereogenic centre with same configuration and at least one with opposite configuration.

Interpretation Introduction

(b)

Interpretation: Each compound is to be labeled as chiral or achiral.

Concept introduction: An atom containing four different atoms or groups, which produce stereoisomers on exchange of any two groups. These centers are known as stereogenic centers.

Interpretation Introduction

(c)

Interpretation: Among the given compounds, optically active compounds are to be determined.

Concept introduction: The phenomenon by which a chiral molecule is observed to rotate the plane polarized light in either a clockwise direction or anticlockwise direction is called as optical activity of the molecule.

Interpretation Introduction

(d)

Interpretation: Among the given compounds, compounds which have plane of symmetry are to be determined.

Concept introduction: An imaginary plane which bisects the molecule into halves such that these halves are mirror images of each other. This is known as plane of symmetry.

Interpretation Introduction

(e)

Interpretation: Among the given pair of compounds, boiling points is to be compared.

Concept introduction: Enantiomers are stereoisomers, which are non-superimposable images of each other. They have identical physical and chemical properties in symmetric environment. They rotate the plane-polarized light in equal amounts and in opposite directions.

Diastereomers of a compound have at least one stereogenic centre with same configuration and at least one with opposite configuration. Diastereomers of compound do not have mirror image relationship. They have different physical and chemical properties.

Interpretation Introduction

(g)

Interpretation: Equal mixtures of compounds C and D and compounds B and C is optically active or not is to be predicted.

Concept introduction: Enantiomers are stereoisomers, which are non-superimposable images of each other. They have identical physical and chemical properties in symmetric environment. They rotate the plane-polarized light in equal amounts and in opposite directions.

Diastereomers of a compound have at least one stereogenic centre with same configuration and at least one with opposite configuration. Diastereomers of compound do not have mirror image relationship. They have different physical and chemical properties.