Chapter 26, Problem 66E

Interpretation Introduction

(a)

Interpretation:

The structure of (R)-1-bromo-1-chloroethane should be drawn.

Concept introduction:

Enantiomers are optical isomers, which can rotate the plane polarized light clockwise or anticlockwise. These molecules must have at least one chiral C atom, i.e., the carbon atom bonded with four different groups. They are assigned by R and S configuration.

The R/S naming follows the Cahn-Ingold-Prelog Rules for naming the enantiomer as R or S-enantiomer. According to Cahn-Ingold-Prelog rules, assign the numbers from 1 to 4 to the groups bonded with chiral C atom on the basis of their molar mass. The essential condition is that the 4^th group or atom must be below the plane. If the movement from 1(2(3 group is clockwise, then it will be R-configuration, and if it is anticlockwise, then it will be S-configuration.

If the 4^th number group is in plane, then follow the following steps:

• Swap the 4^th group with the group with the group present below the plane.
• Assign R/S configuration with clockwise or anticlockwise movement.
• Flip the configuration to get the real configuration.

If the 4^th number group is in above the plane shown by wedge line, then follow the following steps:

• Swap the 4 group with the group with the group present below the plane.
• Assign R/S configuration with clockwise or anticlockwise movement.

Interpretation Introduction

(b)

Interpretation:

The structure of (E)-2-bromopent-2-eneshould be drawn.

Concept introduction:

Alkenes are unsaturated hydrocarbons with double covalent bond between carbon-carbon atoms. On the basis of groups bonded with the double bonded carbon atoms, alkenes can be classified as E and Z-configuration.

The E-configuration stands for anti-configuration, whereas, Z-configuration stands for same side configuration.

The determination of configuration is done on the basis of the atomic/molecular mass of the atoms/groups attached to double bonded carbon atoms. If both higher atomic/molecular mass atom/groups are placed at the same side, then it is said to be Z-configuration and in E-configuration, these groups will be at anti-position.

Interpretation Introduction

(c)

Interpretation:

The structure of (Z)-1-chloro-3-ethylhept-3-ene should be drawn.

Concept introduction:

Alkenes are unsaturated hydrocarbons with double covalent bond between carbon-carbon atoms. On the basis of groups bonded with the double bonded carbon atoms, alkenes can be classified as E and Z-configuration.

The E-configuration stands for anti-configuration, whereas, Z-configuration stands for same side configuration.

The determination of configuration is done on the basis of the atomic/molecular mass of the atoms/groups attached to double bonded carbon atoms. If both higher atomic/molecular mass atom/groups are placed at the same side, then it is said to be Z-configuration and in E-configuration, these groups will be at anti-position.

Interpretation Introduction

(d)

Interpretation:

The structure of (R)-2-hydroxypropanoic acidshould be drawn.

Concept introduction:

Enantiomers are optical isomers, which can rotate the plane polarized light clockwise or anticlockwise. These molecules must have at least one chiral C atom, i.e., the carbon atom bonded with four different groups. They are assigned by R and S configuration.

The R/S naming follows the Cahn-Ingold-Prelog Rules for naming the enantiomer as R or S-enantiomer. According to Cahn-Ingold-Prelog rules, assign the numbers from 1 to 4 to the groups bonded with chiral C atom on the basis of their molar mass. The essential condition is that the 4^th group or atom must be below the plane. If the movement from 1(2(3 group is clockwise, then it will be R-configuration, and if it is anticlockwise, then it will be S-configuration.

If the 4^th number group is in plane, then follow the following steps:

• Swap the 4^th group with the group with the group present below the plane.
• Assign R/S configuration with clockwise or anticlockwise movement.
• Flip the configuration to get the real configuration.

If the 4^th number group is in above the plane shown by wedge line, then follow the following steps:

• Swap the 4 group with the group with the group present below the plane.
• Assign R/S configuration with clockwise or anticlockwise movement.

Interpretation Introduction

(e)

Interpretation:

The structure of (S)-2-aminopropanoate anionshould be drawn.

Concept introduction:

Enantiomers are optical isomers, which can rotate the plane polarized light clockwise or anticlockwise. These molecules must have at least one chiral C atom, i.e., the carbon atom bonded with four different groups. They are assigned by R and S configuration.

The R/S naming follows the Cahn-Ingold-Prelog Rules for naming the enantiomer as R or S-enantiomer. According to Cahn-Ingold-Prelog rules, assign the numbers from 1 to 4 to the groups bonded with chiral C atom on the basis of their molar mass. The essential condition is that the 4^th group or atom must be below the plane. If the movement from 1(2(3 group is clockwise, then it will be R-configuration, and if it is anticlockwise, then it will be S-configuration.

If the 4^th number group is in plane, then follow the following steps:

• Swap the 4^th group with the group with the group present below the plane.
• Assign R/S configuration with clockwise or anticlockwise movement.
• Flip the configuration to get the real configuration.

If the 4^th number group is in above the plane shown by wedge line, then follow the following steps:

• Swap the 4 group with the group with the group present below the plane.
• Assign R/S configuration with clockwise or anticlockwise movement.