Chapter C, Problem C.19P

Interpretation Introduction

(a)

Interpretation:

The configuration of each asymmetric carbon in the given molecule is to be designated as R or S.

Concept introduction:

When assigning priorities to substituents, the atom having the greater atomic number has higher priority. In case of comparison between isotopes, the one having the greater atomic mass gets higher priority. When the fourth priority substituent is pointing away (it is attached by a dash bond) and the first, second, and third priority substituents are arranged clockwise, the configuration is R. When the fourth priority substituent is pointing away (it is attached by a dash bond) and the first, second, and third priority substituents are arranged counterclockwise, the configuration is S. If the fourth priority substituent is attached by a wedge bond, then the clockwise or counterclockwise arrangement of the first, second, and third priority substituents is determined and that arrangement is reversed before assigning R or S. If the fourth priority substituent is in the plane of the page, then it is switched with the substituent that points away. Then the clockwise or counterclockwise arrangement of the first, second and third priority substituents is determined and that arrangement is reversed before assigning R or S. When writing the IUPAC name, the R or S designation is written in parenthesis for each asymmetric carbon atom and hyphens are used to separate those designations from the rest of the IUPAC name.

Interpretation Introduction

(b)

Interpretation:

The configuration of each asymmetric carbon in the given molecule is to be designated as R or S.

Concept introduction:

When assigning priorities to substituents, the atom having the greater atomic number has higher priority. In case of comparison between isotopes, the one having the greater atomic mass gets higher priority. When the fourth priority substituent is pointing away (it is attached by a dash bond) and the first, second, and third priority substituents are arranged clockwise, the configuration is R. When the fourth priority substituent is pointing away (it is attached by a dash bond) and the first, second, and third priority substituents are arranged counterclockwise, the configuration is S. If the fourth priority substituent is attached by a wedge bond, then the clockwise or counterclockwise arrangement of the first, second, and third priority substituents is determined and that arrangement is reversed before assigning R or S. If the fourth priority substituent is in the plane of the page, then it is switched with the substituent that points away. Then the clockwise or counterclockwise arrangement of the first, second, and third priority substituents is determined and that arrangement is reversed before assigning R or S. When writing the IUPAC name, the R or S designation is written in parenthesis for each asymmetric carbon atom and hyphens are used to separate those designations from the rest of the IUPAC name.

Interpretation Introduction

(c)

Interpretation:

The configuration of each asymmetric carbon in the given molecule is to be designated as R or S.

Concept introduction:

When assigning priorities to substituents, the atom having the greater atomic number has higher priority. In case of comparison between isotopes, the one having the greater atomic mass gets higher priority. When the fourth priority substituent is pointing away (it is attached by a dash bond) and the first, second, and third priority substituents are arranged clockwise, the configuration is R. When the fourth priority substituent is pointing away (it is attached by a dash bond) and the first, second, and third priority substituents are arranged counterclockwise, the configuration is S. If the fourth priority substituent is attached by a wedge bond, then the clockwise or counterclockwise arrangement of the first, second, and third priority substituents is determined and that arrangement is reversed before assigning R or S. If the fourth priority substituent is in the plane of the page, then it is switched with the substituent that points away. Then the clockwise or counterclockwise arrangement of the first, second, and third priority substituents is determined and that arrangement is reversed before assigning R or S. When writing the IUPAC name, the R or S designation is written in parenthesis for each asymmetric carbon atom and hyphens are used to separate those designations from the rest of the IUPAC name.

Interpretation Introduction

(d)

Interpretation:

The configuration of each chiral center in the given molecule is to be designated as R or S.

Concept introduction:

When assigning priorities to substituents, the atom having the greater atomic number has higher priority. In case of comparison between isotopes, the one having the greater atomic mass gets higher priority. When the fourth priority substituent is pointing away (it is attached by a dash bond) and the first, second, and third priority substituents are arranged clockwise, the configuration is R. When the fourth priority substituent is pointing away (it is attached by a dash bond) and the first, second, and third priority substituents are arranged counterclockwise, the configuration is S. If the fourth priority substituent is attached by a wedge bond, then the clockwise or counterclockwise arrangement of the first, second, and third priority substituents is determined and that arrangement is reversed before assigning R or S. If the fourth priority substituent is in the plane of the page, then it is switched with the substituent that points away. Then the clockwise or counterclockwise arrangement of the first, second, and third priority substituents is determined and that arrangement is reversed before assigning R or S. When writing the IUPAC name, the R or S designation is written in parenthesis for each asymmetric carbon atom and hyphens are used to separate those designations from the rest of the IUPAC name.