Chapter C, Problem C.7P

Interpretation Introduction

Interpretation:

The complete IUPAC name of the given molecule is to be written.

Concept introduction:

When assigning priorities to substituents, the atom having the greater atomic number has the higher priority. In case of comparison between isotopes, the one having the greater atomic mass gets the higher priority.

If substituents are attached by the same atom, the tiebreaker is applied.

For each substituent, the set of three atoms one bond away from its point of attachment is to be identified.

In each set, arrange the three atoms from the highest to the lowest priority. Compare each set’s highest-priority atom.

If they are different, then the atom that has the higher priority corresponds to the higher-priority substituent.

If the highest-priority atoms from each set are identical, then compare each set’s second highest priority corresponding to the higher priority substituent. If the second-highest-priority atoms from each set are identical, then compare each set’s lowest-priority atom to break the tie.

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 IPUAC 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.