Chapter C, Problem C.17P

Interpretation Introduction

(a)

Interpretation:

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

Concept introduction:

A ring compound with a double bond and eight or more carbon atoms can have both E and Z configurations at the double bond. Rings containing seven carbon atoms or less have only Z configuration. The E configuration is too unstable because of a high ring strain. The E/Z designation is generally left out in this case.

The E/Z configuration is determined on the basis of the priorities of the two groups attached to the double bonded carbon atoms. Priority is assigned on the basis of the atomic number of the atom directly bonded to the double bonded carbon. Higher the atomic number, higher the priority. If the atomic numbers of both atoms attached to a carbon are the same, then the priority is determined on the basis of the atoms one bond away from the point of attachment.

When writing the name, the E/Z designation is written at the start, in parenthesis. If there are two or more double bonds, then they are listed with the respective locants.

If the higher priority groups at the two ends are on the same side of the double bond, then the compound is assigned a Z configuration. If they are on the opposite sides of the double bond, then an E configuration is assigned.

For determining the R/S configuration, the groups attached to the asymmetric center are assigned priorities, following the same rules outlined above. If the groups with priorities 1 to 3 are arranged clockwise with the lowest priority group going away from the observer, the asymmetric center is assigned R configuration. If they are arranged counterclockwise, the configuration assigned is S.

When writing the IUPAC name of a molecule, each R and S designation can be written immediately before the first number used to locate the substituent attached to the asymmetric carbon atom. An alternate way is to write all the R and S designations together at the front of the name. The locator number for each asymmetric carbon atom must appear before its R or S designation, and the designations must be separated from each other by a comma.

Interpretation Introduction

(b)

Interpretation:

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

Concept introduction:

A ring compound with a double bond and eight or more carbon atoms can have both E and Z configurations at the double bond. Rings containing seven carbon atoms or less have only Z configuration. The E configuration is too unstable because of a high ring strain. The E/Z designation is generally left out in this case.

The E/Z configuration is determined on the basis of the priorities of the two groups attached to the double bonded carbon atoms. Priority is assigned on the basis of the atomic number of the atom directly bonded to the double bonded carbon. Higher the atomic number, higher the priority. If the atomic numbers of both atoms attached to a carbon are the same, then the priority is determined on the basis of the atoms one bond away from the point of attachment.

When writing the name, the E/Z designation is written at the start, in parenthesis. If there are two or more double bonds, then they are listed with the respective locants.

If the higher priority groups at the two ends are on the same side of the double bond, then the compound is assigned a Z configuration. If they are on the opposite sides of the double bond, then an E configuration is assigned.

For determining the R/S configuration, the groups attached to the asymmetric center are assigned priorities, following the same rules outlined above. If the groups with priorities 1 to 3 are arranged clockwise with the lowest priority group going away from the observer, the asymmetric center is assigned R configuration. If they are arranged counterclockwise, the configuration assigned is S.

When writing the IUPAC name of a molecule, each R and S designation can be written immediately before the first number used to locate the substituent attached to the asymmetric carbon atom. An alternate way is to write all the R and S designations together at the front of the name. The locator number for each asymmetric carbon atom must appear before its R or S designation, and the designations must be separated from each other by a comma.

Interpretation Introduction

(c)

Interpretation:

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

Concept introduction:

A ring compound with a double bond and eight or more carbon atoms can have both E and Z configurations at the double bond. Rings containing seven carbon atoms or less have only Z configuration. The E configuration is too unstable because of a high ring strain. The E/Z designation is generally left out in this case.

The E/Z configuration is determined on the basis of the priorities of the two groups attached to the double bonded carbon atoms. Priority is assigned on the basis of the atomic number of the atom directly bonded to the double bonded carbon. Higher the atomic number, higher the priority. If the atomic numbers of both atoms attached to a carbon are the same, then the priority is determined on the basis of the atoms one bond away from the point of attachment.

When writing the name, the E/Z designation is written at the start, in parenthesis. If there are two or more double bonds, then they are listed with the respective locants.

If the higher priority groups at the two ends are on the same side of the double bond, then the compound is assigned a Z configuration. If they are on the opposite sides of the double bond, then an E configuration is assigned.

For determining the R/S configuration, the groups attached to the asymmetric center are assigned priorities, following the same rules outlined above. If the groups with priorities 1 to 3 are arranged clockwise with the lowest priority group going away from the observer, the asymmetric center is assigned R configuration. If they are arranged counterclockwise, the configuration assigned is S.

When writing the IUPAC name of a molecule, each R and S designation can be written immediately before the first number used to locate the substituent attached to the asymmetric carbon atom. An alternate way is to write all the R and S designations together at the front of the name. The locator number for each asymmetric carbon atom must appear before its R or S designation, and the designations must be separated from each other by a comma.