Q.75. - Organic Chemistry

Question

Question: Read Appendix B on naming bicyclic compounds. Then give the IUPAC name for each of the following compounds.

a.

b.

c.

d.

Step-by-Step Solution

Answer

Answer

1. 2,3-dimethylbicyclo[3.1.1] heptane.
2. 2-ethyl-7,7-dimethyl bicyclo[2.2.1] heptane.
3. 1-methyl-7- propyl bicyclo[3.2.1] octane.
4. 6-ethyl-3,3-dimethylbicyclo[3.1.0] heptane.

Step 1: Bridged rings

The bicyclic rings that share three or more atoms in common, in which the bridged atoms are separated at least by one atom, are termed bridged rings.

Step 2: Naming bicyclic compounds

The general nomenclature of bridged or fused rings is represented as bicyclo [x.y.z] alkanes.

Here, x, y, and z refer to the number of carbon atoms that connect the shared carbons written in decreasing order, i.e., x represents the highest and z represents the least number.

The numbering of the atoms on the ring starts from the shared carbon, and is continued along the longest bridge.

Step 3: IUPAC naming of the given compounds

a. 

The ring consists of seven carbon atoms; therefore, the name of the parent chain will be heptane.

The number of carbon atoms connecting the shared carbons is 3,1, and 1. Carbon 2 and carbon 3 consists of a methyl substituent.

Therefore, the IUPAC name of the given compound is 2,3-dimethylbicyclo[3.1.1] heptane.

b. 

The parent ring consists of seven carbon atoms and hence will have the parent name heptane.

The number of carbon atoms connecting the shared carbons is 2,2, and 1.Carbon 2 consists of an ethyl group as a substituent, and carbon 7 consists of two methyl substituents.

The IUPAC name of the compound is 2-ethyl-7,7-dimethyl bicyclo[2.2.1] heptane.

 

c. 

The parent ring consists of eight carbon atoms and hence will have the parent name octane.

The number of carbon atoms connecting the shared carbons is 3,2, and 1.Carbon 1 consists of a methyl group as a substituent, and carbon 7 consists of apropyl substituent.

The IUPAC name of the compound is 1-methyl-7- propyl bicyclo[3.2.1] octane.

 

d. 

The ring consists of seven carbon atoms; therefore, the name of the parent chain will be heptane.

The number of carbon atoms connecting the shared carbons is 3 and 2.Carbon 3 consists of two methyl substituents, and carbon 6 consists of an ethyl substituent.

Therefore, the IUPAC name of the given compound is 6-ethyl-3,3-dimethylbicyclo[3.1.0] heptane.