Question

IUPAC name of the following compound (P) is:

• A. 1-Ethyl-5, 5-dimethylcyclohexane
• B. 3-Ethyl-1,1-dimethylcyclohexane
• C. 1-Ethyl-3, 3-dimethylcyclohexane
• D. 1,1-Dimethyl-3-ethylcyclohexane

Answer 1

The Correct Option is B

The compound depicted in the image is a cyclohexane derivative with additional alkyl groups attached. To determine its IUPAC name, we need to follow these steps: 

1. Identify the main carbon chain: The base structure is a cyclohexane ring.
2. Identify substituents:
   • There is an ethyl group attached to the carbon chain.
   • There are two methyl groups attached to the same carbon atom.
3. Number the carbon atoms in the ring to give the substituents the lowest possible numbers:
   • Start numbering from the carbon with the substituents that will obtain the lowest set of locants. Here, the carbon with two methyl groups is numbered as 1.
   • Continuing the numbering around the ring gives the ethyl group position 3 (clockwise numbering).
4. Compile the name:
   • The compound is named as 3-Ethyl-1,1-dimethylcyclohexane, indicating the positions and types of substituents.

Therefore, the correct IUPAC name for the compound is 3-Ethyl-1,1-dimethylcyclohexane.

To confirm the correct choice among the options:

• 1-Ethyl-5,5-dimethylcyclohexane - Incorrect numbering place for substituents.
• 3-Ethyl-1,1-dimethylcyclohexane - Correct, as reasoned above.
• 1-Ethyl-3,3-dimethylcyclohexane - Incorrect placement for ethyl group.
• 1,1-Dimethyl-3-ethylcyclohexane - Incorrect order of substituents.

Answer 2

The correct IUPAC name for the compound shown is 3-Ethyl-1,1-dimethylcyclohexane. The longest carbon chain attached to the cyclohexane ring determines the naming priority. The substituents are numbered to give the lowest possible locants.