Answer:
A. 3–Ethyl–2–methylpentane.
B. 3–Ethyl–1,5,5–trimethylcyclohexene.
Explanation:
To name the compound, we must observe the following:
1. Locate the longest continuous carbon chain. This gives the parent name.
2. Identify the substituent groups attached.
3. Locate the position of the substituent groups by giving them the lowest possible low count alphabetically.
4. Combine the above to name the compound.
Now let us name the above compounds
For compound (A)
1.The longest chain is carbon 5 i.e pentane.
2. The substitute attached are:
Ethyl => CH2CH3
Methyl => CH3
3. Ethyl comes before methyl alphabetically. But considering the structure of the compound, ethyl assume same position from either side of the compound. Therefore, we'll consider the lowest possible count for methyl. Therefore, their position is given below:
Ethyl => CH2CH3 => carbon 3.
Methyl => CH3 => carbon 2.
4. The name of the compound is:
3–Ethyl–2–methylpentane.
Compound B.
This is a cyclic structure.
1. The parent name is cyclohexene.
2. The substitute groups attached are:
Ethyl => CH2CH3
Methyl => CH3
3. Since the compound is unsaturated, the functional group is the double bond. Hence, we shall start our counting from the double bond and also considering alphabetical order of the substituent.
Please note methyl (CH3) appears three times.
Ethyl => CH2CH3 => carbon 3
Methyl => CH3 => carbon 1, 5 and 5.
4. The name of the compound is:
3–Ethyl–1,5,5–trimethylcyclohexene
