Question

Name of the compound is:

A.2-methyl-3-ethyl-1-pentene

B.3-ethyl-4-methyl-4-pentene

C.3-ethyl-2-methyl-1-pentene

D.3-methyl-2-ethyl-1-pentene

Answer 1

The name of the compound should be under the IUPAC nomenclature conditions. So we should be well aware of the IUPAC nomenclature.
First, you should identify the longest carbon chain. They identify the groups attached to this chain.
Number the chain consecutively, starting at the end nearest a substituent group by an appropriate number and name.

Complete step by step answer:
The name of the compound is determined with the help of IUPAC nomenclature. Some of the rules are listed below:
Find the functional group in the compound. This functional group determined the suffix of the name. (For example: If an alkane group is present then the suffix is –ane and if alcohol group present then the suffix is –ol).
Find the longest chain of carbon containing the functional group. Then count the carbon atoms present in the chain. This number is used as a prefix of the compound name. (For example: If three carbon atoms present the prefix is a prop-).
Number the carbons in the longest carbon chain, in this we have to start with the carbon closest to the functional group.
We should combine the elements of the name into a single word.
With the help of the IUPAC nomenclature, we will name the above compound.
In the above compound double bond is attached with the first carbon, thus the suffix is –ene,
The second carbon has methyl group present so 2-methyl, and in the third carbon ethyl group present so 3-ethyl.
In this long chain of carbon is five-carbon so its prefix is “pent”.
And arrange the compound with alphabetic order. In this ethyl is first and methyl is second and pentene is a suffix.
Hence the given compound is 3-ethyl-2-methyl-1-pentene.
Thus the correct option is (C).

Note:
The IUPAC name of every organic compound consists of three parts:
Word root
Suffix
Prefix
In IUPAC nomenclature suffix have two types:
The primary suffix indicates a single bond or multiple bonds present in the hydrocarbon chain that is double bond or triple bond.
A secondary suffix determines the nature of the functional group present in the organic compounds.
Thus the prefix is also two types:
A primary prefix distinguishes the cyclic from the acyclic compound.
A secondary prefix is used for a certain group that is not considered to be functional but treated as a substituent.
Hence the complete IUPAC name is written as:
Secondary prefix + primary prefix + word root + primary suffix + secondary suffix.