Question

According to the IUPAC convention, what is the name of the compound given below?

A.$1 - ethyl - 3 - methyl - 4 - propylcyclohexane$
B.$3 - ethyl - 1 - methyl - 2 - propylcyclohexane$
C.$5 - ethyl - 1 - methyl - 2 - propylcyclohexane$
D.$4 - ethyl - 2 - methyl - 1 - propylcyclohexane$

Answer 1

As we know that the full form of IUPAC is the International Union of Pure and Applied Chemistry. It is a World Wide organisation for the nomenclature of the new elements in the periodic table and chemical molecules. The IUPAC has certain rules and regulations for the naming of the organic compound. In that method only we named the organic molecules in World level. The naming of any organic molecule depends on the parent saturated hydrocarbon.

Complete answer:
We can draw the given structure as,

The rules for naming structure is,
First to calculate the number of carbon atoms in the given ring structure. According to that count we consider our parent hydrocarbon.

There are six carbon atoms present in the given ring structure. The number of carbon atoms representing six hydrocarbons is hexane. But it is the closed ring structure that is the reason we insert cyclo term in front of the parent hydrocarbon. Hence, the parent name of the given cyclic structure is cyclohexane.
The alkanes is the substituent group in the given structure. The number of the substituent in two ways one is clockwise and other is anti-clockwise. Here, we take clockwise it will come in minimum number for the substituent group in the given structure.
Among the three alkanes propane is the largest group. Hence minimum should come in propane.
According to the above discussion, we conclude the IUPAC name of the given structure is
$4 - ethyl - 2 - methyl - 1 - propylcyclohexane$.

Hence, the option D is the correct answer.

Note:
We need to know that the functional group of the molecule is very important for the naming time. If one molecule having more than one functional group means some priority list is also provided from IUPAC. If the number of substituent and functional group is dependent on the minimum number will come from the left side or right of the terminal carbon atom in the chain. If it is a cyclic structure, it means depending on the number we choose clockwise numbering or anti-clockwise numbering in the structure. The main chain is dependent on the large number carbon atom chain in the molecule.