Question

The IUPAC name of ${\left( {C{H_3}} \right)_2}CHC{H_3}$ is:
A) 2-methylpropane
B) 2,2-dimethylethane
C) trimethylmethane
D) none of these

Answer 1

Hint: Identify the longest chain of the carbon as the root. The main functional group is to be written as a suffix and the substitute is written as a prefix. The sequence of the naming should be in the way:
Prefix + root + suffix

Complete step by step answer:
The longest chain of carbon contains three carbon atoms so it will be taken as the main chain of carbon so it is the root and this is a propane molecule. Hence The name would contain propane.
Next, we have to find the atoms or groups of atoms that are bonded to the carbon atoms present in the main chain. We can see here that one methyl group is directly bonded to one carbon atom of the main chain or the root.
We already know that counting should start from that end where the main functional group is assigned lesser numbering. Here, we will assign numbers from the right-hand side.
We now assign numbers to the carbon atoms in the following way,

In the compound, we see that the one methyl group is attached to the 2nd carbon of the longest chain. The longest chain has three carbon atoms, that is it a propane molecule. From these we can conclude that the name of the compound will be 2-methylpropane.

So, the correct answer is Option A .

Note:
The rule set by the International union of pure and applied chemistry (IUPAC) must always be followed. For naming, first identify the main chain and then number the carbon atoms in the chain. Secondly, identify the substituents and then name the compound using suffix and prefix. The counting of the number of carbon is always done from the side in which the main functional group is assigned with a lesser number.