Question

Name the following compounds.

Answer 1

Hint: First of all you have to find out the longest carbon chain. Then identify the groups attached to this chain. Now, number the chain consecutively, starting at the end nearest a substituent group by an appropriate number and name.

Complete step by step answer:
For the first compound, the longest carbon chain is pentane. There are no other substituent groups attached to this chain. So, the name of the compound is n-pentane.
For the second compound, the longest carbon chain is butane. There is a double bond in the second position. So, the name is but-2-ene.
For the third compound, the longest carbon chain is propane. There is a triple bond in the first carbon. So, the name of the compound is prop-1-yne or propyne.
For the fourth compound, the longest carbon chain is butane. There is a methyl group attached to the second carbon of the chain. So, the name is 2-methyl-butane.
For the fifth compound, the longest carbon chain is butane. There are no substituent groups attached to the chain. But there is a triple bond in the second carbon. So, the name is but-2-yne.

So, compound (i) is n-pentane.
Compound (ii) is but-2-ene.
Compound (iii) is prop-1-yne.
Compound (iv) is 2-methyl-butane.
Compound (v) is but-2-yne.

Note: When there are two or more substituent groups, you should number the chain by considering that the highest priority group like acid groups should have the lowest number. Also if two same substituent groups are attached at two different positions, numbering should be done in such a way that the sum of the number of positions has a lower number.