Question

Name the following compound according to IUPAC system of nomenclature: CH₃CH(CH₃)CH₂CH₂CHO

Answer 1

4-Methylpentan-1-al

You can see the numbering will be done from the right side as ,

The functional group should get lowest number.

Then the methyl group will be attached with the fourth carbon atom.

According to that it's IUPAC name will be 4-Methylpentan-1-al

Or you can skip writing 1 and name it as 4-Methylpentanal.

Hope it helps.