What is the IUPAC name of ${\mathit{CH}}_3-C\left({\mathit{CH}}_3\right)\left(\mathit{OH}\right){\mathit{CH}}_2-\mathit{CH}\left({\mathit{CH}}_3\right){\mathit{CH}}_3$ ?

The IUPAC name of ${\mathit{CH}}_3-C\left({\mathit{CH}}_3\right)\left(\mathit{OH}\right){\mathit{CH}}_2-\mathit{CH}\left({\mathit{CH}}_3\right){\mathit{CH}}_3$:

In the longest carbon chain, −OH group is closest to the left-hand side, therefore we number from the left-hand side. There is 5 carbon in the longest chain, in the second and fourth positions methyl group is attached, and in the second position there is an alcoholic group.

Thus IUPAC's name is 2,4-Dimethylpentan-2-ol.