# Naming secondary amine IUPAC system

$\ce{CH3NHCH(CH3)CH2CH3}$
Should this be named as 2-(N-methyl)butanamine or 2-(methylamino)butane?

In other words, do we name the compound as 'alkanamine' or treat amino group as a substituent of butane?

It should be N-methyl-2-butanamine. Amine is treated as a functional group attached. So we write it as alkanamine as it is the only functional group here.

Image source: ChemSpider

• Note that the preferred IUPAC name for the compound drawn is in fact slightly different from what you have written: it should be N-methylbutan-2-amine. In particular the locant '2' should be placed immediately before the suffix 'amine', and the locant 'N' should be italicised. – orthocresol Mar 9 '18 at 15:10