# Can there be two IUPAC names of a compound?

What is the difference between propan-2-amine and 1-methylethanamine?

• in the latter, you have not used the longest carbon-chain for naming it – Gerhard Jan 19 '16 at 9:43

Generally, since many compounds can have two or more names in accordance with several methods recommended by IUPAC, a compound may be named correctly in more ways than one. Therefore, current IUPAC recommendations include the definition of a preferred IUPAC name (PIN), which is the name preferred among two or more names generated from two or more IUPAC recommendations including the many retained names.

In particular for primary amines, the rules given in the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book) are as follows.

P-62.2.1.2 Primary amines, $\ce{R-NH2}$, are systematically named in the following ways:

(1) by adding the suffix ‘amine’ to the name of the parent hydride;

(2) by adding the name of the substituent group $\ce{R-{}}$ to the parent hydride ‘azane’;

(3) by adding the name of the substituent group $\ce{R-{}}$ to the term ‘amine’ used as a preselected parent hydride name for NH3; this method is used only with monoamines.

(…)

Method (1) leads to preferred IUPAC names.

Since, according to the current recommendations, the substituent group $\ce{(CH3)2CH-{}}$ can be named ‘propan-2-yl’, ‘isopropyl’, or ‘1-methylethyl’ (where ‘propan-2-yl’ is the preferred prefix), the compound given in the question can have the following seven names in accordance with methods recommended by IUPAC. The PIN is ‘propan-2-amine’.

Method (1):
propan-2-amine (PIN)

Method (2):
propan-2-ylazane (propan-2-yl is the preferred prefix)
(1-methylethyl)azane
isopropylazane

Method (3):
propan-2-ylamine (propan-2-yl is the preferred prefix)
1-methylethylamine
isopropylamine

• Could you name some amines mostly known as -azane ? – permeakra Jan 19 '16 at 13:34
• @permeakra My first idea are compounds that include the multiplicative substituent group $\ce{{}-NH-{}}$, such as 2,2'-azanediyldiacetic acid. – Loong Jan 19 '16 at 14:28
• nice try, but it is known as iminodiacetic acid. – permeakra Jan 19 '16 at 17:55
• @permeakra Certainly, that compound is known by many names. The name 2,2'-iminodiacetic acid was in accordance with the 1979 recommendations. However, according to the current recommendations, the preferred name is 2,2'-azanediyldiacetic acid because the preselected prefix for the multiplicative substituent group $\ce{{}-NH-{}}$ is now azanediyl; the name imino is used only for $\ce{{}=NH}$ as a substituent. – Loong Jan 19 '16 at 18:31

Yes it is possible. I suppose IUPAC has also accepted some common names also for compounds as of here. Many other compounds have names, still in use, which are not in accordance with IUPAC guidelines but accepted, e.g., camphor, naphthalene, anthracene, isoprene, etc.