I'm writing a publication in which I compare the effect of alkyl, alkene and similar chains of different length connected to a N-atom of a heterocyclic organic compound. Often I have to refer to these chains, without the N-atom.

Right now I'm using something like "the ethyl/propyl/etc. group connected to the N-atom", which feels awkward. Is there a better chemical term I could use? Based on my online research, amine group or amine substituent appears to be the closest, but it includes the nitrogen itself.

Some examples (not from my work):

a few examples

Is there a term that properly describes the encircled parts?

  • $\begingroup$ Though I asked the question in general, the molecule I'm concerned with has the nitrogen in a ring structure, like my examples. If there's no general name, one applying for this specific case would also suffice. $\endgroup$
    – Neinstein
    Jan 23, 2023 at 13:05
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    $\begingroup$ o.O Looks like you have a fundamental misunderstanding. Substituents are named for what they are, not what they are connected to. $\endgroup$
    – Mithoron
    Jan 23, 2023 at 13:52
  • 1
    $\begingroup$ Amyl is an old name for pentyl, so you at least have a misunderstanding. Substituents are substituents, in particular alkyl, or aryl groups. $\endgroup$
    – Mithoron
    Jan 23, 2023 at 14:51
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    $\begingroup$ Where is the problem ? Your first molecule is N-ethylpyrrole; the second is N-acetylpyrrole. $\endgroup$
    – Maurice
    Jan 23, 2023 at 17:56
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    $\begingroup$ If general, what about "N-substituent", "N-substituent in X" or "R-N" in a formula? $\endgroup$
    – Poutnik
    Jan 25, 2023 at 10:14

2 Answers 2


I think "N-substituent" is just fine.

A substituent refers to whatever is sticking off something. The prefix "N-" doesn't change that; rather, it qualifies what it is sticking off. So the N-substituent doesn't mean "the nitrogen plus the substituent", but rather "the substituent sticking off the nitrogen".

(As a parallel example: in, say, aromatic rings it is common to refer to a C-2 substituent or an ortho-substituent or something. This doesn't include the carbon on the ring, it just refers to whatever's sticking off it.)


Inspired by the locant N- and by biochemical nomenclature for glycolisation, I could see use of the term “N-linked moiety”.


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