# Scope of [heterocyclic-compounds] and [aromatic-compounds]

Edit: Following a suggestion by Mithoron I've renamed it to which is also more in line with the tags that we currently have.

Edit 2: I've also done up a tag wiki. Feel free to edit/criticise/comment/praise/worship.

I'll keep this short and sweet, since I've gotta head off in 10 minutes. The tag seems to have popped up recently. I think that this is a good tag to have, there are numerous books written on the topic and I had an entire course on it. There are already plenty of suitable questions.

As far as I know, "heterocyclic" includes saturated and unsaturated rings, therefore chemistry involving piperidine, pyrrolidine, tetrahydrofuran, etc. would come under this tag. So would chemistry about pyrrole and pyridine.

I've personally decided that questions about pyrrole, pyridine, etc. should also be tagged with , since these are aromatic heterocycles. I don't really anticipate any objections, but if there anybody disagrees, please do drop an answer. I'm writing this to make sure that everything is transparent and that there's a record of this discussion.

Note that the previous paragraph is superseded by the following discussion: Functional group tagging - revisited where it was decided that should be restricted to carbocyclic compounds.

• Having done the edit, I think [aromatic-chemistry] is a more reasonable and official-looking name than [aromatic-compounds], but that's another matter. – M.A.R. ಠ_ಠ Feb 24 '17 at 18:34
• I'm sorry, that was a typo. Thanks for correcting it. – orthocresol Feb 24 '17 at 18:51
• I think it should be [heterocyclic-compounds]. Otherwise it would look like chemistry itself was heterocyclic ;) – Mithoron Feb 25 '17 at 12:37
• Well you can have multiple tags so some would just have [aromatic-compounds], some would have [aromatic-compounds] + [heterocyclic-chemistry] and some just [heterocyclic-chemistry] – MaxW Feb 25 '17 at 18:31
• @Mithoron In some ways, that would be more closely aligned with our current tagging system, which has carbonyl-compounds, aromatic-compounds, ... I am glad I have only lumped the tag on two new questions so far! I think we can change it to that. Thanks for your comment. – orthocresol Feb 25 '17 at 20:05
• Does this mean we should also have anti-aromatic-compounds? Doesn't seem like nearly as common a topic, though. – hBy2Py Feb 26 '17 at 13:57
• @hBy2Py No, antiaromaticity is bit controversial. All suspected compound can be tagged as hydrocarbons or heterocyclic. – Mithoron Feb 26 '17 at 15:12

There doesn’t seem to be any need for discussion. Vote up this answer if you approve what Orthocresol suggested, namely:

I have been adding this tag to a few questions every day, starting with the obvious aromatic candidates. My search query has been <heterocycle> -[heterocyclic-compounds] is:question.

• Done: furan, pyrrole, pyridine, thiophene, indole, oxazole, thiazole, isoxazole
• In progress: imidazole

Some other keywords to search for:

• (aromatic 6-membered) pyridazine, pyrimidine, pyrazine;
• (aromatic fused) benzofuran, benzothiophene, isobenzofuran, isoindole, quinoline, isoquinoline, benzopyrylium, purine
• (oxidised) pyrone, pyranone, pyridone, benzopyrone, pyrrolidone, furanone
• (saturated) pyrrolidine, piperidine, pyran, dihydrofuran, tetrahydrofuran (might be questionable), aziridine, lactam

That certainly seems like a lot and I doubt it's exhaustive just because there are so many combinations in which we can arrange atoms nowadays. However, I presume the number will get less and less as I move on to the more exotic heterocycles.