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Would it be a good idea to ask here why uric acid is not what I would have guessed, i.e.

1,3,7,9-tetrahydropurine-2,6,8-trione

but rather is something that I find surprising, i.e.

7,9-dihydro-1H-purine-2,6,8(3H)-trione?

https://en.wikipedia.org/wiki/Uric_acid says it is the complicated name, and the simple name that I had guessed at is nowhere to be seen.

enter image description here

Likewise https://www.chemspider.com/Chemical-Structure.1142.html makes no mention of anything starting "1,3,7,9" in it's list of about fifty names for uric acid.

And yet theacrine does have the name that I would have guessed having looked at the structural formula.

https://en.wikipedia.org/wiki/Theacrine has:

enter image description here

and https://www.chemspider.com/Chemical-Structure.67862.html has "1,3,7,9-tetramethylpurine-2,6,8-trione" in it's list of names.

Since theacrine is so simply named, why is not uric acid likewise named in a straightforward way?


Thanks to Loong for pointing out that Wikipedia may be wrong about the IUPAC name of theacrine. I suspect Loong is right about that. I guess I would omit any reference to theacrine in the hypothetical future question on chemistry about the name of uric acid, or at least not claim that Wikipedia is right about theacrine's IUPAC name.

Also thanks to everyone who pointed out that the issue here isn't "on-topic-ness". I used instead of the phrase "on-topic" the more accurate (and in this case less pretentious) "a good idea to ask here".

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    $\begingroup$ In my opinion: yes. We also have a FAQ post about it: chemistry.meta.stackexchange.com/q/3066/4945 $\endgroup$ Jan 6, 2023 at 10:45
  • $\begingroup$ :/ Well, you should know by now that it's not a matter of being on topic, but if something is too broad, or unclear, or even looks like homework. $\endgroup$
    – Mithoron
    Jan 9, 2023 at 15:14
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    $\begingroup$ Nomenclature questions are on topic and if you presented enough information or claim any erratum, you can ask. It's not necessary to discuss the on-topicness of each case on meta. Just ask it and wait for response. $\endgroup$ Jan 10, 2023 at 4:09
  • $\begingroup$ @NilayGhosh and Mithoron thanks for your thoughts. I have edited the question accordingly. $\endgroup$ Jan 10, 2023 at 9:44

1 Answer 1

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Generally, questions are on topic. Nevertheless, the usual restrictions apply and we really don’t like it if it looks like we are doing your homework for you.

Since nomenclature questions form a distinct group different from other chemistry questions, we have gathered some guidelines about best practices for asking nomenclature questions. However, I should perhaps mention that I have answered more than 300 nomenclature questions myself, so there might be something like an egocentric bias.

Chemical nomenclature relies on large collections of more or less systematic rules. If you try to work with the official rules and you encounter a problem (e.g., you cannot find a particular rule or you don’t understand how to use it in your case), it’s probably a good question for asking it here.

But if you don’t work with the rules and just look at some compounds and their names that you find somewhere, and then try to guess the rules yourself, it probably does not lead to good questions for this site.

For your example, 7,9-dihydro-1H-purine-2,6,8(3H)-trione, a thorough derivation of the complete name would involve many nomenclature rules, and therefore would be too long for this format. You should add details to narrow the answer set or to isolate an issue that can be answered in a few paragraphs. Ideally, try to limit your question to a single nomenclature rule. (Yes, I have simply copied this part from our guidelines.)

Comparing your example to the other name you found somewhere, 1,3,7,9-tetramethylpurine-2,6,8-trione, would probably not improve your question very much since this name is simply not in accordance with IUPAC recommendations.

Your comparison of the hypothetical names 1,3,7,9-tetrahydropurine-2,6,8-trione and 1,3,7,9-tetramethylpurine-2,6,8-trione also looks suspiciously like you are trying to guess the rules yourself – something you probably shouldn’t do in a question, as mentioned above. However, it already gives us a hint of where your problem could lie, since ‘methyl’ is a prefix that describes substitution but ‘hydro’ is a prefix that describes saturation.

Also note that you probably should include an image that shows a chemical structure diagram of 7,9-dihydro-1H-purine-2,6,8(3H)-trione. However, you should avoid using such oversized screenshots in your question.

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  • $\begingroup$ +1 I have edited the question in light of your insightful answer. I did wonder why Google didn't confirm theacrine's name. I was a bit shocked at the size of the screenshots myself. "For your example, 7,9-dihydro-1H-purine-2,6,8(3H)-trione, a thorough derivation of the complete name would involve many nomenclature rules, and therefore would be too long for this format." How many rules roughly and about how long would it be? $\endgroup$ Jan 7, 2023 at 14:45
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    $\begingroup$ I've read your answer several times, and I can't see a way forward. What, in your opinion, would be a specific rule I could ask about? I have no idea, because I don't know the rules, and maybe never will. Or should I just forget about asking the question here? $\endgroup$ Jan 22, 2023 at 19:31

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