Science desk
< February 2	<< Jan \| February \| Mar >>	February 4 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

February 3[edit]

"-Idine" Suffix[edit]

Good night, I've seen that the suffix "-Idine" is used in many words, such as in Pyrimidine and Clorhexidine. I don't see a real connection between these compounds except the amine substituents. Is it a real suffix or how are these words constructed? Thanks in Advance 2800:810:454:482:19FB:8CAC:2CC5:BD62 (talk) 03:41, 3 February 2019 (UTC)[reply]

According to this, it is used to denote "organic ring compounds containing nitrogen". Admittedly, that's a generic reference rather than one from a science specialist. Matt Deres (talk) 13:20, 3 February 2019 (UTC)[reply]

Off-topic. Perhaps English is your second language. "Good night" is not used as a greeting. It is used when bidding other people farewell when leaving each other. The correct phrase would have been "Good evening", which is used right up to midnight. After midnight, it's "Good morning". Akld guy (talk) 18:46, 3 February 2019 (UTC)[reply]

If there is a more definitive answer, then wikt:-idine could get an update. We could do with an etymology. But I can guess that it started with -ine meaning "related to". To investigate further you could see which of those words came first, and then from which language it came, and what the justification for the word coiner was. Graeme Bartlett (talk) 05:58, 4 February 2019 (UTC)[reply]

For such matters, the IUPAC is the authority, and they make an old copy of Principles of Nomenclature available at zero cost. From Chapter 4, §4.5.3.4: the preferred modern nomenclature follows the Hantzsch–Widman nomenclature system, but as a footnote, "The traditional stems 'iridine', 'etidine' and 'olidine' are preferred for rings containing nitrogen."

Regarding etymology: it's probable that there's some connection to hydride and amine, but as the IUPAC editorial staff say, "The reason why ... is historical, and has no obvious logical basis." (ibid, §4.2.2). Isn't it great that we have such well-read volunteers here at the reference desk, navigating that fragile and turbulent boundary-layer between all human-knowledge that is known, and all the rest that is not known?

Nimur (talk) 02:24, 5 February 2019 (UTC)[reply]

wikt:pyrimidine says that it mixes wikt:Pyridin/wikt:pyridine with wikt:amidine. The latter is recognizable from amide but the -mi- is beyond the present scope. And our article pyridine says that, much to my surprise, at this compound's discovery in 1849 the suffix -idine was added to connote a carbon cycle with a nitrogen atom! But it links wikt:-idine giving credit for the suffix to the name of pyridine, so we have a cycle of something more than carbon here. That Wiktionary article links to a list of a dozen words (only!) ending in -idine, but I suspect this is incomplete. Anyway, looking up Kekule structure I see that Kekule's cyclic structure for benzene dates to 1865, which matches my recollection, so I think the pyridine article is simply wrong, while the one-line Wiktionary entry probably has it right. Because pyridine is literally just a ring of carbons with one nitrogen shuffled in, it would be easy to imagine the suffix would spread from there. But I still don't have a clincher for that. Continuing ... we should give equal value to the content of articles and to their references, this being no exception, and the incorrect statement in pyridine cites the very interesting paper at [1] in which an ancient chemistry nut takes a ton of bone oil and converts it to a few grains of various compounds he obtains by fractional distillation and acid-base extraction. He gives no explanation why he gives one the name pyridine and one the name lutidine, but he is aware of the preexisting name of toluidine. He correctly surmised that pyridine, picoline, and lutidine formed a sequence of bases, which we now know to be connected by methyl addition, and also recognized that aniline and toluidine had the same relationship, with structural isomerism between picoline and aniline, and between lutidine and toluidine. For not knowing the actual structure, this is quite an accomplishment. Nonetheless, his addition of "d"s to two compounds in this sequence of isomers beside picoline (which have N in a ring) when before it was only a "d" in toluidine which has N on an amino group would seem to indicate no modern structural significance was intended at that time. Wnt (talk) 13:21, 4 February 2019 (UTC)[reply]

It is even more cyclic than that as I have just added things to the category that you saw and the one line etymology as a result of this question. I agree with you that the structure would not have determined the names in these early times thanks to the lack of knowledge about that. Graeme Bartlett (talk) 03:50, 5 February 2019 (UTC)[reply]

why the comet 67P/ Churyumov–Gerasimenko has bottle neck?[edit]

--Akbarmohammadzade (talk) 07:45, 3 February 2019 (UTC)[reply]

67P/Churyumov–Gerasimenko#Shape. Henry ^Flower 09:03, 3 February 2019 (UTC)[reply]