Wikipedia:Reference desk/Archives/Science/2024 June 27

= June 27 =

More carboxylic acids
1. Why are these maximally symmetric ones "unnatural" but there are major biology omega-3's/6's that start the divinylmethane pattern as little as 1 carbon higher? all-cis-3,6,9-dodecatrienoic acid all-cis-3,6,9,12,15-octadecapentaenoic acid all-cis-3,6,9,12,15,18,21-tetracosaheptaenoic acid. 2. Why does the article stop at hexaenoic? If there's 22:6 shouldn't there be room for 26:7? 3. Would all-cis-2,4,6,8,10-dodecapentaenoic acid melt at lower temperature than all-cis-3,6,9-dodecatrienoic acid, all-cis-2,4,6,8,10,12,14,16-octadecaoctaenoic acid melt at lower temperature than all-cis-3,6,9,12,15-octadecapentaenoic acid and so on? Sagittarian Milky Way (talk) 00:18, 27 June 2024 (UTC)
 * Sounds like you are interested here in conjugated polyunsturated acids, like α-parinaric acid or α-eleostearic acid. In living organisms, there is danger of lipid peroxidation for these. Graeme Bartlett (talk) 12:22, 27 June 2024 (UTC)
 * Slightly off-point but readers may like to know that you can do substructure searches over Wikipedia chemistry articles using Wikipedia Chemical Structure Explorer. It takes a bit of getting used to but allows, for example, searching for all divinylmethanes we have articles about. Similar searches can be run at PubChem with, of course, many more hits likely. PubChem will link the hits back to Wikidata if there is an entry here (possibly not an article or one not in English). Mike Turnbull (talk) 13:38, 27 June 2024 (UTC)
 * According to that there's no ringless unbranched acid on Wikipedia with a double bond at 3, the closest is the very important DHA 22:6 with double bonds at 4, 7, 10, 13, 16 and 19. Sagittarian Milky Way (talk) 18:45, 27 June 2024 (UTC)
 * Carboxylic acid with a double-bond at C3 is often prone to isomerization to become conjugated (double-bond shifting to C2). There's a relevant ref with regards to 3-butenoic acid in our butenoic acid article. Aldrich sells the stuff for about 10–50x the price of crotonic acid. Maybe soeone wants to turn that link blue (per the dewiki article could be a basis; the eowiki article is a hopeless mess). Substituted 3-butenoic acids are known, such as 2-amino-3-butenoic acid (maybe more recognizeable as "vinylglycine"; somehow related to aspartate transaminase, and can also induce inhibition of pyridoxal phosphate-dependent enzymes) and 4-phenyl-3-butenoic acid (identified as an antifungal metabolite of Streptomyces koyangensis). DMacks (talk) 03:16, 7 July 2024 (UTC)

Muonic atoms
If we forget about the muon's half-life, what would matter made from muonic atoms actually be like, in terms of physical and chemical properties?

(Yes, I know this is about as realistic as all those predictions of the chemical and physical properties of things like oganesson. But since there are published papers about that, maybe someone has considered this?) Double sharp (talk) 04:00, 27 June 2024 (UTC)
 * In Muonic atoms you can see that adding one muon instead of an electron in an atom makes it like the element with a one lower atomic number. But if all electrons were replaced with muons, then it would behave like a tiny atom. So then you could expect the materials formed to be much denser. 8,000,000 times denser. Also I would expect chemical bonds to be much, much stronger, and may be capable of making the material dense enough to initiate atomic fusion: (Muon-catalyzed fusion). With much stronger bonds, melting points of covalent network solids would be much higher. However I might expect similar molecular structures, but on a much smaller scale. Graeme Bartlett (talk) 12:05, 27 June 2024 (UTC)
 * In muonic atoms and molecules it is important to account for the QED corrections properly. They are much bigger than those in electronic atoms and molecules. Ruslik_ Zero 20:30, 27 June 2024 (UTC)
 * Interesting. Muon-catalysed fusion does seem to be the show-stopper for this idea, since that makes it likely that a tank of muonic H2 (if we magically turn off the decay of the muons) would undergo significant spontaneous fusion. And the same thing would likely hold in general. So, even if the muon magically didn't decay, matter using it to replace all electrons would likely not be that stable either. :(
 * Thanks for the answers! Double sharp (talk) 13:11, 1 July 2024 (UTC)