Looking for something else in my Oxford Russian dictionary, my eye fell on the entry “рода́нистый, adj. (chem.) thiocyanate (of), sulphocyanate (of).” Naturally I wondered about the etymology; there was no related word in the Oxford, but in my three-volume Russian-English dictionary I found “рода́н а m chem rhodane.” That cleared up the Russian derivation but added another problem: what the devil was “rhodane”? It wasn’t in any of my dictionaries, but Webster’s Third had “rhodanic acid \(ˈ)rō¦danik-\ n [rhodanic ISV rhodan– (modification of Greek rhodon rose) + -ic ] 1 : thiocyanic acid —not used systematically 2 : rhodanine.” OK, that helped, sort of — at least it cleared up the etymology — but was “rhodane” the same thing? Apparently, sort of, since googling родан identified it with SCNCH2COOH (more standardly called изотиоцианатоуксусная кислота), and googling that gave isothiocyanoacetic acid. Searching Google Books for “rhodane” turned up a few hits like “Studies on the Formation of Rhodane in the Case of Abnormal Functioning of the Liver” (1936) and “Experiment 1 Excretion of rhodane” (1962), but it appears to be so marginal as an English word as to barely exist, which means it’s malpractice to provide it as an explanation of Russian родан, to the extent that the latter is an actual word, which leads to the further question of why either родан or роданистый is in a bilingual dictionary at all, given the unlikelihood of a reader running into them in text and the absence of so many more common words I’ve had to add to the margins.

Then something else occurred to me: might Perry Rhodan be somehow related? I couldn’t find any information on the etymology of the name of that galaxy-spanning hero, but my Langenscheidt dictionary had an entry “Rhoˈdan m thiocyanogen,” so I’m assuming that’s what Perry’s creators had at least vaguely in mind. But as always, any further information will be welcome.


  1. Not sure if you checked the OED already, but if not, the OED has it under ‘rhodan‘ as well:

    Etymology: < German Rhodan ( J. J. Berzelius Lehrbuch der Chem. (ed. 5, 1843) I. 829) < ancient Greek ῥόδον rose (see rhodo- comb. form) + -an (in Cyan cyan n.; compare cyanogen n.)

    Definition: Chemistry. Now rare. = thiocyanogen n. at thio- comb. form 1; (also) the thiocyanate ion or radical (—SCN). Frequently attributive.

    I don't know enough about chemistry nomenclature, but I've always gotten the sense that the 50s was when naming moved towards naming things after their constituent parts (as some hand-wavy guess as to why it has fallen out of use).

  2. Ah, thanks! I no longer have access to OED3, and the first edition doesn’t have it.

  3. David Marjanović says

    Haven’t heard of it, but there has been a move toward more systematic nomenclature across the 20th century.

    As ions, cyanide (CN), cyanate (OCN) and thiocyanate (SCN) are the same as their iso- versions, but as parts of larger molecules they’re not: isothiocyanoacetic acid contains S=C=N−, thiocyanoacetic acid would contain N≡C−S−.

  4. My first thought was the Rhod- makes it something to do with rose-coloured or rose-like (failing that, island of Rhodes).

    1913 Websters (via wiktionary) has rhodanate (obsolete), a salt of rhodanic acid.

    English from Latin, not Greek rhodanien is the Provençal dialect spoken on the banks of the Rhône. How did the ‘d’ get in there?

  5. David Eddyshaw says
  6. David Marjanović says

    It dropped out (en Graná no hay na), leaving now vanished vowel length (indicated by the circumflex) behind (unlike in Granada).

  7. Dmitry Pruss says

    The name is totally familiar but it’s used in a slightly different variation in contemporary Russian (роданид for its salts). Leenson’s chemical etymological dictionary derives it from Greek rhodon (rose) (rhodanides are used as indicators for iron (III), producing pink color in its presence)

  8. There’s also Rodan, of the Japanese monster movies. WP: “The Japanese name Radon is a contraction of Pteranodon. It was changed to Rodan for English-speaking markets in order to avoid confusion with the element radon.”

  9. Why would confusion with the element radon be a problem? “Superman” didn’t worry about confusion with the element krypton.

  10. There is an Agatha Christi novel in there.

  11. SCNCH2COOH must be very unpopular acid, no one ever bothered to synthesize it except to write those boring articles back in 1936 and 1962.

  12. Oof, I just had one of those realizations that I had been conflating two things my whole life. When I was young it was Sweden and Switzerland, now it’s rhodanine and rhodamine.

  13. My two cents:
    Rhodanide is the old chemical name for the thiocyanate ion.
    Where does the ‘rhodon’ come from ((red) rose)?
    If you mix a potassium thiocyanate solution with a ferric chloride solution, you’ll get a blood RED solution. Not too toxic and used as fake blood in movies.

  14. David Marjanović says

    Google/Wikipedia confirm that rhodamine is an amine.

  15. Christian Weisgerber says

    From what I vaguely remember about the genesis of Perry Rhodan, the name was simply made up and the -h- added to make it look more exotic. That it is also an old name for thiocyanogen is purely coincidental.

  16. I guess that makes sense.

  17. Allan from Iowa says

    I was disappointed to learn that rhodane is not a molecule with one rhodium and four hydrogens.

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