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I'm running a reaction that has ethylene gas as a byproduct. I have observed gas evolution as my reaction proceeded and I have other ways of verifying the identity of the main product, but I thought it might be cool if I could also test for the presence of ethylene.
Are there any simple tests I can use for this purpose? Obviously it is not easy to detect since it's a fairly non-reactive gas, so it doesn't have to have 100% specificity.

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    $\begingroup$ gas chromatography $\endgroup$
    – Chris
    Jun 7, 2012 at 4:48
  • $\begingroup$ may I recommend GC-MS as being a little bit better than just normal IR-GC for this purpose, but both will work. $\endgroup$
    – picakhu
    Jun 7, 2012 at 15:56
  • $\begingroup$ GC-MS should work quite well, I agree. It will freeze in liquid nitrogen though, if that makes things easier for you. $\endgroup$
    – Canageek
    Jun 7, 2012 at 22:35
  • $\begingroup$ It's totally OK to think "how could I identify it", but why would you actually want to do that if you know for sure it is ethylene? Isn't that kind of pointless? $\endgroup$
    – Karl
    Oct 27, 2015 at 1:29

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If you want something simple and don't mind less than 100% certainty then you could bubble the gas through Bromine Water - in the presence of an alkene the bromine water would be decolourised from brown when reacting with the ethene. Of course this does just indicate the presence of any alkene so isn't exactly specific! There is more about this on this website.

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  • $\begingroup$ You can do NMR experiment on the resulting solution. This should give you at least the negative on ethylene, but maybe also the compound that blows out. $\endgroup$ Jul 30, 2014 at 5:10

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