Sparklehorse - 3-6-2016 at 09:56
Recently synthesized some ether using ethanol and sulfuric per the article in pre pub. I then dried it over some NaOH for a few days. When I came back
to it , it had this yellow cloudiness that I didn't recognize. There was not much water in the ether since none separated out with the hydroxide, but
I'm thinking the yellow coloring was produced by the formation of sodium ethoxide from residual ethanol reacting with the lye. Do you think that could
be the case, or did something else cause the yellow coloring? I also had a small piece of copper wire in the bottle for prevention peroxide formation,
which I didn't not remove before adding the NaOH. I redistilled and it is perfectly clear now.
NitreRat - 3-6-2016 at 10:31
Sounds like a trace aldol condensation contaminant. What was your source of ethanol? I don't know if the sulfuric acid could have oxidized the ethanol
to acetaldehyde.
Sparklehorse - 3-6-2016 at 10:41
Spirytus (same thing as everclear just a percent higher )
byko3y - 3-6-2016 at 11:00
So what's your problem? I see none. Yellow is a common color of some crap. Distillation separates the crap, because ether is much more volatile.
Solution of ethanol+NaOH becomes yellow on heating or standing, but there's a lot of other options.
Sparklehorse - 3-6-2016 at 11:43
No problem since I distilled, just trying to analyze determine what was the yellow stuff.
karlos³ - 3-6-2016 at 11:50
Your ethanol source probably contains ketones, MEK I think, which is in my opinion a likely source of your contamination.
I concur what NitreRat said, and MEK is the most likely substance to undergo aldol condensation.
Did the ether smell different, or did you have a funny smelling residue after distillation? It is probably not much, nearby to be seen, but can
probably be smelt anyway(considering spiritus here contains about 1% of MEK, and much less will have made it into your product if any, if this is even
the source of coloured contamination).
Sparklehorse - 3-6-2016 at 12:05
Thanks for all the helpful replies . No it smells normal, I would be surprised that there would be MEK in my ethanol source since it's basically
everclear just a different brand. I always assumed that if it was for drinking then it would be relatively pure ethanol. But I suppose not.
I also found this post which makes me think something maybe leached out of the container that the hydroxide was in.
http://www.sciencemadness.org/talk/viewthread.php?tid=11189