Foeskes
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Sodium methoxide using sodium sulfate as drying agent
So after seeing nurdrage's trimethyl orthoformate video, I want to try and make sodium methoxide that way but I don't have any molecular sieves. I do
have sodium sulfate and apparently it doesn't dissolve in methanol so can it be used to remove the water and push the equilibrium forward?
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Vomaturge
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It seems like that might work. I know that you can separate water from isopropyl alcohol using table salt. Water cannot dissolve IPA and salt at the
same time. (Isopropyl alcohol can dissolve a bit of salt, though, so that's a contaminant) But I digress. Back to the methoxide. I doubt a simple
"salting out" would work when there's a water absorbing reaction to compete with. The idea of using some anhydrous sodium sulfate might do the trick,
absorbing water without having to dissolve. I wonder if magnesium sulfate could work too, or if it would interfere with the reaction? I know it can be
made anhydrous by baking Epsom salt in the oven (http://www.sciencemadness.org/talk/viewthread.php?tid=9429).
One more crazy idea. This is probably more costly and harder to get than molecular sieves, but I think sodium oxide would likely work: Na2O +CH3OH
-> CH3ONa + NaOH. Once all the methanol was used up, you would have excess hydroxide, but no free water. Probably not practical, but I'm just
throwing it out there.
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Foeskes
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as of right now i'm using sodium metal to prepare it considering 4g of sodium cost the equivalent of 4USD. it's pretty costly.
The procedure of that video involves removing water to push the reaction forward: NaOH + CH3OH => NaOCH3 + H2O
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Sulaiman
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I've not done anhydrous chemistry but due to reading here on SM I bought 3A molecular sieves from this seller https://www.ebay.co.uk/itm/Premium-Grade-3A-Molecular-Sieve-...
They get hot when water is added - that's all I can be sure of.
CAUTION : Hobby Chemist, not Professional or even Amateur
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LearnedAmateur
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Quote: Originally posted by Vomaturge  |
One more crazy idea. This is probably more costly and harder to get than molecular sieves, but I think sodium oxide would likely work: Na2O +CH3OH
-> CH3ONa + NaOH. Once all the methanol was used up, you would have excess hydroxide, but no free water. Probably not practical, but I'm just
throwing it out there.
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Actually if you have an apparatus that you can heat to 850-900C, the sodium carbonate will decompose to sodium oxide with the carbon dioxide
conveniently leaving as a gas. Although I haven’t found any reference to it being used as the reactant here, only sodium metal and the hydroxide, I
don’t see why it wouldn’t be sufficiently strong to deprotonate the methanol since it is more basic than NaOH.
In chemistry, sometimes the solution is the problem.
It’s been a while, but I’m not dead! Updated 7/1/2020. Shout out to Aga, we got along well.
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