Quote: Originally posted by JJay | I don't think the sulfuric acid is ever totally used unless the water is removed somehow. I saw a paper on the reaction kinetics a while back which
suggested that it's hard to get much above 40% in equillibrium with ethanol and sulfuric acid, although someone did reportedly manage to get 70%
starting with completely anhydrous reagents. I don't remember the name of the paper offhand.... Water is a major yield killer as it slows the reaction
considerably and pushes the equillibrium in the wrong direction.
You can use the melting point and check other properties like its solubilities. I think you can also check its purity with a GCMS, and it will give
off ether if refluxed in sulfuric acid.
[Edited on 15-1-2017 by JJay] |
I read a paper on the H2SO4, EtOH, and Na2SO4 route that claimed 'quantitative yields.' The oleum paper claimed 86% yields. Antiocio(sp?) also claimed
'near quantitative' yields with the Na2SO4 route. I would go with that. The way you do it according to the paper is to drip in the H2SO4 slowly so
that it doesn't get too hot to minimize side products. After it's returned to room temperature you grind your Na2SO4 into a fine a powder as possible
to maximize surface area and add it slowly into the solution while it is stirring to evenly disperse the salts. Then you leave it overnight, ~12
hours, or w/e. The Na2SO4 should grab onto all of the water during that time and as it does the reaction will go to completion.
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