Sir_Gawain
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Unknown impurity in ethyl acetate
I recently bought a liter of "MEK substitute" from the hardware store. The MSDS says 100% ethyl acetate. I decided to distill it, and so preceded with
a simple distillation.
It mostly came over at 77C, the boiling point of ethyl acetate, but when around 100 mL were left the temperature started to climb. It climbed slowly,
reaching a maximum of 96C.
I have no idea what the impurity is; it looks and smells just like the ethyl acetate and burns cleanly leaving no residue. I'll do a density
measurement and see from there. I'm thinking of redistilling everything with a fractionating column to get better separation.
“Alchemy is trying to turn things yellow; chemistry is trying to avoid things turning yellow.” -Tom deP.
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Sir_Gawain
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I feel really stupid; I just figured it out. I checked the density, aannndddd it's ethyl acetate. I distilled it from a 1L RBF in a heating mantle, so
when the liquid level got low the heating mantle still heated the entire flask, bringing the temperature of the vapor above its boiling point. I'm
used to distilling from a hotplate (the mantle is a recent acquisition) so I've never come across this phenomenon before.
“Alchemy is trying to turn things yellow; chemistry is trying to avoid things turning yellow.” -Tom deP.
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bnull
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Well, at least you didn't discard the "impure" fraction.
Quod scripsi, scripsi.
B. N. Ull
P.S.: Did you know that we have a Library?
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