LoKi
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breaking a nitroethane/ toluene azeotrope
alright, I have mixture of approx. 75% toluene, 25% nitroethane fractionaly distilled (azeotrope reported bp 106, composition as stated from some site
that references NIST). I was thinking of forming the sodium salt of nitroethane with NaOH, but I'm not sure if adding an acid like HCl will simply
liberate the nitroethane or react with the nitroethane, not to mention the two phase system complicates things. Is this the right approach, or is
there a better solution? Nitroethane is slightly soluble in water (4.5 g/ 100 ml if memory serves), so I outa be able to form the salt with an
aqueous sol. NaOH and heavy stirring for a couple hours, right? I just read a patent that describes forming nitroalkane salts in order to halogenate
them (nitromethane with Cl2, not the same as reacting with HCl I know but I gotta wonder if the salt is more susceptable, ya know?). any help would SO
be appreciated.
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leu
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You'd be better off not bothering with those salts  The nitroethane/toluene
azeotrope boils at 106.2ºC so one would need to add an entrainer that doesn't form an azeotrope with nitroethane but does with toluene and boils at a
lower temperature than the nitroethane/toluene azeotrope  This procedure is
commonly known as azeotropic distillation  Two common entrainers that don't form
azeotropes with nitroethane are water that forms an azeotrope with toluene that boils between 84ºC and 85ºC and methanol that forms an azeotrope
with toluene boiling between 62º to 64ºC 
Chemistry is our Covalent Bond
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Zinc
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Did you find nitroethane in a OTC source?
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Organikum
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Nitroethane properties
Thats an old thread I know but Google brought it quite on top when searching for nitroethane + azeotropes so I think it might be a decent service to
manhood.
Nitroethane forms very well an azeotrope with water, this boils at 87,2°C. So this is not useable here. methanol is usable though.
Thats what astounded me so very much as it is always recommended to use toluene as water carrier in Henry condensations. But the toluene/water
azeotrope itself boils between 84/85°C as stated and the nitroethane/water azeotrope boils at 87,2°C thats to close to get any separation in my
eyes, and what it actually says that toluene as watercarrier is just not nercessary at all, the nitroethane does this already by itself.
If a watercarrier is deemed necessary, something considerably loer boiling would be advised - ether for example or DCM (if this does not mess up the
reaction?).
The lowered temperature in the reaction will of course make it take considerably longer, some days probably.
Attached the nitroethane data sheet with some more useful information
Attachment: nitroethane_properties.pdf (139kB)
This file has been downloaded 952 times
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