Cloner - 11-1-2005 at 06:23
I have need of some aniline. Now there's an old bottle with a red liquid in it. The label says it's aniline
Anyway, since this kind of compound is likely prone to all manner of ugly reactions
inside the bottle, and 30 years old, it might need purification. Anyone know what happens to aniline in a bottle over time, when it gets red and if it
can be purified?
Esplosivo - 11-1-2005 at 06:36
For the purification I can answer briefly by saying that it can be carried out by steam distillation, and subsequent drying using anhydrous sodium
sulfate. Normal distillation is not applicable since it decomposes at the boiling point.
About the red component I would say that it is some form of polymeric oxidation product as occurs in phenols. Aniline/phenylamine tends to carry out
aerial oxidation as does phenol to attain a brownish colouration, although I am not sure if this is it.
[Edited on 11-1-2005 by Esplosivo]
phanchem - 11-1-2005 at 06:46
Also read up on Perkins, who tried to make quinine by oxidizing aniline and instead discovered aniline dyes, and brought in the Mauve Decade (1890s).
unionised - 12-1-2005 at 13:49
You can clean it up to some extent by disolving it in dilute HCl, washing it with a solvent and re precipitating it with NaOH. The aniline separates
out as a layer and can be dried over Na2SO4.
This won't get it as clean as distillation, but you don't need a still.
mick - 28-1-2005 at 13:40
If you have got an old bottle of analine that is brown. Be careful of the brown stuff.
mick
ordenblitz - 28-1-2005 at 19:17
I have a large quantity of aniline dye... methylamino anthraquinone to be exact.
Could one use it, or another alinine dye, and work backward to Aniline.
zbde00 - 18-2-2005 at 23:10
recrystallized in water.
heat it in water then filter the color material.
unionised - 19-2-2005 at 06:56
Pardon?
sparkgap - 19-2-2005 at 06:59
Isn't aniline supposed to be a liquid at ambient temperature? How would you recrystallize? 
Maybe s/he meant to recrystallize an anilinium salt in water, hydrolyze it, and then remove the impurities?
(edited for cosmetic corrections)
sparky (^_^)
[Edited on 20-2-2005 by sparkgap]
zbde00 - 24-2-2005 at 07:01
Sorry.I don't notice aniline is a liquid
The impurities may be removed by filter paper
I have done the purification of p-methoxy aniline by this way.
Caffinehog - 5-3-2005 at 17:45
Aniline is very easily oxidized, so if you distill it, you're going to get some impurities back unless you use an inert atmosphere. Don't
despair, though.... aniline that is quite brown is still usually quite pure.