Sciencemadness Discussion Board

Purifying Phenol

DFliyerz - 6-7-2015 at 13:38

A while ago I made phenol from aspirin, but for some reason after the second distillation the product has been liquid at room temperature. I'm unsure why this is, as it seems to water-free, and my distillation apparatus is currently out of commission. Are there any other ways of conveniently purifying phenol.

Metacelsus - 6-7-2015 at 16:41

Hmm... Can you describe your production process more? If you didn't completely hydrolyze your aspirin prior to decarboxylation, you might have a mixture of phenol and phenyl acetate.

DFliyerz - 6-7-2015 at 21:09

It was a while ago, but I think there was a problem with the hydrolysis where I messed up and ended up with a lot of boiling oil spraying everywhere, but I'm pretty sure it was completely hydrolysed. Also, phenyl acetate has a higher melting point than phenol, and the product was solid at RT before the second distillation.

Zephyr - 6-7-2015 at 21:54

There is still the possibility of residual water. I'd try popping it in a freezer and seeing if you can get anything to crystallize.
To determine if you even still have any phenol, I recommend boiling(at least at 150C) a little bit of it with some phthalic anhydride to create phenolphthalein and then adding some basic solution which will hopefully turn pink.

DFliyerz - 7-7-2015 at 06:57

Well, luckily I just finished a batch of phthalic anhydride, so I'll give that a try. :P

Schizophrenic - 11-7-2015 at 10:14

I did buy brownish phenol, I have the same question actually because phenol is white. Please wear gloves as there are many chemists that went to the ER after performing tests on phenol.

UC235 - 11-7-2015 at 10:30

Quote: Originally posted by Schizophrenic  
I did buy brownish phenol, I have the same question actually because phenol is white. Please wear gloves as there are many chemists that went to the ER after performing tests on phenol.


How's the melting point? Colored impurities can make an almost completely pure sample look like crap (though it may perform just fine in reactions). If the m.p. is okay, or at least close, I would try vacuum distilling it (m.p. should be 40.5C, so don't use cold water in the condenser).

unionised - 12-7-2015 at 01:14

Quote: Originally posted by UC235  
Quote: Originally posted by Schizophrenic  
I did buy brownish phenol, I have the same question actually because phenol is white. Please wear gloves as there are many chemists that went to the ER after performing tests on phenol.


How's the melting point? Colored impurities can make an almost completely pure sample look like crap (though it may perform just fine in reactions). If the m.p. is okay, or at least close, I would try vacuum distilling it (m.p. should be 40.5C, so don't use cold water in the condenser).

did you read the OP? The bit that says it's liquid at RT?

hissingnoise - 12-7-2015 at 02:09

If it has liquefied, it needs drying . . .

DFliyerz - 12-7-2015 at 12:35

I heated it for a bit lightly on a hotplate and it's back to being solid at RT, so I think I've solved it.

Jammyy - 15-7-2015 at 01:49

This is interesting.. Useful information.. Thanks..