Sciencemadness Discussion Board

Crystal Separation

redox - 2-4-2011 at 15:59

Hello all.

Recently I was digging through my father's old photo-developing stuff, and I found (among many other chemicals) a tin can containing Kodak Photo Developer D-76. On the label is listed that it contains p- methyl aminophenol sulfate and hydroquinone. I am interested in isolating the latter, for use as a starting point in organic synthesis.
Does anybody have any thoughts of how to separate these substances? I was thinking along the lines of a solubility difference in a solvent, but little solubility information of these compounds is published on the internet.
Any ideas?

p.s. It is a homogeneous white powder

Mindchemist - 2-4-2011 at 16:21

Try heating it to 180C. The hydroquinone will melt while the metol will remain solid.

redox - 3-4-2011 at 06:08

I considered that method, but it may be difficult to execute. 180C is a little hot for me. Plus, what if the metol is soluble in the molten hydroquinone?

HydroCarbon - 3-4-2011 at 13:42

Just a thought, but you might be able to recrystallize in water. I would imagine the metol to be a good bit more soluble in water. But I could be wrong...

GreenD - 3-4-2011 at 17:44

Solubility of hydroquinone: 5.9 g/100 ml (15 °C)

The solubility of the other product would be nearly 100% due to it being a salt. (atleast thats what I'm seeing!).

I think also if you added a bit of NaCl to the water it would help with the solubility of the prior, and increase precipitation of the latter.

Pretty sure you can take that to the bank :)

smuv - 3-4-2011 at 18:04

you could probably just triturate that stuff with butanone, the hydroquinone will dissolve the aminophenol should not. After that go for a recrystallization, I don't know a lot about the solubility of sulfate salts, but probably with MeOH/butanone you could come up with a good system.

smaerd - 3-4-2011 at 18:06

edit woops had that backwards

[Edited on 4-4-2011 by smaerd]

redox - 4-4-2011 at 12:02

I don't think water solubility separation is an option. The solubility of methylaminophenol sulfate is 5 g/100 mL, almost the exact same as hydroquinone.
Quote: Originally posted by smuv  
you could probably just triturate that stuff with butanone, the hydroquinone will dissolve the aminophenol should not. After that go for a recrystallization, I don't know a lot about the solubility of sulfate salts, but probably with MeOH/butanone you could come up with a good system.


I think this is the best option.