NotANumber
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Mood: so goddamn eepy
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Purification of medium amounts of largly decomposed phenylenediamines and aminophenols
Morning!
I got my hands on a huge stock of photochem compounds, in particular interesting are N,N-diethyl-4-phenylenediamine sulphate and pyrogallol.
Unfortunately, the first one is ~very~ tarry, to the point that each bottle just has a big, sticky clump of it. I have around half a kilo of it total.
I do realize that the best would be a vacuum sublimation, but it's heavily unfeasable to me at this scale. I was going to try to precipitate it as a
free base and filter/wash, but before that I wanted to ask for a second opinion and here I am 
Is there perhaps a method viable at this scale and possible to do at a home-ish lab?
Huge thanks in advance
PS. I'm pretty sure a normal recryst wouldn't work when it comes to this amount of contamination, I could try, but each gram is precious to me, and my
experience with recrystallizing similiar compounds doesn't fare well for this method
mrrp!~
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NotANumber
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For clarification, the exact thing I was going to do was to dissolve the mass in a minimal amount of water, gravity filter to remove solid
contaminants, precipitate NNDPPD as a free base with conc. ammonia water added dropwise until slightly basic, cool the mixture down and salt out the
remaining product. Then filter, wash with ice cold water and dry out. Afterwards I'd add it to cold water, dropwise add HCl until slightly acidic and
evaporate under decreased pressure to recover the final product
[Edited on 12-12-2025 by NotANumber]
mrrp!~
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Gualterio_Malatesta
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There's an Orgsyn (CV2P0501) writeup that goes like this:
"If a purer product is desired, the material (46-50 g of o-phenylenediamine) is dissolved in 150–175 cc. of hot water containing 1–2 g. of sodium
hydrosulfite and treated with decolorizing charcoal. After cooling thoroughly in an ice-salt mixture, the colorless crystals are filtered by suction
and washed with 10–15 cc. of ice water.
The purified o-phenylenediamine weighs 40–46 g. (74–85 per cent of the theoretical amount) and melts at 99–101°".
And an important note:
"The free diamine may also be converted into the dihydrochloride, and the salt purified as follows: The crude o-phenylenediamine is dissolved in a
mixture of 90–100 cc. of concentrated hydrochloric acid (sp.gr. 1.19) and 50–60 cc. of water containing 2–3 g. of stannous chloride, and the hot
solution is treated with decolorizing charcoal. To the hot, colorless filtrate is added 150 cc. of concentrated hydrochloric acid, and the mixture is
cooled thoroughly in an ice-salt bath. The colorless crystals are filtered by suction, washed with a small amount of cold concentrated hydrochloric
acid, and dried in vacuum over solid sodium hydroxide. The yield of o-phenylenediamine dihydrochloride is 77–81 g. (85–90 per cent of the
theoretical amount based on the weight of o-nitroaniline used)."
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