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Author: Subject: unexpected biphasic mother liquor
CaptainPike
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[*] posted on 20-7-2016 at 09:05
unexpected biphasic mother liquor


After re-crystallizing some beta nitro styrenes, using petroleum ether (hardware store naphtha) the remaining cold solvent and washes were left several days. This morning I notice a second phase has separated out.

This solvent boils in the high 90s and may have caused some degradation to the solvated nitro styrene. Could this oxidation have produced some insoluble liquid– like water? I know there's not much to go on. The "two upper phases" are actually an illusion – the dirty dark layer is just a reflection of something yellow – maybe the goo the bottom, refracted. There is a nearly clear layer, about a centimeter thick, on top of the dark syrup on the bottom.

I'll try to include a nice image of the first recrystallized product. We used (up all my) ethanol, and they came out nice reddish, long needles.

ethanol recrystallized nitrostyrene.jpg - 330kB

tri-phased mother liquor.jpg - 796kB
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Crowfjord
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[*] posted on 20-7-2016 at 10:27


I'm a little confused as to what you mean, where the ethanol and naphtha are concerned. Was the naphtha used to extract the nitrostyrene, which then crystallized from the naphtha? And then alcohol was used to recrystallize the nitrostyrene? I would guess that if you extracted from an aqueous solution, maybe that bit that was dissolved in the naphtha (with alcohol maybe?) slowly came out. There isn't much to go on.

That's an interesting color for a nitrostyrene. They are usually yellow or orange, except for the base form of the phenolic nitrostyrenes, which are red. I suppose it has some strong electron-donating group at the 4-position.
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CaptainPike
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[*] posted on 20-7-2016 at 17:40


Sorry for the confusion. See the "Cold Method" preparation by garage chemist, where I got the basic idea.

There is no aqueous extraction, as such.

In the second part of the prep, where the ivory colored slurry is added to cold hydrochloric acid, orangey material appears.

I can't remember now – we first recrystallized with ethanol (yielding red filtrate and crystals), and then maybe the large bulk of material remaining in the filter was recrystallized again, this time in the higher boiling naphtha. This produced the more yellow crystals when the filtrate was cooled down.



different colored crystals.jpg - 539kB
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