nezza
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Yellow residue in ammonia solution
I recently bought a couple of hundred ml of "pure" ammonia from a chemical supplier. It is stated to be 28% or so. It arrived in a dark plastic bottle
and after a few days storage in a fridge there is a pale yellow solid at the bottom of the bottle. I originally thought it might be ammonium
carbonate/carbamate but it does not appear to be.
I have filtered it out and the solid appears to be some sort of organic.
It burns with a smoky flame leaving no residue.
It does not dissolve in dilute acid.
Does anyone have any idea what it might be ?.
If you're not part of the solution, you're part of the precipitate.
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hissingnoise
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| Quote: | | Does anyone have any idea what it might be? |
An aromatic amine, from contaminated hydrocarbon feed gas, would be my guess!
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nezza
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Thanks for the suggestion hissingnoise. I have tried diazotising and coupling it to thymol. No colour reaction so I don't think it is a primary
aromatic amine.
I think I'll start from the top and do a sodium fusion test to see if it contains nitrogen, halogen or sulphur.
[Edited on 24-1-2016 by nezza]
If you're not part of the solution, you're part of the precipitate.
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hissingnoise
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Leaving the soln. in a freezer overnight should precipitate the impurity, leaving it clean enough for most!
If you want pure NH4OH you'll have to distil . . .
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nezza
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Thanks again. I'm just interested in what the inpurity is.
I've had another look at the impurity.
The solid does NOT contain any occluded ammonia (negative with Nesslers).
It melts to a pale yellow liquid and boils with some decomposition (Ammonia smell).
It is insoluble in alcohol, water and toluene.
It does not contain sulphur or halogen but does contain nitrogen.
It does not react appreciably with bromine water (not unsaturated).
The solid appears as pale yellow optically active monoclinic crystals.
If you're not part of the solution, you're part of the precipitate.
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hissingnoise
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| Quote: | | I'm just interested in what the impurity is. |
Wow! That all-too-rare pioneering instinct?
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