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Author: Subject: Drying an impossibly deliquescent iminium salt (how stable are iminium salts?)
unionised
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[*] posted on 16-7-2022 at 04:26


Quote: Originally posted by Fulmen  
I see your point. I'm not sure if it fits the definition of an azeotrope 100%, but you're right in that it should form a constant boiling point.

I'm pretty sure it does meet the definition.

"The term azeotrope is derived from the Greek words ζέειν (boil) and τρόπος (turning) with the prefix α- (no) to give the overall meaning, "no change on boiling". The term was coined in 1911 by English chemist John Wade and Richard William Merriman."

From
https://en.wikipedia.org/wiki/Azeotrope#Etymology

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Lionel Spanner
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[*] posted on 18-7-2022 at 13:07


Quote: Originally posted by unionised  
Quote: Originally posted by Fulmen  
I see your point. I'm not sure if it fits the definition of an azeotrope 100%, but you're right in that it should form a constant boiling point.

I'm pretty sure it does meet the definition.

"The term azeotrope is derived from the Greek words ζέειν (boil) and τρόπος (turning) with the prefix α- (no) to give the overall meaning, "no change on boiling". The term was coined in 1911 by English chemist John Wade and Richard William Merriman."

From
https://en.wikipedia.org/wiki/Azeotrope#Etymology


I'm not being funny here, but an azeotrope is, by definition, a mixture of two liquids with a well-defined composition and boiling point that can't be separated by distillation alone.

Besides the mutually immiscible examples of water/toluene, water/xylene etc., there are numerous examples of mutually miscible azeotropes, e.g. water/ethanol, water/formic acid, water/nitric acid, etc. - so the mutual miscibility of each liquid really is irrelevant.

Mutually immiscible liquids can form an azeotrope on boiling, but that doesn't mean they will.

[Edited on 18-7-2022 by Lionel Spanner]




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[*] posted on 22-7-2022 at 02:28


Update:

I finally managed to dry the salt, I think, fully, however it refuses to crystallize.
A couple of days drying over phosphorus pentoxide seems to have done it, however it doesn't appear to crystallize, it just turns from a liquid into a sort of waxy solid.

It is quite hard to do anything meaningful with it, because it absorbs water too quickly from the air, just 5 seconds is enough to turn it, at least somewhat, into a liquid again.

I suppose some sort of glove-box would be the sensible approach.

I think, on the other hand, if I were to prepare it again, and obtain it in the form of crystals rather than a syrupy mass, then it would be much quicker to dry and easier to handle, the crystals could be dried over phosphorus pentoxide in an open container, and then rapidly sealed once dry, I think that would work.


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[*] posted on 22-7-2022 at 10:55


Funny coincidence: I'm working with magnesium nitrate hexahydrate at the moment, and got similar results. It took multiple attempts of cooling and heating to get crystals, and in humid air it virtually melts before my eyes. Could your product be a hydrate?



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[*] posted on 23-7-2022 at 03:21


Quote: Originally posted by Fulmen  
Funny coincidence: I'm working with magnesium nitrate hexahydrate at the moment, and got similar results. It took multiple attempts of cooling and heating to get crystals, and in humid air it virtually melts before my eyes. Could your product be a hydrate?



Wow, that's surprising!
I would have thought that such a highly hydrated compound would remain quite dry and unwilling to absorb water from the air, perhaps even to the extent of efflorescence.

As for my product, well, I don't think its possible for it to form a hydrate by the coordination of water molecules around it, because it doesn't contain any metals, but perhaps it could have some water of crystallization?
I'm not sure, I would have thought the desiccant would remove that though.

It does appear to be crystallizing somewhat, but it seems to remain somewhat "wet" looking.
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[*] posted on 23-7-2022 at 11:23


So did I, so I left it out to air dry. That was a bit of work wasted. Hopefully the crystals I salvaged will still work as seeds.



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