Rhodanide
Hazard to Others
Posts: 348
Registered: 23-7-2015
Location: Ｔｈｅ ８０ｓ
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Mood: That retro aesthetic
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A most sobering situation
So I thought I'd have a go at making a diazonium salt solution. I made up a saturated solution of Anilinium Hydrochloride in water, and another of
NaNO2 in water. I added the An HCl to the Nitrite, and just about soiled myself when an orange precipitate filled the beaker. My reasoning for being
afraid was this: The beaker in front of me was now filled with (what I thought to be) precipitated BDZ Chloride, and I was probably going to
experience an explosion. I was also expecting to experience the same situation stated on Wikipedia - and I quote: "It is often preferred that the
Diazonium salt remain in solutions, but they do tend to supersaturate. Operators have been injured or even killed by an unexpected crystallization of
the salt followed by its detonation." ...which I thought was gonna be me. However, nothing happened, I massively diluted it with water and poured it
down the drain. I've got pictures of the precipitate, tell me if I was rightfully frightened, or just needlessly spooked.
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LearnedAmateur
National Hazard
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Benzenediazonium chloride reacts with aniline to form Aniline Yellow, which is what I'd presume you have here since it isn't very soluble in water.
Benzenediazonium salts tend to be colourless, and what I think here is the anion exchange bypassed major formation of the BDZ chloride (since the
chloride is now bound to the NaCl). Hopefully someone with more knowledge can help out, but this is the mechanism I believe to be occurring, which
could be wrong so take with a pinch of salt.
PhNH3Cl + NaNO2 -> PhN2OH + NaCl + H2O
PhN2OH + PhNH3Cl -> PhN2Cl + PhNH2 + H2O
PhN2Cl + PhNH2 -> Aniline Yellow + HCl
In chemistry, sometimes the solution is the problem.
It’s been a while, but I’m not dead! Updated 7/1/2020. Shout out to Aga, we got along well.
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zed
International Hazard
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Registered: 6-9-2008
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Ummm. Not sure that precipitation of the Benzene Diazonium Chloride salt actually results in detonation.
I've seen some procedures for intentionally precipitating this salt, and isolating it as an intermediate. Authors do make it clear however, not to
"jostle" the crystals or allow the precipitated material to actually become "dry".
Also of note, converting the Benzene Diazonium Chloride salt to the Tetrafluoroborate salt, is supposed to produce a solid that can safely be
handled. Somewhere, I have a paper on the subject.
https://www.acs.org/content/acs/en/pressroom/cutting-edge-ch...
Question...You were following a published procedure, that instructed you to pour your Aniline solution INTO your Nitrite solution? Seems backwards.
[Edited on 25-10-2017 by zed]
[Edited on 25-10-2017 by zed]
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