Sciencemadness Discussion Board

WARNING: Explosive reaction between pool chlorine chemicals

theAngryLittleBunny - 6-12-2021 at 15:05

Maybe most people here know about it, but I'll still post it for anyone who might not. Since I've been doing chemistry for 6 years now and this accident happened to me just recently, maybe 1 or 2 months ago.

I generated chlorine gas by adding HCl in a flask with TCCA and after generating a bit of chlorine I thought I should make an excess to displace the air. However, I didn't feel like crushing up more TCCA tablets, so I just added 10g of calcium hypochlorite into the flask and continued. Maybe one or two minutes later the flask just exploded while I sat in front of it. I had tiny glass shards on my glasses and my face. I was super lucky and only ended up with a few scratches in my face and my hand. I had no clue what happened, but after researching a bit, turns out TCCA reacts with hypchlorite to nitrogen trichloride and a carbonate salt (C3N3O3Cl3 + 3Ca(OCl)2 -> 3CaCO3 + 3NCl3). I don't know if that's something people who do chemistry generally know about so I wanted to post it so no one else makes the same mistake. I think I just underestimated the danger of these chemicals just because they are OTC.

In general, don't mix TCCA (or Na-DCCA) with any kind of base, including NaOH or Na2CO3. Someone told me they had TCCA powder that was contaminated with Na2CO3 explode. In solution it doesn't result in any explosion (in my experience, still don't try it), when dissolving TCCA or Na-DCCA in a NaOH solution you will see that it starts fizzing a bit giving off an colourless and odourless gas, I'm sure that is nitrogen from tiny amounts of NCl3 decomposing very quickly after being generated. I tried making NaOCl that way (which is not too easy to get here cheaply) which doesn't work. As long as you keep TCCA/ Na-DCCA in neutral or acidic conditions it seems to be safe.

fredsci93 - 6-12-2021 at 15:25

That's terrifying, I can't believe I had never heard about that, makes some sense in retrospect though since CA is a urea derivative.

theAngryLittleBunny - 6-12-2021 at 16:53

Quote: Originally posted by fredsci93  
That's terrifying, I can't believe I had never heard about that, makes some sense in retrospect though since CA is a urea derivative.


I never heard of it either, there were a few accidents from people who used it for their pools because they mixed two different pool chlorinating chemicals (one with TCCA/ Na-DCCA, one with Ca(OCl)2). This can easily happen since Na-DCCA and Ca(OCl)2 are both used to quickly raise hypochlorite levels in pools (so called shock chlorination) since they are both water soluble. Usually the containers for these from the same brand look pretty much identical. In one case a couple mixed them in the kitchen which resulted in 5 violent explosions destroying the entire kitchen, luckly they weren't in the kitchen when it happened and survived.

Afterwards I looked on the label and there is said to not mix them or it could cause an explosive reaction, maybe I should have read that earlier lol. If you mix TCCA/ Na-DCCA with Ca(OCl)2 it's not just an explosion risk, it WILL explode.

Witch's Mix

MadHatter - 6-12-2021 at 21:13

C3Cl3N3O3 + 3Ca(OCl)2 ---> 3CaCO3 + 3NCl3

Nitrogen trichloride theoretical stoichiometric yield: 54.6%
It can be detonated by light, heat, shock and contact with organics.

Monoamine - 6-12-2021 at 23:41

Thank you for the warning and self experiment. So I guess the "safe" way to make Cl2 is just to use sodium hypochlorite and HCl.

karlos³ - 7-12-2021 at 06:58

The worst is that NCl3 even explodes in aqueous medium, something which NI3 is not able to.

Yeah I knew about that, it is pretty unknown though.
There is some aldehyde amidation method which uses that which we ruled out as far too dangerous.

What a relief you still have all your fingers and both eyes!

[Edited on 7-12-2021 by karlos³]

woelen - 7-12-2021 at 07:01

I started a thread about this 13 years ago: https://www.sciencemadness.org/whisper/viewthread.php?tid=11...

Too Dangerous/Unstable

MadHatter - 7-12-2021 at 10:54

NCl3, NI3, sulphur or phosphorus with chlorates and ALL
hypergolic mixtures. I don't even want to be near them.

pantone159 - 7-12-2021 at 16:53

Would cyanuric acid (instead of the chlorinated TCCA or Na-DCCA) cause the dangerous situation as well?

Cyanuric Acid

MadHatter - 7-12-2021 at 23:03

C3H3N3O3 + 3Ca(OCl)2 ---> 3CaCO3 + 2NCl3 + NH3

Nitrogen trichloride theoretical stoichiometric yield: 43.1%

If I have the equation correctly.

woelen - 8-12-2021 at 00:08

Quote: Originally posted by pantone159  
Would cyanuric acid (instead of the chlorinated TCCA or Na-DCCA) cause the dangerous situation as well?
Yes, it does, I tried at test tube scale by mixing solid cyanuric acid, solid Ca(ClO)2 and adding a few drops of water.
Madhatter's equation gives a hint in this direction. The reality is more complicated though. No free NH3, but also NH2Cl (smell!) and N2 (lot of colorless gas is produced).

teodor - 8-12-2021 at 04:17

NCl3 should be an interesting compound. Alas, it has explosive properties. I am wondering, is it possible to stabilize NCl3 binding to some type of complex salt and then study it as an anion?

Bedlasky - 8-12-2021 at 04:47

Teodor: I don't thing that it forms complex anions. I guess maybe some adduct, but I never read about it.

teodor - 8-12-2021 at 04:56

Bedlasky, I really wanted to write "complex or adduct" but I forget the second word, thank you. Yes, I know PCl3 very often forms such adducts.

Update.

Also, quite interesting, from "Comprehensive Inorganic Chemistry":

".. the endothermic character and resulting instability on NCl3 and NI3 ... results not from ... weakness of the N-Cl or N-I bond but rather from ... the stability of the multiple bond in the N2 molecule. The energy of formation of N2 molecules from free N atoms is so large that nitrogen compounds unless they contain bonds of rather high energy, tend to have negative heats of formation..."

[Edited on 8-12-2021 by teodor]

woelen - 8-12-2021 at 08:10

NCl3 is really nasty stuff. It explodes very easily, but its explosions also are very powerful. Even a single drop of liquid in the bottom of a test tube will lead to shattering and flying pieces of glass if it explodes. Really dangerous stuff and if you value your fingers, hands and eyes, then I would be very cautious with NCl3.

When I did the experiment with Na-DCCA and Ca(ClO)2 and saw the drop of NCl3 I was shit scared and quickly put the test tube aside and went away, just waiting it out. Fortunately the drop of NCl3 did not explode and simply was consumed by all alkaline stuff around.

I worked with other explosive stuff (ClO2 and even ClN3), but these are less scary, because they are gaseous and explosions of that tend to be much less powerful (lower density, much larger starting volume). A test tube with exploding ClO2 does not shatter, but the same weight of material (e.g. NCl3) concentrated in a small drop in the bottom of a test tube does lead to flying glass splinters.

teodor - 8-12-2021 at 08:37

Benzene solution of NCl3 is "somehow stable in the dark" as some sources do mention, but that means somebody who wants to experiment with tiny quantities can also do it in a solution to lower the power of the possible explosion.

Admagistr - 8-12-2021 at 08:46

I think that NCl3 could also be made by electrolysis of a concentrated solution of NH4Cl. Has anyone tried it, does anyone know anything about this?

theAngryLittleBunny - 8-12-2021 at 11:08

Quote: Originally posted by karlos³  
The worst is that NCl3 even explodes in aqueous medium, something which NI3 is not able to.

Yeah I knew about that, it is pretty unknown though.
There is some aldehyde amidation method which uses that which we ruled out as far too dangerous.

What a relief you still have all your fingers and both eyes!

[Edited on 7-12-2021 by karlos³]


Yeah that's because NCl3 seperates out as an oil that sinks so it can easily collect there. If you put ammonia in an excess of bleach you'll quickly get a blob of yellow NCl3 forming at the bottom, this stuff is really scary.

theAngryLittleBunny - 8-12-2021 at 11:11

Quote: Originally posted by pantone159  
Would cyanuric acid (instead of the chlorinated TCCA or Na-DCCA) cause the dangerous situation as well?


Absolutely, since hypochlorite would turn the cyanuric acid into TCCA. A lot of things that have nitrogen in the -3 oxidation state will do that, so never mix that with hypochlorite. I think any compound that would form ammonia through alkaline hydrolysis would do that for sure, like urea or any amide.

theAngryLittleBunny - 8-12-2021 at 11:21

Quote: Originally posted by woelen  
NCl3 is really nasty stuff. It explodes very easily, but its explosions also are very powerful. Even a single drop of liquid in the bottom of a test tube will lead to shattering and flying pieces of glass if it explodes. Really dangerous stuff and if you value your fingers, hands and eyes, then I would be very cautious with NCl3.

When I did the experiment with Na-DCCA and Ca(ClO)2 and saw the drop of NCl3 I was shit scared and quickly put the test tube aside and went away, just waiting it out. Fortunately the drop of NCl3 did not explode and simply was consumed by all alkaline stuff around.

I worked with other explosive stuff (ClO2 and even ClN3), but these are less scary, because they are gaseous and explosions of that tend to be much less powerful (lower density, much larger starting volume). A test tube with exploding ClO2 does not shatter, but the same weight of material (e.g. NCl3) concentrated in a small drop in the bottom of a test tube does lead to flying glass splinters.


I poured 10g of Ca(OCl)2 on top of over 100g of TCCA, not sure how much NCl3 this could make in practice. It was a 1L flask, and it just bursted and glass shards were lying everywhere within a 4m radius of where it happened. I was sitting right in front of it so I'm really surprised I got away pretty much completely unharmed. And after the accident I think I came across a thread that talked about that. But it wasn't so easy to find so I think another post about this might be useful.

clearly_not_atara - 8-12-2021 at 11:34

TCCA and its derivatives have caused other explosions as well; see e.g. the chlorination of benzaldehyde. Perhaps we should put a warning in the TCCA article on the SM wiki, since it is a common chemical that even beginners often use while not being aware of the risks.

The partially dehalogenated TCCA can give off HCl and N2, while alkaline hydrolysis can generate chloramines. And hypochlorites are a concern.

theAngryLittleBunny - 8-12-2021 at 15:52

Quote: Originally posted by clearly_not_atara  
TCCA and its derivatives have caused other explosions as well; see e.g. the chlorination of benzaldehyde. Perhaps we should put a warning in the TCCA article on the SM wiki, since it is a common chemical that even beginners often use while not being aware of the risks.

The partially dehalogenated TCCA can give off HCl and N2, while alkaline hydrolysis can generate chloramines. And hypochlorites are a concern.


Oh shiiiit, when I started with chemistry I put solid TCCA to Benzaldehyde in an attempt to make benzoyl chloride. I had no clue this stuff was so dangerous, I think a warning would be a good idea.

Morgan - 8-12-2021 at 18:50

As an aside, I used to mix prilled ammonium nitrate with calcium hypochlorite and it made some unknown violent snap, crackle, popping sound spontaneously starting after a minute or so after the granules were combined one on top the other or you could just wet it. Never was it a seemingly threatening reaction but the pool chlorine hypochlorite product was only 65% with inert ingredients of some sort if that was a factor.
Anyway it seems to liquify and froth somewhat as the reaction takes place if you put it in a wide can and although the popcorn effect was most entertaining like dozens of mini firecrackers going off at the same time for a little less than a minute duration, it was kind of loud but not too. I never knew just what the chemical reaction was. Also youtube has never featured it to my knowledge. I mixed about a pound one time.
I can't say it's safe to try but it never seemed to do more than what I described. I would just like to know what cusp of an explosive was formed and destroyed before it ever became unified enough to become forceful. I avoided the fumes too in which distance from an uncertain reaction is always a good idea. Some of those hypochlorite and brake fluid videos are pretty snap crackly but the prilled NH4NO3 is just a bit more energetic on that spectrum. It never made a flame, just steamy smoke and machine gun pops.
Don't take chances with this reaction. I was younger and foolish when I did it. Maybe it's relatively safe, maybe not.

Maybe the heat of the reaction sets off tiny droplets before the formation of any real quantity of NCl3 can happen.

Wiki tidbits on nitrogen trichloride .. .
"Autoignition temperature 93 °C (199 °F; 366 K)"
"The compound is prepared by treatment of ammonium salts, such as ammonium nitrate with chlorine."
"The pure substance (rarely encountered) is a dangerous explosive, being sensitive to light, heat, even moderate shock, and organic compounds."

And for review ...
"Pierre Louis Dulong first prepared it in 1812, and lost two fingers and an eye in two explosions. In 1813, an NCl3 explosion blinded Sir Humphry Davy temporarily, inducing him to hire Michael Faraday as a co-worker. They were both injured in another NCl3 explosion shortly thereafter."


[Edited on 9-12-2021 by Morgan]

Modified equation

MadHatter - 8-12-2021 at 19:06

woelen, you're probably right about the equation considering you
noticed chloramine. I should've realized this when thinking back
to what happens when ammonia and bleach are mixed together.
It probably depends on the temperature. Anyway:

2C3H3N3O3 + 6Ca(OCl)2 ---> 6CaCO3 + 3NCl3 + 3NH2Cl

Reworked equation I came up with. I detest unbalanced equations.

Nitrogen trichloride theoretical stoichiometric yield: 32.3%
Chloramine theoretical stoichiometric yield: 13.8%

For ammonia and bleach I remember:

NH3 + NaOCl ---> NaOH + NH2Cl (WARM)
2NH3 + NaOCl ---> NaCl + N2H4 + H2O (COLD)

Admagistr, electrolysis of NH4Cl is extremely dangerous because it
produces NH4ClO3 in addition to NCl3. I'm not sure which is more
unstable: Ammonium chlorate or nitrogen trichloride. IMHO, anybody
who does this gets my nomination for the Darwin Award.

[Edited on 2021/12/9 by MadHatter]

woelen - 8-12-2021 at 23:53

Actually, NH4ClO3 is not that dangerous in solution. But I doubt that this will be formed when you electrolyze NH4Cl. You get Cl2 at the anode, which forms NCl3 with the amonium ions. At the cathode you get NH3 and H2. On mixing, the NH3 will react with NCl3 and also with Cl2, giving N2, NH2Cl and maybe even some NH2NH2.

NH4ClO3 is another funny beast, but not in this context.

Correction

MadHatter - 9-12-2021 at 09:58

I should've said that NCl3 can be produced if attempting to produce
NH4ClO3 by electrolysis of NH4Cl. I won't be trying this in any event.

clearly_not_atara - 9-12-2021 at 18:56

Quote: Originally posted by theAngryLittleBunny  
Quote: Originally posted by clearly_not_atara  
TCCA and its derivatives have caused other explosions as well; see e.g. the chlorination of benzaldehyde. Perhaps we should put a warning in the TCCA article on the SM wiki, since it is a common chemical that even beginners often use while not being aware of the risks.

The partially dehalogenated TCCA can give off HCl and N2, while alkaline hydrolysis can generate chloramines. And hypochlorites are a concern.


Oh shiiiit, when I started with chemistry I put solid TCCA to Benzaldehyde in an attempt to make benzoyl chloride. I had no clue this stuff was so dangerous
The rxn works under UV illumination in chlorinated solvents, but heating the rxn mixture to distill BzCl will cause an explosion. It must be done under a strong vacuum, or extracted another way.

woelen - 10-12-2021 at 02:50

In the last reaction, you probably confused the use of TCCA with the use of cyanuric chloride. TCCA is C3N3O3Cl3 and cyanuric chloride is C3N3Cl3 (a trimer of CNCl). The latter is a good chlorinating agent, which easily replaces hydroxyl groups bij chlorine atom, itself being converted to cyanuric acid. TCCA is a strong oxidizing agent, it also can chlorinate things, but it does so by oxidation. It can replace H-atoms by Cl-atoms, which cyanuric chloride cannot do.

Cyanuric chloride also is a nasty one, but it is not explosive. I expect it can be used to make benzoyl chloride from benzoic acid, by replacement of the acidic OH-group by a chlorine atom.

If you add TCCA to benzoic acid, how would this lead to benzoyl chloride? I see no mechanism for replacement of the hydroxyl group by chlorine. TCCA cannot exchange Cl by OH. I indeed only see an oxidative reaction, leading to destruction of the structure of benzoic acid in a strong exothermic reaction, leading to fire or explosion.

theAngryLittleBunny - 11-12-2021 at 12:57

Quote: Originally posted by Morgan  
As an aside, I used to mix prilled ammonium nitrate with calcium hypochlorite and it made some unknown violent snap, crackle, popping sound spontaneously starting after a minute or so after the granules were combined one on top the other or you could just wet it. Never was it a seemingly threatening reaction but the pool chlorine hypochlorite product was only 65% with inert ingredients of some sort if that was a factor.
Anyway it seems to liquify and froth somewhat as the reaction takes place if you put it in a wide can and although the popcorn effect was most entertaining like dozens of mini firecrackers going off at the same time for a little less than a minute duration, it was kind of loud but not too. I never knew just what the chemical reaction was. Also youtube has never featured it to my knowledge. I mixed about a pound one time.
I can't say it's safe to try but it never seemed to do more than what I described. I would just like to know what cusp of an explosive was formed and destroyed before it ever became unified enough to become forceful. I avoided the fumes too in which distance from an uncertain reaction is always a good idea. Some of those hypochlorite and brake fluid videos are pretty snap crackly but the prilled NH4NO3 is just a bit more energetic on that spectrum. It never made a flame, just steamy smoke and machine gun pops.
Don't take chances with this reaction. I was younger and foolish when I did it. Maybe it's relatively safe, maybe not.

Maybe the heat of the reaction sets off tiny droplets before the formation of any real quantity of NCl3 can happen.

Wiki tidbits on nitrogen trichloride .. .
"Autoignition temperature 93 °C (199 °F; 366 K)"
"The compound is prepared by treatment of ammonium salts, such as ammonium nitrate with chlorine."
"The pure substance (rarely encountered) is a dangerous explosive, being sensitive to light, heat, even moderate shock, and organic compounds."

And for review ...
"Pierre Louis Dulong first prepared it in 1812, and lost two fingers and an eye in two explosions. In 1813, an NCl3 explosion blinded Sir Humphry Davy temporarily, inducing him to hire Michael Faraday as a co-worker. They were both injured in another NCl3 explosion shortly thereafter."


[Edited on 9-12-2021 by Morgan]


Maybe it's because in ammonium nitrate there is no chlorine on the nitrogen, so more has to react. With TCCA there is already a chlorine on the nitrogen which might help form the NCl3 faster.

And I think the ammonia being protonated as an ammonium ion also plays a role in slowing the reaction down, so it's very different then the TCCA Ca(OCl)2 reaction.

theAngryLittleBunny - 11-12-2021 at 13:01

Quote: Originally posted by clearly_not_atara  
Quote: Originally posted by theAngryLittleBunny  
Quote: Originally posted by clearly_not_atara  
TCCA and its derivatives have caused other explosions as well; see e.g. the chlorination of benzaldehyde. Perhaps we should put a warning in the TCCA article on the SM wiki, since it is a common chemical that even beginners often use while not being aware of the risks.

The partially dehalogenated TCCA can give off HCl and N2, while alkaline hydrolysis can generate chloramines. And hypochlorites are a concern.


Oh shiiiit, when I started with chemistry I put solid TCCA to Benzaldehyde in an attempt to make benzoyl chloride. I had no clue this stuff was so dangerous
The rxn works under UV illumination in chlorinated solvents, but heating the rxn mixture to distill BzCl will cause an explosion. It must be done under a strong vacuum, or extracted another way.


I remember the flask getting warm, maybe even hot at some point and I smelled some benzoyl chloride (not BzCl). However I didn't know how to get the benzoyl chloride out of that mix and just reacted it with some alcohol. I also did it outside in the sunlight, so maybe this might have done something as well.

theAngryLittleBunny - 11-12-2021 at 13:04

Quote: Originally posted by woelen  
In the last reaction, you probably confused the use of TCCA with the use of cyanuric chloride. TCCA is C3N3O3Cl3 and cyanuric chloride is C3N3Cl3 (a trimer of CNCl). The latter is a good chlorinating agent, which easily replaces hydroxyl groups bij chlorine atom, itself being converted to cyanuric acid. TCCA is a strong oxidizing agent, it also can chlorinate things, but it does so by oxidation. It can replace H-atoms by Cl-atoms, which cyanuric chloride cannot do.

Cyanuric chloride also is a nasty one, but it is not explosive. I expect it can be used to make benzoyl chloride from benzoic acid, by replacement of the acidic OH-group by a chlorine atom.

If you add TCCA to benzoic acid, how would this lead to benzoyl chloride? I see no mechanism for replacement of the hydroxyl group by chlorine. TCCA cannot exchange Cl by OH. I indeed only see an oxidative reaction, leading to destruction of the structure of benzoic acid in a strong exothermic reaction, leading to fire or explosion.


Hmm? I said I added it to benzaldehyde so that it would get chlorinated to benzoyl chloride and the TCCA would turn to cyanuric acid, at least that's how I imagined it would go. I did smell a bit of benzoyl chloride though.

karlos³ - 11-12-2021 at 13:21

Quote: Originally posted by theAngryLittleBunny  
Quote: Originally posted by woelen  
In the last reaction, you probably confused the use of TCCA with the use of cyanuric chloride. TCCA is C3N3O3Cl3 and cyanuric chloride is C3N3Cl3 (a trimer of CNCl). The latter is a good chlorinating agent, which easily replaces hydroxyl groups bij chlorine atom, itself being converted to cyanuric acid. TCCA is a strong oxidizing agent, it also can chlorinate things, but it does so by oxidation. It can replace H-atoms by Cl-atoms, which cyanuric chloride cannot do.

Cyanuric chloride also is a nasty one, but it is not explosive. I expect it can be used to make benzoyl chloride from benzoic acid, by replacement of the acidic OH-group by a chlorine atom.

If you add TCCA to benzoic acid, how would this lead to benzoyl chloride? I see no mechanism for replacement of the hydroxyl group by chlorine. TCCA cannot exchange Cl by OH. I indeed only see an oxidative reaction, leading to destruction of the structure of benzoic acid in a strong exothermic reaction, leading to fire or explosion.


Hmm? I said I added it to benzaldehyde so that it would get chlorinated to benzoyl chloride and the TCCA would turn to cyanuric acid, at least that's how I imagined it would go. I did smell a bit of benzoyl chloride though.

@woelen, he was probably talking about this here: http://www.sciencemadness.org/talk/files.php?pid=648784&...

Not sure if the acyl chloride can be isolated, but its claimed to be produced as an intermediate in that reaction, and given the products it sounds relatively plausible to me.

woelen - 11-12-2021 at 14:33

Quote: Originally posted by theAngryLittleBunny  

Hmm? I said I added it to benzaldehyde so that it would get chlorinated to benzoyl chloride and the TCCA would turn to cyanuric acid, at least that's how I imagined it would go. I did smell a bit of benzoyl chloride though.

My mistake. I read your post and later decided to reply to it, but my mind replaced the benzaldehyde by benzoic acid. With benzaldehyde I can imagine formation of benzoyl chloride (that reaction is oxidative and replaces H by Cl). But it certainly is a risky thing to do.

AJKOER - 12-12-2021 at 10:28

Did read about synthesis based on NCl3 diluted in CCl4 (possibly CHCl3) for organic synthesis.

There is apparently a critical level of dilution required for safe handling, but I still would avoid any UV light sources even if reportedly safe.

Obviously only for professional labs with high purity reagents.

Did find a working reference for NCl3.CCl4 here https://aai.solutions/documents/AA_AN005_Monitoring-NCl3-nit... .

For the record, NCl3 is a high explosive and any drops should be respected as such. Discounting the explosive power for small amounts of NCl3 is likely the main reason for so many reported injuries.

My recollection also is that a previously suggested path based on the electrolysis of aqueous NH4Cl is reportedly a known laboratory explosion hazard. Here is a source https://iopscience.iop.org/article/10.1149/1.3071370 to quote: "Explosions occurred in some cases but these, it is felt, can be avoided as they were probably due to faulty cell construction or to too low electrolyte temperature."

[Edited on 12-12-2021 by AJKOER]