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Author: Subject: Chloropicrin and its Odor
The_Davster
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[*] posted on 23-6-2005 at 21:15


I believe it is called chloropicrin as it was first prepared from picric acid and bleach. Don't question archaic nomenclature, the naming logic used then is so much different then todays nomenclature systems, and the chemists of old did no have the ability to determine the exact composition of most compounds so they were often named based upon their precursors. I believe your "dechloropicrin' would just be nitromethane

[Edited on 24-6-2005 by rogue chemist]




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The_Davster
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[*] posted on 28-8-2005 at 17:42


I found out today that chloropicrin can also be prepared by the action of bleach on styphnic acid. I used around 40mL of 11% bleach and a 1/4 spatula of styphnic acid. Allowed them to sit for a few min, then added an eyedropper of HCl, then after a few hours a puddle of liquid had collected on the bottom on the testtube around the size of 3 .177 BBs. Smelled kinda like chloroform, but made my eyes sting:).



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[*] posted on 9-12-2005 at 12:01


I found the equation of the reaction of picric acid with hypochloric acid:

C6H2(NO2)3OH + 11 HClO -----> 3 CCl3NO2 + 2 HCl + 3 CO2 + 6 H2O

So the aromatic ring is indeed completely destroyed.
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Eclectic
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[*] posted on 9-12-2005 at 13:26


I don't think pure chloropicrin has an "odor". It gives pain and copious tearing on inhalation. Imagine taking a good snort of hot chinese mustard. Now imagine 1000 times as much delivered straight to your sinuses with a sledge hammer. In very high dilution it has a peppery, acrid, teargas smell and was added to the soil fumagant methyl bromine as a warning agent.
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[*] posted on 23-12-2005 at 23:37


On what Eclectic said...

Chloropicrin has a definite odor. You will catch it on initially inhaling it, just before the pain reaction kicks in. It is very unique and very different from any impurities (as you know, I made it from bleach, which has a Chlorine smell, and Nitromethane, which is odorless).

Going off memory now (although I still remember the smell quite clearly--sorta burned into my nose :P ): It has that chlorocarbon smell, like Methylene Chloride or Chloroform. Actually, the smell of Bromine in Methylene Chloride reminded me a lot of Chloropicrin; but I've yet to find anything that has quite the same smell. Some perfumes have reminded me of it, though, which I find funny.

But if you want to know how Chloropicrin feels, I can tell you very easily. It's like cutting an onion when it comes to the eyes (not surprising since onions contain a lachrymator). The only thing I can find that made me cough as badly as Chloropicrin was CS (I sprayed myself). It's not a painful cough, but a persistent and intense one--as if there's something stuck in your chest that you can't quite reach with your coughing. There is a definite pain in your whole respiratory system though; it feels like it's [thermal] burning. It really affects your whole body; I know a guy who caught a whiff of it and fainted instantly. I felt weak after I got a whiff of it

As I recall, it's mixed in with Methyl Bromide more for its irritating properties than its smell.

With that said and in retrospect, I'd strongly discourage home chemists from making Chloropicrin. The synthesis is too easy, so you might regard it as some fun for the weekend; but that's treating it too lightly. PS really isn't any more dangerous than a lot of other lab reagents. In fact I don't even know why I'd discourage you from doing it. I'm trying to think of reasons to, but I'm falling short. Most of us are pretty gung-ho with safety; but don't forget those around you or the environment, please. :)

[Edited on 12-24-05 by Samosa]




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[*] posted on 28-5-2006 at 16:37


I had sucess with the trichlorisocyanuric acid method, Samosa:D:D:D:D:D:D:D!

I was destilling some modell aircaft fuel, to get some metanol. Later I collected the nitrometan, there were around 20% in it. So I had some nitrometan and no use for it.

Just for interrest I took some trichlorisocyanuric acid (C3N3O3Cl3)and added it to the nitromethane but nothing happened. Now I went inside (took my test tube with the mixture with me) and read this threat. I also read that you have to add a base. So I took my Ca(OH)2 (the single base I have) and added it, the reaction was quite vigorous and the stopper blew out. Now I have to sleep in a tear gassed room.:(

About the reaction mechanism: I think the OH- ion shifts the equillibium of nitromethan to the "enol" form of it:

CH3NO2 + OH- <===> - CH2-NO2 + H2O

The "enol"-form can act as a nucleophile with the as intermediate formed hypochlorous acid (hypochlorite) The hypochlorous acid forms slowly when the electron deficient clorine leaves as a Cl+ and gets captured immediately by a OH- This may react to hypochlorite or be used up by the "enolised" nithromethan.
The whole reaction:

CH3NO2 + OH- <===> - CH2-NO2 + H2O

- CH2-NO2 + HOCl <===>>> Cl-CH2-NO2 + HO-

C3N3O3Cl3 + 3 Alkali+ + OH- <===> C3N3O3Alkali3 + 3 HOCl

I'm tired now my eyes are tearing a bit, I hope the reaction mechanisms are more or less true, anyone who finds misstakes is wellcome:)
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[*] posted on 28-5-2006 at 17:37


I was just thinking about the mechanisms behind this earlier today, what I came up with was almost the same as you.
NaOCl+ H2O-->HOCl + NaOH
HOCl--> OH- + 'Cl+'

CH3NO2+ NaOH--> H2O +CH2=NO2- (nitronate)
nitronate goes to the 'enol' form of -CH2-NO2
Cl+ + -CH2-NO2 -->CH2Cl-NO2
Two more nitronate and subsequent rxn with Cl+ and you have the chloropicrin.

However:
3NaOCl +CH3NO2--> CCl3-NO2 +3NaOH
And the NaOH will eventually react with the chloropicrin(forgot and am unable to find the products of this reaction), so soon after the mixing of NM and bleach one must neutralize the base formed with some acid

I would be really interested in the mech of formation of chloropicrin from picric acid, I was not able to come up with anything really plausable.



Also, the reason Samosa had such fun when washing the glass with EtOH is that Chloropicrin and ethanol form an azeotrope that boils at 77C(35% chloropicrin).




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[*] posted on 28-5-2006 at 18:08


I've been neglecting this topic for a while due to some legal issues I ran into with it. Without saying too much, it was a major shakeup in my life and have just now gotten things back in line.

And I've also finished a year of Organic Chemistry ;-) .

Yes it's time we talk about the mechanism of this reaction. You guys nailed it--it's almost identical to the Haloform reaction (e.g.: chloroform from acetone), only there is no Chloroform cleavage in this reaction. Remember, NaOCl is essentially Chlorine dissolved in Sodium Hydroxide solution...

So here we are: CH3NO2 ---(NaOCl)--> CCl3NO2
Step 1: CH3NO2 is deprotonated by OH- : (-)H2C-NO2
Step 2: The nucleophilic carbon then reacts with the Cl+ (from NaOCl) and bonds with it. This, in turn, makes the remaining Hydrogens *more* acidic (electrophilic Cl withdraws electron density from them) and thus will react even more readily with another OH-, then Cl+, a second and third time.

This would explain the "mix and forget" nature of the reaction--it speeds up as it goes along!

Now that we understand this mechanism, it just may have other synthetic use to us. The only difficulty is that it will be near impossible to stop the reaction with a mono or dichlorinated product, since each reaction results in a more reactive product. But the way this is overcome in Alpha halogenations is using an *acidic* medium and Halide ion. So for example:

CH3NO2 --(Acetic Acid/Br2)--> CH2BrNO2

The reaction is stopped at the monohalogenated product! This could definitely have synthetic value, since here we have a Nitro group behaving analogously to a Carbonyl. Perhaps we could extend it further for example, an unsaturated nitro compound, possibly even the infamous "nitroacetylene"

O2N-CH2-CH2-N2O ---(Br2/Acetic acid)--> O2N-CHBr-CHBr-N2O ---(NaOH) --> N2O-C=C-NO2

I might be getting too ambitious here though.

I'm very pleased to hear about the Trichloroisocyanuric Acid method being successful! Shall we try to find a mechanism for this reaction? Who knows what can grow from some juvenile recklessness in a garage!

EDIT: just took time to reread what you wrote, Hinz.
Quote:
I had sucess with the trichlorisocyanuric acid method, Samosa:D:D:D:D:D:D:D!

I was destilling some modell aircaft fuel, to get some metanol. Later I collected the nitrometan, there were around 20% in it. So I had some nitrometan and no use for it.

Just for interrest I took some trichlorisocyanuric acid (C3N3O3Cl3)and added it to the nitromethane but nothing happened. Now I went inside (took my test tube with the mixture with me) and read this threat. I also read that you have to add a base. So I took my Ca(OH)2 (the single base I have) and added it, the reaction was quite vigorous and the stopper blew out. Now I have to sleep in a tear gassed room.:(


[This will be difficult to convey with text...but I'm too lazy to draw nice mechanisms :) ]

Here is my proposed mechanism. From other experiences, we've found that reacting Nitromethane with Sodium Hydroxide leads to "Sodium Nitronate." I believe it is this Nitronate ion that reacts via electrophilic addition:

1. CH2=NO2(-) Na(+) + C3N3O3Cl3 --> C3N3O3Cl2-CH2-NO2 + Na(+) + Cl(-)
This results in charge cancellation and the nitronate ion forming a complex with Trichloroisocyanuric acid--shall we call it "Nitromethyl Dichlorisocyanurate." Dichloroisocyanurate looks like a spectacular leaving group and Cl- a great nucleophile; thus I see an Sn2 reaction occurring on the Methylene.

2. C3N3O3Cl2-CH2-NO2 + Cl(-) ---> CH2Cl-NO2 + C3N3O3Cl2(-)

These two steps repeat twice more, leaving the two products: Chloropicrin and Sodium Isocyanurate (since we used NaOH).

This is just my hypothesis. I say this because Hinz said that no reaction occurred between the Nitromethane and Trichloroisocyanuric Acid until a base was added, which is why I believe it is the Nitronate ion that reacts.

[Edited on 5-29-06 by Samosa]




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[*] posted on 7-8-2006 at 13:34


I just made some for the first(and last) time today - I used a methanol solvent to carry it into the air(like perfume) and dumped it into the sink and then poured hot water over it and put my face above it.

All I had time to smell was a sent that was sharp like HCl but more "organic" like a solvent before I was bent over hacking away.

It didn't make me cry that much - I could still see but I was incapacatated.




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[*] posted on 7-8-2006 at 20:05


Quote:
Originally posted by Quantum
I just made some for the first(and last) time today - I used a methanol solvent to carry it into the air(like perfume) and dumped it into the sink and then poured hot water over it and put my face above it.

All I had time to smell was a sent that was sharp like HCl but more "organic" like a solvent before I was bent over hacking away.

It didn't make me cry that much - I could still see but I was incapacatated.


For those wondering how it feels to be gassed by Chloropicrin: It's almost like being punched in the face and having the wind knocked out of you simultaneously.

It's not just a lachrymator; its effects are truly incapacitating (temporarily). It makes your muscles feel weak, so it becomes hard to get up or walk. Doing what our friend Quantum did (and what I have done) will basically lead to you fainting (not necessarily losing consciousness, but collapsing and hacking/choking until your face is blue).

Keep it safe, and trust that it is, indeed, an incapacitant. Keep self-testing to a minimum :P




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[*] posted on 8-8-2006 at 16:42


That is a very apt description Samosa - its almost like Liquid Knuckles in Snow Crash(sort of) - Really knocked me for a loop

NBK and others would(and do) have a feild day with this stuff. Of course this is a chemistry forum but there are many applications for this chemical expecially combined with a second agent.

It's powerful! I'm not going to expose myself to it again.

Edit: Change KBK to NBK

[Edited on 9-8-2006 by Quantum]




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