Sciencemadness Discussion Board

Explosive hazard

Temporary2 - 22-4-2011 at 18:16

A BS chemist at our plant was trying to repeat a reaction to make chloroacetic acid using the procedure found in <a HREF = "http://www.informaworld.com/smpp/content~db=all~content=a713748943">this paper.</A> After mixing the acetic acid, PCl3, and trichloroisocyanuric acid (trichlor) it promptly exploded. It sounded like a hand grenade going off. Fortunately he was doing a test reaction in a one ounce vial, with eye protection but he received glass fragments and cuts over his face, hands, and neck. One of the fragments destroyed a flat scene monitor 10 feet from the explosion.

Bot0nist - 22-4-2011 at 20:02

Fortunately no one was more seriously hurt. What kind of work do you do?

That is an interesting website profile you have there.

Temporary2 - 22-4-2011 at 20:23

I am the senior production chemist at Natural Advantage flavorings.

Bot0nist - 22-4-2011 at 20:36

<a href="http://www.natural-advantage.net/">Natural Advantage</a> sounds like an interesting place to work. Was it a flavorful explosion? I can imagine a buttery or apple tasting blast. Just joking of course.

jokull - 23-4-2011 at 07:49

Hi.
At this moment I'm not able to access the paper, but in my experience I think that your incident happened because of water presence in reacting system. PCl3 hydrolizes in a highly exothermic way. Acetic acid must be glacial grade.

Hope this may help.

Temporary2 - 23-4-2011 at 08:10

Acetic acid was glacial. We have had no problems using it in the past in production of "Natural" acetyl chloride with PCl3. Further digging has showed me trichlor becomes more reactive as acidity increases. I think this reaction will join the too unsafe for our workplace list.

FYI trichlor also is very incompatible with Ca(ClO)2 swimming pool chlorine which is bad because trichlor is the other major swimming pool chlorine. A mixture of these two with a small amount of water causes an almost instantaneous explosion.

Definition of natural = all carbons coming from modern plant source, nonpetroleum source. This is confirmed by MS isotopic analysis at University of Georgia MS lab.

Saerynide - 23-4-2011 at 08:44

Im glad no one was very badly hurt.

Forgive me if this sounds stupid, but why not just buy the MCA? Since you guys are in a company and are not doing this for the sake of home experimenting? My group insists I buy everything, even when sometimes I want to make it purely out of academic interest (so I just do both to satisfy both parties)

[Edited on 4/23/2011 by Saerynide]

smuv - 23-4-2011 at 20:37

Are you sure he wasn't just an idiot and added all the TCCA at once?

Temporary2 - 24-4-2011 at 17:20

Saerynide , we can't buy "Natural" chloroacetic acid. A major problem in the Natural flavors business is that we must make things sometimes the hard way from carbon sources that came from modern plants and not from mineral or petroleum sources.

Yes he did add it all at once as he did not realize even on the scale he was working it was that great a hazard. He graduated in May and has a lot to learn yet about reading up on materials before using them. I remember being that young once. ;) It is also unfortunate that his supervisors in R and D do not properly train nor supervise him. They keep missing that little word "safety".

HydroCarbon - 24-4-2011 at 17:45

Quote: Originally posted by Temporary2  


Definition of natural = all carbons coming from modern plant source, nonpetroleum source. This is confirmed by MS isotopic analysis at University of Georgia MS lab.


Wow, what a load of shit. As if the carbons coming from plant sources make it so much healthier at the end of the day. Just goes to show how the terms "organic" and "natural" really have no meaning, and are just marketing gimmicks.

While I respect your science, keep that shit out of my food! The products you make are nothing more than tools to make profit at the cost of people's health.

Sorry to knock off topic.

[Edited on 25-4-2011 by HydroCarbon]

Temporary2 - 24-4-2011 at 18:22

Understood HydroCarbon, our products are used by many major food manufacturers: Kraft, Pepsi, Coke, etc. We are going by the standards that the industry places on us. Many of our products are directly extracted from plants as linalool from Ho Wood. Never said it was any more or less healthier just said those were the rules of engagement placed on us by international regulating bodies to define natural flavoring substances and blends.

The WiZard is In - 24-4-2011 at 18:53

Quote: Originally posted by jokull  
Hi.
At this moment I'm not able to access the paper, but in my experience I think that your incident happened because of water presence in reacting system. PCl3 hydrolizes in a highly exothermic way. Acetic acid must be glacial grade.

Hope this may help.


Ye old Bretherick's (6th ed.) I am poor and cannot
afford to keep current with this book.) sez....

"Trichloroisocyanuric acid [87-90-1]

If mixed with a small amount of water, the conc. solution
with a pH around 2) may explode owing to evolution of
nitrogen trichloride.....

NB- By consensus laboratory accidents are reported to -
published in Chemical and Engineering News, they
eventual end up in Bretherick's.

[Edited on 25-4-2011 by The WiZard is In]

Temporary2 - 24-4-2011 at 20:09

Thanks, I had never heard of Bretherick's Handbook of Reactive Chemical Hazards. I will have to dig more myself. I understand cost as current edition from Elsevier is $470. I doubt I could convince the boss to shell out that much, small company 60 people.

smuv - 24-4-2011 at 21:53

well the procedure said add portionwise...so he just didn't follow the procedure. Don't write off a reaction because of an incompetent chemist. So many things can blow up in lab if additions are made too quickly.

Dr.Bob - 25-4-2011 at 09:00

Quote: Originally posted by Temporary2  
Thanks, I had never heard of Bretherick's Handbook of Reactive Chemical Hazards. I will have to dig more myself. I understand cost as current edition from Elsevier is $470. I doubt I could convince the boss to shell out that much, small company 60 people.


You can get an older edition, but still useful for much less at Amazon, for example,

http://www.amazon.com/gp/offer-listing/0408013885/ref=dp_olp...

I think I have an extra one somewhere as well, which I have been meaning to sell. They are very useful.

I do love the concept of "natural" chloroacetic acid, but do understand the rules that regulate foods and drugs, and they are somewhat crazy at times. Best of luck.

Bob

Saerynide - 25-4-2011 at 09:13

Quote: Originally posted by Temporary2  
Saerynide , we can't buy "Natural" chloroacetic acid. A major problem in the Natural flavors business is that we must make things sometimes the hard way from carbon sources that came from modern plants and not from mineral or petroleum sources.


So according to that definition of "natural", only the carbon must come from a modern plant source but the other atoms, like the Cl, can be an industrial product? That hardly seems "natural" to me. If someone told me a food item was "natural", I would hope it was directly extracted from a plant/animal and not just the carbons :P But ok, now when I look at the ingredients and it says "natural strawberry flavors", I'll know they dont actually come from strawberries, just the carbons :o

[Edited on 4/25/2011 by Saerynide]

AndersHoveland - 25-4-2011 at 10:20

Trichloroisocyanuric acid (TCCA) often explodes when acidified. It generally seems to be assumed that formation of nitrogen trichloride is the culprit, but it is quite possible that this assumption is, at least in part, erroneous.

"Upon hydrolysis, trichloroisocyanuric acid yields hypochlorous acid"
Oxidation studies of symmetrical and unsymmetrical ethers : Comparison of trichloroisocyanuric acid and hypochlorous acid reagent. E. C. Juenge, M. D. Corey and D. A. Beal. Kansas State College, Pittsburg, Kansas USA

Hypochlorous acid and hydrogen chloride (from the hydrolysis of PCl3) will form chlorine. Chlorine is certainly known to oxidize TCCA to nitrogen trichloride. There have been many accidents involving chemical waste mixtures that have included hypochlorite or TCCA withsome other acidic compound (such as ammonium sulfate).




[Edited on 25-4-2011 by AndersHoveland]

smuv - 25-4-2011 at 12:04

This thread is ridiculous. TCCA DOES NOT EXPLODE WHEN ACIDIFIED!

AndersHoveland - 26-4-2011 at 15:39

This was mentioned in a previous topic:
http://www.sciencemadness.org/talk/viewthread.php?tid=14278

One of the members noted that mixtures of TCCA and ammonium nitrate could explode.

Magpie - 26-4-2011 at 16:22

So the carbons of the final product must have come from a plant or animal source, if I understand this correctly. But isn't petroleum itself a natural product derived from decayed plants? Also, can said natural carbons be processed using unnatural reagents such as ether? Does this get a bit tricky when the processing can lead to exchanges of carbon between chemicals, natural and unnatural? One might have to use carbon 14 tagging to make sure no unnatural carbon was used....

AJKOER - 1-5-2012 at 15:12

Quote: Originally posted by Temporary2  
After mixing the acetic acid, PCl3, and trichloroisocyanuric acid (trichlor) it promptly exploded. It sounded like a hand grenade going off. Fortunately he was doing a test reaction in a one ounce vial, with eye protection but he received glass fragments and cuts over his face, hands, and neck. One of the fragments destroyed a flat scene monitor 10 feet from the explosion.


Given the intensity of the explosion for the small quantity involved in the test run, the formation of NCl3 is a good candidate as TCCA hydrolysis produces HOCl.

[C(O)NCl]3 + 3 H2O --> (CNOH)3 + 3 HOCl

although this reaction is normally slow. However, Hypochlorous acid is capable, for example even in dilute solutions, of oxidizing ammonia (as an example) to Nitrogen trichloride when heated:

NH3 + 3 HOCl --> NCl3 + 3 H2O

Interestingly, I recently can across a comment that while Oxalic acid, as an example, which is not an explosive, when detonated with a primer, it does explode. If TCCA or Cyanuric acid behave similarly, then a few other candidates are possible.

For one, if the HOCl is sufficiently concentrated, Cl2O is present which, in increasing concentrations, becomes a more violent explosive (or primer). Dichlorine monoxide also explodes in the presence of NH3 and certain organic compounds.

Similarly, the disproportionation of concentrated HOCl into HCl and HClO3, may also form some highly explosive ClO2 (sufficient to act as a primer?) as:

3 HClO --> 2 HCl + HClO3

5 HClO3 + HCl <---> 6 ClO2 + 3 H2O

Finally, the formation of just Chlorine via:

HOCl + HCl <---> Cl2 + H2O

2 HOCl ---> 2 HCl + O2

may be instrumental.

AndersHoveland - 2-5-2012 at 23:06

Quote: Originally posted by AJKOER  
Hypochlorous acid is capable, for example even in dilute solutions, of oxidizing ammonia (as an example) to Nitrogen trichloride when heated:

NH3 + 3 HOCl --> NCl3 + 3 H2O


"Oxidation" is not really the best way to describe the reaction, since it is actually an equilbrium: the reaction can shift in either direction depending on the pH. Indeed, in the absence of an acid, simply reacting NH4OH with HOCl would likely just result in real oxidation of the ammonia to nitrogen gas.

If the reaction is in an alkaline environment, and there is neither too much NH4OH or too much hypochlorite, then chloramine NH2Cl will be the favored product. Chloramine is a gas. There will also be some nitrogen gas produced, especially if the reactants are more concentrated.

NCl3 + 3 H2O + H2SO4 --> NH4SO4H + 3 HOCl

NCl3 + 4 HCl --> NH4Cl + 2 Cl2
(not very surprising, the hypochlorous acid just oxidizes the hydrochloric acid)

2 NCl3 + 6 NaOH --> 3 NaCl + 3 NaOCl + 3 H2O + N2

2 NH3 + Cl2 --> NH4Cl + NH2Cl
(but even mixing NaOCl with NH4OH will also generate chloramine gas, but the reaction will be less efficient since much of the ammonia will get oxidized to nitrogen)

In an excess of ammonia, the chloramine can react with more ammonia to form hydrazine. Usually this is only a transient intermediate, as hydrazine is oxidized at a much faster rate than ammonia.

NH2Cl + 2 NH3 --> NH4Cl + N2H4
6 NH2Cl + 4 NH3 --> 6 NH4Cl + 2 N2

3 NaOCl + 2 NH3 --> 3 NaCl + 3 H2O + N2

The best way to make nitrogen trichloride is to pass chlorine gas into a solution of ammonium sulfate.

(NH4)2SO4 + 3 Cl2 --> NH4SO4H + NCl3 + 3 HCl

If a hypochlorite salt is used to make NCl3, the pH needs to be carefully adjusted. An excess of ammonia will destroy the yield if at any time the pH is not low enough.

WARNING: nitrogen trichloride is a dangerously unstable oily explosive liquid

[Edited on 3-5-2012 by AndersHoveland]

AJKOER - 20-5-2012 at 05:01

AndersHoverland:

Good description. However, believe it or not, in spite of the detail nature of his comments, it appears that the process (Breakpoint chlorination has been extensively studied) is even more complex with some reactions pH dependent and others not. In addition, there apparently are multiple path ways for NH3, HOCl, NH2Cl, NHCl2 and NCl3, and a more honest assessment is that the process is still not entirely understood. For example:

NH2Cl + H2O --> HOCl + NH3 and then:
HOCl + NH2Cl --> NHCl2 + H2O (see Equation 2.49 in the source provided below)

Dichloroamine (NHCl2) can also be formed in a parallel reaction:

NH2Cl + Acid --> [NH2Cl.Acid]
[NH2Cl.Acid] + NH2Cl --> NH2Cl2 + NH3 + Acid (See Equation 2.50)

where this second-order reaction is apparently pH dependent and buffer dependent.

Also, ammonia suppresses the disproportionation of NH2Cl and there must be an excess of HOCl for reactions 2.49 and 2.50 to proceed.

Reference: "White's Handbook of Chlorination and Alternative Disinfectants", by Black & Veatch Corporation.

Link:
http://books.google.com/books?id=mGVbIoW2lNAC&pg=PT129&a...


[Edited on 20-5-2012 by AJKOER]

AJKOER - 27-6-2012 at 08:29

Quote: Originally posted by AndersHoveland  
Trichloroisocyanuric acid (TCCA) often explodes when acidified. It generally seems to be assumed that formation of nitrogen trichloride is the culprit, but it is quite possible that this assumption is, at least in part, erroneous.

"Upon hydrolysis, trichloroisocyanuric acid yields hypochlorous acid"
Oxidation studies of symmetrical and unsymmetrical ethers : Comparison of trichloroisocyanuric acid and hypochlorous acid reagent. E. C. Juenge, M. D. Corey and D. A. Beal. Kansas State College, Pittsburg, Kansas USA

Hypochlorous acid and hydrogen chloride (from the hydrolysis of PCl3) will form chlorine. Chlorine is certainly known to oxidize TCCA to nitrogen trichloride. There have been many accidents involving chemical waste mixtures that have included hypochlorite or TCCA withsome other acidic compound (such as ammonium sulfate).

[Edited on 25-4-2011 by AndersHoveland]


Here is a link to the full paper that AndersHoveland referenced: https://docs.google.com/viewer?a=v&q=cache:-USpkbQ4JdQJ:...

My take on first reading was that it appears that HOCl and aqueous solutions of TCCA (which form HOCl) are not generic substitutes with respect to all reactions. In the particular instance under investigation, a reactive preference appears to be with TCCA over HOCl for reasons speculated by the authors.

I also found an excellent reference: "CYANURIC AND ISOCYANURIC ACIDS", link: http://www.scribd.com/doc/30133467/Cyanuric-and-Iso-Cyan-Uri...