Sciencemadness Discussion Board

Cl+CO reaction?

NWS - 4-8-2015 at 10:15

So I made a rather interesting (and potentially dangerous) mistake while attempting to distill formic acid. I had an unknown quantity of impure sodium formate left from a haloform reaction. I added 150 ml of 30% H2SO4 inside my BRAND NEW thick walled boiling flask. This was the first problem. Immediately this started forming some Cl2 gas, likely from the excess NaOCl used in haloform. I then moved my distilation apparatus out to the middle of a field for safety reasons. I then started the distillation and left due to the Cl2 produced upon heating and the potential for formation of CO. I leave it run for 5-7 mins, unplug it, leave it for a few minutes, and then approach. Lo and behold my flask is scattered over a 20' diameter circle. What happened? Did my distillation run dry and thermal stress cause my glass to break? or was it a reaction between Cl and CO ?

kecskesajt - 4-8-2015 at 10:29

Carbon monoxide reacts with chlorine to make Phosgene.But this requires UV light.Extremely toxic compound,one of our fellow chemist died by this :( R.I.P.
The crack could be because of the Cl2O formation wich is explodes violently in contact with reducing agents.CO is a reducing agent.

Pumukli - 4-8-2015 at 11:40

First, my vote is with the thermal stress theory.

Second, I heard some excessively stupid stories about carelessness but yours is in the top 3 I think! :-(

"moved my apparatus out to the middle of a field for safety reasons" - then you started to tinker with this shebang with heat.

How did you heat it in the middle of a field? By the power of the Sun? Or you had electricity (unplug) there?

Then the glass-shrapnels in a 20' circle? What? Was this flask plugged in??? What did you unplug? The electric heater or the flask?

For god's sake! An energetic material was not even involved but you managed to make a potentially deadly weapon from a flask!

Ehhhww, I can't find words. And amateur chemists are wondering that our hobby is suspicious if not outright dangerous in the eyes of others!

I don't want to sound patronizing but I have seen photos of severed fingers with hanging tendons and nerves (before proper amputation in a hospital) and those pics were not nice!
And this from a few grams of TATP batch went off in a glass flask!

NWS - 4-8-2015 at 11:41

Thanks for the response, In relation to the phosgene, doesn't that need a catalyst to occur with any real prevalence? I was figuring it was some sort of chemical reaction though, I hadn't even considered ClO2 but where would it have come from? I don't believe the NaClO I was using for the haloform reaction had that much chlorate in, it was 12.5% NaClO with 0.5-2% NaOH as a stabilizer and was intended as a pool chlorinator.

NWS - 4-8-2015 at 11:48

I had a 100' heavy gauge extension cord and a cheap electric heating mantel. and it was unplugged from 100' away and allowed to cool and the vapors allowed to disperse, hence it being unplugged before even noticing the resultant destruction. and in all honesty, I didn't start off thinking of a formic acid distillation as a potentially lethal endeavor, and when the Cl2/ClO2 started appearing I figured it would simply be displaced by the formic acid vapor, and I'd be left with some possibly chlorinated formic acid, still an interesting experiment. but I suppose hindsight is 20/20.
Edit- with respect to the TATP, who the blazes is making muti-gram quantities of that? and for what purpose?
Edit- Oh, will you look at that https://en.wikipedia.org/wiki/Chloroformic_acid. Chlorinated formic acid is unstable. It might have been wise to pause the distillation and google that beforehand.

[Edited on 4-8-2015 by NWS]

[Edited on 4-8-2015 by NWS]

IrC - 4-8-2015 at 12:26

Quote: Originally posted by kecskesajt  
Carbon monoxide reacts with chlorine to make Phosgene.But this requires UV light.Extremely toxic compound,one of our fellow chemist died by this :( R.I.P.
The crack could be because of the Cl2O formation wich is explodes violently in contact with reducing agents.CO is a reducing agent.


I assume you mean myfawny, very sad. One would think out in a field in the sun UV light does exist.

"BRAND NEW thick walled boiling flask. This was the first problem. Immediately this started forming some Cl2 gas, likely from the excess NaOCl used in haloform."

How could it be 'brand new' if something leftover was in it? Why do you not clean glassware before using it? One would think a prerequisite to any experiments is study, planning, carefully thinking ahead. Considering all possible reactions and/or side reactions, making safety the first and foremost consideration before doing any experiment. This includes obtaining the proper safety gear and having ready the proper steps to take if things go wrong. Sadly this is precisely why myfawny is no longer with us. He was very bright for his age and had great future potential.



NWS - 4-8-2015 at 12:53

As I mentioned in the initial post, I was using crude formate produced from a haloform reaction, done in a separate flask. In respect to safety, I thought (at the time) that this was covered by moving the apparatus away from everything else and leaving adequate time for the gasses to disperse. IMHO a vacant and open field is equivalent to a very nice, if unfiltered, fume hood, particularly with a light breeze.
But the takeaway from this so far is to look up all elements involved in a particular reaction, and combinations thereof.
Can anyone offer any improvements to the safety system I had in place? namely PVC gloves, an area at least 100' away from anything of value (besides my glassware and the extension cord), vacating the area, having a way to remotely terminate the experiment, and allowing for fumes to disperse
Edit- I have more than realize the danger involved in this particular mistake, now I'm looking for ways to improve my methods and preventing anything similar from happening.

[Edited on 4-8-2015 by NWS]

IrC - 4-8-2015 at 13:51

OK I see what you were saying. The way you started the post looked like two separate statements in the first two sentences. The problem was side reactions going on with impurities in your sodium formate. Well at least you learned to either purify your chemicals or at least consider possible reactions your thinking was not focused on. One thing you might do is get a decent gas mask able to handle what you may be exposed to since one problem with trusting being outside even with some distance is you can never trust the wind will not change direction at the worst possible time.

NWS - 4-8-2015 at 14:15

Now that it's been pointed out, I can see where the confusion came from. And a gas mask would be useful, thanks for the suggestion. Lastly how would one purify formate? I'd normally do a recrystallization except for the solubility of NaHCOO.

AJKOER - 6-8-2015 at 12:31

Per this reference (see http://pubs.acs.org/doi/abs/10.1021/j100865a038 ), the reaction of Chlorine and Formic acid proceeds to produce gases (mainly CO2).

As such, a rapid gas release from solution could produce an explosive effect in a confine space.

Dan Vizine - 11-8-2015 at 19:49

I can assure you that thermal stress isn't the culprit in the failure of most any round bottom flask not under vacuum. When you turn a Variac/mantle way, way up (as long as you don't blow the 10 amp fuse), the glass sags, partially melts almost, but it never shatters. It is borosilicate, after all.



[Edited on 12-8-2015 by Dan Vizine]

Deathunter88 - 12-8-2015 at 04:35

Well, thermal stress can cause a borosilicate flask to shatter, just not in this particular case. When I was distilling Oleum from potassium pyrosulfate, I though it would be fun to test the thermal resistance of my flask. The flask had many star cracks in it so I was not afraid to lose it. It had been heated with a blow torch for the last 20 minutes and when I poured ice cold water on it instantly turned into a frag grenade. I knew this would happen so it was behind a blast shield but it was still pretty cool.