Wednesday, May 25, 2011

Process Wednesday: a drum is a living thing

From my browsings of Organic Process Research and Development comes a story too freaky not to mention:
The material in question was in a poly drum that contained approximately 20 kg of the aniline as an oil. After storing the unused portion of the 4-trifluoromethylaniline for 6 months in a warehouse, the material was brought into the laboratory to be sampled for further pilot work. This particular storage facility did not have temperature control, and no information was received that this material required special storage conditions. Upon examination of the drum contents, the material had formed a solid crystalline mass. [snip -- description of warming the drum in a 50°C air drier] 
With this unexpected result it was decided to examine the contents of the drum by NMR. The entire drum was brought into the laboratory and was placed in a large, empty, stainless steel tub as an added safety precaution. With the bung loose the contents were allowed to equilibrate for 5 h at which point some liquid was removed for analysis, and the bung was tightened. Approximately 15-30 min after sealing the drum it ruptured near the bottom and a white gas exited the drum with tremendous force. This gas quickly filled the entire laboratory, and fortunately the only occupant of the laboratory at the time was able to exit from a rear fire door without being affected. When the gas evolution ceased after 15 min, an investigation of the incident was immediately initiated.
The authors went on to describe their analyses of the remaining material; they believed that the material is a trimerized form of the trifluoromethylaniline. The offgassing, they believed, was the release of HF. Needless to say, someone could have been seriously injured if they had been close enough to the drum. The article has a number of intelligent cautionary things to say about storing of trifluoromethylaniline and its potential reactivity.

Personally, I like drums. They're really useful things and they contain plenty of material (or compound or solvent) for the typical chemist. But I am always a little wary around them because they are so large; it's not like you can pick a drum up and throw it out into the parking lot (which is not recommended for any number of reasons). But something being larger than you is always something to be treated with more respect, in my novice mind.

4 comments:

  1. Yikes. Not that they expected it to become a pressure hazard, but I'm always a little wary of tightening unknown containers too tight.

    Same when I mix in some new acid or base into the aqueous waste, lest I inadvertently evolve CO2 or something.

    I also wince and look away when I open a gas cylinder... Not that looking away would help if the cylinder were to rupture :)

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  2. Not working in process, I've never been in a situation where my reagents out-weighed me, but I was riding the elevator up to my lab early one morning when the dry-ice guys rolled in with a big container of the stuff to re-fill the labs. I joked about hoping the elevator didn't get stuck, but I don't think they got it, or the potential danger we we were all in.

    I half thought about getting out.

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  3. I've been in that situation; I've decided that if it got stuck, I'd start smashing the stuff into smaller pieces and stuffing it down the cracks of the shaft that I could access.

    Yes, I'm that paranoid.

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  4. OK, here is another drum story: someone in a process group did not screw on the drum stopper. The drum contained 200L of hexamethyl disilazane. During a storm a leak in the roof caused some drip on the barrel. Water got in which produced ammonia gas. The escaping gas lifted the stopper and the drum sealed temporarily but the ammonia evolution went on. Workers on the plant floor heard a hissing sound and saw the round barrel. The stopper then flew out and with a whooosh a geyser of (TMS)2NH shot up from the barrel.

    No-one got hurt - all chemists bolted just in time. The evacuated staff was then standing around on the lawn and everyone was scratching their crotch: apparently hexamethyl disilazane is a potent irritant and its the heavy vapors attached the low-lying body parts first...

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looks like Blogger doesn't work with anonymous comments from Chrome browsers at the moment - works in Microsoft Edge, or from Chrome with a Blogger account - sorry! CJ 3/21/20