Org Prep Daily

July 26, 2011

Expanding liquids break closed vessels

Filed under: lab destruction — milkshake @ 2:05 pm

I had a dumb mishap today: A 100mL Schlenk storage flask with 1,5-cyclooctadiene shattered. When I distilled my COD by vacuum transfer this morning I filled the storage flask all the way to the top and then turned the teflon stopcock shut. There was no head space left in the flask; as the liquid warmed from about 10C up to room temperature it expanded enough to burst the glass.

Coincidentally, my colleague finished off a 20L jacketed glass reactor in a similar manner just yesterday – he was cleaning it after the experiment and the heating jacket was shut off, both the inlet and outlet valves were closed while the jacket was still filled with polysiloxane heat transfer fluid. When the reactor was rinsed with ambient water it suddenly shattered: a small temperature difference was apparently enough to cause the silicone fluid expansion in the jacket and there was no air bubble space nor a tubing attachment whereto the silicone liquid could expand. Looking back, this jacket over-pressurizing would not have happened if one of the valves was left open.

I suppose we proved that liquids are incompressible and expand with heat.

Link: The Great Boston Molasses Disaster

16 Comments »

  1. I can’t help but wish the Schlenk shattered in the fume hood. The pungency of COD is… notorious, let’s say. Nothing compared to your historical phosphines I suppose! ;)

    Comment by HPCC — July 26, 2011 @ 3:08 pm

    • yeah, but still a pretty smelly puddle – it made me clean the hood. (COD is supposedly not that bad unless you are an aquatic creature)

      Comment by milkshake — July 26, 2011 @ 3:21 pm

  2. I think COD kind of smells good. Then again, I used it weekly for ~8 months, and my partner on the project thinks I’m a tad crazy.

    Comment by stop — July 26, 2011 @ 3:20 pm

  3. How embarrassing. I’ve been away so long, that I had to think to recall what a Schlenk is.

    Comment by Sili — July 26, 2011 @ 6:53 pm

  4. For some reason, this reminded me of the time in grad school on of my lab mates tried to extract an aqueous solution with acetone. He was confused for a good while trying to figure out why there was no phase separation.

    Comment by milo — July 27, 2011 @ 8:20 am

    • I can’t decide which is worse: trying to make up a TLC solvent mixture of hexane:acetonitrile, or trying to extract from water with acetonitrile. I have done both.

      Comment by opsomath — July 27, 2011 @ 3:46 pm

  5. I’m glad no one got hurt with either of those mishaps!

    Comment by Crystallinity — July 27, 2011 @ 4:55 pm

  6. didn’t you have a 250 ml flask that you had to fill it full.

    Comment by vasili — July 28, 2011 @ 6:26 am

    • yeah, I took a 100mL one because it has been already dried in the oven. To save time, you see.

      Comment by milkshake — July 28, 2011 @ 9:59 am

      • we wouldn’t have such a problem as we have no oven, flasks dry at RT hanged just after dishwasher. And yes we perform organometallic chemistry inside. That is one advantage of this dry climate we have.

        Comment by vasili — July 29, 2011 @ 1:39 am

  7. Reminds me of the (somewhat related) experiment described by Michael Faraday in “The Chemical History of a Candle”:

    Fill a thick-walled cast-iron screw-cap bottle to the brim with water, seal tightly, then drop into a “freezing mixture” (ice and salt). After a little while the bottle bursts, cracking the cast iron.

    Comment by Joe Q. — July 29, 2011 @ 2:09 pm

  8. Wow, this Boston Molasses Megaleak is definitely worth the read. How did you know about that, Milkshake?

    Comment by HPCC — August 1, 2011 @ 5:05 am

    • from living in Boston (…but not from firsthand experience, I am not that old)

      Comment by milkshake — August 1, 2011 @ 9:35 am

  9. Reminds me of a labmate that quench acetic anhydride in a 50 L
    with the jacket valves closed. Heat of expansion shattered the
    outer wall of the jacket fortunately, turned the lab into
    skating rink with over 5 gallons of 50/50 glycol.

    Comment by Okemist — August 2, 2011 @ 12:35 pm

  10. Does this mean your blog is back?

    I know I’m a bit late, but I wanted to say that I was sad to read of your June post ending the blog. I understand the reasons, but yours was a fascinating blog, and I’m sad to see it go. More importantly, congratulations on the new job!

    Comment by Curt F. — August 11, 2011 @ 7:29 am

    • I don’t think the site is really going to be active. I just had this curious accident that surprised me. And the danger of a jacket rupturing on a reactor when the inlet/outlet valves are shut off was not recognized here, apparently the reactor has been used without a mishap for some time – I thought it would be worth mentioning it

      Comment by milkshake — August 11, 2011 @ 11:40 am


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