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A Grignard reagant was prepared from an alkyl halide and magnesium chips, then reacted with a ketone. The resulting solution has been stirring for a few days at low temperature (0-5°C). It's now time to transfer the reaction solution slowly to a vessel containing an acid quench. My problem is the unreacted magnesium chips (smaller than when we started, of course) have settled, and are plugging the tubing and stopper valve.

What solvents could I use to flush the magnesium through, breaking it up, and possibly dissolve it? This can't be added to the reaction solution (the Drain-O method), but only through the tubing itself. Obviously water is a bad idea. Any insights?

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  • $\begingroup$ Plug the tubing with improvised filter made of mineral wool ? $\endgroup$
    – permeakra
    Commented Jul 20, 2014 at 7:02

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Pure water would certainly be a bad idea, but a 1% solution of 1 M hydrochloric acid in ether would probably work without a vigorous reaction.

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We had what we would call "filtersticks", they were a cannula with a metal cylinder with a bore at one end, around which we would tie glass filter paper. Larger quantities we transfer through polyethylene tubing to a filtration column and filter through a pad of Celite. Both methods worked well.

Since your product doesn't sound air-sensitive, you might consider quenching with wet THF. Have an ice bath and a fire extinguisher ready.

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