Swim ran a 4x MM in a 6 gal bucket with a 3" stirbar (3" round x 1/2" thick). Swim has a decent hotplate/stirrer. 110g foil were added to 2.5L methanol and stirring started. The stir bar did an ok job but was not able to move the foil at the very edges of the bucket. .5L methanol w/ 1g HgCl2 was added, stirring was fine until the reaction got going and about 30g of ketone added then swim could not see any indication that the stir bar was still turning (no vortex, and for that matter, no movement). The bucket was swirled gently by hand, but swim could still see no activity from the stir bar.
Now the reaction mix was pretty hot, and it was clear that that Al was amalgamating, so swim said WTF and kept going, basically adding ketone to a mix that wasn't visibly stirring. Total addition of 100g ketone took about 22 minutes (it appeared to drip on TOP of the sludge, run across it and get really hot and turn white). Methanol bubbled out of the condenser from time to time when it got really hot and more was added down the condenser. Once all the ketone was in swim added another 500mL of methanol to the mix. This helped quite a bit with regards to stirring. Once the foil had broken down substantially then the stirbar was able to get going and the vortex was back. Swim doesn't know if the bar spun the entire time or if it got stuck in the mud halfway through.
Swim also doesn't yet know what the yield is on this batch, since the product is sitting in DCM waiting to be distilled, but it seems like it was ok. He will likely recover the DCM, boil off any water and the weigh the crude oil he has just to check. Swim would like to know if he should expect a significant loss in yield from the mix not being stirred efficiently the entire time?
Swim may try another batch with an extra liter of MeOH in from the start, or just build an overhead stirrer. Nevertheless, this is really pushing it with a 3" stirbar.
A watched pot will indeed boil.