Hi Guys, Just sharing a recent findings. I have returned to the `good old Al/Hg amalgam reaction, simply for not having enough NaBH4, and not wanted to spend money on it. I used to use Al/Hg, but was never successful with the rinse wth water thing, which - as I can see - bothers a lot of newbies here. The key is, which I think will help you out is emphesising some small and vital details:
- using as thick foil as possible is a must, forget supermarket foils, although sometimes thicker foils can be found there too. I have ordered Al foil online, with a known thickness, I think it is about 25 microns. This makes Amalgamation MUCH slower, so you have more time to choose the right moment and even prepare other ingredients if you haven`t already done so.
- The foil does not necessarily need to be coffee ground, although I haven`t done a comparison, my yields were close to 80%.
- Be quick with the rinse, and don`t use too much water. I have only tried one rinse.
- Speed: add water quickly, do a couple of shakes and quicly filter it.
- When you have the Amalgamated foil, add your reagents/precursors and monitor what is happening. Do not use ice water bath to cool it at this stage. The reaction will start less violently and after a few seconds, so you have more time to attach the condenser without inhaling too much gas.
- Wait until the reaction has definitely started and is almost starting to get out of hand (but don`t wait too long either until it starst to boil over otherwise you will KILL your reaction. Basically wait until there i bubbling and the flask is getting very hot, then start cooling it .
- I cut up 45g of foil amd it wasn`t to much, the size was around half a small match box size. Add the cut up foil to the flask immediately.
- With this method I reached about 80%, I didn`t calculate the exact yield but it was quite good amount.
= I used HgCl2 instead of HgNO3, but I don`t think this is imporrant.
- Using f two condenserrs I reduced 35g P2NP in a 2 L flask, I will try to scale up when I have a larger flask. E.g. 70g in a 5l flask, the reagent/flask size is probably not linear.
- I have tried one quick wash only and this woked fan1tastic. I recommend this to others too, then try and increase the number of rinses.
In summary: thickness of foil is important, especially as a beginner and not to cool it straight away; it is also important to be patient and wait until all the foil goes to the surface, don`t be too fast as this takes longer, but you have also a bigger window of opportunity.
