A lifetime ago, when I was a stupid kid, I tried something, well, stupid.
I set up a bog standard aluminum-mercury amalgam (in 'wet' methanol) inside a 2 liter pop bottle.
Once the amalgamation was complete, I tossed in a fairly generous amount of nitromethane. My main question was whether the reaction could be managed
simply by cooling the pop bottle in a tub of ice water as needed. Since the reaction was certain to release some hydrogen gas, I was also prepared to
uncap it to release pressure if needed.
It performed as you would expect, with a lot of gas evolution, bubbling, and ultimately a lot of heat production, but it turned out that it was
actually pretty easy to manage the reaction by shaking it a bit by hand and cooling it now and then in the tub when the pressure in the pop bottle
rose. (It was easy to tell by feel of the bottle.) I kept the bottle sealed through the entire reaction.
The strange thing was that when it was all done, when it had cooled back down to room temperature...there was absolutely no pressure built up in it.
There was no sign of the hydrogen that had been produced.
Which brings me to the topic at hand: Perhaps the hydrogen being produced was being adsorbed onto the aluminum. From there, it's easy to imagine
it being converted into hydride by the exposed aluminum.
To this day I can't say that I really know how the mechanics of the amalgam reduction work, but...perhaps it's a hydride formation in situ?
For what it's worth, in another spot test I added some nitromethane to a small amount (perhaps a gram) of aluminum that had been covered with a sodium
hydroxide solution. As it heated up, the reduction became absolutely fearsome, cracking the nitromethane all the way down to brown nitrogen oxides.
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