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I have spent some time researching basic magnesium chemistry. Not anything synthetic but more safety and thermochemically related. I am not able to give a lot of particulars motivating the study, but I can say that one should consider that nitrogen over activated magnesium may not be as innocent as you think. While lithium is widely known to react with nitrogen gas to form a passivating nitride layer, the reaction of dinitrogen with magnesium is rarely encountered.

Activated magnesium residues from a Grignard or other magnesium metallation reaction may self-heat to incandescence under a nitrogen atmosphere in the right circumstances. Activated residues left isolated on the reactor wall or other features in a nitrogen blanketed reactor during an aqueous quenching procedure may self-heat to incandescence. In the presence of reactive gas-phase components like water vapor in nitrogen, activated metals can self-heat over an induction period of minutes to hours or longer.

Many metals, including magnesium and aluminum, can be rendered kinetically stable to air or humidity by the formation of a protective oxide layer. Once heated to some onset temperature by a low activation reaction, penetration of the protective layer by reactive gas composition can occur, leading to an exothermic reaction.

Performing a “kill reaction” or a quench of a reactive metal at the bench or at scale is always problematic and requires the skill and close attention of the process chemists and operators. I guess what I’d like to pass on is that nitrogen is not an innocent spectator in the presence of finely divided, activated magnesium. Humid nitrogen can support a combustion reaction to produce nitrided magnesium once preheated to an onset temperature.

If you mean to kill any reactive residues, it is important to apply the quenching agent in such a manner that the heat generated can be readily absorbed in the quenching medium itself. A good example of a quenching agent is water. Often a reactive must be killed slowly due to gas generation or some particular. Adding a quenching agent to a solution or slurry by slow feed or titration may be your best bet. If you have another vessel available, a feed to a chilled quenching agent will also work.  Dribs and drabs of water on a neat reactive material will lead to hotspots that may be incendive.


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