please forgive my long-winded post, but i'm up at 1:30 in the morning with nothing to do but ponder this little question.
OK, so the imine might not be very stable, so i guess getting it in as fast as possible would be a good idea. But in the procedures for the borohydride reduction, the MDP2P is mixed with a methanolic solution of methylamine, and stirred with silica gel. My understanding was that the silica gel was only there to remove formed water because of the belief that removing water drove the reaction farther to the right. But then I saw some thoughts posted here that removing the water was not really necessary. But the procedure does call for forming the imine beforehand, then reducing, and the yeilds are close to quantitative. The Al/Hg is not all that harsh of a reaction. It does not leave tar or polymerization afterwards. Pretty much the only two products are the amine and the alcohol, with the alcohol only being formed because the imine did not fully form. So just how redily does MDP2P form the imine with methylamine? and when it does, how stable is it?
Now for a few clarifications on my thoughts on the Al/Hg. The methylamine solution is normally made as an aqueous solution. So i'm just asking what everyone's thoughts are on making it in a solution that MDP2P is also soluble in? And if you used methanolic NaOH or KOH to basify the MeAm*HCl, then you wouldn't have to mess with bubbling dry MeAm gas into anything. The only thing you'd have to worry about is the NaCl or KCl that would precipitate from the alcohol. But that has no effect at all on the reaction, so it wouldn't even be worth the trouble to remove. Then the MDP2P could be added to the solution and sat aside for a length of time in order to let the imine form, then the amalgumation could be started. And I also read in the borohydride procedure that some literature suggested that cold temps also drove the imine formation forward. So how hard would it be to set a solution of methanolic MDP2P and MeAm in the freezer overnight, the running the reaction? Would this help? Any thoughts?
And I'm sorry for not providing any sources for what I'm saying, but right now I'm just kinda musing.