Al/Hg drip time

[slick14]

i had a dream, in that dream a dog had asked me if the drip time on an Al/Hg rxn using MeNO2 and using very small pieces of Al is the drip time dependant on the Al taken up or an actual time limit. The dog said it took him 65 mins for the total drip time and got decent results could his results have been better if he had sped up the process? He said the drip was finished about the time all the Al was taken up. Did he do ok?

[rudebwoy]

dependant on the Al taken up and reacting with nitromethane + water to make methylamine

read some more.

[Antibody2]

increasing the drip rate runs the rxn hotter and therefore faster. the folklore that increasing drip rate increases yeilds may have something to do with slow drip rates resulting in ketone being added after the Al has all been consumed.

Its hard to say how well you did, as you didn't mention the scale of your rxn or yeilds. If you were reacting the amount (25g or so) in the MM write-up, i'd be inclined to say 65 minutes is on the slow side.

[nitrous351]

If you were doing a MM Al/Hg, I would say 65 minutes is way too slow for that scale. There really isn't a set drip time... the point is to drip in your ketone at a rate slow enough that the reaction doesn't get out of hand, but fast enough so you aren't adding ketone when the Al is already done reacting. MM gives an addition time of around 40mins. and a drip rate of 1 drop per second. In Dr. Gonzo's photo essay of the MM procedure, the author explains that he adjusted his drip rate to match the rate of the reaction... i.e., sometimes one drop per second was too slow. This reaction is really important to yields, so I think anyone doing a MM amination should keep close watch on it and not just start it and walk away. There are a lot of variables for the rxn, and each amination will be unique, therefore requiring constant attention. good luck peace