Author Topic: reflux rate in Al/Hg-Nitro  (Read 4005 times)

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photoman

  • Guest
reflux rate in Al/Hg-Nitro
« on: December 30, 2002, 02:24:00 AM »
Just read the very informing

Post 53662 (missing)

(baalchemist: "Al/Hg-Nitro kickin up the yield", Methods Discourse)
, and have a question on the post

Post 169874 (missing)

(Antibody2: "Re: Al/Hg-Nitro kickin up the yield", Methods Discourse)
of that thread. Even more specifically, on the comment "if your reaction is actually moving up the condenser you've really overshot the mark and are really trying to minimize losses at that point." In his writeup, MM says that MeOH is literally pouring down out of the condenser during the addition. So how could the methanol me pouring down the condenser if it's not up the condenser? All of SWIM's runs had a reflux that was a little less than halfway up his 400mm West condenser.  He's only done one successful run though, which is why he wants to know if this is a problem.


pickler

  • Guest
clarification
« Reply #1 on: December 30, 2002, 06:48:00 AM »
Antibody is actually saying if your reaction(which is the gray mix gets into the condenser) your trying to minimize losses. A strong reflux is fine.


gabd

  • Guest
I like to run mine like a volcano
« Reply #2 on: December 30, 2002, 07:47:00 AM »
trying to be just on the limit. Refluxing real strong with a 600mm alihin condenser. But you need a lot of ice to make sure your methylamine doesnt fly off.
One thing I like to add is 1 or 2 ml of water. The MeOH used contains no water whatsoever. It seems that that little 1 or 2 ml water, makes the reaction even more violent, but still you can control it with your addition rate. I always try to run it as hot as possible without loosing control of it.

I also like to start by adding a 5 to 10 ml^pure nitro before dripping in the nitro/ketone mix.
That way, you already have methyl amine in the mix when you add your ketone.
Practice is the key to all answers

scram

  • Guest
I know someone that solely did an nitro ...
« Reply #3 on: December 30, 2002, 02:09:00 PM »
I know someone that solely did an nitro reduction in 2 solvents. One was only methanol and the other was done in tap water. The reactants were the same in both cases. However, the amalgam run in only water produced a much stronger MeAm smell with the PH paper turning nearly 12 obove the vapors. The PH paper would only turn 8.5 - 9.0 on the methanol run. The MeAm smell was so much stronger on the water run that it seemed the condensate comming off had to be at least 1/2 the strength (by smell) of lab grade aqueous 40%. I was wondering just how, if possible, this could be measured by weight to determine MeAm content. Is there a proportional graph or some formula to determine, say, if it weighs 0.95 g/ml that its xx percent MeAm? This stuff seemed to be worth collecting.

Rhodium

  • Guest
Methylamine density
« Reply #4 on: December 30, 2002, 07:05:00 PM »
100% H2O, 0% MeNH2 = 1.0 g/ml
60% H2O, 40% MeNH2 = 0.9 g/ml

Make the graph yourself and draw a line between these two data points. It should be pretty much a straight line for most practical purposes.