10-24-03 19:35
No 466545
So, ning found a cool paper about reducing imines with zinc. Ning knows that imines are the addition product of ketones/aldehydes and amines. But the reduction is done, oddly enough, under BASIC conditions. Will imines still form from ketone and ammonia in 5% NaOH solution?
P.s. Will post if desired. Very cool. Yields high, procedure simple.
(Chief Bee)
10-25-03 01:13
No 466597
Always post interesting articles, or at least the citation (journal/volume/pages/year/abstract).
Imines will form in slightly basic solution, see fore example the Al/Hg reductive amination in Pihkal #109 (http://www.erowid.org/library/books_onl
But - as you probably have heard before - imines with ammonia are very unstable and will always give very low yield, you need to form the imine with hydroxylamine (the oxime) and then reduce that all the way to the amine to be able to reductively aminate your way from a ketone to a primary amine. Alternatively form the imine with a benzylamine and remove the N-benzyl group to get the primary amine. UTFSE for references.
(Hive Bee)
10-26-03 03:51
No 466789
Looks like 25 ml 25% into about 750 ml other stuff. Maybe in total less than 1% concentration?
Why did he add salt?
As for that article, you bet I will type it up--
reduction of imines with zinc powder in aqueous solution at room temperature, with no sonication, in 50 to 80% yield.
They didn't create the imines in situ, but ning figures if that is the only problem, well...
They had a methylamine and an ammonia imine, as well as assorted other things.
Rhodium, Ning believes a new era of OTC metallic reductions is about to dawn. It's just a matter of time.
Also, remember that p2p acetic anhydride electrolysis paper? Found some newer stuff by those guys. Turns out, you can do any kind of reduction in an undivided cell with the sacrificial anode. Including reductive aminations. They have a patent in french on that. And acetic anhydride is not the only thing that can donate an acetate thingy.
Must type that, too. It will overcome the major problem with the festerlytic, which is the cell divider.
The basic idea seems to be that the sacrificial anode eats the oxygens or hydroxides that would otherwise oxidize what you are trying to reduce. This allows you to get rid of the cell divider, whose purpose is only to keep your precious ketone/imine away from the oxidizing anode, right?
Clever.
Specially using aluminum.
Since the same cell can do both coupling of AA and reduction of ketone, maybe its almost one-pot from benzyl chloride and AA to...well...amphetamine at least. Maybe still need to make methylamine. Anyway....so much to do, so little time.
(Chief Bee)
10-26-03 04:04
No 466795
Why did he add salt?
So that the solution would be exactly identical to the alternative, which used MeNH2.HCl as the amine source - upon addition of sodium hydroxide to freebase the amine, sodium chloride is formed.
It can be argued whether or not it makes any significant difference, but the dear doctor is very meticulous in his work.
(Hive Bee)
10-26-03 18:39
No 466871
I'd love to take a look at those articles, english, french, whatever, could you provide us with the references?
Thanks
(Hive Bee)
10-28-03 15:23
No 467267
Please allow poor, overworked ning a short while, and they will be duly posted. Promise. Ning knows how cruel it is to tempt bees with tasty articles never delivered
....