06-13-02 20:09
No 321013
Swim used to make md-p2p with acetone/performic - the yields weren't as good as modified performic (DCM/performic baking soda) that swim uses now.
Problem is - only time swim ever got above 50% yields on MDA rxn was with old style md-p2p (no silica/ no pressure / crappy stirring). But same time swim switched to modified performic - he scaled up like 3 times.
swim has spent lots of time trying to bring yields up to where other bees say they are (and where swim has seen in real life)
Swim has improved stirring, vacuum, pressure and at the very least swim believes all other things are equal, he cant figure why yields now are around 30%?
Must be the quality of the md-p2p - in swims modified performic he turns 750 isosafrole into approx 600-650 MD-P2p, but how much of it is actually md-p2p and not some (close to same boiling point)crap oil.
Does anyone out there use modified performic method then cyano/ammonium acetate/methanol MDA method (approx 2400 grams md-p2p) and get plus %50 yields?
Swim is going to try to make old way again, but cant find notes - anyone know good thread on acetone performic?
Swim wonders if some of the higer volume md-p2p methods produce more oil, just not all md-p2p (less purity)?
So when swim puts in 600 grams md-p2p (what he thinks is 100%) it may only be 400 grams md-p2p (200 grams who-knows-what?) and is wasting reactants and making swim stressed.
Any help or thoughts would be appreciated.
(Stranger)
06-14-02 01:15
No 321106
This Recruit would also bee interested on what kind of impurities one could find in MDp-2-p. Also, if any one has any info on impurities by method ( even info on articles in chem mags ) this Recruit would appreciate!!
(Rehabilitated)
06-14-02 11:30
No 321309
take 1ml of your freshly distilled ketone. Do a sodium bisulfite (or metabisulfite) test on it. If it reacts quantitatively, you have have very pure ketone. If however at the end of your efforts you have oil floating to the surface of your solution, refusing to form the adduct, you have impure ketone.
In five minutes you will know whether the problem is with your ketone or in your amination attempt
. I expect though that if your ketone had a boiling range of less than 2deg C, your problem more likely exists with your amination or it's work-up.sodium bisulfite is available at wine brewing stores
(I'm not Cheesie)
06-14-02 15:46
No 321395
First try a bisulphite addition with some acetone in a vial.
-If you get crystals to form like the ones that form with the acetone, your ketone is pure.
-If you get chicken fat, there's impurities.
I'm not reccomonding this but you might be able to take that 600g ketone and crystalize it using a bucket of bisulphite sol. Then wash your crystal/fat with DCM then fresh dH2O, then mix back with 10%HCl for the oil to come back pure MDP-2-P. Proably a big mess. Theoretically it works though.
You could take 20g of your MDP-2-P and try aminating with reagents in proportion to 15g of pure ketone and see if yields are the same, then you might know more of the purity.
Bubba Fatt - LA's Biggest Bounty Hunter. His subjects are at large and so is HE!
(Pioneer Researcher)
06-14-02 15:58
No 321402
I think you can put reagents for 20 gr. If you only have 15 gr of ketone in the 20 gr it won't affect, you'll get the yields corresponding to 15 gr. Then you can adjust your reagents if you want.
(Chief Bee)
06-14-02 16:17
No 321408
Yeah, what Sunlight said. Excess amination reagents won't hurt the reaction.