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Ephoton
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| Joined: 03 Jul 2005 |
| Posts: 72 |
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2474.98 Points
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idea for p2p route
Mon Jul 11, 2005 6:29 pm |
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benzaldehyde + aniline --> ppa via akabori-momotani
ppa + SnCl2 ---> P2P
no nitro ethane 
both steps should be high yeild |
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Elementary
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| Joined: 18 Apr 2005 |
| Posts: 100 |
| Location: UK |
3449.86 Points
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re: idea for p2p route
Mon Jul 11, 2005 10:49 pm |
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| Can you provide some references please ? |
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hAzzBEEn
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| Joined: 09 May 2005 |
| Posts: 126 |
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4955.86 Points
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re: idea for p2p route
Tue Jul 12, 2005 2:16 am |
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Perhaps Ephoton means l-alanine rather than aniline.
I'm not familiar with this, but remember a thread: "alanine" - click here for thread.
| Bumblebee wrote: |
The originally Procedure was taken from Chem. Abs. Volume 47, column3347.
They did the Akabori with N-methyl-d,l-alanine to yield a mixture of d,l-Pseudoephedrine and d,l-ephedrine.
I substituted food grade l-alanine for the N-methyl-d,l-alanine, to yield PPA.
100g Benzaldehyde was placed in an flask and heated on an oil bath to 140-160°C. as the Benzaldehyde reached the temerature i started adding 40g l-alanine. the magnet stirrer was set to "high" to achive a heavy stirring.
after one hour the addition of l-alanine was complete, an i began refluxing for 4 hours.
while adding the benzaldehyde became first yellow then orange and later deep red to brown in colour.
the mixture was cooled and mixed with 300ml of toluene, and filtered.
something like unreacted alanine (a white clumpy mass) was filtered off.
the PPA was extracted by shaking this solution with 300ml of 10% HCl.
the dil. hydrochloric acid was boiled down to a volume of 50 -100 ml and cooled to room temperature. A little bit of activated carbon was added to decolorize the solution.
the solution was made alkaline with lye (don´t know anymore how much i used) until it was strongly alkaline to litmus paper.
the PPA Freebase was extrcted three times with toluene and finally bubbled with dry HCl-gas to get PPA Hydrochloride.
i got never more then 5-8 grams PPA-HCl out of it.
I think i did something wrong while Extraction. after shaking with HCl there were 2 layers the toluene layer above and the aqueous layer at the bottom, but there was always a brown mess at the bottom that seemed to have the same or higher density than water, so it sank to ground.
let me know what your experiences are if you try to do this reaction.
BB
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where "Chem. Abs. Volume 47, column3347" would be the reference to which you are referring.
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hAzzBEEn
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| Joined: 09 May 2005 |
| Posts: 126 |
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4955.86 Points
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re: idea for p2p route
Tue Jul 12, 2005 2:35 am |
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...and for PPA => P2P (not via SnCl)...
From Rhodium's:
| Rhodium's Page wrote: |
Phenyl-2-propanone from Ephedrine Derivatives [10]
When ephedrine and related compounds are heated in strong aqueous acid, they are dehydrated to the enamine, which spontaneously can rearrange to the isomeric imine (Schiff Base), which then can be hydrolyzed into phenyl-2-propanone and an amine salt. As all the steps are reversible processes, the reaction equilibrium is driven towards the desired product by continuously removing the formed phenyl-2-propanone by the aid of steam distillation.
Ephedrine derivatives that can be used in this procedure include Ephedrine, Pseudoephedrine, Norephedrine and Norpseudoephedrine (Phenylpropanolamine). Many other metal salts can be used instead of the zinc chloride, for details, see the translation of the original patents.
1025g 75% sulfuric acid was mixed with 1g ZnCl2, and 192g (1.16 mol) Ephedrine or Pseudoephedrine freebase was dissolved at a temperature of 50-100°C, and the reaction mixture was heated further to 145-150°C. At 125°C steam is passed through the solution to facilitate mixing of the contents. At 145°C the stream of steam is increased, and during 2.5-3 hours the phenylacetone is steam distilled from the reaction mixture. The the crude phenyl-2-propanone, which is free from propiophenone, is isolated by toluene extraction of the distillate. After distillation through a short vigreaux column, 130g (82%) of phenyl-2-propanone is isolated in a purity of 99.8%.
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From [10] German Patents 3,026,698 and 3,200,232
and also From this link on Rhodium's
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loki
guinea pig
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| Joined: 09 Mar 2005 |
| Posts: 391 |
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14167.88 Points
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re: idea for p2p route
Tue Jul 12, 2005 6:07 am |
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i would be a hell of a lot more interested in the akabori reaction if there was an easy way to get that alanine.
Would be nice to find a way to do a direct substitution of the amine for a halide, then use the saccharin/gabriel reagent route. Is it possible to only oxidise the amine back to chiral alcohol by any chance? My reason for enquiring in this direction is the preservation of chirality.
Something else which i came across in a synthesis for selegiline was the use of an inversely aminated version of ephedrine, with the amine on the beta and the hydroxyl on the alpha. This was then reduced to the aziridine and further reduced to yield the amphetamine. Finding a source or a way to synthesise this chiral specific alcohol they start with and plugging the amine on back to front would be a neat trick... I would suspect that this chiral alcohol and possibly even the amine it is made into would not be watched... Selective halogenation of the beta hydroxyl (wait a sec, isn't that the first site of halogenation) would allow a gabriel synth to the amine here too.
yes i am in love with the gabriel reaction system just at the moment. (and halides, preferably the one which has pink vapour). |
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