Author Topic: One pot synthesis of 4-methylaminorex  (Read 6203 times)

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  • Guest
One pot synthesis of 4-methylaminorex
« on: September 12, 2003, 01:23:00 AM »

Further exploration of an initial suggestion by Rhodium - to perform both the preparation of the carbamoyl norephedrine as well as its cyclization to trans-4-MAR in one pot gave the following results:

When the initial norephedrine hydrochloride is mixed with potassion cyanate, it forms the carbamoyl coumpound in near quantitatie yeilds with respect to the norephedrine. The original patent's uses a slight molar excess of the cyanate in order to give complete conversion. When the first reaction is done, there should thus be a mixture of: N-carbamoyl-norephedrine, potassiumchloride and traces of of cyanate. The remaining cyanate will be destroyed by the huge excess of acid which will be added later. In the end these impurities should have no influence of the ring formation, catalysed by the acid. It should in theory be possible to do the initial reaction and simply add the acid in one portion while heating continusouly till the reaction is over. With this in mind, it seems kind of a waste to isolate the intermediate, so this has to be tested :)

Practice:(in theory of course)
5 grammes of norephedrine.HCl(26,5 mmoles), was placed in a 100 mL FBF, and 2,3 grammes of KOCN(28,4 mmoles) and 25 mL's of distilled water was immediately added in succession. This was heated to reflux directly on the hotplate for two hours.

After this time, 30 mL's of 2M HCl(60 mmoles) was added. This caused a bit of bubbling(probably from the excess cyanate being broken down to gasseus -i-cant-remember-what-). Reflux was continued for an additional two hours. The mixture took on an ever so slight pinkish tint, which the "old" synth also tend to do at this stage.

After 2½ hours of reflux, the mixture was cooled and basified with sodium carbonate and presto a lot of pretty white crystals precipitated on the bottom of the beaker. The yeild looked like that which is expected from the normal reaction. They will be measured shortly.

Total success!!
We'll the usual cyanate route to 4-methylaminorex was easy, but this is more like baking a shake-n-bake cake really ;)(which is VERY easy if you didn't know). Bioassay's are pending though, but nothing that was put into the flask would have reacted the way, the final product did. The yeild will also be measured shortly!

Have a nice and productive weekend!

Kind Regards


  • Guest
This caused a bit of bubbling(probably from...
« Reply #1 on: September 12, 2003, 06:35:00 AM »
This caused a bit of bubbling(probably from the excess cyanate being broken down to gasseus -i-cant-remember-what-).

The isocyanic acid hydrolyzes to NH3 and CO2.

Congrats, what a beautifull procedure  :-[  :) .


  • Guest
« Reply #2 on: September 13, 2003, 08:40:00 PM »
What a breakthrough!

Look so easy! Very very nice!

Thank you for the good work (altough were i live E4Euh is illegal  :( ), but still!

I cant wait the final yield! 8)


  • Guest
(4-Methyl)Aminorex related forensic article
« Reply #3 on: September 16, 2003, 12:25:00 PM »
Appearance of Aminorex as a Designer Analog of 4-Methylaminorex
Marcus E. Brewster and Frank T. Davis

Journal of Forensic Sciences 36(2), 587-592 (1991)



A case in which aminorex (cis (±)-4,5-dihydro-5-phenyl-2-oxazolamine) was prepared as a "designer" analog of a controlled substance, methylaminorex (cis-(±)-4,5-dihydro-4-methyl-5-phenyl-2-oxazolamine) is described. The confiscated drug sample was analyzed by high-field (300-MHz) proton nuclear magnetic resonance (NMR) and carbon-13 NMR spectroscopy, as well as electron impact mass spectrometry (70 eV). These examinations proved conclusively that the material in question was aminorex.


  • Guest
Final yield
« Reply #4 on: September 19, 2003, 10:41:00 AM »
The final yield has now been measured: 77% mole wise from the PPA.HCl

From 5,0 grammes of PPA.HCl there where prepared 3,6 grammes of 4-methylaminorex freebase with the new method. Compared to the 3,4-dimethylaminorex synthesis from J Chem Soc, 850-854 (1952), it's at least as high as they get, if not higher(i don't have their article lying around, so it's from my clouded memory). This could be attribited to the fact that no collection of the intermediate product is required.

All in all, it's not to shabby if i may say so  ;)


  • Guest
4-MAR mentioned in a blog
« Reply #5 on: September 19, 2003, 11:36:00 AM »
I just wanted to say that I found someones blog with some

comments about 4-MAR


Same blog, a few days later -

Arguments for 4-MAR



  • Guest
Too bad norephedrine hydrochloride / potassium
« Reply #6 on: October 14, 2003, 05:33:00 PM »


  • Guest
How can you speak for most bees?
« Reply #7 on: October 14, 2003, 05:42:00 PM »
I do agree that norephedrine is harder to obtain, but there is always synthesis (eg. synth the benzaldehyde and nitroethane yourself) and pill extraction for some countries.

But for KOCN you are *definately* talking outta your ass!


  • Guest
Potassium ferricyanide and potassium ...
« Reply #8 on: October 16, 2003, 12:54:00 PM »
Potassium ferricyanide and potassium thiocyanate are easy
to obtain, will they work here?


  • Guest
« Reply #9 on: October 16, 2003, 02:06:00 PM »
That question has already been asked:

Post 455750

(placebo: "If one had a choice between...", Methods Discourse)
...and replied to:

Post 455759

(Rhodium: "All three are wrong, unfortunately.", Methods Discourse)


  • Guest
« Reply #10 on: October 26, 2003, 04:42:00 AM »
You could be quite mistaken on this one, Rhodium.

In the original patent on McNeil Labs 4-methylaminorex

Patent GB1021012

, page 3, they suggest potassium thiocyanate instead of an alkali cyanate and using this for the ring-closure in an equivalent manner to the normal cyanate-route.

In this fascinating little patent, the norephedrine+cyanate+acid method which Bandil, Prometheuz and I thought we had been the first to discover is also suggested.


  • Guest
thiocyanate worked
« Reply #11 on: October 28, 2003, 12:19:00 AM »
Swim did not have any luck finding potassium cyanate so he
purchased a small amount of potassium thiocyanate, did a
small scale rxn assumeing failure. Seeing the rxn take on
the pinkish tone surely put a smile on swim's face.


  • Guest
interesting so
« Reply #12 on: October 29, 2003, 11:12:00 PM »
the oxygen on the oxazoline ring could have possibly been substituted by sulfur.
Find a guinee pig and try to elucidate the pharmcodynamics of this.


  • Guest
cyanate preparation
« Reply #13 on: October 30, 2003, 12:19:00 PM »
Cyanates are easy to prepare. Simply heat an alkali hydroxide with urea.

NaOH + CO(NH2)2 ----> NaOCN + H2O + NH3


  • Guest
« Reply #14 on: November 28, 2003, 06:55:00 AM »
Anyone think that useing the thiocyanate would create
something like 4-Methyl-Thio-Amino-Rex?

Ive heard of 4-MTA [methyl-thio-amphetamine] a
non-nerotoxic seratonin realeaser so....

I wonder if the thio is not a good thing?


  • Guest
That is completely flawed reasoning
« Reply #15 on: November 28, 2003, 08:16:00 AM »
If you look at the structure of 4-Methylthio-Amphetamine and 4-Methylaminorex, you will see that their structures are completely different and that the 4-substituent resides in different parts of their structures.


  • Guest
« Reply #16 on: November 30, 2003, 11:08:00 AM »
Would Phenyl-1-Hydroxy-2-ethanamine work,
Is benzaldehyde + Nitromethane yielding the Hydroxynitroalkan instead of Nitrostyrene possible?
Could the 1-Hydroxyamine be obtained from reduction of nitrostyrene in any way?

Post 404813

(GC_MS: "benzaldehydes + nitromethane pt 1", Methods Discourse)


  • Guest
phenylethanolamine use & prep
« Reply #17 on: November 30, 2003, 01:56:00 PM »
Would Phenyl-1-Hydroxy-2-ethanamine work

That would yield plain amionorex, rather than the desired 4-methylaminorex.

Is benzaldehyde + Nitromethane yielding the Hydroxynitroalkan instead of Nitrostyrene possible?

Yes, using sodium hydroxide as the base and quenching with dropwise addition of dilute acetic acid. It has been discussed before.


  • Guest
Could 5% acetic acid be used instead of the 2m
« Reply #18 on: December 16, 2003, 02:51:00 PM »
Could 5% acetic acid be used instead of the 2m [7%?] hcl?


  • Guest
Good work
« Reply #19 on: December 21, 2003, 05:16:00 PM »
What a simple reaction, relatively speaking.  Is a fume hood a good idea, or just outdoor with a light breeze?