Trans 4-Methylaminorex via Potassium Cyanate
Chemicals:
28.2 g (0.15 moles) (+/-) norephedrine-HCl. NOTE: (+/-) norephedrine-HCl and (+/-) norspeudoephedrine all fall under the rubric of PPA. You want norephedrine, not norspeudoephedrine.
12.0 g potassium cyanate (KOCN)
172 ml 2M hydrochloric acid (HCl)
20% sodium carbonate (Na2CO3)
Dichloromethane (DCM)
Distilled water (dH2O)
Equipment:
500 ml flat bottom flask
Magnetic hotplate with stir bar
Thermometer
Put 28.2 g PPA-HCl in about 150 ml dH2O in your 500 ml Erlenmeyer. It should all dissolve easily. Next add 12.0 g KOCN and magnetically stir. About 75% of the KOCN should dissolve readily. Reflux the mixture directly on your hotplate. Hotplate should just be hot enough to boil your mixture. At about 35 deg C, all the KOCN should dissolve. Reflux for about 2.5 hours, then allow to cool to room temp. First you should notice a clear oil precipitating to the top. Further cooling will precipitate white flakes on the bottom. Place the flask in your freezer for about ½ hour or until temp drops to 5 deg C. Pour the solution into a pyrex dish and slowly evaporate over low heat. Do not evaporate completely. Next, place the solution back in your washed Erlenmeyer and add about 275 ml dH2O. It should dissolve slightly. Magnetically stir and begin heating the solution. Add 172 ml of 2M HCl and continue stirring and heating until just boiling. At about 50-60 deg C the white solution should turn clear again. Reflux again for about 2.5 hours magnetically stirring the whole time. Allow to cool to room temp. White powder will appear.
Wash the solution 3 times with a small amount of DCM. Isolate the water phase and basify it with your 20% Na2CO3 until no more white powder precipitates. Gravity filter the white powder and allow to dry at room temp with a fan or in an oven at low temp. Your yield should be about 15.5 g (+/-) trans 4-MAR freebase. [Forms Hcl salt readily.]
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