Manufacturing Process
548.0 g (2 mol) of 2,5-dimethoxy-α-bromopropiophenone was dissolved in
500 ml of acetanitrile and 365.0 g (5 mol) of t-butylamine was added. The
solution was allowed to stand at room temperature for 64 h and was then
diluted with 2 L of anhydrous ether. The precipitated t-butylamine
hydrobromide was filtered off and washed with ether. The filtrate and
washings were concentrated in vacuo using a water-bath kept at 40°C. When
most of the solvent had been removed, the residual material was dissolve in
cold methanol and acidified with hydrochloric acid. The solution was then
taken down to dryness in vacuo on the steam bath and the 1-(2,5-
dimethoxyphenyl)-2-(t-butylamino)propiophenone was obtained, melting point
175-176°C (recrystallised from an ethanol ether mixture).
The bulk of the 1-(2,5-dimethoxyphenyl)-2-(t-butylamino)propiophenone was
dissolved in methanol and hydrogenated over platinum (Adams' catalyst).
After removal of the catalyst, the solvent was removed in vacuo and the
residual solid was dissolved in water and the solution was washed with ether.
The aqueous layer was basified (dilute sodium hydroxide solution) and the
base was taken into ether. After drying over anhydrous potassium carbonate,
the ether was evaporated and the base was distille at 0.3 mm pressure. So
the DL-erythro 1-(2,5-dimethoxyphenyl)-2-(t-butylamino)propanol, boiling
point 127-128°C was obtained.
