Alupent, Boehringer Ingelheim ,W. Germany ,1961
In an initial operation, 3,5-diacetoxyacetophenone was reacted first with
bromine and then with isopropylamine to give 1-(3,5-dihydroxyphenyl)-2-
isopropylaminoethanone.
59 g of 1-(3,5-dihydroxy-phenyl)-2-isopropylaminoethanone (free base) were
dissolved in 590 cc of methanol, and the solution was hydrogenated in the
presence of about 80 g Raney nickel at room temperature and under a
pressure of 5 atm. Hydrogen absorption was terminated after a few minutes.
The catalyst was separated by vacuum filtration, and the filtrate, an ethanolic
solution of 1-(3,5-dihydroxyphenyl)-1-hydroxy-2-isopropylaminoethane, was
admixed with the calculated amount of an alcoholic 20% sulfuric acid solution.
A crystalline precipitate formed which was filtered off and washed with
alcohol. For purification, the product was dissolved in water and the solution
was filtered through iron-free charcoal.
Thereafter, the filtrate was evaporated to dryness in vacuo and the residue
was taken up in alcohol. The crystalline precipitate which separated out after
some standing was separated by vacuum filtration and washed with alcohol.
After recrystallization from 90% alcohol, 61 g (83.2% of theory) of 1-(3,5-
dihydroxyphenyl)-1-hydroxy-2-isopropylamino-ethane sulfate, MP 202° to
203°C, was obtained.
