Hydrochloric Acid → 3-(Dimethylamino)-1-(thiophen-2-yl)propan-1-one hydrochloride

Temperature

0 °C

A mixture of 8.18 g of 2-acetylthiophene, 6.66 g of dimethylamine hydrochloride, 2.9 g of paraformaldahyde and 0.31 g of concentrated hydrochloric acid in 20 ml of isopropanol was heated to reflux and stirred for 6 hours. The mixture was then cooled to 0° C. and stirred for one hour more. The slurry was then filtered, and the solid was washed with cold ethanol. The washed solid was dried for 16 hours at 50° C. to obtain 12.5 g of 2-thienyl 2-dimethylaminoethyl ketone hydrochloride, as a white solid. A 12.0 g portion of that intermediate product was stirred in 40 ml of ethanol at ambient temperature, and the pH of the solution was raised to 11-12 by slow addition of sodium hydroxide. A 1.03 g portion of sodium borohydride was added, and the mixture was stirred at ambient temperature for 4 hours. Then 7.5 ml of acetone was added, and the mixture was stirred for 20 minutes more. The mixture was then concentrated by evaporation to a white slurry, and 120 ml of methyl t-butyl ether was added. The mixture was acidified to pH 1-1.5 by addition of concentrated hydrochloric acid, and the solution was stirred for ten minutes. The pH was then made basic to pH 12 by slow addition of sodium hydroxide.

1. temperaturewas heated
2. temperatureto reflux
3. stirringstirred for one hour more
4. filtrationThe slurry was then filtered
5. washthe solid was washed with cold ethanol
6. customThe washed solid was dried for 16 hours at 50° C.

ORD record

ord-bd0e67420dc74495b47a5f125a4fc68f

Source dataset

uspto-grants-1996_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05491243