Dimethylformamide dimethyl acetal → HCID 53423662, compound

Participants

Reaction Conditions

Reaction Steps

(b′) A 3 L, 4-necked, round-bottomed flask, equipped with a mechanical stirrer, digital thermometer, reflux condenser, and nitrogen inlet-outlet, is charged with 953 g (1.05 L) of a toluene solution containing 1-(4-chlorophenyl)-3,3-dimethyl-2-butanone and 173 g (200 mL) of toluene; then add by pump 232 g (259 mL) of N,N-dimethylformamide dimethyl acetal. The solution is heated to an internal temperature at 97-109° C. (reflux) and stirred at this temperature for 5 hours. One hundred (100) mL of solvent is distilled off over a period of 0.5 hours. After distillation is stopped, the mixture is heated to an internal temperature at 107-114° C. (reflux). The mixture is stirred at this temperature for an additional 1 hour. Three more distillations follow in a similar procedure. Then the reaction mixture is cooled to an internal temperature at 20-25° C. over 1 hour, and stirred at this temperature for 1 hour, filtered over a pad of 70 g of Celite and the pad was washed with 300 mL of toluene. Filtrates are combined and concentrated under vacuum (30-80 torr) at an internal temperature at 25-40° C. (maximum jacket temperature 50° C.) to collect about 800 g or 925 mL of solvent to afford 275 g of crude 2-(4-chlorophenyl)-1-(dimethylamino)-4,4-dimethyl-1-pentene-3-one (Theoretical yield: 173.6 g). This crude product is dissolved in 440 mL (380 g) of toluene and the removal of excess N,N-dimethylformamide dimethyl acetal is confirmed by 1H NMR. The solution can be held at 21-23° C. under nitrogen and then used in the next step.

Provenance & Evidence