Phosgene → Piperonal

Participants

Reaction Conditions

Reaction Steps

Into a mixture of 97.6 g (0.80 mole) of 1,2-methylenedioxybenzene and 108 g (0.80 mole) of N-methylformanilide was introduced 87.1 g (0.88 mole) of phosgene at 50° C. over a 1-hour period. Then, the mixture was cooled to 15° C. On the other hand, 29.3 g (0.24 mole) of 1,2-methylenedioxybenzene was charged into another reactor and kept at 90° C. The above mixture was added to this reactor over a 5-hour period. After completion of the addition, the reaction mixture was kept at 90° C. for 30 minutes, poured into ice water, and allowed to stand for 1 hour. Then, the resulting mixture was extracted with toluene. By vacuum distillation, the toluene was removed and the distillate at 84°-85° C./30 mmHg was then collected to recover 63.4 g (0.52 mole) of unreacted 1,2-methylenedioxybenzene. Subsequently, the distillate at 131°-134° C./10 mmHg was collected to obtain 76.8 g (0.512 mole) of piperonal having a purity of 99.5%. The yield (expressed in terms of mole percentage based on the amount of N-methylformanilide used) and selectivity (expressed in terms of mole percentage based on the amount of 1,2-methylenedioxybenzene having reacted) of piperonal were 64.0% and 98.5%, respectively. This product had a melting point of 37° C.

Provenance & Evidence