反应详情

温度

0 °C

Pyridiniumtetrafluoroborate (283.7 g, 1.70 mol) was added to a solution of methyl-(2E)-3-(3-dimethylamino)prop-2-enoate in 442.5 ml acetic anhydride/acetic acid (2:1). The resulting suspension was cooled to 0° C. and 3-dimethylaminoacroleine (169.9 ml, 1.70 mol) was added slowly (3 h) while vigorously stirring and cooling with an ice bath to yield a yellow-brown precipitate. After further stirring for 2 h at room temperature the reaction mixture was filtered. The remaining solid was washed with diethylether several times and dried under reduced pressure. Recrystallization from i-propanol/ethanol (2:1) gave 326.7 g (65%) of the pentamethinium salt as yellow crystals.

1. temperaturecooling with an ice bath
2. customto yield a yellow-brown precipitate
3. stirringAfter further stirring for 2 h at room temperature the reaction mixture
4. filtrationwas filtered
5. washThe remaining solid was washed with diethylether several times
6. customdried under reduced pressure
7. customRecrystallization from i-propanol/ethanol (2:1)