反应详情

A mixture of 55 parts of anhydrous potassium fluoride and 45.32 parts of 3,5-dichloro-4-fluorobenzotrifluoride in 291 parts of sulfolane was heated and maintained at about 216° to 256° for a period of about 55 hours, while product vapors were removed through a distillation column at a head temperature of about 130°-150° C. A total of 32.02 parts of distillate was collected and analyzed by gas chromatography/mass spectrometry. The distillate was found to be 25.1 percent 3,5-dichloro-4-fluorobenzotrifluoride; 65.9 percent 3-chloro-4,5-difluorobenzotrifluoride; 8.6 percent 3,4,5-trifluorobenzotrifluoride and trace amounts of 4-chloro-3,5-difluorobenzotrifluoride. The desired 3-chloro-4,5-difluorobenzotrifluoride was isolated by distillation (b.p. 122° C.) to recover it in essentially pure form (greater than 99 percent pure). The 3,5-dichloro-4-fluoro isomer is recycled.

1. temperaturewas heated
2. temperaturemaintained at about 216° to 256° for a period of about 55 hours, while product vapors
3. customwere removed through a distillation column at a head temperature of about 130°-150° C
4. distillationA total of 32.02 parts of distillate was collected