prepare | 2. 5kg 3,4,5_crude trifluorophenol, in which toluene content is 2%, near boiling impurity 3,5_difluorophenol content is 0. 05%, 3,4-difluorophenol content is 0. 03%, 2,4-difluorophenol content is 0. 025%, 2, 3, the content of 5-trifluorophenol is 0. 07%, 2, 3,4-trifluorophenol is 0. 042%, 2,4,6-trifluorophenol is 0. 01%, and the content of 3,4,5-trifluorophenol is 97.8%. The crude material was put into a 5L rectification kettle, and the p-tert-butyl toluene 1. 5kgo was added to depressurize to 100mmHg after full reflux Ihr, and the p-tert-butyl toluene fraction was collected from the top of the tower at a 1 : 1 reflux ratio. After collection, the tower kettle sampling GC analysis showed that the toluene content was not detected. 3,5-difluorophenol contained 50ppm,3,4-difluorophenol 62ppm,2,4-difluorophenol 2ppm,2,3,5-trifluorophenol 3ppm,2,3,4-trifluorophenol 2ppm. The material was evaporated from the top of the tower, and the obtained high-purity 3,4,5-trifluorophenol weighed 2. 2kg, the content was 99. 98%, and the rectification yield was 89. 97%. |