反应详情

To a stirred solution of 2,3,4-Trifluorobenzoic acid (70 Kg, 398 Mol) in sulphuric acid (96 wt %; 194 L) and hexamethyldisiloxane (6.5 Kg, 40 Mol), at 23° C., was added a 1:1 mixture of sulphuric acid (96 wt %) and nitric acid (98 wt %) (total 70.1 Kg), over 75 min. The temperature of the reaction mixture was maintained between 15 and 25° C. during the addition. The mixture was stirred for a further 5 hours and then run onto ice (700 Kg), keeping the temperature of the ice mixture below 0° C. Water (35 L) was used to rinse the nitration reactor into the quench reactor and the obtained mixture was stirred for 2 hours at 0° C., then isolated on a centrifuge. The resultant wet cake was washed with cold water (350 L), and the solid was then suspended in water (280 L) and stirred for 2 hours at 0° C. This suspension was then centrifuged and the cake was washed with cold water (210 L), then dried in a vacuum oven at 45° C. for 2 days, to provide 2,3,4-Trifluoro-5-nitro benzoic acid (69.4 Kg, 74.3% yield). 1H NMR (400 MHz, d6 DMSO) δ 8.44 (1H, apparent dt, J 2, 7, Ar—H). 19F NMR (376 MHz, d6 DMSO) δ−153.9, −131.5, −120.9. 13C NMR (100 MHz, d6 DMSO) δ 117 (C, m), 124 (CH, b s), 134 (C, s), 141 (C—F, dt, J 251, 10), 148 (C—F, dd, J 265, 13), 154 (C—F, dd, J 265, 10), 163 (COOH). IR vmax/cm−1 3108 (br), 1712, 1555, 1345, 1082. MS APCI (−) m/z 220 (M−1) detected.

1. temperatureThe temperature of the reaction mixture was maintained between 15 and 25° C. during the addition
2. washto rinse the nitration reactor into the quench reactor
3. stirringthe obtained mixture was stirred for 2 hours at 0° C.
4. customisolated on a centrifuge
5. washThe resultant wet cake was washed with cold water (350 L)
6. stirringstirred for 2 hours at 0° C
7. washthe cake was washed with cold water (210 L)
8. customdried in a vacuum oven at 45° C. for 2 days