Azobisisobutyronitrile → 4-(Bromomethyl)-3-fluorobenzonitrile

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1,2-Dichloroethane (151 kg) was charged to a suitable vessel along with 4-cyano-2-fluorotoluene (24 kg) and AIBN (2 kg). The mixture was heated to 70˜74° C. Once the batch temperature reached 70° C., N-bromosuccinimide (47.4 kg) was added in portions at the rate of 12 kg/h, maintaining the temperature at 70˜74° C. (it is important to control addition rate to avoid exothermic reaction). The mixture was sampled via GC detection after 24 kg of N-bromosuccinimide was added, and the reaction was heated at 70-74° C. until complete reaction was observed. The mixture was cooled to 0-5° C. and allowed to stand for 2 additional hours. The mixture was filtered, and the cake was washed with MTBE (24 kg). The filtrate was washed with water (3×65 kg). The organic layer was dried with sodium sulfate (10.3 kg) for 6 hours, filtered and the cake was washed with MTBE (24 kg). The solution was evaporated under reduced pressure, ethanol (12 kg) was added and the mixture was heated to 40-45° C., then cooled slowly to 0-5° C. while stirring to crystallize. The mixture was filtered and the cake was washed with cold ethanol (5 kg). The crude solid was recrystallized from petroleum ether, filtered and washed with petroleum ether (10 kg), giving the title compound 4-(bromomethyl)-3-fluorobenzonitrile as an off white solid (21 kg, 55% yield). 1H NMR (300 MHz, CDCl3) δ ppm 4.46-4.50 (m, 2H) 7.36 (dd, J=8.85, 1.32 Hz, 1H) 7.44 (dd, J7.91, 1.32 Hz, 1 H) 7.52 (dd, J7.91, 7.16 Hz, 1 H). 13C NMR (75 MHz, CDCl3) δ ppm 23.65 (d, J=4.60 Hz, 1 C) 113.76 (d, J=9.77 Hz, 1 C) 117.09 (d, J=2.87 Hz, 1 C) 119.44 (d, J=24.71 Hz, 1 C) 128.44 (d, J=4.02 Hz, 1 C) 130.66-130.81 (s, 1 C) 130.81-131.06 (s, 1 C) 132.18 (d, J=3.45 Hz, 1 C) 159.86 (d, J=254.03 Hz, 1C). IR: (KBr) 3088, 3077, 3040, 2982, 2250, 1571, 1508, 1439, 1248 cm−1. Anal. Calcd for C8H5BrFN: Calc. C, 44.89; H, 2.35; N, 6.54; F, 8.88. Found: C, 44.94; H, 2.73; N, 6.56; F, 8.73.

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