1,3-Dibromo-5,5-dimethylhydantoin → 1-Bromo-3,5-bis(trifluoromethyl)benzene

Temperature

35 °C

To glacial acetic acid (22.0 mL), cooled to 15° C. in a 1 L 3-n RB flask (equipped with mechanical stirrer, thermocouple, and addition funnel), was added concentrated (96%) sulfuric acid (142 mL) in one portion. An exothermic heat of solution raised the temperature to 35° C. After cooling to 25° C., 1,3-bis(trifluoromethyl)benzene (107 g, 500 mmol) was added. With the acid mixture rapidly stirring, 1,3-dibromo-5,5-dimethylhydantoin (77.25 g; 270 mmol) was added over 2 min to give a multiple phase mixture (solid and two liquid). An exothermic reaction occured that raised the internal temperature to ˜40° C. (jacket cooling at 15° C.). After the reaction temperature began to drop (after 5 min) the reaction mixture was maintained at 45° C. for 4.5 hr.

1. customequipped with mechanical stirrer
2. additionthermocouple, and addition funnel),
3. additionwas added
4. concentrationconcentrated (96%) sulfuric acid (142 mL) in one portion
5. temperatureAn exothermic heat of solution
6. temperatureAfter cooling to 25° C.
7. customto give a multiple phase mixture (solid and two liquid)
8. customAn exothermic reaction
9. temperaturethat raised the internal temperature to ˜40° C.
10. temperature(jacket cooling at 15° C.)
11. custom(after 5 min)
12. temperaturewas maintained at 45° C. for 4.5 hr

ORD record

ord-0201f74071ba45a994fbac07c35e5c40

Source dataset

uspto-grants-2004_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06814895B2