First 154.36 g (0.887 mol) of sodium dithionite and then 50 g (0.467 mol) of o-toluidine (2-methylaniline) were added at room temperature to a mixture of 900 ml of water, 350 ml of tert-butyl methyl ether, 74.48 g (0.887 mol) of sodium hydrogencarbonate and 12.68 g of tetra-n-butylammonium hydrogensulphate. Subsequently, a solution of 274.684 g of 1,2-dibromo-1,1,2,3,3,3-hexafluoropropane in 100 ml of tert-butyl methyl ether was added dropwise at 35–40° C. and, on completion of addition, the mixture was stirred at 40° C. for a further 18 h. If necessary, sodium carbonate was used to adjust to a pH of 5 and the organic phase was removed, dried and concentrated. The remaining residue is incipiently distilled under reduced pressure at 0.3 mbar up to an internal temperature of 100° C.
