A cooled mixture of concentrated sulfuric acid (6.5 ml.) and nitric acid (4.4 ml.) is added with stirring to an ice cold solution of 1,3-bis(2,6-dichloro-α,α,α-trifluoro-p-tolyloxy)-benzene (11.1 g. 0.021 mol) in 1,2-dichloroethane (30 ml.). After thirty minutes at room temperature, the phases are allowed to separate and the organic phase washed twice with water. Benzene (200 ml.) is added and the solution washed twice with dilute sodium carbonate solution, dried, filtered through activated silica gel (~25 g.), and the solvents removed. The residual crystals are triturated with pentane, filtered, and dried to obtain 1,3-bis(2,6-dichloro-α,α,α-trifluoro-p-tolyloxy)-4-nitrobenzene (9.9 g., 82%) m.p. 137.5°-140.5° C., 90% pure.
