N([O-])=O.[Na+].N[C:6]1[C:7]([Cl:17])=[C:8]([Cl:16])[CH:9]=[C:10]([C:12]([F:15])([F:14])[F:13])[CH:11]=1.[ClH:18]>O>[Cl:18][C:6]1[CH:11]=[C:10]([C:12]([F:15])([F:14])[F:13])[CH:9]=[C:8]([Cl:16])[C:7]=1[Cl:17]A solution of sodium nitrite (39 g.) in water (85 ml.) is added over 1 hour to a solution of 5-amino-3,4-dichloro-α,α,α-trifluorotoluene (117.5 g., 0.51 mol) in 1700 ml. concentrated hydrochloric acid at -6° C. and the solution stirred for 1 hour then filtered. The filtrate is added to a solution of cuprous chloride (76.5 g.) in concentrated hydrochloric acid (500 ml.) over 5 minutes at 0° to 8° C. and gradually heated to 80° C. over 80 minutes. The reaction mixture is cooled to 35° C. and extracted with hexane (2×300 ml.). The extract is washed with water, 2% sodium hydroxide solution, dried and distilled to give 3,4,5-trichloro-α,α,α-trifluorotoluene (70 g., 55%) b.p. 82°-86° C./10 mm, 95% pure.
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