| abstract |
The invention relates to a process for the preparation of a compound of the formula wherein R 1 represents halogen, haloalkyl, haloalkoxy, R 4 S (O) n - or -SF 5; R2 is hydrogen or halogen; R3 - halogen; R4-alkyl or haloalkyl; and n is 0, 1 or 2. The method consists in oxidizing a compound of formula (II) as described in the description, wherein R1, R1 and W are as defined above, with trifluoroacetic acid in the presence of a corrosion inhibitor. |