POLYHALOGENONITROBENZENES AND DERIVED COMPOUNDS .5. IMPROVED PREPARATIONS OF 1,2,3,4-TETRAFLUORO-5,6-DINITROBENZENE AND 3,4,5,6-TETRAFLUORO-1,2-PHENYLENEDIAMINE, AND THE USE OF THE LATTER FOR THE SYNTHESIS OF TETRAFLUOROBENZHETEROCYCLES

The preparation of 2,3,4,5-tetrafluoro-6-nitroaniline (3) by amination of pentafluoronitrobenzene has been speeded up, scaled up and the yie ld increased by controlling the reaction by TLC monitoring and using ' dry column' chromatography. Compound (3) was readily converted to 1,2, 3,4-tetrafluoro-5,6-dinitrobenzene (2) by peroxytrifluoroacetic acid a nd to 3,4,5,6-tetrafluoro-1,2-phenylenediamine (1) by SnCl2/HCl. Compo und (1) was shown to be a versatile intermediate for the synthesis of tetrafluora-benzimidazoles, -triazoles and -quinoxalines. The fungicid al activity of the latter are reported here.