| 摘要 |
<p>Fluorobenzenes of formula (I) are prepd. by reaction of chlorobenzenes of formula (II) with potassium fluoride in a suitable solvent. In the formulae, R1=nitro or cyano and R2=H, an aliphatic radical or halo. The reaction is effected using catalytic quantities of cesium fluoride or when (II) is a m-nitrochlorobenzene or m-cyanochlorobenzene it is not necessary to use cesium fluoride. Suitable solvents are N, N-disubstd. carboxylic acid amides, nitrobenzene, nitriles, aliphatic sulphones and/or aliphatic sulphoxides. (I) are intermediates for dyes, pharmaceuticals and parasiticides. (I) may be reduced to the corresp. aniline deriv. which are used in paints, as germicides and is welding fluxes. Compared with known processes the present process gives higher yields and purer products. The reaction is effected at low temperatures is rapid, economic and suitable for industrial scale prodn.</p> |
