| 摘要 |
The present invention relates to an improved process for the preparation of 2,3,4,6-tetrachlorophenol by chlorination of 2,4,6-trichlorophenol. There has now been found a process for the chlorination, by gaseous chlorine, of 2,4,6-trichlorophenol in a molten medium to 2,3,4,6-tetrachlorophenol, containing a small proportion of pentachlorophenol, characterised in that the reaction is carried out in the presence of an effective amount: - of a zirconium, hafnium, tellurium, antimony or niobium halide or of one of their precursers, - and/or of a strong protonic acid. The halides which can be used as catalysts are the chlorides, bromides, iodides and fluorides of zirconium, hafnium, tellurium, antimony and niobium.
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