GB866810A - Process for the manufacture of tetrafluoro-benzoquinone-1 : 4 - Google Patents

Abstract

The invention comprises tetrafluoro-benzoquinone-1:4, and processes of making it from tetrachloro-benzoquinone-1:4 by reaction with potassium fluoride. According to one method, the dry tetrachloro-benzoquinone is conducted in vapour form over heated dry potassium fluoride, and in an alternative method, the dry tetrachloro-benzoquinone is reacted with dry potassium fluoride at a raised temperature, the tetrafluoro-benzoquinone so p obtained is reduced to the corresponding hydroquinone, the latter is purified by distillation with toluene vapour, and the purified hydroquinone compound is converted by oxidation into tetrafluoro-benzoquinone-1:4. Reaction with potassium fluoride may be carried out at a temperature within the range of 175 DEG -350 DEG C. The reaction product may be purified by sublimation e.g. under reduced pressure. In an example, potassium fluoride is dried in a drying chamber, then ground and charged into part of a reaction tube which is then heated at 350 DEG C. while passing dry nitrogen through it, water vapour being expelled from the fluoride and passed to an absorption apparatus. A mixture of dry chloranil and calcium fluoride is then charged into the tube, and then a portion of calcium fluoride only. The tube is heated to 320 DEG C. and nitrogen is passed through. The product separates out as a sublimate in a receiver attached to the reaction tube. The product is soluble in benzene toluene, alcohol, ether, chloroform, carbon tetrachloride, petroleum ether, and 1-dichlorofluoro-2-dichlorofluoro-ethane. In another example, a mixture of dry potassium fluoride and chloranil is heated in a glass tube at 105 DEG C. under a pressure of 20 mm. Hg. for several hours and then brought to a reaction temperature of 320 DEG C. The products formed are sublimed out of the hot zone by again reducing the pressure. The sublimed substance is dissolved in toluene and hydrogenated in presence of platinic oxide. Tetrafluoro-hydroquinone-1:4 is obtained from the solution by crystallisation. This compound is dissolved in ether and mixed with calcined magnesium sulphate and active lead dioxide and the mixture is shaken vigorously. The solution is passed through a filter into a sublimation apparatus and after distillation of the ether, the tetrafluoro-benzoquinone-1:4 is sublimed out at 50 DEG C. under a pressure of 15 mm. Hg. Tetrafluoro-benzoquinone-1:4 may be used as a fungicide, or as an agent for controlling the polymerisation of olefines and vinyl compounds.ALSO:1-Dimethylamino-4-aminobenzene is oxidized to "Wursters' Red" using tetrafluorobenzoquinone 1 : 4 as oxidizing agent.