SYNTHESIS OF p-TRIFLUOROMETHYL-TOLUENE AND 3,6-BIS(TRIFLUOROMETHYL) PHENANTHRENE USING SULFUR TETRAFLUORIDE

The object of the work was to investigate, on a laboratory scale, the individual reactions of SF4 with p-toluic acid to produce p-trifluoromethyl toluene and of 3,6-phenanthrene dicarboxylic acid to produce 3,6- bistrifluoromethylphenanthrene. This laboratory data was to serve as a basis for scaleup of this reactions to a commercial process. The parameters investigated were temperature over the range of 20C to 225C, pressure over the range of 140 to 3,000 psig, reaction times from one to 18 hours, SF4 concentrations at 50 to 4,500 excess, catalysis with hydrogen fluoride and the use of inert solvents for the 3,6-phenanthrene dicarboxylic acid runs. The highest conversion 22.5 of 3,6-bistrifluoromethylphenanthrene was obtained by suspending the 3,6-phenanthrene dicarboxylic acid in benzotrifluoride and reacting at a temperature of 210 to 220C, pressure of 1950-2150 psig, reaction time of 16 hours with a 1100 excess of SF4. A purified sample of 3,6- bistrifluoromethylphenanthrene was not obtained from these reactions but studies on the soxhlet extractors showed promise that separation and isolation is possible. Corrosion data gathered during the course of the p-toluic acid reactions showed a corrosion rate of 0.002 inches per year on 316 stainless steel under reaction conditions. An economic evaluation of the production of 3, 6-bistrifluoromethyl phenanthrene based on a 20 conversion to 3,6- bistrifluoromethyl phenanthrene plus an additional 30 yield of recycleable intermediates showed that a selling price excluding 3,6-phenanthrene dicarboxylic acid costs of 15pound could be achieved at 30,000 to 50,000 lbs per year 3,6-bistrifluoromethylphenanthrene.