Bromine → Perfluorooctyl bromide

Participants

Reaction Conditions

Reaction Steps

Perfluorononanoic acid 100 g (0.215 mole), bromine 41 g (0.258 mole) and Freon 113 (500 ml) were mixed in a 2-liter Teflon plastic bottle. This plastic reactor was equipped with a Teflon-coated magnetic stir bar, inlet and outlet tubes made of Teflon-FEP, and a thermocouple coated with Teflon-FEP. The outlet tube was connected to a condensor which was chilled with an ethylene glycol-water mixture. The acid solution was warmed to 30 ° C. through agitation while the reactor was purged of air by flushing it with an inert gas, such as nitrogen, through the inlet tube; The nitrogen flow was terminated and fluorine gas was bubbled into the mixture at 30 cc/min. The fluorine, supplied by Air Products, was used without further purification. The fluorine flow rate was controlled with a Monel needle valve and monitored with a Hastings mass flow transducer. Despite an exothermic reaction occurring immediately, the reaction temperature was kept at 30°-40° C. throughout the reactor by external cooling. The fluorine flow was maintained until the color of the solution turned from deep red to light yellow. Approximately 2.2 fold excess of fluorine (based on the initial amount of acid used) was required to produce this result. After the fluorine gas was terminated, the reactor was again purged with nitrogen and the mixture was carefully poured into water. The organic precipitate was washed with water containing a small amount of sodium thiosulfite, and then dried over magnesium sulfate. Fractional distillation of the precipitate produced 100 grams of perfluorooctyl bromide (97% yield) having a boiling point between 142°-144° C.

Provenance & Evidence