Luckily it was not my reaction, but this is the reason why fluorinated componds are pretty expensive. This black thing in the flask and the condenser is the reaction product, a gunk from a Swart’s reaction, what is a halogen exchange reaction done with Swart’s reagent (antimony trifluoride).

Usually Swart’s reagent changes every single chlorine atoms on an organic molecule to a fluorine, but the high reaction temperature often cause the decomposition of the reaction mixture and forms a black tar, just as in this case.

9:30 pm • 11 August 2014 • 49 notes • View comments