HF release from unexpected trimer
A drum contained about 30kg of 4-trifluoromethylaniline, last used about 1 year ago. It was found to be a solid. M.Pt. was listed as 38°C, so it assumed to have crystallized, the material was attempted to melt by placing in an air drier at 50°C, without success. It was taken from the drier, allowed to cool, and a sample taken. A few minutes later the drum ruptured and filled lab with white fumes. NMR on solid showed new product with several sets of aromatic protons, and was confirmed as being derived from three molecules of starter, this also liberating three moles of HF.
DSC shows an onset (in fresh) of 182°C. It appears that this reduces with age, and older (but liquid ) sample showed an onset of 140°C
If this material is found solid, then extreme care should be applied, and the material not heated until its stability has been checked beforehand.