Fractional sublimation of various metal acetylacetonates

A simple fractional sublimator is described which possesses a continuous temperature gradient along its length. Samples are placed in the high temperature end of the tube and volatilized at 1-mm pressure. The gases are moved through the tube with air as a carrier. The metal chelates recrystallize on the walls of the tube in discrete and reproducible temperature zones. Characteristic recrystallization zones are reported for 21 metal acetylacetonates. The chelates can be grouped according to zone temperatures into 6 fairly distinct groups over the range 15 to 200°, which makes many separations possible. Separations of mixtures of Mg, Al and Be ; Ni, Fe and Be ; and, Cu and Fe were studied quantitatively. The separations achieved compared favorably with those reported by gas chromatography. The method offers real promise for the purification of a number of metals but appears especially good as a method for beryllium and certain platinum group metals.