A GC Experiment for an Inorganic Chemistry Course Bromination of Metal Acetylacetonates T. J. Cardwell and T. H. Lorman La Trobe University, Bundoora. Victoria. 3083, Australia T h e electrophilic substitution of metal tris-acetylacetonates has been well known since the early 1960's due mainlyto the efforts of Collman and coworkers (1,2 and refs. therein). Some of these reactions are relatively easy to perform and are accented as reliahle standard nrocedures (3. . . 4 ) . Thev have alsb proven to he successful iahoratory experiments, the nitration reactions having received more attention than others ( 5 , 6 ) .In general, the above procedures use stoichiometric quantities of the electrophilic reagent which are claimed to lead to complete replacement of the hydrogen atoms on the central (or r) carbon of the chelate rings. If limited amounts of reagent(s) for generation of the ele&ophile are used, stepwise formation of mono-, hi-, and trisubstituted chelates takes place and a t certain stages of the reaction, all three substituted derivatives and unreacted metal acetylacetonate may exist simultaneously in solution. Separation of the mixture of chelates can be achieved by classical chromatographic procedures ( I ) , however, we wish to describe here a modern instrumental procedure suitable for an undergraduate course. The volatility and associated gas chromatographic elution of tris(2,4-pentanediono)chromium(III), Cr(acac)s, is well established (7).We have recently reported that the partially and fullv brominated acetylacetonates of chromium can be succrdully eluted at temperatures
