2- Pentanone, 4-imino- derivative

This procedure, a variant of method 3, is also potentially a very useful method. An advantage is that the pH of the reaction mixture is controlled by the amount of amine present. In theory, the use of this method would permit the preparation of metal derivatives of a wide variety of /8-keto imines and obviate the need for preparation and isolation of the individual ligands. In practice, it appears that of the possible compounds the most stable metal chelate compound is formed. This may not always be the desired compound. Thus, even in the presence of copper-(II) ion, the condensation of 4-imino-2-pentanone and trimethylenediamine was not successful, the product isolated being bis(4-imino-2-pentanonato)copper(II). ... 

With this method, highly basic conditions no longer exist, an amine-exchange reaction does not occur, and contamination with anions is avoided. An incidental asset is that the two metal derivatives involved usually have different colors, and the extent of reaction can be judged visually. An obvious disadvantage is that the equilibrium may be unfavorable, as was described for the attempted reaction of bis(4-imino-2-pentanonato)copper(II) and 4,4 -tri-methylenedinitrilo)di-2-pentanone [bis(acetylacetone)tri-methylenediimine]. For successful isolation of a pure product, the metal derivative must be the most insoluble species present often, this condition is met. 

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