Nickel-catalysed reactions of olefins with =C=N- double bond systems

Abstract

The reactions of Schiffs' bases, hydrazones, 2,3diazabutadienes and 2-azabutadienes with butadiene or activated monoenes in the presence of nickel catalysts lead to new classes of compounds, which are isolated as mixtures of isomers. The ratio of the isomer distribution can be controlled inside wide limits by variation of the nickel ligands and the reaction parameters. A comparison with the nickel-catalysed oligomerisation of butadiene or the cooligomerisation of butadiene with mono-olef ins shows that the reaction products in the two cases are not analogous. INTRODUCTION In the last twenty years the chemistry of nickel-catalysed reactions of olefins and alkynes has undergone a vigorous upsurge. This interest is connected above all with the discovery of bis(cycloocta-l,5-diene) nickel(O) in the year 1960 (1). In the following years the Mulheirn group particularly occupied itself with possible new syntheses of cyclic and linear compounds from simple olefins and acetylenes. 2 ' L) + L) + LJ — _ ___ , — Ii + Fig. 1 Characteristic nickel-catalysed reactions In spite of the multiplicity of reactions catalysed homogeneously by nickel and their simplicity and selectivity only very few have awakened the interest of the chemical industry. In addition to the trimerisation of butadiene to 1,5,9-cyclododecatriene (2), the starting material for 'Nylon 12 and dodecandicarboxylic acid, they are: a) The addition of HCN to butadiene giving adiponitrile, the starting material for hexamethylenediamine (3). b) The cooligomerisation of ethylene and butadiene to 1,4hexadiene, an important comonomer for the polymerisation of ethylene arxpropylene with an unsymmetrical diene (4).