Selective isomerization and linear dimerization of olefins using cobalt catalysts

#This invention is in the field of olefin catalysis. Various olefins are produced by a process employing a tridentate cobalt catalyst.

#Alpha-olefins, especially those containing about 6 to about 20 carbon atoms, are important items of commerce, with about 1.5 million tons reportedly being produced in 1992. Alpha-olefins are also used as intermediates in the manufacture of detergents, as monomers (especially in linear low density polyethylene), and as intermediates for many other types of products. As a consequence, improved methods of making these compounds are of value.

#The dimerization of olefins by transition metal complexes represents an important class of industrially relevant chemistry.1 For example, ethylene dimerization to 1-butene can provide a source of comonomer in the production of polyethylene;2 and olefins such as propylene and butene are dimerized to give C6-C8 materials that serve as feedstocks for gasoline blending or alcohol production.

#FIG. 1 illustrates the propylene dimer content of an oligomerization product made in accordance with the present invention.

#FIG. 2 illustrates the propylene trimer content of an oligomerization product made in accordance with the present invention.

#The invention provides ligands and cobalt complexes useful in the production of alpha-olefins via catalysis, and additionally the catalytic dimerization and isomerization of alpha-olefins. The ligands provided are tridentate ligands (or “ligands”), such as that shown complexed with Cobalt in Formula I, which may be identified by the three nitrogen atoms present in the molecule. When producing a metal complex from a tridentate ligand, the ligand may be reacted with the salt of a transition metal, such as Cobalt. The reaction is a coordination reaction between the ligand and the metal salt, which forms a metallic complex such as shown in Formula I. The cobalt complexes employed herein were shown to possess a higher degree of selectivity for producing linear dimers than their iron analogs 4, and are also highly selective for isomerizing the starting material.

#The cobalt complex of formula I may be employed in the production of alpha-olefins: wherein: each X is an anion; n is 1, 2 or 3 so that the total number of negative charges on said anion or anions is equal to the oxidation state of a Co atom present in Formula I; R1, R2 and R3 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or an inert functional group; R4 and R5 are each independently hydrogen, hydrocarbyl, an inert functional group or substituted hydrocarbyl; R9, R10, R11, R14, R15 and R16 are each independently hydrogen, hydrocarbyl, an inert functional group or substituted hydrocarbyl; R8 and R17 are each hydrogen, fluorine, an inert functional group, a primary carbon group, a secondary carbon group or a tertiary carbon group; and provided that: when R8 is a primary carbon group none, one or two of R12, R13 and R17 are primary carbon groups, secondary carbon groups, or inert functional groups, and the remainder of R12, R13, and R17 are hydrogen or fluorine; when R8 is a secondary carbon group, none or one or two of R12, R13 and R17 is a primary carbon group or a secondary carbon group or an inert functional group and the remainder of R12, R13, and R17 are hydrogen or fluorine; when R8 is a tertiary carbon group all of R12, R13, and R17 are hydrogen or fluorine; and any two of R8, R9, R10, R11, R12, R13, R14, R15, R16 and R17 vicinal to one another, taken together may form a ring.

#The following terms are provided: