Transition metal catalysts for diene polymerizations

Abstract

This invention is based upon the unexpected discovery that certain catalyst systems which are comprised of (A) a transition metal compound selected from the group consisting of iron (II) compounds, iron (III) compounds, cobalt (II) compounds, cobalt (III) compounds, and nickel (II) compounds; (B) a ligand selected from the group consisting of certain azopyridines and certain iminopyridines; and (C) methylalumoxane can be used to catalyze the polymerization of diene monomers, such as 1,3-butadiene and isoprene, into polymers, such as high cis-1,4-polybutadiene rubber. Some representative examples of azopyridines that can be utilized in the catalyst systems of this invention include 2-phenylazopyridine, 4-methyl-2-phenylazopyridine, and 2,6-diphenylazopyridine. The subject invention more specifically discloses a process for synthesizing a polybutadiene rubber which comprises polymerizing 1,3-butadiene at a temperature which is within the range of about 10° C. to about 100° C. in the presence of a catalyst system which is comprised of (A) a transition metal compound selected from the group consisting of iron (II) compounds, iron (III) compounds, cobalt (II) compounds, cobalt (III) compounds, and nickel (II) compounds; (B) an azopyridine ligand selected from the group consisting of 2-phenylazopyridine, 4-methyl-2-phenylazopyridine, and 2,6-diphenylazopyridine; and (C) methylalumoxane.

Dependencies are inferred from the claim text.