Transition metal catalysts for olefin polymerization

Details Transition metal catalysts for olefin polymerization Transition metal catalysts for olefin polymerization

2001-09-06

2004-02-17

Rabago, Roberto (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S141000, C526S147000, C526S161000, C526S169100, C526S172000, C502S103000, C502S117000, C502S167000

Reexamination Certificate

active

06693154

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to catalyst systems useful for polymerizing olefins. In particular, the invention relates to transition metal catalysts that are easy to make and have exceptional activities.
BACKGROUND OF THE INVENTION
“Single-site” and metallocene catalysts continue to lure polyolefin producers because of the unique performance attributes of the catalysts and polymers made from them. Since the late 1990s, olefin polymerization catalysts that incorporate late transition metals (especially iron, nickel, or cobalt) and bulky &agr;-diimine ligands (or “bis(imines)”) have been extensively studied and described by scientists at DuPont, the University of North Carolina at Chapel Hill, Imperial College of London University, and BP Chemicals. Late transition metal catalysts are of interest because they can be highly active and, unlike traditional early transition metal-based metallocenes, they can tolerate and incorporate polar comonomers. (For a few examples, see
Chem. & Eng. News,
Apr. 13, 1998, p. 11;
Chemtech,
Jul. 1999, p. 24;
Chem. Commun.
(1998) 849;
J. Am. Chem. Soc.
120 (1998) 4049;
Chem. Rev.
100 (2000) 1169; PCT Int. Publ. WO 99/12981; and U.S. Pat. Nos. 5,866,663 and 5,955,555.)
The bis(imine) complexes described above, when used with an activator, efficiently polymerize olefins, but more active catalysts are desirable because using less catalyst to make the same amount of polyolefin reduces cost. Moreover, the variety of polymers available from the bis(imine) complexes explored so far is somewhat limited.
In 1977, Walter Siegl reported a remarkably simple synthetic route to 1,3-bis(heteroarylimino)isoindolines from phthalonitriles using alkaline earth salts and transition metals to facilitate the reaction via a template effect (
J. Org. Chem.
(1977) 42 1872). The reaction of phthalonitrile with two equivalents of 2-aminopyridine is illustrative:
Soon after Siegl's report, scientists at DuPont and Sumitomo Chemical used complexes that incorporate a Group 8 metal and one or more 1,3-bis(heteroarylimino)isoindoline ligands to catalyze the decomposition of cyclohexanehydroperoxide to cyclohexanol and cyclohexanone, which are key intermediates for making adipic acid. See, for example, U.S. Pat. Nos. 4,499,305, 4,482,746, and 4,568,769. Ruthenium complexes of 1,3-bis(2-pyridylimino)isoindoline are known to oxidize alcohols (see
Inorg. Chem.
23 (1984) 65).
Despite their known utility for hydroperoxide decompositions, transition metal complexes that incorporate 1,3-bis(heteroarylimino)-isoindoline ligands have not been previously explored as catalysts for olefin polymerization reactions. Moreover, transition metal complexes from 1,3-bis(arylimino)isoindolines, i.e., condensation products of phthalimide and two equivalents of an aniline, have apparently not been used at all to catalyze organic reactions.
SUMMARY OF THE INVENTION
The invention is a catalyst system useful for polymerizing olefins. The catalyst system comprises an activator and an organometallic complex. The complex comprises a Group 3-10 transition or lanthanide metal and a 1,3-bis(arylimino)isoindoline or 1,3-bis(heteroarylimino)-isoindoline ligand.
We surprisingly found that catalyst systems of the invention are valuable for polymerizing olefins. In particular, the late transition metal catalysts have activities that rival or even exceed, sometimes by a wide margin, those of late transition metal bis(imines). The resulting polyolefins typically have high molecular weights, broad molecular weight distributions, and a high degree of crystallinity, attributes that make them exceptionally useful for film applications.
DETAILED DESCRIPTION OF THE INVENTION
Catalyst systems of the invention are useful for polymerizing olefins. They comprise an organometallic complex and an activator. The activator interacts with the complex to produce a catalytically active species. The complex includes a Group 3-10 transition or lanthanide metal and an isoindoline ligand.
Preferably, the complex includes a Group 8-10 transition metal, i.e., iron, cobalt, nickel, copper, zinc, and elements directly below them on the Periodic Table. More preferably, the complex includes a Group 8 metal such as iron, cobalt, or nickel. The oxidation number of the Group
8-10
metal is preferably 1+ or 2+, with 2+ being most preferred.
In addition to the Group 3-10 transition or lanthanide metal and isoindoline ligand, the organometallic complex normally includes additional neutral and/or anionic ligands, which may be organic or inorganic. Examples are halides, alkyls, alkoxys, aryloxys, alkylamidos, acetate, acetylacetonate, citrate, nitrate, sulfate, carbonate, tetrafluoroborate, thiocyanate, or the like. The additional ligands of the complex usually derive from the Group 3-10 compound that is used as a source of the metal. In general, any convenient source of the Group 3-10 metal can be used, but transition or lanthanide metal salts are preferred. Particularly preferred are Group 8-10 transition metal salts. Examples include iron(II) chloride, iron(III) chloride, iron(II) acetate, iron(II) sulfate heptahydrate, cobalt(II) chloride, cobalt(II) thiocyanate, cobalt(II) tetrafluoroborate hexahydrate, nickel(II) bromide, nickel(II) acetate, nickel(II) carbonate hydroxide tetrahydrate, nickel(II) acetylacetonate, copper(II) nitrate, zinc acetate, zinc citrate dihydrate, and the like.
The organometallic complex includes an isoindoline ligand. Structurally, isoindolines are condensation products of phthalimides with two equivalents of an aniline or an amino-substituted heteroarene (e.g., 2-aminopyridine or 2-aminothiazole). Isoindolines can be prepared by the condensation reaction suggested above, but they can also be made by other well-established synthetic methods.
In particular, useful isoindoline ligands are 1,3-bis(arylimino)- and 1,3-bis(heteroarylimino)isoindolines. The isoindolines preferably have the structure:
in which A is an aryl or a heteroaryl group, which may or may not be substituted with non-interfering groups (halide, nitro, alkyl, etc.). When A is aryl, it preferably a phenyl or alkyl-substituted phenyl group, such as 4-methylphenyl or 2,4,6-trimethylphenyl (2-mesityl). When A is heteroaryl, it is preferably 2-pyridyl, 2-pyrimidinyl, 4-pyrimidinyl, 2-pyrazinyl, 2-imidazolyl, 2-thiazolyl, or 2-oxazolyl. The aryl and heteroaryl groups can be fused to other rings, as in a 2-naphthyl, 2-benzothiazolyl or 2-benzimidazolyl group. The benzene ring of the isoindoline can also be substituted with groups that do not interfere with preparation of the isoindoline, preparation of the organometallic complex, or olefin polymerization. For example, the benzene ring can be substituted with halide, nitro, alkoxy, thioalkyl, alkyl, or aryl groups, or the like. A few exemplary isoindolines appear below:
In one approach to making 1,3-bis(arylimino)- or 1,3-bis(heteroarylimino)isoindoline ligands, a phthalimide reacts with two equivalents of an aniline or an amino-substituted heteroarene, optionally in the presence of a condensation catalyst (e.g., formic acid, acetic acid, p-toluenesulfonic acid, or the like). Often, the condensation involves little more than stirring the reactants at room temperature until the isoindoline compound precipitates from the reaction mixture. The first part of Example 2 below is illustrative.
In another approach to making the isoindoline ligands, the aniline or an amino-substituted heteroarene is reacted with a phthalonitrile (a 1,2-dicyanobenzene), preferably in the presence of an alkaline earth salt and an organic solvent, to produce the isoindoline. The reaction is preferably performed at the reflux temperature of the organic solvent, and the isoindoline can be isolated and recrystallized if desired. See, for example, the first part of Example 9 below. More examples of this procedure appear in
J. Org. Chem.
42 (1977) 1872.
The isoindoline ligand, once prepared, can be reacted with a Group 3-10 transition metal source, usually a salt, to give an organometallic compl

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