Sulfur-containing and sulfur-nitrogen-containing catalysts...

Details Sulfur-containing and sulfur-nitrogen-containing catalysts... Sulfur-containing and sulfur-nitrogen-containing catalysts...

2002-03-08

2004-05-04

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...

C526S160000, C526S169100, C526S171000, C526S172000, C526S328000, C526S329000, C502S117000, C502S155000, C502S167000, C502S168000

Reexamination Certificate

active

06730757

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is directed towards late transition metal polymerization catalysts and their use in forming homopolymers from olefins or polar monomers and forming copolymers from olefins and polar monomers. In particular, the present invention relates to sulfur-containing and sulfur-nitrogen containing catalysts for the polymerization of olefins and polar monomers.
2. Description of the Related Art
Despite the technological and commercial success of Group 4 Ziegler-Natta and metallocene catalysts for polyolefins, the search for new catalysts and polymerization reactions continues. There is a drive to obtain even greater control over product properties and to extend the family of products to new monomer combinations. Catalysts that tolerate a variety of functional groups are of particular interest because they not only open up new product possibilities, but also allow for the use of cheaper, less pure monomer feeds. Late transition metal complexes are generally more tolerant of polar groups than those of early transition metals.
Late transition metal polyolefin catalysts have recently been reviewed (G. J. P. Britovsek, et al.,
Chem. Int. Ed
., 1999, 38, 428; S. D. Ittel, et al.,
Chem. Rev
., 2000, 100, 1169). To date, there are only a few examples of catalysts based on Group 11 metals (Cu, Au, Ag), which appeared only very recently in the literature. For example, Stibrany, et al. (PCT Pat. No. WO 99/30822) has disclosed LMX
1
X
2
complexes, wherein M is Cu, Ag or Au, and L is a bidentate ligand, such as bis-benzimidazole, with activating cocatalysts for the homopolymerization and copolymerization of certain olefin and polar monomers. Copolymers of ethylene and certain polar monomers (e.g., alkyl acrylates, vinyl ethers) have been claimed. In PCT Pat. No. WO 98/35996 and Japanese Pat. No. 99171915, polymerization methods using CuX
n
, LCuX
n
, or L(L′)CuX
n
catalysts with and without activating cocatalysts have been claimed. Specifically, these disclosures relate to Cu(II) amidinates, quinolates and acetoacetonates with MAO and other activators.
The rich coordination and redox chemistry of transition metal complexes with sulfur ligands provides a unique opportunity in the area of olefin oligomerization and polymerization. Metal complexes of sulfur-nitrogen chelating ligands have attracted considerable attention because of their interesting physicochemical properties and structural similarity to metalloprotein and metalloenzyme active sites. For example, it is known that histidine imidazole nitrogen atoms and methionine thioether sulfur atoms play key roles in the coordination of metals at the active sites of numerous metallo-biomolecules. Non-cyclic tetradentate chelating ligands with an NSSN-donor system are most utilized as models for such systems. An example for this type of ligand is the biomimetic N
2
S
2
ligand, 1,7-bis(5-methyl-4-imidazolyl)-2,6-dithiaheptane (bidhp), which forms complexes like M(bidhp)X
2
, where M is Mn, Ni or Cu, and X is Br, Cl or NCS. In these complexes, the metal ions are hexacoordinated by two anions and the tetradentate ligand. The structures have distorted octahedral coordination.
Despite this broad range of activity on sulfur-containing complexes, those being reported as oligomerization and polymerization catalysts are extremely rare. The only known sulfur-containing polymerization systems based on a group 11 metal (Cu) have been disclosed by Hiraike, et al. (Japanese Pat. No. 200108119) and by Nishimura, et al. (
Polym. Prepr
., 1999, 40, 470), and both systems are free radical processes. In Japanese Pat. No. 200108119 to Hiraike, et al., radical polymerization of vinylic monomers using Cu(II)-thioether dihalide catalysts is disclosed. However, whether this system can polymerize olefins, such as ethylene, and copolymerize olefin and polar monomers are not mentioned. Living radical polymerization of styrene with a Cu bis(dithiocarbamate)/AIBN system have been disclosed by Nishimura, et al. (
Polym. Prepr
., 1999, 40, 470). It is not disclosed whether the system can polymerize olefins, such as ethylene, or whether it can tolerate polar monomers. Obviously, these systems fall in the category of free radical-initiated polymerization; and it is not clear whether they can polymerize or copolymerize olefins, such as ethylene and polar monomers.
Consequently, there remains a need for polymerization catalysts capable of forming olefinic polymers and copolymers and that are effective polymerization catalysts in the presence of polar monomers. Further, it is even more desirable to have a catalyst that can copolymerize olefin and polar monomers, forming functional copolymers.
It has been demonstrated by Wang, et al. (U.S. Pat. No. 6,120,692) that, under certain conditions, sulfur-containing complexes can tolerate contaminants (catalyst poisons), like H
2
S, H
2
O, C
2
H
2
, CO and H
2
. Therefore, another potential advantage of sulfur-containing polymerization catalysts is their resistance to poisons, which may potentially allow for the use of impure feeds.
SUMMARY OF THE INVENTION
It is one object of this invention to teach a catalyst system made from the combination of a complex having a formula selected from LMX
1
X
2
or LML′ and an activating cocatalyst. In either formula, L is a chelating ligand containing sulfur donors; M is a transition metal selected from either copper, silver, gold, manganese, iron, cobalt, palladium or nickel; X
1
and X
2
are independently selected from either halides, hydride, triflate, acetate, borate, alkyl, alkoxyl, cycloalkyl, cycloalkoxyl, aryl, thiolate, carbon monoxide, cyanate or olefins; and L′ is a bidentate ligand selected from either dithiolene, dithiolate, diphosphine, bisimine, bispyridine, phenanthroline, oxolate, catecholate, thiolatoamide, thiolatoimine or thiolatophosphine. It is most preferred that L′ is a dithiolene having the formula S
2
C
2
(CN)
2
.
In one embodiment, L has the formula R
n
ZCS
2
, wherein R is either hydrogen, alkyl, substituted alkyl, alkenyl, substituted alkenyl, aryl, substituted aryl, alkoxyl, substituted alkoxyl, cycloalkyl, substituted cycloalkyl, amino or substituted amino groups; n=1 or 2; and Z is nitrogen or oxygen. If Z is oxygen, then n=1. Alternatively, if Z is nitrogen, then n=2; in this case, the preferred ligand L is
i
Bu
2
NCS
2
.
In another embodiment, L is a bisimidazolyl dithioalkane ligand having the structure:
In the structure shown above, R
1
, R
2
, R
3
and R
4
are independently selected from either hydrogen, alkyl, substituted alkyl, alkenyl, substituted alkenyl, aryl, substituted aryl, alkoxyl, substituted alkoxyl, cycloalkyl, substituted cycloalkyl, amino or substituted amino groups; and n=1 to 6. It is most preferred that L be either 1,7-bis(5-methyl-4-imidazolyl)-2,6-dithioheptane (bidhp) or 1,6-bis(5-methyl-4-imidazolyl)-2,5-dithiohexane (bidhx).
In a preferred embodiment, when X
1
=X
2
, each of X
1
and X
2
can be either bromine or chlorine.
Among the cocatalysts that may be used in the instant catalyst system, the preferred ones are alkylaluminoxanes, aluminum alkyls, aluminum halides, alkyl aluminum halides, Lewis acids other than any of the foregoing, alkylating agents and mixtures thereof. The most preferred cocatalyst is methylaluminoxane.
A further object of the present invention is to demonstrate that the sulfur/sulfur-nitrogen catalyst system taught herein may be successfully utilized to polymerize olefinic monomers under polymerization conditions. Preferred olefinic monomers are: acyclic aliphatic olefins; olefins having a hydrocarbyl polar functionality; and mixtures of at least one olefin having a hydrocarbyl polar functionality and at least one acyclic aliphatic olefin. For example, in addition to ethylene and acrylates, other monomers such as vinyl acetate, a-olefins, styrene and butadiene can also be polymerized.
It is believed that, under certain conditions, these systems can tolerate contaminants (i.e., are poison resis

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