Iron-based catalyst for producing oligomers of conjugated...

Details Iron-based catalyst for producing oligomers of conjugated... Iron-based catalyst for producing oligomers of conjugated...

1999-11-05

2001-08-28

Wood, Elizabeth D. (Department: 1755)

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

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C502S152000, C502S153000, C502S154000, C502S155000, C502S162000, C502S171000, C526S136000, C526S160000, C526S171000, C526S335000

Reexamination Certificate

active

06281305

ABSTRACT:

FIELD OF THE INVENTION
The present invention generally relates to a catalyst composition for use in oligomerizing conjugated dienes into oligomers. More particularly, the present invention is directed toward an iron-based catalyst composition, and specifically toward one that is formed by combining an iron-containing compound, a hydrogen phosphite, a halogen-containing compound, and an organoaluminum compound.
BACKGROUND OF THE INVENTION
Conjugated dienes such as 1,3-butadiene and isoprene undergo a variety of catalytic oligomerization reactions to give cyclic or acyclic oligomers. These oligomers are valuable feedstocks in the industrial production of fine organic chemicals. For example, the dimers and trimers are utilized as intermediates for synthesizing flame retardants, terpenoid and sesquiterpenoid compounds of biological interest, and fragrances.
Various coordination catalyst systems based on nickel, palladium, cobalt, titanium, chromium, and iron have been reported in the prior art for catalyzing the oligomerization of conjugated dienes (see, e.g., R. Baker, in
Chemical Reviews
1973, Volume 73, Page 487). The majority of these catalyst systems, however, have no practical utility because they have low activity and poor selectivity. The resulting oligomerization product is often a complicated mixture of cyclic and acyclic dimers, trimers, tetramers, and higher oligomers. Furthermore, some oligomerization catalyst systems also generate a certain amount of polymer in the oligomerization product mixtures.
Several iron-based coordination catalyst systems are known in the prior art for the oligomerization of conjugated dienes. The
Bulletin of Chemical Society of Japan
1965, Volume 38, Page 1243 discloses a process for the oligomerization of 1,3-butadiene by using a catalyst system comprising iron(III) acetylacetonate and triethylaluminum. The
Bulletin of Chemical Society of Japan
1966, Volume 39, Page 1357 discloses a process for the oligomerization of 1,3-butadiene by using a catalyst system comprising iron(III) acetylacetonate, triethylaluminum, and triphenylphosphine. And, the
Journal of Organic Chemistry
1965, Volume 30, Page 1661 discloses a process for oligomerizing 1,3-butadiene in the presence of a catalyst system comprising iron(III) chloride, triphenylphosphine, and triethylaluminum. All of these iron-based catalyst systems, however, have very low activity and poor selectivity, and the resulting oligomerization product is a mixture of cyclic and acyclic dimers, trimers, and higher oligomers, as well as polymer. Therefore, these iron-based catalyst systems have no industrial utility.
Because the oligomers of conjugated dienes are useful and the catalyst systems known heretofore in the art have many shortcomings, it would be advantageous to develop a new and significantly improved catalyst system that has high activity and selectivity for oligomerizing conjugated dienes into oligomers.
SUMMARY OF THE INVENTION
In general the present invention provides a catalyst composition that is the combination of or the reaction product of ingredients comprising an iron-containing compound, a hydrogen phosphite, a halogen-containing compound, and an organoaluminum compound.
The present invention also provides a catalyst composition formed by a process comprising the step of combining an iron-containing compound, a hydrogen phosphite, a halogen-containing compound, and an organoaluminum compound.
The present invention also includes a process for forming conjugated diene oligomers comprising the step of oligomerizing conjugated diene monomers in the presence of a catalytically effective amount of a catalyst composition formed by combining an iron-containing compound, a hydrogen phosphite, a halogen-containing compound, and an organoaluminum compound.
Advantageously, the catalyst composition of the present invention has very high activity, which allows conjugated diene oligomers to be produced in very high yields with low catalyst levels after relatively short oligomerization times. In addition, since the catalyst composition of this invention is highly active, even at low temperatures, the oligomerization of conjugated dienes may be carried out under very mild temperature conditions, thereby avoiding thermal polymerization and/or cracking or other deleterious effects on the oligomerization product. Further, the catalyst composition of the present invention is iron-based, and iron compounds are generally stable, non-toxic, inexpensive and readily available. Furthermore, the catalyst composition of the present invention is very selective. For instance, by utilizing the catalyst composition and the process of the present invention, 1,3-butadiene can be converted substantially quantitatively to acyclic dimers substantially without the production of any other products.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
It has now been found that conjugated dienes can be efficiently oligomerized by using an iron-based catalyst composition. The catalyst composition of this invention is formed by combining (a) an iron-containing compound, (b) a hydrogen phosphite, (c) a halogen-containing compound, and (d) an organoaluminum compound. In addition to the iron-containing compound, the hydrogen phosphite, the halogen-containing compound, and the organoaluminum compound, other organometallic compounds or Lewis bases that are known in the art can be added, if desired.
Various iron-containing compounds or mixtures thereof can be utilized as ingredient (a) of the catalyst composition of this invention. It is generally advantageous to employ iron-containing compounds that are soluble in a hydrocarbon solvent such as aromatic hydrocarbons, aliphatic hydrocarbons, or cycloaliphatic hydrocarbons. Hydrocarbon-insoluble iron-containing compounds, however, can be suspended in the oligomerization medium to form the catalytically active species, and are therefore also useful.
The iron atom in the iron-containing compounds can be in various oxidation states including, but not limited to, the 0, +2, +3, and +4 oxidation states. It is preferable to use divalent iron compounds -also called ferrous compounds—wherein the iron is in the +2 oxidation state, and trivalent iron compounds—also called ferric compounds—wherein the iron is in the +3 oxidation state. Suitable types of iron-containing compounds that can be utilized in the catalyst composition of this invention include, but are not limited to, iron carboxylates, iron carbamates, iron dithiocarbamates, iron xanthates, iron &bgr;-diketonates, iron alkoxides or aryloxides, iron halides, iron pseudo-halides, iron oxyhalides, and organoiron compounds.
Some specific examples of suitable iron carboxylates include iron(II) formate, iron(III) formate, iron(II) acetate, iron(III) acetate, iron(II) acrylate, iron (III) acrylate, iron (II) methacrylate, iron(III) methacrylate, iron (II) valerate, iron(III) valerate, iron(II) gluconate, iron(III) gluconate, iron(II) citrate, iron(III) citrate, iron(II) fumarate, iron(III) fumarate, iron(II) lactate, iron(III) lactate, iron(II) maleate, iron(III) maleate, iron(II) oxalate, iron(III) oxalate, iron(II) 2-ethylhexanoate, iron(III) 2-ethylhexanoate, iron(II) neodecanoate, iron(III) neodecanoate, iron(II) naphthenate, iron(III) naphthenate, iron(II) stearate, iron(III) stearate, iron(II) oleate, iron(III) oleate, iron(II) benzoate, iron(III) benzoate, iron(II) picolinate, and iron(III) picolinate.
Some specific examples of suitable iron carbamates include iron(II) dimethylcarbamate, iron(III) dimethylcarbamate, iron(II) dietlylcarbamate, iron(III) diethylcarbamate, iron(II) duisopropylcarbamate, iron(II) diisopropylcarbamate, iron (II) dibutylcarbamate, iron (III) dibutylcarbamate, iron(II) dibenzylcarbamate, and iron (III) dibenzylcarbamate.
Some specific examples of suitable iron dithiocarbamates include iron(II) dimethyldithiocarbamate, iron(III) dimethyldithiocarbamate, iron(II) diethyldithiocarbamate, iron(III) diethyldithiocarbamate, iron(II) diisopropyldithiocarbamate, iron (III) dliisop

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