ALUMINOXANE SYNTHESIS EMPLOYING REDUCED AMOUNT OF TRIALKYLALUMINUM COMPOUND

Abstract: A catalytically active aluminoxane can be synthesized from a precursor formed by the combination of at least one trialkylaluminum compound, such as trimethylaluminum, and at least one organoaluminum compound containing a carbon-oxygen bond therein, such as a compound of the formula: (CH3)2AIOR', wherein R' is a linear or branched C1-C10 alkyl group, such as a tert-butyl group. The trialkylaluminum compound may be used as such or after reaction with at least one organic compound containing a carbon-oxygen bond, such as carbon dioxide. The aluminoxane may be formed by thermolysis, a combination of hydrolysis and thermolysis or hydrolysis.

Description: ALUMINOXANE SYNTHESIS EMPLOYING REDUCED AMOUNT OF TRIALKYLALUMINUM COMPOUND It is well known in the art to synthesize aluminoxane compositions, which have utility as co-catalyst components, utilizing at least one trialkylaluminum compound as a reagent. It is further well known to synthesize these aluminoxane compositions by reacting the trialkylaluminum reagent(s) with a water source. More recently, as described in U.S. Patent No. 5,831 ,109 or in U.S. Patent No. 5,777,143, methods using a compound containing a carbon- oxygen bond, such as carbon dioxide, to form a precursor composition that can be converted to the desired aluminoxane product have been disclosed. These methods can also be combined. For instance, a precursor formed using a carbon-oxygen bond containing reagent could be partially hydroiyzed, and then finally converted to an aluminoxane composition. Alternatively, hydrolysis could be conducted prior to reaction with a carbon-oxygen bond containing reagent. It is also known in the art to synthesize aluminoxane compositions, which have utility as co-catalyst components, by utilizing at least one trialkylaluminum compound as a reagent which is treated with an organic compound containing a carbon-oxygen double bond, such as carbon dioxide, and water, as described in U.S. Patent No. 5,728,855. In the foregoing preparative schemes, the aluminum in the aluminoxane is substantially derived from the trialkylaluminum compound, which is commonly trimethylaluminum. This trialkylaluminum reagent is generally the most expensive component in the reagent system. If all or a portion of the trialkylaluminum compound could be replaced as the source for the aluminum in the final product, the manufacturing process could be made correspondingly less expensive. This invention is directed to a less costly aluminoxane manufacturing procedure in which all or a portion of the trialkylaluminum compound is replaced as the source for the aluminum in the final aluminoxane product by a less costly aluminum-containing reagent. The present invention is a process for the synthesis of an aluminoxane which comprises conversion of a precursor formed by the combination of at least one trialkylaluminum compound and, as the generally less costly reagent, at least one organoaluminum compound containing a carbon-oxygen bond therein. The trialkylaluminum compound may be used as such or after reaction with at least one organic compound containing a carbon-oxygen bond, such as carbon dioxide. Conversion of the precursor to an aluminoxane can comprise exclusively nonhydrolytic processes, hydrolysis with water, or a combination of hydrolysis and nonhydrolytic processes. The present invention relies upon the replacement of all or a portion of the trialkylaluminum reagent conventionally used as the aluminum source in synthesis of a cocatalytically active aluminoxane (regardless of process). The cocatalytically active aluminoxane may be useful in a number of processes, including but not limited to Ziegler-Natta olefin polymerization, metallocene catalyzed olefin polymerization, polymerization using single-site catalysts, or other polymerization processes using molecular catalysts that are activated by aluminoxanes. The replacement is made by an organoaluminum compound containing a carbon-oxygen bond therein and may be illustrated by the following set of reactions (wherein R and R" independently represent a linear or branched 0,-0, 0 alkyl group, preferably a linear C 1 -C 4 alkyl group, most preferably a methyl group and R' represents a linear or branched C,-C 10 alkyl group, preferably a linear or branched C 4 -C 8 alkyl group, more preferably a tertiary C 4 - C 8 alkyl group, most preferably a tert-butyl group): 0.8 R 2 AI-OR' + 0.2 R 3 AI → R 2.2 AI(OR') 08 The foregoing reaction can be carried out at room temperature in a suitable hydrocarbon solvent. Examples of suitable solvents include, but are not limited to, aromatic solvents such as benzene, toluene, xylene and cumene, or linear or branched aliphatic solvents such as butane, pentane, isopentane, hexane, heptane, etc. Many compounds other than R 2 AI-OR' can also be employed, if desired. For instance: 0.4 RAI(OR') 2 + 0.6 R 3 AI → R 2.2 AI(OR') 08 0.4 R 2 AI(0 2 CR") + 0.6 R 3 AI → R 1 8 AIO 04 (OCR"R 2 ) 04 Workers skilled in the art could easily envision additional examples. The R 2 AIOR', preferably Me 2 AIOR' compound, or similar effective compounds, may be prepared by any number of means known to persons skilled in the art. As a trivial example, it could be formed by reaction of dimethylaiuminum chloride with an alkali metal alkoxide, such as sodium t-butoxide in accordance with the formula: NaOt-Bu + Me 2 AICI → NaCli + Me 2 AIOt-Bu Then, the product of the foregoing reaction where part or all of the trialkylaluminum reagent is replaced by an organoaluminum compound containing a carbon-oxygen bond therein can be converted to an aluminoxane product. The conversion could be simple hydrolysis as described in U.S. Patent No. 5,728,855, or it could be a nonhydrolytic process as described, for instance, in U.S. Patent No. 5,831 ,109 or in U.S. Patent No. 5,777,143. The conversion could also be a combination of the foregoing, such as hydrolysis followed by nonhydrolytic conversion, e.g., thermolysis, to aluminoxane. One example of nonhydrolytic conversion of that precursor compositioμJnto an aluminoxane product, as further described in U.S. Patent No. 5,831 ,109 or in U.S. Patent No. 5,777,143, would be: R 2.2 AI(OR') 08 → ^ .4 ^(0) 0.8 + Organic By-Products It is well within the skill in the art to vary the stoichiometries depicted above, which are presented for illustrative purposes only, to employ a combination of water and thermal conversion techniques with the precursor which is formed, and to employ other C-0 containing compounds (as further described in U.S. Patent No. 5,831 ,109 or in U.S. Patent No. 5,777,143). For example, in regard to the general types of reaction which can be used, the following additional reaction exemplifies one alternative: 0.4 R 2 AI-OR' + 0.6 R 3 AI → R 2.6 AI(OR') 4 R 26 AI(OR') 4 + 0.4 H 2 0 - R, 4 AI(O) 08 + Organic By-Products The conversion of the previously described precursor, where some or all of the conventionally used trialkylaluminum compound is replaced, into the desired aluminoxane product takes place more quickly (e.g., about fourteen hours versus about twenty hours) as compared to the thermolysis reaction described in U.S. Patent No. 5,831 ,109 or in U.S. Patent No. 5,777,143 where only a trialkylaluminum reagent is employed as the initial reagent to supply the aluminum values to the ultimate aluminoxane product. Also, the aluminoxane produced by the process of the present invention has a proton NMR spectrum which is characteristic of conventional aluminoxane as well as the non- hydrolytically treated aluminoxane obtained from the process described and claimed in U.S. Patent No. 5,831 ,109 or in U.S. Patent No. 5,777,143. The aluminoxane formed by the process of the present invention can be used in the same applications previously taught for conventional aluminoxane compositions. The present invention is further illustrated by the Examples that follow. Example 1 Dimethylaluminum tert-butoxide (DMAL-TB) (8.874 g, 44.4 mmoles of Al); trimethylaluminum (TMAL) (0.801 g, 11.1 mmoles of Al); polymethylaluminoxane (PMAO) (2.350 g, 11.4 mmoles of Al), which is synthesized by the reaction described and claimed in U.S. Patent No. 5,831 ,109; tri-n-octylaluminum (TNOAL) (0.410 g, 1.12 mmoles of Al); and toluene (2.882 g) were combined in a three-neck, 250 ml round bottom. This was thermolyzed at a bulk temperature of 105°C for thirteen and one-half hours. The progress of the reaction was followed by proton nuclear magnetic resonance spectroscopy ( 1 H NMR). The result was a clear, viscous fluid that was active as a co-catalyst in ethylene polymerization. Example 2 In this Example, DMAL-TB (15.338 g, 76.8 mmoles of Al), TMAL (1.385 g, 19.2 mmoles of Al), C0 2 -treated TMAL (8.997, 38.4 mmoles of Al), TNOAL (0.700 g, 1.92 mmoles of Al) and toluene (4.585 g) were placed in a three-neck, 250 ml round bottom flask. This was thermolyzed at a bulk temperature of 105 C C. The product was a clear, viscous liquid that functioned as an active co-catalyst in ethylene polymerization.

Claims: CLAIMS 1. A process for the synthesis of an aluminoxane which comprises conversion of a precursor, formed by the combination of at least one trialkylaluminum compound and at least one organoaluminum compound containing a carbon-oxygen bond therein, to form a catalytically active aluminoxane. 2. A process for the synthesis of an aluminoxane which comprises conversion of a precursor, formed by the combination of a) the product from reaction of at least one trialkylaluminum compound with at least one organic compound containing a carbon-oxygen bond and b) at least one organoaluminum compound containing a carbon-oxygen bond therein, to form a catalytically active aluminoxane. 3. A process according to claim 1 or 2, characterized in that the conversion to the catalytically active aluminoxane is accomplished by thermolysis, a combination of hydrolysis and thermolysis or hydrolysis. 4. A process according to any one of claims 1-3, characterized in that the trialkylaluminum compound is trimethylaluminum. 5. A process according to any one of claims 1 -4, characterized in that the organoaluminum compound containing a carbon-oxygen bond is of the formula Me 2 AIOR', wherein R' is a linear or branched C,-C 10 alkyl group. 6. A process according to claim 5, characterized in that R' is a tertiary C 4 -C 8 alkyl group. 7. A process according to claim 6, characterized in that R' is a tert-butyl group. 8. A process according to any one of claims 2-7, characterized in that the organic compound containing a carbon-oxygen bond is carbon dioxide. 9. A catalyst for the polymerization of olefins, comprising the product formed by the process according to any one of claims 1-8, optionally on a support.

Inventors: BAND ELLIOT I, JONES PAUL D, MALPASS DENNIS B, SIMMS HUDOCK BARBARA L, SMITH GREGORY M, BAND, ELLIOT, I., JONES, PAUL, D., MALPASS, DENNIS, B., SIMMS HUDOCK, BARBARA, L., SMITH, GREGORY, M.
Applicants: AKZO NOBEL NV, AKZO NOBEL N.V.
Application year: 1999
Main classification: C07F5
IPC codes: C07F5, C08F4, C08F10, C08G79