from first principles PP-I-1

PP-II-3Isobutylalumoxanes as Effective Activators of Dimethylated Zirconocenesin Propylene PolymerizationBravaya N.M. 1 , Faingol’d E.E. 1 , Babkina O.N. 1 , Saratovskikh S.L. 1 , Panin A.N. 1 ,Fushman E.A. 21 The Institute of Problems of Chemical Physics RAS, Chernogolovka, Russia2 N.N. Semenov Institute of Chemical Physics RAS, Moscow, Russianbravaya@cat.icp.ac.ruHere we present the results on synthesis of isobutylalumoxanes of different composition, theircharacterization by 1 H NMR, as well as their usage as activators of dimethylated isospecificzirconocenes rac-Me 2 Si(2-Me,4-PhInd) 2 ZrMe 2 (1) and rac-Et(2-MeInd) 2 ZrMe 2 (2) inpropylene polymerization.Isobutylalumoxanes have been synthesized by hydrolysis of triisobutylaluminum (TIBA) with (i)CuSO 4·5H 2 O at molar ratios of Al TIBA /H 2 O equal to 4, 2, 1.5, and 1; (ii) water suspension intoluene (2 mol/mol); (iii) diffusion of water vapour into toluene solution of TIBA (2 mol/mol).Method (i) is the most selective in synthesis of desirable alumoxane which mainly depends on theAl TIBA /H 2 O molar ratio. This method gives rise to associates of tetraisobutylalumoxane (TIBAO)with TIBA at Al TIBA /H 2 O=4 mol/mol (IBAO 1), TIBAO, most probably, as dimer atAl TIBA /H 2 O=2 mol/mol (IBAO 2), oligomeric (IBAO 3), and polymeric (IBAO 4) alumoxanes atfurther increased water proportion to TIBA. Methods (ii) and (iii) implemented at Al TIBA /H 2 O=2mol/mol gave rise to predominantly oligomeric alumoxanes associated with residual TIBA(IBAO 5 (ii), IBAO 6 (ii), and IBAO 7 (iii)) instead of TIBAO. Associates of oligomericalumoxanes with TIBA (IBAO 3, IBAO 5-7) demonstrate very high activating ability forzirconocenes 1, 2 at low Al/Zr molar ratios (50-300) in propylene polymerization with activities2-10 times higher than those with polymethylalumoxane (MAO) at Al/Zr=1000 under othersimilar conditions. Molecular weights of produced isotactic polypropylenes are also considerablyhigher, at M w /M n ~2. Activating ability of IBAO 1 is about one-third of MAO. TIBAO showed noactivating ability that does not meet to Galimberti et al. results [e.g. 1,2]. IBAO 4 also does notactivate 1, 2.So, simple, cheap, and effective way for activation of metallocene precatalysts instead ofMAO will be presented.The financial support from Ministry of Education and Science of RF (ContractN 02.740.11.0646) is acknowledged.References:[1] M. Galimberti et. al, Macromolecules, 1999, 32, 258.[2] E. Polo et. al, J. Mol. Catal. A: Chem., 2000, 160, 229.134