Off-campus UMass Amherst users: To download dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.

Non-UMass Amherst users, please click the view more button below to purchase a copy of this dissertation from Proquest.

(Some titles may also be available free of charge in our Open Access Dissertation Collection, so please check there first.)

Design, synthesis and evaluation of new Ziegler -Natta catalyst components

Barrie Rhodes, University of Massachusetts - Amherst

Abstract

The compound (η5-pentamethylcyclopentadienyl)tin tetrakis(pentafluorophenyl)borate (2) has been synthesized. This cation proved to be an effective Ziegler/Natta α-olefin cocatalyst. Activities for ethylene polymerizations using dimethylzirconocene and 2 were 7.3 × 105 g PE/mol 2·[C2H4]·h at 20°C and 1.2 × 106 g PE/mol 2·[C2H 4]·h at 70°C. This system was also effective for the polymerization of propylene. Activities using rac-ethylenebis(indenyl)dimethylzirconium with the tin cation were 3.0 × 105 g PP/mol 2·[C 3H6]·h at 20°C. Activities increased markedly when using zirconocene dichlorides/tri(i-butyl)aluminum/ 2. Activities for ethylene polymerization using zirconocene dichloride/tri( i-butyl)aluminum/2 at 20°C were 7.0 × 10 6 g PE/mol 2·[C2H4]·h. Activities for the polymerization of propylene using rac-ethylenebis(indenyl)zirconium dichloride/tri(ibutyl)aluminum/2 at 20°C were 5.4 × 106 g PP/mol 2·[C3H6]·h. ^ Several titanium(IV) complexes of the type CpTi(NMe 2)3 (Cp-cyclopentadienyl (10 ), (dimethylaminoethyl)cyclopentadienyl (11), indenyl (12) and pentamethylcyclopentadienyl (13)) have been prepared and their catalytic properties in the polymerization of α-olefins examined. Complexes 10 and 11 catalyzed the polymerization of ethylene in the presence of MAO with much higher activity than 12 or 13. Complexes 12 and 13 polymerized ethylene with an activity similar to that of CpTiCl3. Also, 10 and 11 were used as ethylene/1-hexene copolymerization catalysts. Complex 10 effectively polymerized styrene with a higher activity and higher syndiospecificity than the other three catalysts. ^ Two new Ti(IV) complexes of the type (OCHRCH2N-2,6-Me 2Ph) Ti(NMe2)2 have been synthesized. The two complexes were studied as Ziegler-Natta type polymerization catalysts in the presence of an excess of methylaluminoxane. It was found that ethylene polymerization activity for both catalysts increased by increasing the polymerization temperature from 25 to 70°C. If the catalysts were pretreated with trimethylaluminum, the activities increased at 25°C, but decreased slightly at 70°C. Both complexes were found to be ineffective for the polymerization of propylene. An X-ray crystal structure of (OCH2CH2N-2,6-Me 2Ph)Ti(NMe2)2 shows the complex to be dimeric in the solid state. ^ Four titanium ansa-cyclopentadienyl-amido complexes of the general formula [C5H3RMe2SiN(2,6-Me 2C6H5)]TiX2 (R = H, Me, Bz, tBu; X = NMe2 or Cl) have been synthesized. The complexes polymerize both ethylene and propylene and were most active at lower temperatures. In general, the smaller the substituent on the cyclopentadienyl group, the more active the catalyst. The catalysts were found to be poorly stereoselective. ^

Subject Area

Chemistry, Inorganic

Recommended Citation

Barrie Rhodes, "Design, synthesis and evaluation of new Ziegler -Natta catalyst components" (January 1, 2000). Doctoral Dissertations Available from Proquest. Paper AAI9988836.
http://scholarworks.umass.edu/dissertations/AAI9988836

Share

COinS