Aluminium Alkyl or Hydride-activated

In contrast to TiCl4, Til4 is only slightly soluble in hydrocarbon solvents, and therefore alternative catalysts based on soluble iodine-containing precursors, such as T1CI2I2. or iodine-containing activators, such as e.g. AlEt2l, have been developed [49-52]. These catalysts lead to practically the same contents of cis- 

Catalysts of the Ti(OR)4—A1R3 type are soluble in hydrocarbon solvents and polymerise butadiene and isoprene into polymers having predominant 1,2 and 

There are also known soluble vanadium-based catalysts. Those obtained from soluble compounds such as V(Acac)3 or VO(OR)3 as precursors being activated 

Chromium- and molybdenum-based catalysts yield predominantly 1,2-poly-butadiene. Several soluble chromium compounds such as Cr(Acac)3 give apparently hydrocarbon-soluble catalysts when activated with AIR3. Also, soluble catalysts are formed from soluble molybdenum compounds such as Mo(Acac)3 or Mo02(Acac)2 on reaction with AlEt3 in the presence of ethyl acetate or sulphides. ESR studies of Mo(OR)xCl4 x-based catalysts showed the Mo(III) species to be present in the catalysts. It should be mentioned, however, that catalysts based on group 6 metals have not been extensively studied [7], 

The microstructure of representative conjugated diene polymers obtained by polymerisation with various aluminium alkyl or hydride-activated Ziegler-Natta catalysts is presented in Table 5.1 [7,12,26,41,49,57,58,62,73,77,81,83, 89-106] and Table 5.2 [7,12,13,17-19,41,57,77,81,83,91,92,100,104,105,107-113]. 

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Table 5.1 Polymerisation of 1,3-butadiene with aluminium alkyl or hydride-activated Ziegler-Natta catalysts...

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