Relationship between the ionic nature of some organoaluminum—transition metal catalysts and the rate of polymerization

Abstract

AbstractThe electrical conductivity of several trialkylaluminum and alkyl‐aluminum halides was investigated in dry benzene at 25°C. within the concentration range of 10−1–10−3M. The equivalent conductance of the trialkylaluminum systems decreased in the following order: Al(n‐C6H13)3 > Al(n‐C10H19)3 > Al(n‐C4H9)3 > Al(i‐C4H9)3 > Al(n‐C3H7)3 > Al(C2H5)3. The conductance (1/R) of a given series was also examined and found to decrease as each alkyl group was successively replaced by a chlorine atom, thus: Al(C2H5)3 > Al(C2H5)2Cl > Al(C2H5)1.5Cl1.5 > Al(C2H5)Cl2 and Al(i‐C4H9)3 > Al(i‐C4H9)2Cl > Al(i‐C4H9)Cl2. The ion pair dissociation constants K were calculated and show in a qualitative manner the difference between various organoaluminum systems. The relative rate of olefin polymerization was related to the conductivity of various organoaluminum–transition metal catalyst systems used. The effect of Lewis bases such as monoglyme, diglyme, triglyme, and tetraglyme on triethylaluminum indicated that the first‐mentioned base forms a 1:1 type of complex as ordinary ethers do, whereas the remaining three bases utilize only two of their available oxygen atoms to coordinate with triethylaluminum. The effect of TiCl3 (in the presence of an ether) on the conductance was also determined.