Electron spin resonance studies on Ziegler‐Natta type catalyst systems

Abstract

Electron spin resonance spectra of Ziegler‐Natta type catalyst systems (titanium trichloride and alkyl aluminums) have been studied. When triethylaluminum was added to titanium trichloride, an absorption with a g value of 1.96 was observed from the solid phase of the system. The number of spins of this signal is equal to that of the active centers for propylene polymerization. The solid phase from the mixture of titanium trichloride and diethylaluminum chloride also gives the same signal, which suggests the identity of the action of two alkyl aluminums on titanium trichloride surface. The signals obtained from the liquid phase of the both systems are all ascribed to the reaction products of the reaction of alkyl aluminum with titanium tetrachloride occluded in solid.

Reactions Between AIRCl2and Ti (OR)4and Activity in Diolefin Polymerization

“…already formed show a broad signal with a g-value of 1.959, attributed to the trivalent titanium species, in agreement with other authors [9]. No EPR signal is present before separation of the insoluble compounds.…”

A new route to atactic polypropylene: The second life of premetallocene homogeneous polymerization catalyst

“…Reactions 1 are very rapid and irreversible . When the [Al]:[Ti] ratio is high (as in the present case, see Table ), the alkylation reaction of the Ti species usually continues …”

“…All the Ti species, both the Ti IV species produced in Reactions 1–3 and the Ti III species produced in the reduction reactions, form numerous hydrocarbon‐soluble complexes with one or two molecules of AlR 2 (O R ) or AlR(O R )Cl. Some of the dinuclear and trinuclear complexes of Ti III , such as [Ti(O R ) 3 ]·2AlR 2 (O R ), [Ti(O R ) 3 ]·AlR 2 (O R ) and [( R O) 2 Ti–R]·AlR(O R )Cl, were characterized in detail by esr …”

“…Reactions between titanium tetraalkoxides and organoaluminum compounds were thoroughly investigated in the past, [33][34][35][36] mostly because the products of these reactions are soluble in hydrocarbons and could be subjected to detailed esr and UV-vis analysis. Chemical interactions in the Ti(OR) 4 -AlR 3 and Ti(OR) 4 -AlR 2 Cl systems are very complex.…”

A novel efficient Ti(O-iso-C3H7)4-based olefin polymerization catalyst system

“…Reactions between Ti(OR) 4 and organoaluminum compounds were described in detail previously [28][29][30][31]. These reactions lead to the alkylation of Ti(OR) 4 to (RO) 3 Ti IV -R and (RO) 2 Ti IV R 2 ; the reduction of these compounds to Ti III (RO) 3 The active sites of olefin polymerization are cationic complexes of Ti IV or Ti III that contain a Ti + -C bond [11].…”