Titanium tetrachloride, catalyst

Ashikari, Kanemitsu, Yanagisawa, Nakagawa, Okomoto, Ko-bayashi and Nishioko (59) have studied the copolymerization of propylene and styrene. They found decreasing styrene content and conversion of the copolymer by increasing aluminum to titanium ratios with triisobutyl aluminum and titanium trichloride catalysts. The trialkylaluminum titanium tetrachloride catalyst had relatively low steric control on the polymerization while trialkylaluminum-titanium trichloride had higher steric control. The ionicity which is required for atactic polymerization is more cationic for styrene than for propylene which is more cationic than that for ethylene. Some of the catalyst systems for these three monomers are shown on the ionicity chart in Fig. 9. 

High-Density Polyethylene (HDPE). Polymerization of ethylene to polyethylenes is most often carried out at low temperature and pressure, using either the Ziegler aluminum triethyl plus titanium tetrachloride catalyst system, the Phillips chromic oxide plus silica plus alumina system, or more recently the newer metallocene single-site catalyst systems. 

Preformed Alkylaluminum-Titanium Tetrachloride Catalysts for the Polymerization of Isoprene... 

Unseparated Catalyst. Unaged Catalysts. Our previous work (13) with the triisobutylaluminum-titanium tetrachloride catalysts preformed at 20° C. had shown that the optimum Al/Ti ratio for c is-1,4 poly isoprene formation is about 0.9 to 0.1. The yields of solid polymer fell off rapidly on either side of this ratio. Lower ratios led to mixed leathery-rubbery products of high gel, whereas higher ratios (above 1.3) produced increasing amounts of low molecular weight oily materials, so-called extractables. 

The dependence of the polymer microstructure on the ratio of catalyst components is related to the nature of these components. The structure of polybuta-diene obtained with an aluminum triisobutyl (AIBU3)-titanium tetrachloride catalyst system is a function of the Al/Ti molar ratio (Table II). Polybutadiene prepared at Al/Ti ratios of 0.5 to 8 in benzene or heptane and at 3° or 25° C. contain at least 90% 1,4- units. Polymerizations carried out at ratios of 1.0 and less at 25° C. in heptane and at ratios of 1.25 or less at 3° C. in heptane or benzene give crystalline polymers containing more than 96% trans-, A- structure (6). A similar temperature dependence of polymer structure has been reported in the polymerization of butadiene with a diethylcadmium-titanium tetrachloride catalyst system (3). Polybutadiene obtained with a triethylaluminum-titanium tetrachloride catalyst system at a 0.9 Al/Ti ratio at 30° C. in benzene is reported to contain 67% cis-1,4- units (19). 

As in the case of butadiene polymerization, the microstructure of polyisoprene is dependent upon the ratio of catalyst components, the reaction temperature, and the reaction medium. As shown in Table V, using an aluminum triethyl-titanium tetrachloride catalyst system, an Al/Ti ratio of 1.0 or higher yields a polyisoprene containing 96% cis-1,4-, 4% 3,4-, and essentially no trans-, A- or 1,2- units. Below this ratio, the trans-, A- structure is produced apparently at the expense of the cis-1,4- structure (I). An AlBua-TiCLt catalyst system is reported (7) to yield an essentially all- rarw-l,4-polyisoprene at an Al/Ti ratio of 0.67 and below. 

The polymerization of cyclopentadiene (5) was investigated in bulk and in solution with lithium aluminum hydride-titanium tetrachloride and lithium aluminum tetraoctyl-titanium tetrachloride catalyst systems. The polymerizations were carried out in nitrogen atmosphere using highly purified—i.e., freshly distilled— reactants. 

Cyclohexadiene has been reported to polymerize by 1,4- addition by means of aluminum triisobutyl-titanium tetrachloride catalyst (9). 

The polymerization of cyclopentadiene with triisobutyl aluminum-titanium tetrachloride catalyst system is reported (7) to yield polycyclopentadiene with 1,4- structure. Apparently the polymerization of cyclopentadiene is analogous to that of butadiene, wherein, as shown in Table I, in a TiC catalyst system, AIR3 yields a 1,4- structure and LiAlH4 yields a 1,2- structure. 

Until recently ethylene itself could be polymerized only at high pressure and high temperatures. Ziegler and his colleagues27 have, however, shown that ethylene, which is otherwise so inert, can be polymerized at atmospheric pressure by use of a triethylaluminum-titanium tetrachloride catalyst in a suitable solvent details for the laboratory preparation of this interesting and technically important variety of polyethylene have been given by Ziegler and Martin.28... 

Poly(2-phenylbutadienes) with a high cis content are also produced with the triisobuthyl-aluminum/titanium tetrachloride catalysts [349]. Phenyl-1,3-butadienes can also be considered as vinyl-substituted styrenes, which explains the effects on activities and microstructures. Poly(2-phenyl butadienes) occur in trans-, A, cw-1,4, 3,4, and 1,2 structures. Maximum conversions are achieved with a molar Al/Ti ratio of 1, which leads to the formation of 73% cis-, A and 27% 1,2 structures. At higher Al/Ti ratios the d -1,4 content goes up to 96%. The molecular weights are low, ranging from 2000 to 18,000. 

Ketimines derived from cycloalkanones may be prepared under neutral, azeotropic conditions, using five mole percent of dibutyltin dichloride.Less epimerization a to the carbonyl group was noted compared to reactions using acid or titanium tetrachloride catalysts, esters and nitriles remaining unaffected under the dibutyltin dichloride reaction conditions. 

Additional examples of the remarkable specificity exhibited by this type of polymerization are shown in Eqs. (11-38), (11-39), and (11-40). Low yields of soluble, polymeric product of unspecified molecular weights were obtained when polymerization was initiated by a triisobutylaluminum-titanium tetrachloride catalyst (36). Insoluble product was also obtained. The polymer structures [89], [91], and [93] were consistent with infrared spectral data. 

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