Monomer-isomerization polymerization. VI. Isomerizations of butene-2 with TiCl3 or Al(C2H5)3–TiCl3 catalyst

A study of the isomerization of butene-2 with TiCl₃ or Al(C₂H₅)₃–TiCl₃ catalyst in n-heptane has been investigated at 60–80°C to elucidate further the mechanism of monomer-isomerization polymerization. It was found that positional and geometrical isomerizations in the presence of these catalysts occurred concurrently with activation energies of 14–16 kcal/mole. The presence of Al(C₂H₅)₃ with TiCl₃ catalyst could accelerate the initial rates of these isomerizations and initiate the monomer-isomerization polymerization of butene-2. From the results obtained, it was concluded that the isomerization of butene-2 proceeds via an intermediate σ-complex between the transition metal hydride and butene isomers.     

Monomer-Isomerization polymerization. XXVIII. Catalytic activity of transition metals and alkylaluminums in monomer-isomerization polymerization of 2-butene

Monomer-isomerization polymerization of cis-2-butene (c2B) with Ziegler–Natta catalysts was studied to find a highly active catalyst. Among the transition metals [TiCl₃, TiCl₄, VCl₃, VOCl₃, and V (acac)₃] and alkylauminums used, TiCl₃? R₃Al (R = C₂H₅ and i-C₄H₉) was found to show a high-activity for monomer-isomerization polymerization of c2B. The polymer yield was low with TiCl₄? (C₂H₅)₃Al catalyst. However, when NiCl₂ was added to this catalyst, the polymer yield increased. With TiCl₃? (C₂H₅)₃Al catalyst, the effect of the Al/Ti molar ratio was observed and a maximum for the polymer yields was obtained at molar ratios of 2.0–3.0, but the isomerization increased as a function of Al/Ti molar ratio. The valence state of titanium on active sites for isomerization and polymerization is discussed.     

Monomer-isomerization polymerization. XXVI. Formation of polyallylcyclohexane from propenylcyclohexane through monomer-isomerization polymerization with Ziegler–Natta catalysts

Monomer-isomerization polymerization of propenycyclohexane (PCH) with TiCl₃ and R_3-xAICI_x (R = C₂H₅ or i-C₄H₉, x = 1–3) catalysts was studied. It was found that PCH underwent monomer-isomerization polymerization to give a high molecular weight polymer consisting of an allylcyclohexane (ACH) repeat unit. Among the alkyaluminum cocatalysts examined, (C₂H₅)₃Al was the most effective cocatalyst for the monomer-isomerization polymerization of PCH, and a maximum for the polymerization was observed at a molar ratio of Al/Ti of about 2.0. The addition of isomerization catalysts such as nickel acetylacetonate [Ni(acac)₂] to the TiCl₃–(C₂H₅)₃Al catalyst accelerated the monomer-isomerization polymerization of PCH and gave a maximum for the polymerization at a Ni/Ti molar ratio of 0.5. PCH also undergoes monomer-isomerization copolymerization with 2-butene (2B).     

Monomer-isomerization polymerization. XXII.. Isomerization and polymerization of propenylbenzene with various ziegler–natta catalysts

The isomerization and polymerization of propenylbenzene (PB) with various Ziegler–Natta catalyst systems have been investigated. With the TiCl₃–(C₂H₅)₃Al (Al/Ti > 2.0) catalyst at 80°C, PB polymerized to give a polymer exclusively consisting of allylbenzene (AB) unit. During the polymerization, AB, which polymerized readily with the catalyst, was produced through isomerization of PB, indicating that PB underwent monomer-isomerization polymerization. PB also polymerized with isomerization to AB in the presence of TiCl₃?(C₂H₅)₂AlCl?NiCl₂ catalyst system, and a copolymer with PB and AB units was obtained. With TiCl₃?C₂H₅AlCl₂ catalyst, poly(PB) was formed via ordinary vinylene polymerization without isomerization. From these facts, it was concluded that the structure of the polymers produced from PB widely changed, depending on the catalyst systems used, which determine the rate of isomerization to AB and the polymerization reactivity of the PB and AB isomers formed.     

Monomer-isomerization polymerization. V. Effects of transition metal compounds on monomer-isomerization polymerizations of butene-2 and pentene-2

In order to clarify the correlation between polymerization and monomer isomerization in the monomer-isomerization polymerization of β-olefins, the effects of some transition metal compounds which have been known to catalyze olefin isomerizations on the polymerizations of butene-2 and pentene-2 with Al(C₂H₅)₃–TiCl₃ or Al(C₂H₅)₃–VCl₃ catalyst have been investigated. It was found that some transition metal compounds such as acetylacetonates of Fe(III), Co(II), and Cr(III) or nickel dimethylglyoxime remarkably accelerate these polymerizations with Al(C₂H₅)₃–TiCl₃ catalyst at 80°C. All the polymers from butene-2 were high molecular weight polybutene-1. With Al(C₂H₅)₃–VCl₃ catalyst, which polymerizes α-olefins but does not catalyze polymerization of β-olefins, no monomer-isomerization polymerizations of butene-2 and pentene-2 were observed. When Fe(III) acetylacetonate was added to this catalyst system, however, polymerization occurred. These results strongly indicate that two independent active centers for the olefin isomerization and the polymerizations of α-olefins were necessary for the monomer-isomerization polymerizations of β-olefins.     

Monomer-isomerization polymerization. XX. Monomer-isomerization polymerization of 2-, 3-, and 4-octenes with Ziegler–Natta catalyst

A study of the monomer isomerization polymerization of 2-, 3-, and 4-octenes has been made with TiCl₃–(C₂H₅)₃Al catalyst at 80°C in comparison with the ordinary polymerization of 1-octene. It was found that all these octenes underwent monomer-isomerization polymerization to give high-molecular-weight homopolymer consisting exclusively of the 1-octene unit. The addition of an isomerization catalyst such as nickel acetylacetonate accelerated this polymerization. The rates of polymerization were found to decrease in the following order: 1-octene > 2-octene > 3-octene > 4-octene. These results indicate that the isomerization proceeded by a stepwise double-bond migration. It was also found that the monomer-isomerization copolymerization of 2-octene and 2-butene occurred under similar conditions and produced copolymers of both 1-olefin units.     

Monomer-isomerization polymerization. XXIII.. Monomer-isomerization polymerization of 5-phenyl-2-pentene with ziegler–natta catalysts

5-Phenyl-2-pentene (5Ph2P) was found to undergo monomer-isomerization polymerization with TiCl₃–R₃Al (R = C₂H₅ or i-C₄H₉, Al/Ti > 2) catalysts to give a polymer consisting of exclusively 5-phenyl-1-pentene (5Ph1P) unit. The geometric and positional isomerizations of 5Ph2P to its terminal and other internal isomers were observed to occur during polymerization. The catalyst activity of alkylaluminum examined to TiCl₃ was in the following order: (C₂H₅)₃Al > (i-C₄H₉)₃Al > (C₂H₅)₂AlCl. The rate of monomer-isomerization polymerization of 5Ph2P with TiCl₃–(C₂H₅)₃Al catalyst was influenced by both the Al/Ti molar ratio and the addition of nickel acetylacetonate [Ni(acac)₂], and the maximum rate was observed at Al/Ti = 2.0 and Ni/Ti = 0.4 in molar ratios.     

Monomer-isomerization polymerization. XIII. Monomer-isomerization polymerization of 1,4-cyclohexadiene with Ziegler-Natta catalyst

1,4-Cyclohexadiene underwent monomer-isomerization polymerization to yield poly(1,3-cyclohexadiene) with a Ziegler-Natta catalyst comprising TiCl₄–Al(C₂H₅)₃ catalyst with Al/Ti molar ratios of 0.5–3.0 at 60°C for 96 hr. Good yields of polymer were obtained (49.5% yield at Al/Ti = 3.0; [η] = 0.04 dl/g). The infrared and NMR spectra of the polymer were identical to those of poly-(1,3-cyclohexadiene), confirming that 1,4-cyclohexadiene first isomerizes to 1,3-cyclohexadiene and then homopolymerizes to give poly-1,3-cyclohexadiene. 1,3-Cyclohexadiene polymerized without isomerization easily in the presence of TiCl₃–Al(C₂H₅)₃ catalyst at Al/Ti molar ratios of 0.5–3.0 at 60°C for 3 hr (76.3% yield at Al/Ti = 3.0; [η] = 0.06 dl/g).     

Monomer-isomerization polymerization. XVI. Monomer-isomerization polymerization of methylpentenes with Ziegler-Natta catalyst

The polymerizations of 4-methyl-1-pentene(4M1P), 4-methyl-2-pentene (4M2P), 2-methyl-2-pentene (2M2P), and 2-methyl-1-pentene (2M1P) with Ziegler-Natta catalyst have been investigated. Both 4M1P and 4M2P were found to polymerize with TiCl₃–(C₂H₅)Al catalyst to give high molecular weight poly(4M1P), while 2M2P and 2M1P did not give polymers with 4M1P units. However, when the polymerizations of 2M1P and 2M2P were carried out with ternary catalyst systems, TiCl₃–(C₂H₅)AlCl–(PPh₃)₂PdCl₂ and TiCl₃–(C₂H₅)AlCl–Ni(SCN)₂ polymers with 4M1P units were obtained in low yield. It was concluded that these four methylpentenes could polymerize with the monomer-isomerization polymerization mechanism to poly(4M1P). The results of the observed isomer distribution of methylpentenes recovered, and the rate of polymerization of four methylpentenes suggest that the isomerization from 2M1P to 4M1P with the above ternary catalyst systems might proceed via a direct one-step isomerization mechanism.     

Monomer-isomerization polymerization. XXXVIII. Monomer-isomerization copolymerizations of styrene and 2-Butene with Ziegler–Natta catalyst

Monomer-isomerization copolymerizations of styrene (St) and cis-2-butene (c2B) with TiCl₃-(C₂H₅)₃Al catalyst were studied. St and c2B were found to undergo a new type of monomer-isomerization copolymerization, i.e., only isomerization of 2B to 1-butene ( 1B ) took place to give a copolymer consisting of St and 1B units. The apparent copolymerization parameters were determined to be r_st = 16.0 and r_c2b = 0.003. The parameters were changed by the addition of NiCl₂ (r_St = 8.4, r_c2b = 0.05). The copolymers containing the major amount of St units were produced easily through monomer-isomerization copolymerization of St and 2B. © 1995 John Wiley & Sons, Inc.     

Polymerization of vinylcyclohexane with ziegler–natta catalyst

Polymerization of vinylcyclohexane (VCHA) with TiCl₃–aluminum alkyl catalysts was investigated. The polymerization rate of VCHA was low due to the branch at the position adjacent to the reacting double bond. The effects of aluminum alkyl on the polymerization and monomer-isomerization were observed; the polymer yield decreased in the following order: (CH₃)₃Al > (i–C₄H₉)₃Al > (C₂H₅)₃Al. Isomerization of VCHA was observed with the TiCl₃–(i–C₄H₉)₃Al and the TiCl₃–(C₂H₅)₃Al catalysts during the polymerization, while with the TiCl₃–(CH₃)₃Al catalyst such isomerization was not observed. Monomer-isomerization copolymerization of VCHA and trans-2-butene took place to give copolymers consisting of VCHA and 1-butene units.     

Kinetic studies of polymerization of propylene with active TiCl3–Zn(C2H5)2

In order to elucidate the structure of the Ziegler-Natta polymerization center, we have carried out some kinetic studies on the polymerization of propylene with active TiCl₃—Zn(C₂H₅)₂ in the temperature range of 25–56°C. and the Zn(C₂H₅)₂ concentration range of 4 × 10^?3–8 × 10^?2 mole/1., and compared the results with those obtained with active TiCl₃—Al(C₂H₅)₃. The following differences were found: (1) the activation energy of the stationary rate of polymerization is 6.5 kcal/mole with Zn(C₂H₅)₂ and 13.8 kcal./mole with Al(C₂H₅)₃; (2) the growth rate of the polymer chains with Zn(C₂H₅)₂ is about times slower at 43.5°C.; and (3) the polymerization centers formed with Zn(C₂H₅)₂ are more unstable. It can be concluded that the structure of the polymerization center with Zn(C₂H₅)₂ is different from that with Al(C₂H₅)₃.     

Influence of SeOCl2 on the polymerization of propylene by TiCl3–Al(C2H5)3

The influence of SeOCl₂ on the polymerization of propylene by TiCl₃–Al(C₂H₅)₃, and the temperature dependence of the stereospecificity of the catalyst, TiCl₃–Al(C₂H₅)₃, have been investigated. SeOCl₂ decreases the rate of polymerization and increase the stereospecificity of the catalyst, which could be explained on the basis of a decrease of the concentration of Al(C₂H₅)₃ accompanied by a reaction between Al(C₂H₅)₃ and SeOCl₂. On the other hand, the stereospecificity of the catalyst, TiCl₃–Al(C₂H₅)₃, increases gradually with a decrease in polymerization temperature from 40 to 0°C. From these results, we conclude that SeOCl₂ exerts no essential influence on the polymerization of propylene by TiCl₃–Al(C₂H₅)₃, and that the stereospecificity of the catalyst is attributed mainly to the reducing ability of the organometallic compound.     

Polymerization with heterogeneous metalorganic catalysts. VI. Differences in polymerization activity of α-olefins and some kinetic results on butene-1 polymerization

Relative changes in polymerization activity of ethylene, propylene, and butene-1 in Ziegler-Natta polymerization were compared by use of TiCl₃ samples contaminated with O₂ and H₂O to various extents. Catalyst depletion varied for the three monomers which supported the existence of different active centers. In butene-1 polymerizations with the system Al(C₂H₅)₂Cl–TiCl₃, the formation of active centers involves an irreversible and a reversible (adsorption) reaction, the former pertaining to the formation of Al(C₂H₅)Cl₂ and dependent upon the purity of the TiCl₃. The kinetic treatment of the rate curves suggests a mixed order of catalyst deactivation and again points to the importance of Al(C₂H₅)Cl₂.     

Monomer-isomerization polymerization. XXI.. Monomer-isomerization copolymerization of 3-methyl-1-butene and 2-pentene with ziegler–natta catalyst

3-Methyl-1-butene (3M1B) was found to undergo monomer-isomerization copolymerization with 2-pentene (2P) in the presence of Ziegler–Natta catalyst to give a copolymer exclusively consisting of 3M1B and 1-pentene (1P) units, the same as that obtained from copolymerization of 3M1B and 1P. The apparent copolymerization parameters were determined. The amount of 3M1B unit incorporated in the copolymers was found to increase in the copolymerization system of 3M1B-2P more than in that of 3M1B-1P. The polymers consisting of nearly complete 3M1B units were produced at a rapid rate through monomer-isomerization copolymerization of 3M1B with 2P in the presence of TiCl₃ ? (C₂H₅)₃Al catalyst.     

Polymerization of β-cyanopropionaldehyde. III. Polymerization by organoaluminum and by organoaluminum–titanium chloride complexes

The mechanism of formation and stereoregularity of poly(cyanoethyl)oxymethylene have been studied. The polymerization was carried out at ?78°C with use of aluminum compounds [Al(C₂H₅)₃, Al(C₂H₅)₂Cl, Al(C₂H₅)Cl₂, and AlCl₃] and complex catalysts [Al(C₂H₅)₃–TiCl₄, Al(C₂H₅)₃–TiCl₃, and Al(C₂H₅)₂Cl–TiCl₃] as initiators. The stereoregularity of poly(cyanoethyl)oxymethylene was estimated from the optical density ratio, D₁₂₅₈/D₁₂₇₀, in the infrared absorption spectrum. Polymer yields were observed to depend upon the aluminum compound used as initiators, while the stereoregularity of the polymer was nearly independent of the particular aluminum compound used. As the catalyst ratio of titanium chloride to aluminum compound increased, the polymer yield was found to increase to a maximum and then to decrease with further increase of the ratio. It is supposed that titanium chlorides themselves increase the acid strength of aluminum compounds through chlorination, resulting in the change of the polymer yield. The highest stereoregularity of poly(cyanoethyl)oxymethylene was attained by increasing the molar ratio of titanium trichloride to aluminum and by treating β-cyanopropionaldehyde (CPA) with titanium trichloride prior to the polymerization. Complex formation of the nitrile group of CPA with titanium is considered responsible for the increase in stereoregularity. A propagation mechanism is also proposed.     

Monomer-isomerization polymerization. XIX. Monomer-isomerization copolymerizations of methylbutenes and 2-butene with Ziegler-Natta catalyst

The copolymerization of 3-methyl-1-butene (3M1B), 2-methyl-2-butene (2M2B), or 2-methyl-1-butene (2M1B) with trans-2-butene (2B) was attempted in the presence of a Ziegler-Natta catalyst. It was found the 3M1B underwent monomer-isomerization copolymerization with 2B to give a copolymer consisting of both 3M1B and 1-butene (1B) units, with an infrared (IR) spectrum in good agreement with that obtained from the copolymerization of 3M1B with 1B under similar conditions. When the apparent copolymerization parameters obtained by a TiCl₃–(C₂H₅)₃Al catalyst were compared, the apparent reactivity of 3M1B observed in the 3M1B-2B system was much higher than that in the 3M1B-1B system. However, 2M2B and 2M1B did not undergo monomer-isomerization copolymerization with 2B, and only the homopolymer of 1B was obtained under similar conditions.     

Monomer-isomerization polymerization. XI. Monomer-isomerization copolymerizations of 2-butene with 2-pentene and 2-hexene with Ziegler-Natta catalyst

2-Pentene and 2-hexene were found to undergo monomer-isomerization copolymerizations with 2-butene by Al(C₂H₅)₃–VCl₃ and Al(C₂H₅)₃–TiCl₃ catalysts in the presence of nickel dimethylglyoxime or transition metal acetylacetonates to yield copolymers consisting of the respective 1-olefin units. For comparison, the copolymerizations of 1-pentene with 1-butene and 1-hexene with 1-butene by Al(C₂H₅)₃–VCl₃ catalyst were also attempted. The compositions of the copolymers obtained from these copolymerizations were determined by using the calibration curves between the compositions of the respective homopolymer mixtures and the values of D₇₆₆/D₁₃₈₀ in the infrared spectra. The monomer reactivity ratios for the monomer-isomerization copolymerizations of 2-butene (M₁) with 2-pentene and 2-hexene, in which the concentrations of both 1-olefins calculated from the observed isomer distribution were used as those in the monomer feed mixture, and for the ordinary copolymerizations of 1-butene (M₁) with 1-pentene and 1-hexene by Al(C₂H₅)₃-VCl₃ catalyst were determined as follows: 2-butene (M₁)/2-pentene (M₂): r₁ = 0.14, r₂ = 0.99; 1-butene (M₁)/1-pentene (M₂): r₁ = 0.30, r₂ = 0.74; 2-butene (M₁)/2-hexene (M₂): r₁ = 0.11, r₂ = 0.62; 1-butene (M₁)/1-hexene (M₂): r₁ = 0.13, r₂ = 0.90.     

Modification mechanism in olefin polymerization catalysts TiCl4/MgCl2–aromatic ester–Al(C2H5)3

An IR/UV study of the interaction between ethyl benzoate and Al(C₂H₅)₃ in dilute heptane solution at 25–75°C demonstrated that the ester is readily reduced under these conditions with the formation of two aluminum dialkyl alkoxides, Al(C₂H₅)₂ and Al(C₂H₅)₂OC(C₂H₅)₂C₆H₅, as major products. Rate constants of the reduction of the initial AI(C₂H₅)₃ · ester complex by free AI(C₂H₅)₃ are 2.9 (26°C), 14.4 (50°C), and 59.6 (75°C) L/mol min; E_act = 52.0 kj/mol. Study of propylene polymerization with this catalytic system at 50°C showed that preliminary aging of the AI(C₂H₅)₄–ethyl benzoate mixtures at 25°C for 24 h and at 50°C for 2 h does not adversely affect catalyst performance. These data suggest that the possible actual modifier in this catalytic system is aluminum alkoxide with a highly branched tertiary alkoxy group.