Copolymerization of butadiene and styrene with a gadolinium tricarboxylate catalyst

Abstract

Homo‐ and copolymerizations of butadiene (BD) and styrene (St) were carried out by gadolinium catalysts having various tricarboxylate ligands [Gd(OCOR)3: R = CH3, CH2Cl, CHCl2, CCl3, and CF3], to investigate the effects of ligands and discuss the cis polymerization mechanism. Polymerization of BD with Gd(OCOR)3—(i—Bu)3Al—Et2AlCl catalysts was carried out in hexane at 50°C. By each catalyst, poly(BD) having a high cis content (cis = 97–99%) in 22–85% yields for 2–24 h were obtained. The ligands with low pKa values increased the polymerization activity as follows: R of Gd(OCOR)3: CF3 > CCl3 > CHCl2 > CH2Cl ∼ CH3. On the other hand, in the polymerization of St or copolymerization of BD and St under similar conditions, the highest activity was attained by a Gd(OCOCCI3)3‐ based catalyst. The difference in the optimum ligand among the homo‐ and copolymerization of BD and St was discussed on the basis of energy levels of the catalysts. In the copolymers of BD and St, the cis‐1,4 content of the BD unit decreased with increasing St content. Furthermore, according to the diad analysis of copolymers (St content ∼ 14.5 mol %) by 13C NMR spectroscopy, the low cis value of the BD unit was observed in the St‐BD diad (cis/trans/vinyl = 24/53/23), while the high cis value of the BD unit remained in the BD‐BD diad (cis/trans/vinyl = 89/10/1). These results suggest that the terminal BD unit is controlled by the cis configuration by the coordination between the penultimate cis vinylene unit and the gadolinium metal catalyst, whereas the presence of the penultimate St unit interferes with cis polymerization of the terminal BD unit. The difference in the coordination mechanism in the course of polymerization between rare earth metal and transition metal catalysts such as the Ni(acac)2 and Co(acac)3‐based catalyst was also discussed. © 1995 John Wiley & Sons, Inc.

Kinetics of the Addition Reactions of Thiobenzoic Acids to Styrenes or Ethynylbenzenes as the Model of Polyaddition. Study on the Rate-Determining Step and Substituent Effect

“…Such difference in reactivity has been already expected from polyadditions. In the case of polyadditions, apparent reactivity was expected from the polymerization conditions and polymer yields to decrease in the order of BDT-DEB, 30 BDT-DVB, 31 BDTC-DVB, 5 and BDTC-DEB, 6 this being the same as the order in Table V. Here, estimated reactivity does not mean a difference in the absolute rate but apparent and relative values, since the rate-determining step of the addition reaction of TP to EB was different from that of TP-St, TBA-St, and TBA-EB as is mentioned in the next section.…”

“…Recently, the authors investigated the polyaddition of 1,4-benzenebiscarbothioic acid (BDTC) to 1,4-divinylbenzene (DVB) 5 or 1,4-diethynylbenzene (DEB). 6 The polyaddition took place successfully to give saturated or conjugated polythioesters in high yields.…”

Addition Reaction of Phenylphosphines to Styrenes as the Model of Polyaddition. Study on the Rate-Determining Step and Substituent Effect

“…Phosphorus content of the adducts was determined by the phosphovanadomolybdic acid method l l • 12 as described in the previous paper. 5 The simulation curves of the adduct formations of PH to St or MSt were obtained by the laboratory made program 13 based on the algorithm theory. The concentrations of the substances in the simulation curves were calculated by the equation on the consecutive reaction with A-+B-+C.…”

“…These results were discussed by comparing with the addition reaction ofthiophenol (TP) to St 4 and with the polyaddition of PH to DVB 5 or DIPB. 5 …”

“…The detailed kinetic behavior such as the rate-determining step and substituent effect on the addition reaction of P-H group to vinyl group were also inves-tigated by the model addition reaction of diphenylphosphine (DPH) to St. These results were discussed by comparing with the addition reaction ofthiophenol (TP) to St 4 and with the polyaddition of PH to DVB 5 or DIPB. 5 …”