Polymerization of conjugated diolefins by homogeneous aluminum alkyl‐titanium alkoxide catalyst systems. I. <i>Cis</i>‐1,4 isotactic poly (1,3‐pentadiene)

Amorphous atactic polypropylene (PP) with an average molecular weight of 50,000-100,000 is produced by polymerizing propylene with a ternary Ti(Oiso-Pr) 4 -AlEt 2 Cl/MgBu 2 catalyst at 30-50. Main advantages of this catalyst compared with other catalysts capable of nearly exclusively producing atactic PP (such as some heterogeneous Ziegler-Natta, metallocene and postmetallocene catalysts) are high activity, low cost and the ease of use: the catalyst is prepared in situ from three commercially available compounds readily soluble in aliphatic and aromatic hydrocarbons.

“…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

{true(R O true)}_{3} Ti - R + {AlR}_{3} true({or AlR}_{2} Cl true) \to {true(R O true)}_{2} {TiR}_{2} + {AlR}_{2} true(O R true) true[or AlR true(O R true) Cl true]

…”

Section: Resultsmentioning

confidence: 73%

Section: Resultsmentioning

confidence: 99%

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

Kissin

Rishina

Lalayan

et al. 2015

“…However, data on the presence of 3,4‐units in stereoregular PPD were not so unambiguous. It was found by means of IR‐ and 13 C NMR spectroscopy that stereoregular PPDs contain from 3 to 15 mol % of 3,4‐units . The calculations have been made based on the band at 910 cm −1 in IR spectra or signal at 114.8–115.5 ppm in 13 C NMR spectra .…”

Section: Introductionmentioning

confidence: 99%

A new insight into the mechanism of 1,3‐dienes cationic polymerization. II. Structure of poly(1,3‐pentadiene) synthesized with ^tBuCl/TiCl₄ initiating system

Розенцвет¹,

Korovina²,

Иванова

et al. 2013

The microstructure of poly(1,3‐pentadiene) synthesized by cationic polymerization of 1,3‐pentadiene with tBuCl/TiCl4 initiating system is analyzed using one‐dimensional‐ and two‐dimensional‐NMR spectroscopy. It is shown that unsaturated part of chain contains only homo and mixed dyads with trans−1,4‐, trans−1,2‐, and cis−1,2‐structures with regular and inverse (head‐to‐head or tail‐to‐tail) enchainment, whereas cis−1,4‐ and 3,4‐units are totally absent. The new quantitative method for the calculation of content of different structural units in poly(1,3‐pentadiene)s based on the comparison of methyl region of 13C NMR spectra of original and hydrogenated polymer is proposed. The signals of tert‐butyl head and chloromethyl end groups are identified in a structure of poly(1,3‐pentadiene) chain and the new approaches for the quantitative calculation of number‐average functionality at the α‐ and ω‐end are proposed. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3297–3307

“…In the case of the coordination polymerization of 1,3‐pentadiene, the chemoselectivity and stereoselectivity as well as the catalytic activity of the polymerization reaction strongly depend on the types of monomer isomers and the resulting polymers usually exhibit different physical and chemical properties . In detail, various transition metal catalytic systems, for example, Co(acac) 3 –AlEt 2 Cl–H 2 O, Nd(OCOR) 3 –Al( i Bu) 3 –AlEt 2 Cl, Co(acac) 3 –MAO, VCl 3 –AlEt 3 , CoCl 2 (P i PrPh 2 ) 2 –MAO, have been employed for the polymerization of EP to give polypentadiene with a predominant structures of cis ‐1,4, trans ‐1,4 or 1,2‐units.…”

Section: Introductionmentioning

confidence: 99%

“…In detail, various transition metal catalytic systems, for example, Co(acac) 3 –AlEt 2 Cl–H 2 O, Nd(OCOR) 3 –Al( i Bu) 3 –AlEt 2 Cl, Co(acac) 3 –MAO, VCl 3 –AlEt 3 , CoCl 2 (P i PrPh 2 ) 2 –MAO, have been employed for the polymerization of EP to give polypentadiene with a predominant structures of cis ‐1,4, trans ‐1,4 or 1,2‐units. However, less reactive ZP isomer can only be polymerized by relatively limited catalytic systems to generate cis ‐1,4, cis ‐1,2, or a mixture of 1,2/1,4 structure, based on Ti(OnBu) 4 –AlEt 3 , CrCl 2 (dmpe) 2 –MAO, Cr(CH 3 ) 2 –(dmpe) 2 –MAO, and C p TiCl 3 –MAO 9 complexes. To the best of our knowledge, the yield of polypentadiene obtained by most reported catalysts can hardly reach to 90% within several hours, and the stereospecific polymerization shows almost no livingness due to the existence of the β‐elimination reaction or chain transfer reaction to the aluminum center of the co‐catalyst …”

Section: Introductionmentioning

confidence: 99%

Living anionic polymerization of (E)-1,3-pentadiene and (Z)-1,3-pentadiene isomers

Liu

Ren

et al. 2016

The anionic polymerization of (E)-1,3-pentadiene (EP) and (Z)-1,3-pentadiene (ZP) together with mixture of the E/ Z isomers are investigated, respectively. The kinetic analysis shows that the activation energy for EP (86.17 kJ/mol) is much higher than that for ZP (59.03 kJ/mol). GPC shows that it is the EP rather than the ZP isomer that undergoes anionic living polymerization affording quantitative products of the polymers with well-controlled molecular weights and narrow molecular weight distributions (1.05 -D 1.09). In addition, THF as polar additive has proved its validity to reduce the molecular weight distribution of poly (ZP) INTRODUCTIONThe asymmetrical 4-alkyl-and 4-aryl-substituted 1,3-butadiene derivatives, like 1,3-pentadiene and 2-methyl-1,3-pentadiene, usually have E and Z configurations which commonly display different thermodynamics stability and reaction activity. Especially for 1,3-pentadiene, (E)-1,3-pentadiene and (Z)-1,3-pentadiene (EP and ZP for short) isomers are both thermodynamically stable and the tautomerism is hardly observed at room temperature for the high barrier. 1 Thus, the investigation of the polymerization of EP