Copolymerization of ethylene and cyclopentene with bis(β‐enaminoketonato) titanium complexes

Abstract

The copolymerizations of ethylene and cyclopentene with bis(β‐enaminoketonato) titanium complexes {[(Ph)NC(R2)CHC(R1)O]2TiCl2; R1 = CF3 and R2 = CH3 for 1a, R1 = Ph and R2 = CF3 for 1b; and R1 = t‐Bu and R2 = CF3 for 1c} activated with modified methylaluminoxane (MMAO) as a cocatalyst were investigated. High‐molecular‐weight copolymers with cis‐1,2‐cyclopentene units were obtained. The catalyst activity, cyclopentene incorporation, polymer molecular weight, and polydispersity could be controlled over a wide range through the variation of the catalyst structure and reaction parameters, such as the Al/Ti molar ratio, cyclopentene feed concentration, and polymerization reaction temperature. The complex 1b/MMAO catalyst system exhibited the characteristics of a quasi‐living ethylene polymerization and an ethylene–cyclopentene copolymerization and allowed the synthesis of polyethylene‐block‐poly(ethylene‐co‐cyclopentene) diblock copolymer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1681–1689, 2005

Ring-opening polymerization of ε-caprolactone and cyclohexene oxide initiated by aluminum β-ketoamino complexes: steric and electronic effect of 3-position substituents of the ligands

“…Keywords:Gring-opening polymerization, ε-caprolactone, cyclohexene oxide, aluminum β-ketoamino complexesU Introdution Mono-anionic β-ketoamino ligand has emerged as one of the most versatile ligands in coordination chemistry for their strong metal-ligand bonds [1][2][3][4][5][6][7][8][9][10][11] and for their relatively facile tunablility to access derivatives containing a range of substituents around the ligands' skeleton. In the past, most work paid their attentions to the steric and electronic effects of substituents (R) on the nitrogen donor atom and side groups (R 1 and/or R 2 ) of these ligands backbone (see the Scheme I) of metal complexes on the catalyst behavior.…”

“…In the past, most work paid their attentions to the steric and electronic effects of substituents (R) on the nitrogen donor atom and side groups (R 1 and/or R 2 ) of these ligands backbone (see the Scheme I) of metal complexes on the catalyst behavior. [4][5][6][7][8][9] However, few investigations were focused on the effect of the substituents (X) on the 3-position of the β-ketoamino ligands skeleton. 10 The aluminum complexes draw considerable attention for both organic synthesis 12 and polymerization, 13 due to their strong Lewis acidity, relatively low toxicity, and ready availability.…”

Stereo-controlled synthesis of polyolefins with cycloalkane groups by using late transition metals

“…25 Compared with the corresponding homopolymers, the copolymerization of cyclic alkenes with ethylene or a-olefins produces polymers with cycloalkane groups in a relatively low density. [26][27][28][29][30][31][32][33][34] The average density of cyclic units along the polymer chain can be controlled by changing the molar ratio of monomers, and the polymer properties also vary accordingly. However, the accurate control of the distribution of cyclic units in the polymer chain has not been achieved.…”

Microstructure of Copolymers of Norbornene Based on Assignments of 13C NMR Spectra: Evolution of a Methodology

“…2D data allowed us to assign the other signals: (i) from the correlations of the two methyls in the HMBC spectrum, along the proton dimension, it was possible to assign the closest carbon atoms C3, C4, and C5; (ii) the methyl protons at 0.82 ppm, (CH3 at 22.69 ppm) correlate with three carbons at 26.77, 35.65, and 39.34 ppm, respectively, and allowed us to assign the C4 atom, C5 and C3 of trans stereoisomer; (iii) from HMBC spectrum, the resonances of the cis stereoisomer positioning at 30.36, 33.59, and 37.56 ppm were assigned to C5, C4, and C3, respectively; (iv) the other signals were assigned as follows: 42.18 ppm to C1; 37.14 ppm to C2; 33.73 ppm to C6 of the trans stereoisomer; 41.58 ppm to C1; 37.89 ppm to C2; 34.64 ppm to C6 of the cis stereoisomer. Figure 10 shows 13 C NMR spectra and a DEPT for poly(ethylene-co-1-MeCPE) prepared by ( t BuC5H4)TiCl2(O-2,6-Cl2C6H3)-MAO (8) Most resonances were assigned on the basis of DEPT spectra and comparison with those of poly(ethylene-co-CPE) [47][48][49][50][51][52][53].…”

“…HED can be inserted as a linear α-olefin; however, after insertion, Most resonances were assigned on the basis of DEPT spectra and comparison with those of poly(ethylene-co-CPE) [47][48][49][50][51][52][53].…”