Synthesis of novel functional polyolefin containing carboxylic acid via Friedel-Crafts acylation reaction

The strong polar group, carboxylic acid, has triumphantly been introduced into ethylene and allylbenzene copolymers without obvious degradation or crosslinking via Friedel-Crafts (F-C) acylation reaction with glutaric anhydride (GA), succinic anhydride (SA) and phthalic anhydride (PA) in the presence of anhydrous aluminum chloride in carbon disulfide. Some important reaction parameters were examined in order to optimize the acylation process. In the optimum reaction conditions, almost all of the phenyls can be acylated with any anhydride. The microstructure of acylated copolymer was characterized by Fr-IR, H-1 NMR and H-1-H-1 COSY. All the peaks of acylated copolymers can be accurately attributed, which indicates that all the acylation reactions occur only at the para-positions of the substituent of the aromatic rings. The thermal behavior was studied by differential scanning calorimetry (DSC), showing that the melting temperatures (T(m)s) of acylated copolymers with GA firstly decrease slowly and then increase significantly with the increase of the amount of carboxyl acid groups.

Living Copolymerization of Ethylene with Norbornene Mediated by Heteroligated (Salicylaldiminato) (beta-enaminoketonato)Titanium Catalysts

Three heteroligated (salicylaldiminato)(beta-enaminoketonato)titanium complexes [3-Bu-t-2-OC6H3CH=N(C6F5)][(p-XC6H4)N=C(Bu-t)CHC(CF3)O]TiCl2 (3a: X = F, 3b: X = Cl, 3c: X = Br) were synthesized and investigated as the catalysts for ethylene polymerization and ethylene/norbornene copolymerization. In the presence of modified methylaluminoxane as a cocatalyst, these unsymmetric catalysts exhibited high activities toward ethylene polymerization, similar to their parallel parent catalysts. Furthermore, they also displayed favorable ability to efficiently incorporate norbornene into the polymer chains and produce high molecular weight copolymers under the mild conditions, though the copolymerization of ethylene with norbornene leads to relatively lower activities. The sterically open structure of the beta-enaminoketonato ligand is responsible for the high norbornene incorporation. The norbornene concentration in the polymerization medium had a profound influence on the molecular weight distribution of the resulting copolymer.

Novel polymer synthesis methodologies using combination of thermally and photochemically-induced nitroxide mediated polymerisation

The combination of thermally- and photochemically-induced polymerization using light sensitive alkoxyamines was investigated. The thermally driven polymerizations were performed via the cleavage of the alkoxyamine functionality, whereas the photochemically-induced polymerizations were carried out either by nitroxide mediated photo-polymerization (NMP2) or by a classical type II mechanism, depending on the structure of the light-sensitive alkoxyamine employed. Once the potential of the various structures as initiators of thermally- and photo-induced polymerizations was established, their use in combination for block copolymer syntheses was investigated. With each alkoxyamine investigated, block copolymers were successfully obtained and the system was applied to the post-modification of polymer coatings for application in patterning and photografting.

Iso-specific Ziegler-Natta polymerization of α-olefins with a single-component organoyttrium catalyst

The synthesis of a sterically tailored ligand array (M)_2((C_5H_2-2-Si(CH_3)_3-4-C(CH_3)_3)S_2i(CH_3)_2]("M_2Bp") (M = Li, 16; K, 19) is described. Transmetallation of Li_2Bp with YCl_3(THF)_3 affords exclusively the C_2 symmetric product rac-[BpY(µ_2-Cl)_2Li(THF)_2], 20. A X-ray crystal structure of 20 has been determined; triclinic, P1, a= 13.110 (8), b = 17.163 (15), c = 20.623 (14) Å, α = 104.02 (7), β = 99.38 (5), γ = 100.24 (6)° , Z = 4, R = 0.056. Transmetallation of K_2Bp with YCl_3(THF)_3 affords the halide free complex rac-BpYCl, 23. The corresponding rac-BpLaCl, 28, is prepared in an anlogous manner. In all cases the achiral meso isomer is not obtained since only for the racemic isomers are the unfavorable steric interactions between the Si(CH3)_3 groups in the narrow portion of the [Cp-M'-Cp] wedge avoided. Alkylation of 20 or 23 with LiCH(Si(CH_3)_3)_2 affords rac-BpYCH(Si(CH_3)_3)_2, 26 in good yield. Alkylation of 28 with LiCH(Si(CH_3)_3)_2 affords rac-BpLaCH(Si(CH_3)_3)_2 29. Hydrogenation of 26 cleanly affords the bridging hydride species [BpY(µ_2-H)]_2, 27, as the homochiral (R,R) and (S,S) dimeric pairs. 26 is an efficient initiator for the polymerization of ethylene to high molecular weight linear polyethylene. 27 catalyzes the polymerization of propylene (25% v/v in methylcyclohexane) and neat samples of 1-butene, 1-pentene, 1-hexene to moderately high molecular weight polymers: polypropylene (M_n = 4,200, PDI 2.32, T_m 157 °C); poly-1-butene (M_n = 8,500, PDI 3.44, T_m 105 °C); poly-1-pentene (M_n = 20,000, PDI 1.99, T_m 73 °C); poly-1-hexene (M_n = 24,000, PDI 1.75, T_m < 25 °C). ^(13)C NMR spectra at the pentad analysis level indicates that the degree of isotacticity is 99% mmmm for all polymer samples. 27 is the first single component iso-specific α-olefin polymerization catalyst. The presumed origins of the high isospecificity are presented.

Styrene polymerization catalyzed by metal porphyrin complex/MAO for in situ synthesizing polystyrene containing air stable pi cation radicals

A novel catalyst system based on nickel(II) tetraphenylporphyrin (Ni(II)TPP) and methylaluminoxane for styrene polymerization was developed. This catalyst system has a high thermal stability and show fairly good activity. The obtained polystyrene (PS) was isotactic-rich atactic polymer by C-13 NMR analysis, and its molecular weight distribution was rather narrow (M-w/M-n approximate to 1.6, by GPC analysis). ESR revealed that Ni(II)TPP pi cation radicals were formed in the polymerization and could remain in the resulting PS stably. The mechanism of the polymerization was discussed and a special coordination mechanism was proposed. The PS product containing Ni(II)TPP pi cation radicals can be used as a potential functional material.

Thiophene-NPN Ligand Supported Rare-Earth Metal Bis(alkyl) Complexes. Synthesis and Catalysis toward Highly trans-1,4 Selective Polymerization of Butadiene

A series of new rare-earth metal bis(alkyl) complexes [L(1-3)Ln(CH2SiMe3)(2)(THF)(n)] (L-1 = MeC4H2SCH2NC6H4(Ph)(2)P=NC6H2Me3-2,4,6: Ln = Sc, n = 1 (1a); Ln = Lu, n = 1 (1b); L-2 = MeC4H2SCH2NC6H4(Ph)(2)P=NC6H3Et2-2,6: Ln = Sc, n = 1 (2a); Ln = Lu, n = 1 (2b); Ln = Y, n = 1 (2c); L-3 = MeC4H2SCH2NC6H4(Ph)(2)P=(NC6H3Pr2)-Pr-i-2,6: Ln = Sc, n = 0 (3a)) and (LSc)-Sc-4(CH2SiMe3)(2()THF) (4a) (L-4 = C6H5CH2NC6H4(Ph)(2)P=NC6H3Et2-2,6) have been prepared by reaction of rare-earth metal tris(alkyl)s with the corresponding HL1-4 ligands via alkane elimination.

Ethylene polymerization, and the copolymerizations of ethylene with hexene or norbornene with highly active mono(beta-enaminoketonato) vanadium(III) catalysts

Five novel vanadium(III) complexes [PhN = C(R-2)CHC(R-1)O]VCl2(THF)(2) (4a: R-1 = Ph, R-2 = CF3; 4b: R-1 =t-Bu, R-2 = CF3; 4c: R-1 = CF3, R-2 = CH3; 4d: R-1 = Ph, R-2 = CH3; 4e: R-1 = Ph, R-2 = H) have been synthesized and characterized. On activation with Et2AlCl, all the complexes, in the presence of ethyl trichloroacetate (ETA) as a promoter, are highly active precatalysts for ethylene polymerization, and produce high molecular weight and linear polymers. Catalyst activities more than 16.8 kg PE/mmolv h bar and weight-average molecular weights higher than 173 kg/ mol were observed under mild conditions.

Ethylene Polymerization of the New Titanium Complexes Bearing a Phosphine Oxide-Bridged Bisphenolato Ligand

A series of novel titanium(IV) complexes combining a phosphine oxide-bridged bisphenolato ligand TiCl2{2,2'-O=P-R-3 (4-R-2-6-R-1-C6H2O)(2)}(THF) (6a: R-1 = tBu, R-2 - H, R-3 Ph; 6b: R-1 - Ph, R-2 = H, R-3 = Ph; 6c: R-1 = R-2 = tBu, R-3 = Ph; 6d: R-1 = R-2 cumyl, R-3 = Ph; 6e: R-1 = tBu, R-2 = H, R-3 = PhF5) were prepared by the reaction of corresponding bisphenolato ligands with TiCl4 in THF. X-ray analysis reveals that complex 6a adopts distorted octahedral geometry around the titanium center. These catalysts were performed for ethylene polymerization in the presence of modified methyaluminoxane (MMAO).

Polymerization of ethylene to branched polyethylene with silica and Merrifield resin supported nickel(II) catalysts with alpha-diimine ligands

Silica and Merrifield resin were used as carriers for the support of alpha-diimine nickel(II) precatalysts for ethylene polymerization. The alpha-diimine ligands containing allyl were modified by introducing the reactive Si-Cl end-group, allowing their immobilization via a direct reaction of the Si-Cl groups with the silanols on silica surface or the hydroxyls on the ethanolamine-modified Merrifield resin. The resulting supported alpha-diimine ligands were characterized by analytical and spectroscopic techniques (NMR and Fr-IR).

Synthesis, structural characterization, and ethylene polymerization behavior of the vanadium(III) complexes bearing salicylaldiminato ligands

Vanadium(III) complexes bearing salicylaldiminato ligands (2a-k) [RN=CH(Ar0)]VCl2(THF)2 (Ar C61714, R = Ph, 2a; p-CF3Ph, 2b; p-CH3Ph, 2c; 2,6-Me2Ph, 2d; 2,6-iPr2Ph, 2e; cyclohexyl, 2f; Ar = C6H3tBu(2), R = Ph, 2g; 2,6-iPr2Ph, 2h; Ar = C6H2tBU2(2,4), R = Ph, 2i; 2,6-iPr2Ph, 2j; Ar = C6H2Br2, R = Ph, 2k) were prepared from VC13(THF)3 by treating with 1.0 equiv of (RN=CH)ArOH in tetrahydrofuran (THF) in the presence of excess triethylamine (TEA).

Synthesis and characterization of titanium complexes bearing two beta-enaminoketonato ligands with electron-withdrawing groups and their behavior in ethylene polymerization

A series of new titanium complexes with two asymmetric bidentate beta-enaminoketonato (N,O) ligands (4b-t), [RN=CCF3)CHC(t-BU)O](2)TiCl2 (4b, R = -C6H4F(o); 4c, R = -C6H4F(m);4d, R = -C6H4F(p); 4e, R = - C6H3F2(2,3); 4f, R = -C6H3F2(2,4); 4g, R = -C6H3F2(2,5); 4h, R = -C6H3F2(2,6); 4i, R = -C6H3F2(3,4); 4j, R = -C6H3F2(3,5); 4k, R = -C6H2F3(2,3,4); 4l, R = -C6H2F3(3,4,5); 4m, R = -C6H4CF3(o); 4n, R =-C6H4CF3(m); 4o, R = -C6H4CF3(p); 4p, R = -C6H4Cl(p); 4q, R = -C6H4I(p); 4r, R = -C6H4NO2(P); 4s, R = -CH2C6H5; 4t, R = -C6H11), have been synthesized and characterized.

Highly Active Neutral Nickel(II) Catalysts for Ethylene Polymerization Bearing Modified,beta-Ketoiminato Ligands

A series of novel neutral nickel complexes 4a-e bearing modified beta-ketoiminato ligands [(2,6-(Pr2C6H3)-Pr-i)N=C(R-1)CHC(2 '-R2C6H4)O]Ni(Ph)(PPh3) (4a, R-1 R-2 = H; 4b, R-1 = H, R-2 = Ph; 4c, R-1 = H, R-2 = Naphth; 4d, R-1 = CH3, R-2 = Ph; 4e, R-1 = CF3, R-2 Ph) have been synthesized and characterized. Molecular structures of 4b and 4e were further confirmed by X-ray crystallographic analysis. Activated with B(C6F5)(3), all the complexes are active for the polymerization of ethylene to branched polyethylenes. Ligand structure, i.e., substituents R-1 and R-2, greatly influences not only catalytic activity but also the molecular weight and branch content of the polyethylene produced. The phenyl-substituted complex 4b exhibits the highest activity of lip to 145 kg PE/mol(Ni)center dot h center dot atm under optimized conditions, which is about 10 times more than unsubstituted complex 4a (14.0 kg PE/mol(Ni center dot)h center dot atm). Highly branched polyethylene with 103 branches per 1000 carbon atoms has been prepared using catalyst 4e.

Ethylene Polymerization by the New Chromium Catalysts Based on Amino-Pyrrolide Ligands

A series of amino-pyrrolide ligands (1-4a) and their derivatives aminothiophene ligand (5a), amino-indole ligand (6a) were prepared. Chromium catalysts, which were generated in situ by mixing the ligands with CrCl3(thf)(3) in toluene, were tested for ethylene polymerization. The preliminary screening results revealed that the tridentate amino-pyrrolide ligands containing soft pendant donor, 3a, 4a/CrCl3(thf)(3) systems displayed high catalytic activities towards ethylene polymerization in the presence of modified methyaluminoxane. The electronic and steric factors attached to the ligand backbone significantly affected both the catalyst activity and the polymer molecular weight. Complex 4b was obtained by the reaction of CrCl3(thf)(3) with one equivalent of the lithium salts of 4a, which was the most efficient ligand among the tested ones. The effect of polymerization parameters such as cocatalyst concentration, ethylene pressure, reaction temperature, and time on polymerization behavior were investigated in detail. The resulting polymer obtained by 4b display wax-like and possess linear structure, low molecular weight, and unimodal distribution.

Ethylene Polymerization and Ethylene/Hexene Copolymerization with Vanadium(III) Catalysts Bearing Heteroatom-Containing Salicylaldiminato Ligands

A series of novel vanadium(III) complexes hearing heteroatoill-containing group-substituted salicylaldiminato ligands [RN=CH(ArO)]VCl2(THF)(2) (Ar = C6H4, R = C3H2NS, 2a; C7H4NS, 2c; C7H5N2, 2d; Ar = C(6)H(2)tBu(2) (2,4), R = C3H2NS, 2b) have been synthesized and characterized. Structure of complex 2c was further confirmed by X-ray crystallographic analysis. The complexes were investigated as the catalysts for ethylene polymerization in the presence of Et2AlCl. Complexes 2a-d exhibited high catalytic activities (up to 22.8 kg polyethylene/mmolv h bar), and affording polymer with unimodal molecular weight distributions at 25-70 degrees C in the first 5-min polymerization, whereas produced bimodal molecular weight distribution polymers at 70 degrees C when polymerization time prolonged to 30 min. The catalyst structure plays an important role in controlling the molecular weight and molecular weight distribution of the resultant polymers produced in 30 min polymerization. In addition, ethylene/hexene copolymerizations with catalysts 2a-d were also explored in the presence of Et2AlCl, which leads to the high molecular weight and unimodal distributions copolymers with high comonomer incorporation.

Novel vanadium(III) complexes with bidentate N,N-chelating iminopyrrolide ligands: synthesis, characterization and catalytic behaviour of ethylene polymerization and copolymerization with 10-undecen-1-ol

A series of novel vanadium(III) complexes bearing iminopyrrolide chelating ligands [2-(RN=CH)C4H3N]V(THF)(2)Cl-2 (2a: R = cyclohexyl; 2b: R = Ph; 2c: R = 2,6-iPr(2)C(6)H(3); 2d: R = p-CF3C6H4; 2e: R = C6F5) have been synthesized and characterized. Single-crystal X-ray diffraction revealed that complexes 2a, 2c and 2e adopt an octahedral geometry around the vanadium center. In the presence of Et2AlCl as a co-catalyst, these complexes displayed high catalytic activities up to 48.6 kg PE mmol(V)(-1) h(-1) bar(-1) for ethylene polymerization, and produced high molecular weight polymers. 2a-e/Et2AlCl catalytic systems were tolerant to elevated temperature (70 degrees C) and yielded unimodal polyethylenes, indicating the single site behaviour of these catalysts. By pre-treating with equimolar amounts of alkylaluminums, functional alpha-olefin 10-undecen-1-ol can be efficiently incorporated into polyethylene chains. 10-Undecen-1-ol incorporation can easily reach 15.8 mol% under the mild conditions.