Asymmetric oxidative coupling polymerization affording polynaphthylene with 1,1′-bi-2-naphthol units

The oxidative coupling polymerizations of racemic-, (R)-, and (S)-2,2′-dimethoxymethoxy-1,1′-binaphthalene-3,3′-diols were carried out with a copper catalyst with various ligands, such as N,N,N′,N′-tetramethylethylenediamine (TMEDA), (S)-(+)-1-(2-pyrrolidinylmethyl)pyrrolidine, (−)-sparteine, and (S)-(−)-2,2′-isopropylidenebis(4-phenyl-2-oxazoline) [(−)-Phbox], under an O₂ atmosphere. For example, a 10/1 (v/v) MeOH · H₂O-insoluble polymer with a number-average molecular weight of 3.8 × 10³, from a polymerization with CuCl–TMEDA followed by acetylation of the hydroxyl groups, was obtained in a 71% yield. Polymerization with (−)-Phbox proceeded in an S-selective manner to give a polymer with the highest negative specific rotation from the (S)-monomer. The obtained polymer was successfully converted into a polymer with the optically pure 1,1′-bi-2-naphthol unit based on the original monomer structure, which could be used as a polymeric chiral auxiliary and showed catalytic activity for the asymmetric diethylzinc addition reaction to aldehydes. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4528–4534, 2004     

Oxidative coupling polymerization of 2,3‐dihydroxynaphthalene with dinuclear‐type copper(II) catalyst

The oxidative coupling polymerization of 2,3‐dihydroxynaphthalene with the novel dinuclear‐type copper(II) catalysts successfully produced poly(2,3‐dihydroxy‐1,4‐naphthylene). For example, the MeOH‐insoluble polymer with a number average molecular weight of 4.4 × 10³ from the polymerization using the complex of CuCl₂ and N,N′‐bis(2‐morpholinoethyl)‐p‐xylylenediamine ( p ‐ 1 ) at room temperature under an O₂ atmosphere followed by acetylation of the hydroxyl groups was obtained in 63% yield. The structures of the tetraamine ligands and the counter anion of the copper(II) salts significantly influenced the catalyst activity. The polymerization of 2,2′‐dimethoxy‐1,1′‐binaphthalene‐3,3′‐diol with the 2CuCl₂‐ p ‐ 1 catalyst, however, resulted in a lower yield. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1635–1640, 2005     

Highly selective oxidative cross‐coupling polymerization with copper(I)‐bisoxazoline catalysts

The asymmetric oxidative coupling polymerization of methyl 6,6′‐dihydroxy‐2,2′‐binaphthalene‐7‐carboxylate with the copper‐diamine catalysts under an O₂ atmosphere was carried out. As is the case with the CuCl‐2,2′‐(S)‐isopropylidenbis(4‐phenyl‐2‐oxazoline) [(S)IPhO] catalyst, a polymer with a high cross‐coupling selectivity of 96% was obtained in 71% yield, whose THF‐soluble part had a number‐average molecular weight of 4.5 × 10³. To estimate the enantioselectivity with respect to the cross‐coupling linkage in the obtained polymer, the model asymmetric oxidative cross‐coupling reaction with CuCl‐(S)IPhO was also conducted, and the products showed a 94% cross‐coupling selectivity and enantioselectivity of 31% ee (S). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6287–6294, 2005     

Synthesis of hyperbranched polymer having binaphthol units via oxidative cross‐coupling polymerization

The oxidative coupling polymerization of triphenylamine derivatives having 2‐naphthol moieties with a CuCl‐2,2′‐isopropylidenebis(4‐phenyl‐2‐oxazoline) catalyst under an O₂ atmosphere was carried out. The polymerization of the monomer bearing both the hydroxynaphthoate and naphthol units afforded a hyperbranched polymer with a high cross‐coupling selectivity of > 99%, which showed a number‐average molecular weight of 20.3 × 10³. In addition, the obtained polymer was quite soluble in THF. The photoluminescence and electrochemical properties of the obtained polymers were also examined. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1034–1041, 2008     

Synthesis of regiocontrolled polymer having 2-naphthol unit by CuCl-amine catalyzed oxidative coupling polymerization

Regiocontrolled polymer (2) having 2-naphthol unit was prepared by oxidative coupling polymerization of bis(2-naphthol) (1). Polymerizations were conducted in dichloromethane in the presence of [di-μ-hydroxo-bis(N,N,N′,N′-tetramethylethylenediamine)copper(II)] chloride [CuCl(OH)TMEDA] under air at room temperature, producing polymers with number-average molecular weights up to 12,000. The structure of polymer 2 was characterized by 270 MHz ¹H–NMR and 68.5 MHz ¹³C–NMR spectroscopies and was estimated to consist almost completely of 1,1′-linkage. The polymer was readily soluble in polar aprotic solvents and tetrahydrofuran at room temperature. Thermogravimetric analysis of polymer 2 showed 10% weight loss at 450°C in nitrogen. The model reactions were studied to clarify the applicability of CuCl(OH)TMEDA for coupling of naphthol derivatives. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3702–3709, 1999     

Characterization of vanadium-based olefin polymerization catalyst precursors by solid-state 51v-nmr

Several VOCL₃-based ethylene polymerization catalyst precursors were prepared on silica and studied by solid-state ⁵¹V-NMR. The structure of the vanadium species in these samples, as determined by ⁵¹V-NMR, did not have any significant effect on the resultant polyethylene MI or MWD. This result is significant since conventional wisdom says the attachment of the transition metal to the silica plays a key role in polymer properties. VOCl₃ reacted with hexamethyldisilazane-treated silica and with 250°C dried silica results in double attachment of the vanadium to the silica, yet the catalysts which formed had different reactivities and produced polyethylene with different HLMIs. On the other hand, VOCl₃ reacted with 600°C dried silica results in single attachment of the vanadium to the silica, yet this catalyst had a similar reactivity and produced polymer properties similar to the doubly attached vanadium on 250°C dried silica. Two theories are offered to explain the lack of correlation between catalyst precursor structure and catalyst performance. © 1995 John Wiley & Sons, Inc.     

Emitting stability of poly（9,9-dialkylfluorene-co-N-butylcarbazole） by solid-state oxidative coupling polymerization

Dihexylfluorene and N-butylcarbazole were copolymerized by solid-state oxidative coupling polymerization in the presence of anhydrous FeCl_3 at room temperature.The solid-state films of the copolymers emitted blue light after heating at 150℃in air for 24 h,no red-shifted emission was observed by fluorescence spectroscopy.     

Synthesis of regiocontrolled poly(4,6-di-n-butoxy-1,3-phenylene) by oxidative coupling polymerization

Poly(4,6-di-n-butoxy-1,3-phenylene) ( 6 ) was prepared by oxidative coupling polymerization of 1,3-di-n-butoxybenzene ( 1 ) or 2,2′,4,4′-tetra-n-butoxy biphenyl (3). Polymerizations were conducted in nitrobenzene in the presence of FeCl₃ at room temperature and produced polymers with number-average molecular weights up to 42,000. The effects of various factors, such as amount of FeCl₃ and reaction temperature and time were studied. The structure of polymer 6 was characterized by 270 MHz ¹H- and 68.5 MHz ¹³C-NMR spectroscopies and was estimated to consist of almost completely 1,3-linkage. The regiocontrolled polymer was readily soluble in common organic solvents. Thermogravimetric analysis of polymer 6 showed 10% weight loss at 390°C in nitrogen. © 1997 John Wiley & Sons, Inc. J Polym Chem 35 : 2259–2266, 1997     

Multi-electron transfer process of vanadyl complexes for oxidative polymerization of diphenyl disulfide

Oligo(p-phenylene sulfide) is synthesized by oxidative polymerization of diphenyl disulfide with oxygen catalyzed by vanadyl acetylacetonate under strongly acidic conditions. The mechanistic studies reveal that the redox cycles of the vanadyl complexes give rise to catalysis through a two-electron transfer between diphenyl disulfide and molecular oxygen. The VO catalysts act as an excellent electron mediator to bridge a 1.0 V potential gap between the oxidation potential of disulfides and the reduction potential of oxygen. The VO-catalyzed oxygen-oxidative polymerization provides pure oligo(pphenylene sulfide)s containing an S–S bond. The polymeric product is of low molecular weight due to the insolubility under these conditions. (N,N′-ethylenebis(salicylideneaminato))oxovanadium-(IV), VO(salen), was used as an inert model compound to elucidate the redox chemistry of the vanadium complex. VO(salen) reacts with trifluoromethanesulfonic acid (CF₃SO₃H) or triphenylmethyl tetrafluoroborate (?₃C(BF₄)) to form a deoxygenated complex, V^IV(salen)²⁺, and a μ-oxodinuclear complex, [(salen)VOV(salen)]X₂, (X = CF₃SO₃^? or BF₄^?). The dimerization of VO(salen) is initiated by deoxygenation to produce V(salen)²⁺ which enters into an equilibrium with a second VO(salen) complex to produce the μ-oxo dimer. The two-electron transfer of the μ-oxo dinuclear vanadium complex is elucidated.     

Magnetic methylene-based mesoporous organosilica composite-supported IL/Pd: a powerful and highly recoverable catalyst for oxidative coupling of phenols and naphthols

A novel magnetic methylene-based mesoporous organosilica composite-supported IL/Pd complex (Fe₃O₄@MePMO-IL/Pd) was synthesized and characterized, and its catalytic performance was investigated. The preparation of the Fe₃O₄@MePMO composite was achieved through coating of Fe₃O₄ nanoparticles with a mixture of tetramethoxysilane, bis(triethoxysilyl)methane, and (3-chloropropyl)-trimethoxysilane in the presence of cetyltrimethylammonium bromide surfactant. The Fe₃O₄@MePMO was then modified with alkyl imidazolium ionic liquid and palladium species to deliver the Fe₃O₄@MePMO-IL/Pd nanocatalyst. This catalyst was characterized using Fourier transform infrared, thermal gravimetric, wide-angle powder X-ray diffraction, low-angle powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometer, energy-dispersive X-ray, and nitrogen adsorption–desorption analyses. The Fe₃O₄@MePMO-IL/Pd was effectively used as a highly recoverable and durable catalyst for the selective oxidative coupling of phenols and 2-naphthols under aerobic conditions.     

Oxidative coupling polymerization of bishydrazide for the synthesis of poly(diacylhydrazine): Oxidative preparation of oxidatively degradable polymer

The oxidative coupling polymerization of bishydrazide is successfully performed to form poly(diacylhydrazine) (PDAH), which is an oxidatively degradable polymer. Oxone is an effective oxidant, and a mixture of an aprotic polar solvent, water, and acetonitrile or N,N‐dimethylacetamide is necessary as the solvent. On treatment of PDAH with sodium hypochlorite solution or hydrogen peroxide, the PDAH is rapidly oxidized and degraded to the corresponding dicarboxylic acid. When hydrogen peroxide is used as the oxidant, the addition of acetonitrile and potassium carbonate is necessary for effective degradation. PDAH exhibits high thermal stability in air and a high T_g value. No oxidation is observed in air. Thus, PDAH is an oxidatively degradable high‐performance polymer that is stable toward oxygen. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Formation of regioregular head‐to‐tail poly[3‐(4‐butylphenyl)thiophene] by an oxidative coupling polymerization with vanadium acetylacetonate

The mechanism for the formation of head‐to‐tail (H–T) poly[3‐(4‐butylphenyl)thiophene] by oxidative coupling polymerization with a catalytic amount of vanadium acetylacetonate was investigated. Polymerization was carried out in the presence of vanadium acetylacetonate, trifluoromethane sulfonic acid, and trifluoroacetic anhydride under an oxygen atmosphere in 1,2‐dichloroethane at room temperature. Polymers and oligomers obtained after several polymerization times were characterized by gel permeation chromatography, IR, and NMR spectroscopies. With these findings and the reactivity of monomer and dimers based on ab initio density functional theory, the polymerization was found to proceed mainly through the formation of H–T linkages due to the high spin density at the 2‐position of 3‐(4‐butylphenyl)thiophene and the calculated total energy of dimers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2287–2295, 2001     

Ethylenebis(5‐chlorosalicylideneiminato)vanadium dichloride immobilized on MgCl2‐based supports as a highly effective precursor for ethylene polymerization

Ethylenebis(5‐chlorosalicylideneiminato)vanadium dichloride supported on MgCl₂(THF)₂ or on the same carrier modified by Et_nAlCl_3?n, where n = 1–3, was used in ethylene polymerization in the presence of MAO or a common alkylaluminium compounds as a cocatalyst. The support type alter vanadium loading and also change the characteristic of the catalytic active sites. Et₂AlCl is the best activator for a catalyst which has been immobilized on a nonmodified support, whereas the systems which contain a carrier which has been modified by an organoaluminium compound reveal the highest activity in conjunction with MAO. That difference, together with different temperature effects on polymerization efficiency (i.e., decrease and increase of catalytic activity for increasing temperatures, respectively) suggest the formation of different types of active sites in the catalytic systems supported on modified and nonmodified magnesium carrier. However, all supported precatalysts possess a long lifetime, still being active towards ethylene polymerization after 2 h. All the systems yield wide MWD polyethylene, while bimodal MWD is found for some part of analyzed samples. Polyethylene with bimodal particle size distribution is formed with the system which contain modified carriers at higher temperatures. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3480–3489, 2009     

Synthesis of polymer microspheres functionalized with chiral ligand by precipitation polymerization and their application to asymmetric transfer hydrogenation

Monodisperse, crosslinked poly(divinylbenzene) and poly(methacrylic acid‐co‐ethylene glycol dimethacrylate) microspheres with (1R,2R)‐N¹‐toluenesulfonyl‐1,2‐diphenylethylene‐1,2‐diamine ((R,R)‐TsDPEN) moiety were successfully prepared by precipitation polymerization. Introduction site of the (R,R)‐TsDPEN moiety into the polymer microspheres could be controlled by changing the order of addition of the corresponding monomers. The functionalized polymer microspheres were applied to asymmetric transfer hydrogenation of ketone and imine. Polymer microsphere‐supported chiral catalysts showed good reactivity and enantioselectivity in the catalytic asymmetric transfer hydrogenations. Chiral secondary alcohol was quantitatively obtained with 94% ee in the asymmetric transfer hydrogenation of acetophenone in water. We also found that introduction site of the chiral catalyst and hydrophobicity of the microspheres, as well as degree of the crosslinking, affected the yield and enantioselectivity of chiral product in this reaction. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3340–3349, 2010     

Highly active and thermo-stable iminopyridyl vanadium oxychloride catalyzed isoprene polymerization

Stereoregular polymerizations are of high importance, which disclosing the relationships between microstructures and physical properties of polymers. In this contribution, a series of iminopyridyl vanadium oxychloride complexes V1 – V8 (R = H, R¹ = CH₂Ph for V1 ; R = H, R¹ = CHPh₂ for V2 ; R = H, R¹ = octamyl for V3 ; R = H, R¹ = Ph for V4 ; R = H, R¹ = 4-OMe-C₆H₄ for V5 ; R = H, R¹ = 4-CF₃ C₆H₄ for V6 ; R = H, R¹ = 2,4,6-Ph₃ C₆H₂ for V7 and R = Me, R¹ = Ph for V8 ) have been prepared, and were investigated for their catalytic capacity of isoprene polymerization. A single crystal structure of V7′ was reported, which was reduced from V(v) to V(iv) in the oxidation state of vanadium central atom. The catalytic activity was up to 408 kg (mol V)⁻¹ hr⁻¹, when V4 was used. The catalyst V6 was found to be highly thermo-stable with excellent activity even at 100°C. Most importantly, resultant polymers mainly possessed cis-1,4 units (up to 75%) with 25% side-chain 3,4 functional group, which is particularly important component to enhance the application of these synthetic rubbers.     

Synthesis,structural characterization,and ethylene polymerization behavior of (arylimido)vanadium(V) complexes bearing tridentate Schiff base ligands

A series of novel (arylimido)vanadium(V) complexes bearing tridentate salicylaldiminato chelating ligands, V(N‐2,6‐Me₂C₆H₃)Cl₂[(O‐2‐^tBu‐4‐R‐C₆H₃)CH?ND] (R = H, D = 2‐CH₃O? C₆H₄ ( 2a ); 2‐CH₃S? C₆H₄ ( 2b ); 2‐Ph₂P? C₆H₄ ( 2c ); 8‐C₉H₆N (quinoline) ( 2d ); CH₂C₅H₄N ( 2e ); R = ^tBu, D = 2‐Ph₂P? C₆H₄ ( 2f )), were prepared from V(NAr)Cl₃ by reacting with 1.0 equiv of the ligands in the presence of triethylamine in tetrahydrofuran. These complexes were characterized by ¹H, ¹³C, ³¹P, and ⁵¹V NMR spectra and elemental analysis. The structures of 2c and 2f were further confirmed by X‐ray crystallographic analysis. These (arylimido)vanadium(V) complexes are effective catalyst precursors for ethylene polymerization in the presence of Et₂AlCl as a cocatalyst and ethyl trichloroacetate as a reactivating agent. Complex 2c with a ? PPh₂ group in the sidearm was found to exhibit an exceptional activity up to 133800 kg polyethylene/mol_V h for ethylene polymerization at 75 °C, which is one of the highest activities displayed by homogeneous vanadium(V) catalysts at high temperature. Moreover, high molecular weight polymers with unimodal molecular weight distribution can be obtained, indicating the single site behavior of these catalysts. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2633‐2642     

Effect of lithium addition on the performance of proton-conducting catalysts for oxidative coupling of methane under microwave irradiation

The oxidative coupling of methane over lithium modified proton-conducting catalysts irradiated by microwaves has been studied. Compared with protonconducting catalysts, lithium addition to proton-conducting catalysts resulted in changes in product species and product selectivities, favoring the production of C₂ compounds.     

Ethylene polymerization and ethylene/hexene copolymerization by vanadium(III) complexes bearing bidentate phenoxy‐phosphine oxide ligands

A series of novel vanadium(III) complexes bearing bidentate phenoxy‐phosphine oxide [O,P=O] ligands, (2‐R₁‐4‐R₂‐6‐Ph₂P=O‐C₆H₂O)VCl₂(THF)₂ ( 2a : R₁ = R₂ = H; 2b : R₁ = F, R₂ = H; 2c : R₁ = tBu, R₂ = H; 2d : R₁ = Ph, R₂ = H; 2e : R₁ = R₂ = Me; 2f : R₁ = R₂ = tBu; 2g : R₁ = R₂ = CMe₂Ph) have been synthesized by adding 1 equiv of the ligand to VCl₃(THF)₃ dropwise in the presence of excess triethylamine. Under the same conditions, the adding of VCl₃(THF)₃ to 2.0 equiv of the ligand afforded vanadium(III) complexes bearing two [O,P=O] ligands ( 3c , 3f ). All the complexes were characterized by FTIR and mass spectra as well as elemental analysis. Structures of complexes 2c and 3c were further confirmed by X‐ray crystallographic analysis. On activation with Et₂AlCl and ethyl trichloroacetate, these complexes displayed high catalytic activities for ethylene polymerization (up to 26.4 kg PE/mmol_V·h·bar) even at high reaction temperature (70 °C) indicative of high thermal stability, and produced high molecular weight polymers with unimodal molecular weight distributions. Additionally, the complexes with optimized structure exhibited high catalytic activities for ethylene/1‐hexene copolymerization. Catalytic activity, comonomer incorporation, and polymer molecular weight can be controlled in a wide range via the variation of catalyst structure and the reaction parameters such as Al/V molar ratio, comonomer feed concentration, and reaction temperature. The monomer reactivity ratios r_E and r_H were determined according to ¹³C NMR spectra, which indicated these complexes preferred ethylene to 1‐hexene in the copolymerization. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5298–5306     

Electroactive polyimide with oligoaniline in the main chain via oxidative coupling polymerization

By oxidative coupling polymerization of the imidic macromonomer of oligoaniline and p-phenylenediamine we have prepared an electroactive polyimide, exhibiting exciting molecular structure, electrochemical properties and excellent thermal stability. The polymerization characteristics and structure of the electroactive polyimide were systematically studied by Fourier-transform infrared (FTIR) spectra and X-ray powder diffraction (XRD). Electrochemical activity of the polyimide was tested in 1.0 M H₂SO₄ aqueous solution and it shows two redox peaks, which is the same as that of polyaniline. Moreover, the thermal properties of the polyimide were evaluated by thermogravimetric analysis (TGA). Its electrical conductivity is about 8.87 × 10⁻⁶ S cm⁻¹ at room temperature upon preliminarily protonic-doped experiment.