Living polymerization of substituted acetylenes by a novel ternary catalyst,MoOCl4?Et2Zn?EtOH

A novel molybdenum oxytetrachloride (MoOCl₄)-based ternary catalyst, molybdenum oxytetrachloride/diethylzinc/ethanol (MoOCl₄? Et₂Zn? EtOH), induces the living polymerization of o-(trifluoromethyl)phenylacetylene. A catalyst composition of MoOCl₄:Et₂Zn: EtOH (mole ratio = 1:1:3) and anisole as polymerization solvent are favorable. The ratio of weight- to number-average molecular weights M _w/M _n of the polymer was as small as 1,03, and the initiator efficiency was 8%. Living polymerization was verified by multistage polymerization. The polymerization proceeded in a living fashion in the temperature range from 0 to 30°C. The catalyst yielded polymers with small M _w/M _n values also from other phenylacetylenes with bulky ortho substituents and 1-chloro-1-octyne.     

Living polymerization of several substituted acetylenes with WOCl4–Bu4Sn–tert‐BuOH (1 : 1 : 1) as a catalyst

Living polymerization of several substituted acetylenes was studied with a W‐based ternary catalyst, WOCl₄–Bu₄Sn–tert‐BuOH (1 : 1 : 1). [o‐(Trimethylsilyl)phenyl]acetylene forms a polymer with a narrow molecular weight distribution (MWD) (M_w/M_n 1.08). The living nature of this polymerization system was proved by both multistage polymerization and the conversion dependence of the polymer molecular weight. Linear internal alkynes (e. g., 5‐dodecyne) also yield polymers with a narrow MWD (M_w/M_n ∼︁ 1.10), which were proven to be obtained by living polymerization by examination of the conversion dependence of the polymer molecular weight. However, neither 1‐chloro‐1‐alkynes nor tert‐butylacetylene, polymerize in a living fashion with this catalyst. A block copolymer was selectively prepared by sequential polymerization of [o‐(trimethylsilyl)phenyl]acetylene and [o‐(trifluoromethyl)phenyl]acetylene.     

Living coordination polymerization of end‐allenyloxy poly(ethylene glycol) macromonomer by a π‐allylnickel catalyst

The living coordination polymerization of end‐allenyloxy poly(ethylene oxide)s ( 2A – 2C ) was carried out by [(η³‐allyl)NiOCOCF₃]₂ ( 1 ) in the presence of PPh₃ to produce narrowly dispersed polyallenes bearing poly(ethylene oxide) side chains. For instance, the polymerization of 2B (M_n = 590, [ 2 ]/[ 1 ] = 100) proceeded smoothly to give a polymer (M_n = 39 800, M_w/M_n = 1.13) in high yield. The molecular weight of poly( 2 ) could be controlled by the ratio of 2 to 1 and by the molecular weight of 2 . The block copolymers of 2B with various alkoxyallenes ( 3A – 3C ) or with 1‐phenylethyl isonitrile ( 3D ) were also obtained by the two‐stage copolymerization process (i. e., the polymerization of 2 , followed by that of 3A – 3D ). The resulting block copolymers were found to serve as polymeric surfactants in the polymer blend systems of PSt and PMMA.     

Synthesis of new polymers containing α-(trifluoromethyl)-acrylate units

Free radical polymerization of both α-(trifluoromethyl)acrylic acid (TFMAA) and its methyl ester MTFMA is shown to be possible in the presence of bis(4-tert-butylcyclohexyl) peroxycarbonate (Percadox) as initiator and dioxane or THF as solvent. Also it is shown that copolymers of TFMAA with α-olefins (1-decene, 2-methyl-1-hexene) and of methyl α-(trifluoromethyl)acrylate (MTFMA) with vinyl ethers (butyl, 2-ethylhexyl, and menthyl vinyl ether) can be simply obtained with AIBN as initiator; these copolymers have a predominantly alternating structure.     

Protection and polymerization of functional monomers, 26. Synthesis of well-defined poly[4-(3′-butynyl)styrene] by means of anionic polymerization of 4-(4′-trimethylsilyl-3′-butynyl)styrene

Anionic polymerization of 4-(4′-trimethylsilyl-3′-butynyl)styrene ( 2 ) was carried out in THF at ?78°C for 0.5 h with oligo(α-methylstyryl)lithium, -dilithium, and -dipotassium. Poly( 2 )s possessing predicted molecular weights and narrow molecular weight distributions (M?_w/M?_n < 1.11) were quantitatively obtained in all cases. By sequential anionic copolymerization of 2 and styrene, novel block copolymers, polystyrene-block-poly( 2 ) starting either from living polystyrene or living poly( 2 ), were synthesized. After completion of the polymerization, there occurred some gradual deactivation of the propagating carbanion of poly( 2 ) at ?78°C. This deactivation reaction could be almost completely suppressed at ?95°C. The deprotection of poly( 2 ) was performed by treating with Bu₄NF in THF at 0°C for 1 h. The trimethylsilyl protecting group of poly( 2 ) was completely removed to afford a poly[4-(3′-butynyl)styrene] of a controlled molecular structure.     

Copolymerization of propene and higher α-olefins with the metallocene catalyst Et[Ind]2HfCl2/methylaluminoxane

Copolymerizations of propene with higher α-olefins including 1-butene, 1-hexene, 1-octene, 1-dodecene and 1-hexadecene were carried out with an isospecific metallocene catalyst (Et[Ind]₂HfCl₂/methylaluminoxane) at 30°C in toluene. ¹³C NMR analysis showed that all products obtained are random copolymers (r₁ · r₂ ～ 1). The reactivity of the higher α-olefins in the copolymerization is surprisingly high and decreases only slightly with increasing length of the olefin. The incorporation rates of the comonomers in this study were found to be much higher than those obtained by the use of heterogeneous Ziegler-Natta catalysts. Hence, copolymers with every desired composition and α-olefin homopolymers can be prepared. The molecular weight of the copolymers is reduced with rising comonomer content. Melting points and glass transition temperatures studied by means of differential scanning calorimetry show a decrease with rising comonomer content and increasing length of the α-olefin.     

Electrochemical polymerization of 1H,7H-pyrrolo[2′,3′:4,5]-thieno[3,2-b]pyrrole and 4H-dithieno[3,2-b;2′,3′-d]pyrrole

Electrochemical polymerization of 1H,7H-pyrrolo[2′,3′:4,5]thieno[3,2-b]pyrrole and 4H-dithieno[3,2-b;2′,3′-d]pyrrole in CH₃CN + 0,1 M p-toluenesulfonate and tetraethylammonium perchlorate, respectively, yields polymers with a conductivity of ca. 5 S/cm. Electrochemistry and elemental analysis indicate the presence of 0,6-0,7 anions per monomeric unit, while spectroelectrochemistry agrees with a polypyrrole structure for polypyrrolothienopyrrole and a polythiophene structure for polydithienopyrrole. The redox cycle for polypyrrolothienopyrrole (at ?0,53 V vs. Ag/Ag⁺) is close to that of polypyrrole, while that of polydithienopyrrole (at 0,0 V) is intermediate between those of polythiophene and polypyrrole. N-Alkylsubstituted dithienopyrroles produce soluble polymers with higher conductivity (40 S/cm) and the lowest band-gap (1,7 eV) ever reported for a polythiophene-like polymer.     

Synthesis of ethylene‐α‐olefin alternating copolymers with Et(1‐Ind)(9‐Flu)ZrCl2‐MAO catalyst system

Copolymerizations of ethylene and α‐olefins (4‐methyl‐1‐pentene, 1‐hexene, 1‐decene and 1‐hexadecene) were carried out with Et(1‐Ind)(9‐Flu)ZrCl₂‐MAO as the catalyst system. The degree of alternation in the resulting copolymers is higher than 92.1% for all the copolymers and close to 100% for ethylene‐1‐decene copolymer. Copolymerization behaviours focusing on the misinsertions during the polymerizations are investigated in detail from dyad and triad distributions estimated by ¹³C NMR analysis of copolymers. A reactivity ratio, r^B_E, was obtained for ethylene‐1‐hexene copolymers using a simplified two sites alternating mechanism and found to be 8.7, which is the same order of that reported in ethylene‐propene copolymerizations with Me₂C(3‐RCp)(Flu)ZrCl₂‐MAO as the catalyst system.     

Living coordination polymerization of allene (1,2‐propadiene) by π‐allylnickel catalyst and selective hydrosilylation reaction of polymers having polyallene units

The coordination polymerization of allene (1,2‐propadiene, 2A ) was carried out by [(η³‐allyl)NiOCOCF₃]₂ ( 1 ) to obtain narrowly dispersed poly( 2A ) in high yield. The linear relationship between the ratio of 2A/1 and the molecular weight of the polymer supported the living character of the polymerization. The block copolymer of 2A with 1‐phenylethyl isonitrile ( 2B ) was obtained in a two‐stage process, the polymerization of 2A followed by that of 2B . Hydrosilylation of poly( 2A ) or poly( 2A )‐block‐poly( 2B ) with silicon hydrides ( 3A and 3B ) in the presence of H₂PtCl₆ catalyst successfully incorporated the silyl groups into the polyallene segments.     

4-(α,α-dimethylbenzyl)phenyl methacrylate, 1. Synthesis and crystal structure

4-(α,α-dimethylbenzyl)phenyl methacrylate ( 1 ) was prepared by reaction of 4-(α,α-dimethylbenzyl)phenol and methacryloyl chloride in ether. By careful crystallization from ether large monoclinic crystals could be obtained with the following crystal data: a = 6,622 (2) Å, b = 12,578 (2) Å, c = 9,892 (3) Å, β = 99,86° (3), D_c = 1,147 g · cm^?3, V = 811,1 ų, M = 280,4, λ = 0,7107 Å, μ = (Mo K_α) = 0,7 cm^?1, F(000) = 300, space group P2₁, Z = 2. Attempts to polymerize the monomer (m.p. 46–48°C) by γ-irradiation at ambient temperature gave only a small amount of a crosslinked product.     

Asymmetric radical polymerization of (–)-3-p-menthyl sorbate

The radical polymerization of (–)-3-p-menthyl sorbate ( 2 ) was performed with azoisobutyronitrile (AIBN) as an initiator in benzene at 50°C. The chiral (–)-menthyl group in the resulting poly- 2 was removed by hydrolysis in potassium hydroxide solution to give optically active poly(sorbic acid), indicating that an asymmetric induction took place during the polymerization. It was concluded from the results of ozonolysis and optical rotatory dispersion measurements on the poly(sorbic acid) that the asymmetry was induced only at 1-position of the monomeric unit in the poly- 2 main chain.     

Poly(2-[α-3H]vinylpyridine 1-oxide)

Poly(2-vinylpyridine 1-oxide), when injected into animals, counteracts the pathogenic effects of inhaled silica dust. To study its distribution in the cells, a specifically labelled polymer has been synthesised by reducing 2-acetylpyridine with tritium, dehydrating, polymerising then oxidizing the polyvinyl product. Some of the tritium (17%) enters the aromatic ring by exchange and there is a small loss of tritium by exchange with solvents. At the stage of reduction, there is preference for C? T bond formation rather then C? H.     

Synthesis and characterization of new cardo polyamides derived from 8,8-bis[4-(4-aminophenoxy)phenyl]tricyclo[5.2.1.02,6]decane

A series of novel cardo polyamides were prepared by direct polycondensation of 8,8-bis[4-(4-aminophenoxy)phenyl]tricyclo[5.2.1.0^2,6]decane and various aromatic dicarboxylic acids in N-methyl-2-pyrrolidinone (NMP) using triphenyl phosphite and pyridine as condensing agents. The polymers were produced with high yield and moderate to high inherent viscosities of 0.71–1.40 dL·g^–1. Nearly all the polymers could be readily dissolved in polar aprotic solvents such as NMP, N,N-dimethylacetamide (DMAc) and N,N-dimethylformamide, dimethyl sulfoxide as well as less polar solvents such as pyridine and γ-butyrolactone. The polymers were solution-cast from DMAc solution into transparent, flexible, and tough films which were further characterized by X-ray and mechanical analysis. Nearly all the polymers were amorphous, and the polyamide films had a tensile strength range of 97–111 MPa, an elongation at break range of 9–11%, and a tensile modulus range of 1.9–2.3 GPa. The polyamides had glass transition temperatures between 251–272°C and 10% weight loss temperatures in the range of 468–490 and 499–532°C in nitrogen and air atmosphere, respectively.     

4-(α,α-dimethylbenzyl)phenyl methacrylate, 2. Polymerization in N,N-dimethylformamide

The polymerization rate of 4-(α,α-dimethylbenzyl)phenyl methacrylate in DMF at 70°C is of the order 1,6 in [monomer] and first order in [AIBN], which deviates from classical kinetics. This could be reconciled by a reaction scheme in which dimeric monomer associates and a spontaneous termination are postulated. The scheme is supported by the dependence of the kinetic chain length, v, on the 1,6-th power in [monomer] and zeroth power in [AIBN]. The degree of polymerization is smaller than v, which indicates some chain transfer. A remarkable feature is the constancy of the dispersion degree, M?_w/M?_n, of the polymers of about 1,4 up to high degrees of conversion. The overall activation energy of the polymerization, E_a, is 60,1 kJ · mol^?1, and the preexponential factor ln A ≈ 15,5 (A in (mol · dm^?3)^?1,5 · s^?1). The polymer chains seem to have a rod-like character in THF as deduced from the Mark-Houwink exponent of 1,46. In toluene the polymer tends to form associates.     

Synthesis of 2,3,4-tri-O-benzyl-[1→6]-α-D-glucopyranan and [1→6]-α-D-glucopyranan with high molecular weight by polymerization of 1,6-anhydro-2,3,4-tri-O-benzyl-β-D-glucopyranose

The polymerization mechanism of 1,6-anhydro-2,3,4-tri-O-benzyl-β-D -glucopyranose ( 1 ) was investigated in order to synthesize 2,3,4-tri-O-benzyl-[1→6]-α-D -glucopyranan ( 2a ) and [1→6]-α-D -glucopyranan ( 2b ) (dextran) with high molecular weight. It was found that the optimum polymerization time to obtain high molecular weights was 40min when the monomer was polymerized in methylene chloride at ?60°C. Stereoregular 2a with a \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {DP} _{\rm n} $ of 1800 (M?_n = 777000), which was about twice as high as the highest \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {DP} _{\rm n} $ previously reported, was obtained in 77% yield by polymerizing the monomer with 0.8 mole-% PF₅ as catalyst applying a monomer-to-solvent weight/volume ratio of 50%. 2a with a high molecular weight was debenzylated to give 2b with a \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {DP} _{\rm n} $ of 446 (M?_n = 72300). The α-stereospecificity and the solid state of the synthetic dextran were investigated by means of optical rotation, NMR spectroscopy, and X-ray diffraction pattern.     

1-[4-Fluoro-2-(2-nitrovinyl)phenyl]pyrrolidine Suppresses Toll-Like Receptor 4 Dimerization Induced by Lipopolysaccharide

Toll-like receptor 4 (TLR4) recognizes LPS and triggers the activation of the myeloid differential factor 88 (MyD88)- and toll-interleukin-1 receptor domain-containing adapter, inducing interferon-β (TRIF)-dependent major downstream signaling pathways. Previously, we presented biochemical evidence that 1-[4-Fluoro-2-(2-nitrovinyl)phenyl]pyrrolidine (FPP), which was synthesized in our laboratory, inhibits NF-κB activation induced by LPS. Here, we investigated whether FPP modulates the TLR4 downstream signaling pathways and what anti-inflammatory target in TLR4 signaling is regulated by FPP. FPP inhibited LPS-induced NF-κB activation by targeting TLR4 dimerization. These results suggest that FPP can modulate the TLR4 signaling pathway at the receptor level to decrease inflammatory gene expression.     

Propene polymerization with δ-TiCl3/AlCl(C2H5)2 and δ-TiCl3/Al(C2H5)3 catalyst systems, 1. Effect of external donors

The effect of ethyl benzoate (EB), diisobutyl phthalate (DIBP), dibutyl ether (DBE) and triethoxy(phenyl)silane (EPS) as third components on the propene polymerization with the catalyst systems δ-TiCl₃/AlCl(C₂H₅)₂ and δ-TiCl₃/Al(C₂H₅)₃ was investigated. The influence of external donors on the isotacticity, catalyst activity and average molecular weight (M _v) was tested. If external donors are employed, M _v decreases, the insoluble fraction in boiling isooctane increases and the catalyst activity is strongly influenced by the mole ratio external donor/TiCl₃. The results indicate that all external donors employed have the same qualitative effect on catalytic active centers.     

Side-chain liquid-crystalline polysalts. Synthesis and thermal properties of poly{1-[ω-(4′-methoxy-4-biphenylyloxy)alkyl]-4-vinylpyridinium bromide} or poly[1-(2-{2-[2-(4′-methoxy-4-biphenylyloxy)ethoxy]ethoxy}ethyl)-4-vinylpyridinium bromide]

The synthesis and thermal properties of a new type of side-chain liquid-crystalline polymers, incorporating ionic groups, are described. The polymers are obtained upon spontaneous polymerization (simultaneous quaternization and polymerization) of 4-vinylpyridine in the presence of ω-(4′-methoxy-4-biphenylyloxy)alkyl or 2-{2-[2-(4′-methoxy-4-biphenylyloxy)ethoxy]ethoxy}-ethyl bromide. Fully quaternized polymers of high molecular weight are obtained. As the analogous low-molecular-weight molecules previously studied these polymers form smectic mesophases, although the mesogenic groups, which include the pyridinium rings, are directly connected to the polyvinylic backbone.     

Novel Organosoluble Poly(amide‐imide)s Derived from Kink Diamine Bis[4‐(4‐trimellitimidophenoxy)phenyl]‐diphenylmethane. Synthesis and Characterization

A new kink diimide‐dicarboxylic acid, 2,2‐bis[4‐(4‐trimellitimidophenoxy)phenyl]diphenylmethane (BTPDM), was synthesized by the condensation reaction of bis[4‐(4‐aminophenoxy)phenyl]diphenylmethane (BAPDM ) with trimellitic anhydride. A series of new poly(amide‐imide)s were prepared by direct polycondensation of BTPDM and various aromatic diamines in N‐methyl‐2‐pyrrolidinone (NMP) using triphenyl phosphite and pyridine as condensing agents. The polymers were produced in high yield revealing moderate to high inherent viscosities of 0.80–0.89 dL·g^–1. Wide‐angle X‐ray diffractograms revealed that the polymers are amorphous. Most of the polymers exhibit good solubility and could be readily dissolved in various solvents such as NMP, N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide, dimethyl sulfoxide, pyridine, cyclohexanone and tetrahydrofuran. These poly(amide‐imide)s have glass transition temperatures between 244–248°C and show 10% weight loss in the range of 453–469°C under a nitrogen atmosphere. The tough polymer films, obtained by casting from DMAc solution, had tensile strengths ranging between 82 and 95 MPa and tensile moduli ranging between 1.7 and 1.9 GPa.     

δ-Thalassemic phenotype due to two “novel” δ-globin gene mutations: CD11[GTC → GGC (A8)-HbA2-pylos] and CD 85 [TTT → TCT (F1)-HbA2-etolia]

δ-Thalassemia reduces the expected HbA₂ percentage, altering the normal as well as the β-thalassemia trait phenotype. An attempt to elucidate the molecular basis of δ-thalassemia in the Greek population, revealed two cases with unknown molecular defects that presented low levels of HbA₂ (about 1.5%). DNA sequence analysis of δ-globin gene identified two “novel” mutations in the coding regions of the gene; the cd11 (GTC→GGC) resulting in the substitution of valine for glycine (:HbA₂-Pylos) and the cd85 (TTT→TCT) resulting in the substitution of phenylalanine for serine (:HbA₂-Etolia). Because these mutations are localized at the helical positions A8 and F1 of the HbA₂ respectively, they potentially cause molecular instability of the tetramer, thus leading to reduced HbA₂ percentage. Hum Mutat 9:344–347, 1997. © 1997 Wiley-Liss, Inc.