Polymerization and copolymerization of 2-phthalimidomethyll 1,3-butadiene. II. Kinetic study of the polymerization of 1,3-butadiene and of the copolymerization of 1,3-butadiene with 2-phthalimidomethyl 1,3-butadiene initiated by bis-(η3-allyl nickel trifluoroacetate)

The kinetics of the polymerization of 1,3-butadiene initiated by bis(η³-allyl nickel trifluoroacetate) prepared in benzene was studied in methylene chloride at 40°C. The reaction is first order with respect to the monomer, second order with respect to the catalyst in contrast to the case in which solvent is benzene. We have shown that the presence of a polar molecule (fe, N-methyl phthalimide) decreases the overall rate of polymerization. The apparent reactivity ratios for the system 2-phthalimidomethyl 1,3-butadiene (1)-1,3-butadiene (2) are r₁ = 0.65 ± 0.006 and r₂ = 0.48 ± 0.015.     

Facile synthesis of blocky styrene(1,3)‐butadiene copolymers having stereoregular monomeric sequences

Half titanocenes (CpCH₂CH₂O)TiCl₂ 1 and (CpCH₂CH₂ OCH₃)TiCl₃ 2 , activated by methylaluminoxane are tested in styrene–1,3‐butadiene copolymerization. The titanocene 1 is able to copolymerize styrene and 1,3‐butadiene, with a facile procedure, to give products with high molecular weight. The analysis of microstructure by ¹³C‐NMR reveals that the styrene homosequences in copolymers are in syndiotactic arrangement, while the butadiene homosequences are, prevailingly, in 1,4‐cis configuration, according with behavior of 1 in the homopolymerizations of styrene and 1,3‐butadiene, respectively. The reactivity ratios of copolymerization are estimated by diad composition analysis. All obtained copolymers have r₁ × r₂ values much larger than 1, indicating blocky nature of homosequences. The structural characterization by wide‐angle X‐ray powder diffraction and differential scanning calorimetry indicates that all copolymers are crystalline, with T_m varying from 171 to 239 °C, depending on the styrene content. The titanocene 2 did not succeed in styrene–1,3‐butadiene copolymerization, giving rise to a blend of homopolymers. Compounds 1 and 2 were also tested in the polymerization of several conjugated dienes, and the obtained results were very useful to rationalize the behavior of both catalysts in the copolymerization of styrene and butadiene. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 815–822, 2010     

Organometallic polymers. XIV. Copolymerization of vinylcyclopentadienyl manganese tricarbonyl and vinylferrocene with N-vinyl-2-pyrrolidone

N-Vinyl-2-pyrrolidone(I) has been copolymerized with vinylferrocene(II) and vinylcyclopentadienyl manganese tricarbonyl(III) in degassed benzene solutions with the use of azobisisobutyronitrile (AIBN) as the initiator. The polymerizations proceed smoothly, and the relative reactivity ratios were determined as r₁ = 0.66, r₂ = 0.40 (for copolymerization of I with II, M₁ defined as II) and r₁ = 0.14 and r₂ = 0.09 (for copolymerization of I with III, M₁ defined as III). These copolymers were soluble in benzene, THF, chloroform, CCl₄, and DMF. Molecular weights were determined by viscosity and gel-permeation chromatography studies (universal calibration technique.) The copolymers exhibited values of M?_n between 5 × 10³ and 10 × 10³ and M?_w between 7 × 10³ and 17 × 10³ with M?_w/M?_n < 2. Upon heating to 260°C under N₂, copolymers of III underwent gas evolution and weight loss. The weight loss was enhanced at 300°C, and the polymers became in creasingly insoluble. Copolymers of vinylferrocene were oxidized to polyferricinium salts upon treatment with dichlorodicyanoquinone (DDQ) or o-chloranil (o-CA) in benzene. Each unit of quinone incorporated into the polysalts had been reduced to its radical anion. The ratio of ferrocene to ferricinium units in the polysalts was determined. The polysalts did not melt at 360°C and were readily soluble only in DMF.     

Effect of solvent in radical polymerization of butadiene 1-carboxylic acid

The radical polymerization and copolymerization of butadiene 1-carboxylic acid (Bu-1-Acid) were studied in a variety of the electron-donor solvents such as dimethylformamide (DMF), tetrahydrofuran (THF), methyl ethyl ketone (MEK), acetonitrile (ACN), and benzene (BZ) using AIBN as an initiator at 50°C. Under these conditions, the polymerization rate of Bu-1-Acid increased in the order, DMF < THF < MEK < ACN < BZ in the various solvents. In copolymerization with styrene [M₂] and acrylonitrile [M₂], the monomer reactivity ratio r₁ increased and r₂ decreased in the same order. Moreover, it was found that Alfrey-Price Q-e value of Bu-1-Acid increased depending on solvent in the order DMF < THF < MEK < ACN < BZ. These variations were correlated to the electron-donating power (Δvcm^?) of the solvents used and are discussed on the basis of the solvation of Bu-1-Acid into the solvent. Also, it was found that the microstructures of these polymers were always trans-1,4 and did not change with the solvent used.     

Styrene/1,3‐butadiene copolymerization by C2‐symmetric group 4 metallocenes based catalysts

C₂‐symmetric group 4 metallocenes based catalysts (rac‐[CH₂(3‐tert‐butyl‐1‐indenyl)₂]ZrCl₂ (1) , rac‐[CH₂(1‐indenyl)₂]ZrCl₂ (2) and rac‐[CH₂(3‐tert‐butyl‐1‐indenyl)₂]TiCl₂ (3) ) are able to copolymerize styrene and 1,3‐butadiene, to give products with high molecular weight. In agreement with symmetry properties of metallocene precatalysts, styrene homosequences are in isotactic arrangements. Full determination of microstructure of copolymers was obtained by ¹³C NMR and FTIR analysis and it reveals that insertion of butadiene on styrene chain‐end happens prevailingly with 1,4‐trans configuration. In the butadiene homosequences, using zirconocene‐based catalysts, the 1,4‐trans arrangement is favored over 1,4‐cis, but the latter is prevailing in the presence of titanocene (3) . Diad composition analysis of the copolymers makes possible to estimate the reactivity ratios of copolymerization: zirconocenes (1) and (2) produced copolymers having r₁ × r₂ = 0.5 and 3.0, respectively (where 1 refers to styrene and 2 to butadiene); while titanocene (3) gave tendencially blocky styrene–butadiene copolymers (r₁ × r₂ = 8.5). The copolymers do not exhibit crystallinity, even when they contain a high molar fraction of styrene. Probably, comonomer homosequences are too short to crystallize (n_s = 16, in the copolymer at highest styrene molar fraction). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1476–1487, 2008     

Structure and reactivity in cationic polymerization of butadiene derivatives. IV. 1-alkoxybutadienes

The reactivity of trans-1-alkoxybutadienes in cationic homopolymerization and copolymerizations and structure of the polymers produced were investigated. 1-Ethoxybutadiene is polymerized easily at ?78°C by various acidic catalysis. The reactivity of 1-ethoxybutadiene was similar to that of ethyl vinyl ether. The polymers produced possessed molecular weights of several thousands, and were composed of 70–95% 1,4 structure and 5–30% 3,4 structure. In the copolymerization of ethyl vinyl ether (M₁) with 1-ethoxybutadiene at ?78°C in toluene by boron trifluoride diethyl etherate, r₁ = 1.15, r₂ = 2.62. From the Hammett plot of the relative reactivities of alkoxybutadienes (alkoxy: CH₃O, C₂H₅O, i-C₃H₇O), the reaction constant _p^* was determined to be ?2.9. Results of the present study were compared with those of various butadiene derivatives.     

Organometallic polymers. XVI. Copolymerization of styrenetricarbonylchromium and the reaction of polystyrene with chromium hexacarbonyl

Styrenetricarbonylchromium (IV) has been synthesized. Monomer IV did not homopolymerize with free-radical initiation but copolymerized with styrene, methyl acrylate, and vinylcymantrene. The copolymerizations were carried out in benzene solutions at 70°C with azobisisobutyronitrile as the initiator. The relative reactivity ratios were determined for the styrene and methyl acrylate copolymerizations. They were (defining M₁ as monomer IV) r₁ ? 0, r₂ ? 1.39 for styrene copolymerizations and r₁ ? 0, r₂ ? 0.75 for methyl acrylate copolymerization. Polystyrene reacted with chromium-hexacarbonyl in refluxing DME to produce a polymer in which about 32% of the benzene rings were complexed with ? Cr(CO)₃ units. The use of a polystyrene of narrow molecular weight distribution in this reaction demonstrated that no decomposition of the polystyrene chains occurred.     

Polymerization of 1,3‐dienes with functional groups. II. Free‐radical polymerization of N‐(2‐methylene‐3‐butenoyl)piperidine

The free‐radical homopolymerization and copolymerization behavior of N‐(2‐methylene‐3‐butenoyl)piperidine was investigated. When the monomer was heated in bulk at 60 °C for 25 h without an initiator, about 30% of the monomer was consumed by the thermal polymerization and the Diels–Alder reaction. No such side reaction was observed when the polymerization was carried out in a benzene solution with 1 mol % 2,2′‐azobisisobutylonitrile (AIBN) as an initiator. The polymerization rate equation was found to be R_p ∝ [AIBN]^0.507[M]^1.04, and the overall activation energy of polymerization was calculated to be 89.5 kJ/mol. The microstructure of the resulting polymer was exclusively a 1,4‐structure that included both 1,4‐E and 1,4‐Z configurations. The copolymerizations of this monomer with styrene and/or chloroprene as comonomers were carried out in benzene solutions at 60 °C with AIBN as an initiator. In the copolymerization with styrene, the monomer reactivity ratios were r₁ = 6.10 and r₂ = 0.03, and the Q and e values were calculated to be 10.8 and 0.45, respectively. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1545–1552, 2003     

Influence of the catalyst on monomer insertion in the syndiospecific copolymerization of styrene and para‐methylstyrene

The effect of the kind of transition‐metal catalyst on the extent of comonomer insertion in the syndiospecific complex‐coordinative copolymerization of styrene and para‐methylstyrene has been investigated. The results for the influence of the polymerization conditions have shown that there is no real difference between solution copolymerization in toluene and solvent‐free styrene copolymerization in bulk, with respect to the reactivity ratio for para‐methylstyrene (r₂), under comparable conditions in the presence of methylaluminoxane and triisobutylaluminum and at low polymerization conversions. All the investigated catalysts lead to a preferred incorporation of para‐methylstyrene into the polymer chain in comparison with styrene and over the whole range of monomer compositions. The increasing capability of the different catalysts to provide copolymers with enhanced para‐methylstyrene concentrations can be summarized by the increasing r₂ values for the copolymerization in bulk as follows: η⁵‐pentamethylcyclopentadienyl titanium trichloride < η⁵‐octahydrofluorenyl titanium trimethoxide < η⁵‐octahydrofluorenyl titanium tristrifluoroacetate < η⁵‐cyclopentadienyl titanium(N,N‐dicyclohexylamido)dichloride < η⁵‐cyclopentadienyl titanium trichloride. For a correlation between the catalyst structure and the comonomer insertion, the catalysts can be described by electronic effects (electrostatic charge of the transition‐metal atom) and steric effects (minimum structural cone angle). The results show that the steric properties of the transition‐metal complexes have the most important effect on the insertion of para‐methylstyrene into the copolymer. If the minimum structural cone angle of the ligand of the transition‐metal catalyst decreases, the incorporation of the comonomer para‐methylstyrene increases significantly. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2061–2067, 2005     

Copolymerization of butadiene with vinyl chloride by radiation

The copolymerization of butadiene with vinyl chloride was demonstrated in homogeneous phase by radiation. The reactivity parameters were r₁ = 10 and r₂ = 0.02 (M₁ = butadiene) in bulk at ?10°C. The average molecular weight of the product was about 1000–2500, depending reaction conditions.     

Copolymerization of styrene and butadiene with Ni(acac)2-methylaluminoxane catalyst

Copolymerization of styrene (St) and butadiene (Bd) with nickel(II) acetylacetonate [Ni(acac)₂]-methylaluminoxane (MAO) catalyst was investigated. Among the metal acetylacetonates [Mt(acac)_x] examined, Ni(acac)₂ showed a high activity for the copolymerization of St and Bd giving copolymers having high cis-1,4-microstructure in Bd units in the copolymer. The effect of alkylaluminum as a cocatalyst on the copolymerization of St and Bd with the Ni(acac)₂-MAO catalyst was observed, and MAO was found to be the most effective cocatalyst for the copolymerization. The monomer reactivity ratios for the copolymerization of St and Bd with the Ni(acac)₂-MAO catalyst were determined to be r_St = 0.07 and r_Bd = 3.6. Based on the obtained results, it was presumed that the random copolymers with high cis-1,4-microstructure in Bd units could be synthesized with the Ni(acac)₂-MAO catalyst without formation of each homopolymer. The polymerization mechanism with the Ni(acac)₂-MAO catalyst was also discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3838–3844, 1999     

Cationic copolymerization of 2-methylene-5,5-dimethyl-1,3-dioxane with 2-methylene-1,3-dioxolane and 2-methylene-1,3-dioxane

Copolymers of the cyclic ketene acetals, 2-methylene-5,5-dimethyl-1,3-dioxane, 3 , (M₁) with 2-methylene-1,3-dioxolane, 4 , (M₂) or 2-methylene-1,3-dioxane, 5 , (M₂), were synthesized by cationic copolymerization. An experimental method was designed to study the reactivity of these very reactive and extremely acid sensitive cyclic ketene acetal monomers. The reactivity ratios, calculated using a computer program based on a nonlinear minimization algorithm, were r₁ = 6.36 and r₂ = 1.25 for the copolymerization of 3 with 4 , and r₁ = 1.56 and r₂ = 1.42 for the copolymerization of 3 with 5. FTIR and ¹H-NMR spectra when combined with the values of r₁ and r₂ showed that these copolymers were formed by a cationic 1,2-polymerization (ring-retained) route. Furthermore the tendency existed to form very short blocks of M₁ or M₂ within the copolymers. Cationic copolymerization of cyclic ketene acetals have the potential to be used for synthesis of novel polymers. © 1996 John Wiley & Sons, Inc.     

Butadiene 1,4 polymerization catalysis : II. An nmr study of the structure and dynamics of bis(η3-allylnickel trifluoroacetate) and its significance for the mechanism of the polymerization

¹H NMR study of the molecular dynamics of bis(η³-allylnickel trifluoroacetate) has revealed not only the important role of the metalanion bond breaking in intra- and inter-molecular rearrangements but also stability of the η³-allyl coordination on the NMR time-scale. Implications for the mechanism of butadiene polymerization are discussed, and an interpretation of the control of the cistrans isomer ratio is tentatively proposed.     

Polymerization of 1,3‐dienes with functional groups. III. Free‐radical polymerization of N,N‐diethyl‐2‐methylene‐3‐butenamide

Free‐radical homo‐ and copolymerization behavior of N,N‐diethyl‐2‐methylene‐3‐butenamide (DEA) was investigated. When the monomer was heated in bulk at 60 °C for 25 h without initiator, rubbery, solid gel was formed by the thermal polymerization. No such reaction was observed when the polymerization was carried out in 2 mol/L of benzene solution with with 1 mol % of azobisisobutyronitrile (AIBN) as an initiator. The polymerization rate (R_p) equation was R_p ∝ [DEA]^1.1[AIBN]^0.51, and the overall activation energy of polymerization was calculated 84.1 kJ/mol. The microstructure of the resulting polymer was exclusively a 1,4‐structure where both 1,4‐E and 1,4‐Z structures were included. From the product analysis of the telomerization with tert‐butylmercaptan as a telogen, the modes of monomer addition were estimated to be both 1,4‐ and 4,1‐addition. The copolymerizations of this monomer with styrene and/or chloroprene as comonomers were also carried out in benzene solution at 60 °C. In the copolymerization with styrene, the monomer reactivity ratios obtained were r₁ = 5.83 and r₂ = 0.05, and the Q and e values were Q = 8.4 and e = 0.33, respectively. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 999–1007, 2004     

Studies of the polymerization of diallyl compounds. XXVII. Copolymerization of diallyl tartrate with several vinyl monomers

The radical copolymerization of diallyl tartrate (DATa) (M₁) with diallyl succinate (DASu), diallyl phthalate (DAP), allyl benzoate (ABz), vinyl acetate (VAc), or styrene (St) was investigated in order to disclose in more detail the characteristic hydroxyl group's effect observed in the homopolymerization of DATa. In the copolymerization with DASu or DAP as a typical diallyldicarboxylate, the dependence of the rate of copolymerization on monomer composition was different for different copolymerization systems and unusual values larger than unity for the product of monomer reactivity ratios, r₁r₂, were obtained. In the copolymerization with ABz or VAc (M₂), the r₁ and r₂ values were estimated to be 1.50 and 0.64 for the DATa/ABz system and 0.76 and 2.34 for the DATa/VAc system, respectively; the product r₁r₂ for the latter copolymerization system was found again to be larger than unity. In the copolymerization with St, the largest effect due to DATa monomer of high polarity was observed. Solvent effects were tentatively examined to improve the copolymerizability of DATa. These results are discussed in terms of hydrogen-bonding ability of DATa.     

Copolymerization of acrylamide and styrene. II. Reactivity ratios with unperturbed acrylamide

It was reported earlier that the copolymerization of acrylamide and styrene is strongly affected by the copolymerization medium. The effect was attributed to a change in the polarity of the ethylenic bond in the acrylamide monomer due to hydrogen bonding and/or dipole—dipole interaction, depending on the medium. In view of those findings, it was suggested that absolute values for the reactivity ratios for the copolymerization of these two monomers might be obtained only when the acrylamide monomer is unperturbed. Copolymerizations of these monomers at a number of ratios, therefore, were done in benzene, which does not undergo hydrogen bonding and has no dipole moment, at high dilution, when amide—amide interactions between acrylamide molecules should be essentially eliminated. The values of r₁ and r₂(M₁ = acrylamide) were 9.14 ± 0.27 and 0.67 ± 0.08, respectively. There appears to be some indication in this system that high dilution adversely affects the reactivity of the acrylamide monomer while enhancing that of styrene. This aspect requires more study.     

Acrylonitrile Copolymerizations. IV. Butadiene Copolymerization

The kinetics of the acrylonitrile–butadiene radical copolymerization, carried out in solution at 60°C, have been followed using gas chromatographic analysis. Remote units effects are observed only on the butadiene-ended radicals but they seem to involve a quite long sequence of butadiene units. The following values of the reactivity ratios are proposed: r_A = 0.067, r_AB = 0.70, r_ABB = 0.66, rABB = ^0.17,rBi → 001 to 0-06 for large values of L The results are discussed in terms of either polarity effects, or differences in reactivities between 1,4- or 1,2-butadiene radicals, or finally of charge transfer complexes between the monomers.     

Alternating copolymer of butadiene and propylene. III

Alternating copolymerizations of butadiene with propylene and other olefins were investigated by using VO(acac)₂–Et₃Al–Et₂AlCl system as catalyst. Butadiene–propylene copolymer with high degree of alternation was prepared with a monomer feed ratio (propylene/butadiene) of 4. Alternating copolymers of butadiene and other terminal olefins such as butene-1, pentene-1, dodecene-1, and octadiene-1,7 were also obtained. However, the butadiene–butene-2 copolymerization did not yield an alternating copolymer but a trans-1,4-polybutadiene.     

Radical Copolymerization of Vinylidene Chloride with 3(2-Methyl)-6-methylpyridazinone in Several Solvents

The radical copolymerization of vinylidene chloride (Vc, M₁) with 3(2-methyl)-6-methylpyridazinone (I, M₂) was carried out in benzene, ethanol, phenol, and acetic acid at 60 and 80°C. The monomer reactivity ratios were found to vary with the reaction conditions. The linear correlationships were obtained by plotting the values of log r₁ against those of ^V C[dbnd]O and ^V C[dbnd]C of monomers determined in the solvents.     

Reaction of (η-arylaldehyde)nickel(0) complexes with Me3SiX (X=OTf, Cl). Application to catalytic reductive homocoupling reaction of arylaldehyde

Arylaldehydes can coordinate to nickel(0) in η²-fashion to give η²-arylaldehydenickel complexes, which react with Me₃SiOTf or Me₃SiCl to give η¹:η¹-siloxybenzylnickel or η³-siloxybenzyl complex. In the presence of PCy₃ or CO, η¹:η¹-siloxybenzylnickel complex underwent homocoupling reaction to give a pinacol type product. In the presence of zinc dust, the reductive homocoupling reaction of arylaldehyde proceeded catalytically to form pinacol derivatives in 70-99% yield. On the other hand, η³-siloxybenzylnickel complex regenerated benzaldehyde and Me₃SiOTf under a carbon monoxide pressure.