Synthesis of A-B-A Type Block Copolymer of Methyl Methacrylate and Styrene by Living Free-Radical Polymerization†

Abstract

A newly synthesized iniferter, N,N′-dimethyl-N,N′-bis(phenethyl)-thiuram disulfide, has been used in the free-radical living polymerization of styrene by a photochemical method. The low molecular weight (M _w = 6000) difunctionalized polystyrene was used as a macroiniferter to photopolymerize methyl methacrylate, and was fractionated to obtain an A-B-A type block copolymer containing two poly(methyl methacrylate) units and one polystyrene unit in each block. The glass transition temperature, thermal stability, and ¹³C NMR of the block copolymer are discussed.     

Copolymerization of 4‐Propanoylphenyl Acrylate with Methyl Methacrylate: Synthesis,Characterization and Reactivity Ratios

The new acrylic monomer 4‐propanoylphenyl acrylate (PPA) was synthesized and copolymerized with methyl methacrylate (MMA) in methyl ethyl ketone at 70±1°C using benzoyl peroxide as a free radical initiator. The copolymers were characterized by FT‐IR, ¹H‐NMR and ¹³C‐NMR spectroscopic techniques. The compositions of the copolymers were determined by ¹H‐NMR analysis. The reactivity ratios of the monomers were determined using Fineman‐Ross (r₁=0.5535 and r₂=1.5428), Kelen‐Tüdös (r₁=0.5307 and r₂=1.4482), and Ext. Kelen‐Tüdös (r₁=0.5044 and r₂=1.4614), as well as by a nonlinear error‐in‐variables model (EVM) method using a computer program, RREVM (r₁=0.5314 and r₂=1.4530). The solubility of the polymers was tested in various polar and non‐polar solvents. The elemental analysis was determined by a Perkin‐Elmer C‐H analyzer. The molecular weights (M_w and M_n) of the copolymers were determined by gel permeation chromatography. Thermogravimetric analysis of the polymers reveals that the thermal stability of the copolymers increases with an increase in the mole fraction of MMA in the copolymers. Glass transition temperatures of the copolymers were found to increase with an increase in the mole fraction of MMA in the copolymers.     

Synthesis of volatile copper(II) β-diketonates, β-ketiminates, and β-diiminates. The problem of synthesis of copper(II) Bis(2,2,6,6-tetramethyl-3-methylaminoheptane-5-onate)

The methods of synthesis of the copper(II) β-diketonates, β-ketiminates, and β-diiminates containing in the composition CH₃, CF₃, C(CH₃)₃, and Ph substituents were summarized. At the formation of metallocycles with 2,2,6,6-tetramethyl-3-methylaminoheptane-5-one ligand the intraligand repulsion of tret-butyl group and the methyl group at the nitrogen atom is noted, impeding the complexation.     

Synthesis and spectral characterization of sparteine and α -isosparteine complexes with copper(II) sulfate

Complexes of CuSO₄ of the general formula [Cu(C₁₅H₂₆N₂)SO₄] where [C₁₅H₂₆N₂] is sparteine or α-isosparteine have been obtained from copper(II) and an appropriate alkaloid. The 1?:?1 (metal?:?alkaloid) stoichiometry was confirmed by elemental analysis. The compounds have been characterized by mass spectrometry, IR, and UV–Vis spectroscopy. The magnetic properties were also determined; no anti-ferromagnetic behavior was observed. Information on the geometry of newly obtained compounds was obtained using quantum-chemical calculations.     

Synthesis and Characterization of Amphiphilic Block Copolymer Containing PVP and Poly(5-benzyloxytrimethylene carbonate)

Amphiphilic block copolymers have attracted great interest recently, especially for thebiomedical uses1, . The hydrophilic blocks improve the biocompatibility of copolymer, 2while the hydrophobic blocks enhance the mechanics of the material and providever…     

Enantioselective α-arylation of N-acyloxazolidinones with copper(II)-bisoxazoline catalysts and diaryliodonium salts

A new strategy for the catalytic enantioselective α-arylation of N-acyloxazolidinones with chiral copper(II)-bisoxazoline complexes and diaryliodonium salts is described. The mild catalytic conditions are operationally simple, produce valuable synthetic building blocks in excellent yields and enantioselectivities, and can be applied to the synthesis of important nonsteroidal anti-inflammatory agents and their analogues.     

Synthesis and characterization of β-diketonato- and phenoxoderivatives of mono(dizirconium-ennea-isopropoxy)copper(II)

Summary -Diketonato- and phenoxo-derivatives of mono(dizirconium-ennea-isopropoxy) copper(II), [Cu{Zr₂(OPr-i)₉}-(RCOCHCOR)] and [Cu{Zr₂(OPr-i)₉}(-OAr)], have been prepared by the interaction of K(RCOCHCOR) or KOAr (1 mol) [R = R = Me (1a); R = R = CF₃ (1b); R = Me, R = CF₃ (1c); OAr = 2,6-Me₂C₆H₃O (2a), 3,5-Me₂C₆H₃O (2b), p-ClC₆H₄O (2c)] with [Cu{Zr₂-(OPr-i) ₉}(-Cl)] (1 mol) in PhH. Alcohol interchanges of the derivative [Cu{Zr₂(OPr-i)₉}(-Cl)] have also been studied. These new compounds have been characterized by elemental analyses, i.r., electronic and e.s.r. spectra, and magnetic susceptibility measurements. The studies indicate a distorted octahedral geometry around Cu^II.     

Linear/branched Block Polyethylene Produced by α-Diimine Nickel(Ⅱ)Catalyst and Bis(phenoxy-imine) Zirconium Binary Catalyst System in the Presence of Diethyl Zinc

In order to promote development of linear/branched block polyethylenes based on new catalytic systems,we synthesized a novel α-diimine nickel(Ⅱ) complex with isopropyl substituents on ortho-N-aryl and hydroxymethyl phenyl substituents on para-N-aryl structures.The activity of α-diimine nickel(Ⅱ) catalyst was 3.02×106 g·molNi-1·h-1 at 70 ℃,and resultant polyethylene possessed 135/1000C branches.The linear/branched block polyethylenes were synthesized from ethylene polymerization catalyzed by the α-diimine nickel(Ⅱ) complex/bis(phenoxy-imine) zirconium in the presence of diethyl zinc.With the addition of ZnEt2 (from 0 to 400),the melting peak of resultant polyethylene changed from a single melting peak to bimodal melting peaks.The molecular weights of resultant polyethylene ranging from 26.8 kg/mol to 17.1 kg/mol and PDI values varying gradually from 24.4 to 15.2 were obtained via adjusting ZnEt2 equiv.and molar ratio of two catalysts.In addition,the branching degree of the polyethylene increased from 13/1000C to 56/1000C with the increase of the proportion of α-diimine nickel(Ⅱ) catalyst.Using this binary catalyst system,the reaction temperature of chain shuttling polymerization can be carried out at 70 ℃,which is more conducive to industrial application.     

Synthesis and Crystal Structures of the α and β Forms of Bis(salicylaldoxime)copper(Ⅱ) Complexes

Modified α and β bis(salicylaldoxime)copper(Ⅱ) have been obtained by recrystallization from ethyl acetate(CCDC Nos. 212157 & 212158). The X-ray analysis reveals that the two modificated forms have the same structure with different geometric parameters. The α form crystallizes in the P2(1)/c space group and the β form in the P1 space group. Both the crystal structures consist of centrosymmetric monomeric molecules of Cu(OC6H4CNOH)2. The IR spectra are in agreement with the structural data.     

Complexes of copper(II) with sugar α-amino acids as ligands

Summary Complexes of Cu^II with 2-(benzylamino)-2-deoxy-d-glycero-d-talo heptonic acid (BnMa) and 2-(benzylamino)-2-deoxy-d-glycero-l-gluco heptonic acid (BnGa) were prepared and characterized by elemental analysis, thermal data, i.r., electronic and e.s.r. spectra, magnetic susceptibility measurements, and X-ray powder diffraction. The metal:ligand stoichiometry of these complexes is 12 and coordination around Cu^II seems to be octahedral, with the ligands bound through the N atom of the amino group and O atoms of the bridging carboxylate group.     

Synthesis and Thermal Rearrangement of Tetramethyldisilane-bridged Bis(cyclopentadienyl) Diiron Complexes with Bis(phosphine)Substitution

Photolysis of [Me2SiSiMe2)[C5H4Fe(CO2)]2with a series of bis(phosphine)ligands Ph2P(CH2)n PPh2(n=1-4) leads to the formation of the corresponding diiron complexes with intramolecular and intermolecular bis(phosphine) substitution.When these complexes were heated in refluxing xylene.only in the complexes with intermolecular bis(phosphine )substitution the thermal rearrangement reaction occurred.     

Effect of Bis(6-methylpyridazinyl)-3,3′-disulfide in the Radical Polymerizations of Styrene and Methyl Methacrylate

Thermal and photo polymerizations of styrene (St) have been carried out in the presence of bis-(6-methylpyridazinyl)-3,3′-disulfide (I). I was found to initiate the photo polymerization of St but to retard the thermal polymerization of St. The chain transfer constants of I in the polymerizations of St and methyl methacrylate were determined to be 1.64 and 1.8 × 10^?2, respectively, from which the Q_tr and e_tr values were calculated to be 5.32 × 10^?2 and 3.86, respectively.     

Complexes of tris(o-phenanthroline)nickel(II) and copper(II) bromide with dithiocarbamates derived from α-amino acids

Complexes of 1,10-o-phenanthroline (o-phen)-Ni^II and Cu^II with dithiocarbamates derived from -amino acids (glycine, phenylalanine, alanine, methionine and tryptophan) were synthesized and characterized by chemical analysis, spectral and thermal studies and by biological screening; the complexes are non-electrolytes. The empirical formula are [Ni(o-phen)₂(aadtc)] and [Cu₂(o-phen)₂(phaladtc)(H₂O)₂Br₂] where, aadtc = glycinyl-, phenylalaninyl-, alaninyl-, methioninyl- and tryptophanyldithiocarbamate and phaladtc = phenylalaninyldithiocarbamate. The structure of these complexes is probably octahedral. Molecular association through hydrogen bonding between the —NH and the carboxylate groups is proposed for the Ni^II complexes. The Cu^II complex is dimeric with the phenylalaninyldithiocarbamate acting as a bridge.     

Features of сhitosan interaction with copper(II) and cobalt(II) tetrasulfophthalocyanines

The interaction of chitosan with copper(II) and cobalt(II) tetrasulfophthalocyanines is studied by spectral methods. The main parameters of binding of chitosan to anionic metal phthalocyanines are determined by Scatchard analysis. It is found that the formation of the polymer complex is considerably contributed by donor?acceptor interactions between the coordinately unsaturated metal phthalocyanine and chitosan amino groups. Сhitosan reacts with a monomeric cobalt(II) tetrasulfophthalocyanine, whereas copper(II) tetrasulfophthalocyanine in its complex with chitosan remains in the dimeric state. The reaction centers responsible for the Cu(SO₃H)₄Pc)₂–chitosan and Co(SO₃H)₄Pc–chitosan complexes are revealed by means of IR spectroscopy.     

Synthesis and Electrochemical Studies of Ruthenium(II) Dicarbonyl Bis(ferrocenyl-β-diketonates)

The reaction of [Ru₃(CO)₁₂] ( 1 ) with six equiv. of FcC(O)CH₂C(O)R ( 2a , R = Me; 2b , R = Fc; Fc = Fe(η⁵-C₅H₄)(η⁵-C₅H₅)) produced the Ru^II compounds [Ru(CO)₂(FcC(O)CHC(O)R)₂] ( 3a , R = Me; 3b , R = Fc) in moderate yields. IR studies and single-crystal X-ray analysis ( 3a ) confirmed that the CO ligands are cis-oriented and that the respective β-diketonates O,O'-chelate-bonded setting-up an octahedral surrounding at Ru^II. Electrochemical (cyclic and square-wave voltammetry) and spectroelectrochemical (UV/Vis-NIR, IR) measurements were additionally carried out. Compounds 3a , b display two ( 3a : E₁^o' = 140; E₂^o' = 255 mV; ΔE^o' = 115 mV for [ 3a ]⁺/[ 3a ]²⁺) or four ( 3b : E₁^o' = 80 mV, E₂^o' 190 mV (ΔE^o' = 110 mV, [ 3b ]⁺/[ 3b ]²⁺), E₃^o' = 355 mV (ΔE^o' = 165 mV, [ 3b ]²⁺/[ 3b ]³⁺), E₄^o' = 490 mV (ΔE^o' = 135 mV, [ 3b ]³⁺/[ 3b ]⁴⁺)) electrochemical reversible one-electron redox processes indicating electrostatic interactions among the ferrocenyl groups as oxidation progresses, which was confirmed by UV/Vis-NIR and in situ IR spectroscopy. One ferrocenyl group on each β-diketonate ligand is by this means 1^st oxidized before the 2^nd ferrocenyl group of the same β-diketonate building block follows.     

Synthesis and properties of double copper(I)–nickel(II) sulfite

Pourbaix diagrams of Cu–H₂SO4–H₂O and Ni–H₂SO₄–H₂O systems have been refined, and stability regions of the sulfite phases have been determined. State diagrams of double copper(I)–copper(II) and copper(I)–nickel(II) sulfites have been constructed. Double copper(I)–nickel(II) sulfite has been isolated from aqueous solutions saturated with sulfur dioxide. The solutions at different ratios of the metals have been studied by spectrophotometry; the isolated double sulfite has been studied by X-ray diffraction, IR spectroscopy, dispersion analysis, and thermal analysis. Fundamentals of thermodynamic prognostication of the Cu₂SO₃·MSO₃ double sulfites synthesis have been elaborated.     

Synthesis and Characterization of Poly(isoprene-b-butyl methacrylate) Block Copolymer in the Presence of Rare Earth Catalyst

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Kinetics and mechanism of reactions of bis(biguanide)copper(II) ion with glycine and α-alanine in aqueous media

Summary The kinetics of the reaction of [Cu(bigH)₂]²⁺ (bigH = biguanide) with an excess of amino acid (LH), namely glycine or -alanine, in aqueous solution in the 7.6–9.0 pH range at different temperatures (30–40° C) have been followed by stopped-flow spectrophotometry. The ligand replacement process has been found to pass through intermediate formation of a ternary complex, [Cu(bigH)L]⁺ at the slower step, followed by rapid transformation into the binary complex, [CuL₂]. The overall ligand replacement process has a ligand dependent (k ₁) path which is first order with respect to the incoming ligand (L^-), and a ligand independent (k ₀) path. Under pseudo-first order conditions containing excess amino acid, the experimental observations conform to the rate law k _obs = k ₀ + k ₁ K _a[L]_T/([H⁼] + K _a), where [L]_T stands for the total concentration of amino acid and K _a gives the deprotonation constant of LH. The solvent assisted dissociation (i.e. k ₀ path) leads to a copper(II) mono-biguanide complex followed by rapid nucleophilic substitution; the k ₁ path is in agreement with an associative mechanism. The activation parameters (H , S ) for each step have been determined.