Oxidation of 2,6-di-tert-butylphenol by molecular oxygen catalyzed by tetrasodium phthalocyaninatocobalt(II)tetrasulfonate bound to a polymer colloid

Crosslinked cationic latexes based on polystyrene, poly[styrene-co-(methyl methacrylate)] and poly(methyl methacrylate) were prepared by an emulsion polymerization process using 2 mol-% of a quaternary ammonium surfactant monomer. Phthalocyaninatocobalt(II)tetrasulfonate (CoPcTs) bound to these latexes were found to enhance the rate of autoxidation of 2,6-di-tert-butylphenol in water. All CoPcTs-latex catalysts were more active than the water soluble CoPcTsNa₄. The styrene latex bound with CoPcTs was the most active catalyst. The reaction products were identified as the oxidative coupling products 3,3′,5,55′-tetra-tert-butyl-4,4′-dioxo-1,1′-bicyclohexadienylidene (DPQ) and 2,6-di-tert-butyl-1,4-benzoquinone (BQ). The ratio DPQ/BQ was found to be affected by the nature of microenvironment. The rate of autoxidation catalyzed by CoPcTs bound to the styrene latex was found to be zero order with respect to the phenol concentration. The reaction rates increase with pH in the range 7–9. The rate of autoxidation increases with increasing concentration of CoPcTs from 1,0 · 10^?6 to 2,5 · 10^?5 mol/L and then it levels off. At constant concentration of CoPcTs in the reaction mixture, the rate as a function of the weight of latex shows a maximum. The rate shows a linear dependence on partial pressure of dioxygen. Recycling of the latex catalyst results in a reduced activity after successive runs.     

Photochemical reactions and stabilizing properties of 2,6-Di-tert-butyl-4-methylphenol, 1. Photochemical reactions of 2,6-Di-tert-butyl-4-methylphenol in hexane solutions

Photochemical reactions of 2,6-di-tert-butyl-4-methylphenol ( 3 ) in hexane solutions lead to the formation of 2,6,2′,6′-tetra-tert-butyl-4,4′-ethylenediphenol ( 1 ) and 2,6,2′,6′-tetra-tert-butyl-4,4′-ethanediylidenedi(2,5-cyclohexadien-1-one) ( 2 ) in a mole ratio of 10:1 in the first step. The formation of acetophenone due to the decomposition of di(α,α-dimethylbenzyl) peroxide (dicumyl peroxide) ( 6 ) is inhibited by 3 in hexane solution. The inhibiting effect of 3 is greater if the reaction is initiated by light absorbed by 6 than when it is initiated by light absorbed by both 3 and 6 .     

Stabile Polyphenoxyle, 4. Polymere aus sterisch gehinderten,geschützten Vinylphenolen

2,6-Di-tert-butyl-4-vinylphenyl trimethylsilyl ether ( 1e ) and 2,6-di-tert-butyl-4-vinylphenyl acetate ( 1c ) were synthesized and polymerized by cationic and free radical initiators. The protecting groups could be splitted off from the polymers by hydrolysis in acidic medium or by reduction with lithium aluminium hydride, resp., yielding high molecular sterically hindered free polyphenols.     

Preparation of 4-tert-butyloxocalix[n]arenes and their properties as UV-absorbers

5,11,17,23-Tetra-tert-butyl-25,26,27,28-tetrahydroxy-2-oxocalix[4]arene ( 4a ), 5,11,17,23,29,35-hexa-tert-butyl-37,38,39,40,41,42-hexahydroxy-2-oxocalix[6]arene ( 4b ), and octa-tert-butyl-octahydroxy-trioxocalix[8]arene ( 4c ) were synthesized via 4-tert-butylcalix[4]-, [6]- and [8]arenes from 4-tert-butylphenol as a starting material. 5,5′-Di-tert-butyl-2,2′-dihydroxybenzophenone ( 7 ) was synthesized via 5,5′-di-tert-butyl-2,2′-dimethoxybenzophenone ( 6 ) from bis(5-tert-butyl-2-methoxyphenyl)methane ( 5 ). 1,4-Dioxane solutions of 4a , 4b , 4c , 6 , and 7 were irradiated. The photostabilities of 4b and 4c were found to be better than those of 4a , 6 , and 7 . A poly(vinyl chloride) film, containing 0,06 mmol/g of 4b , was found to be most stable against photoxidation.     

Über polyarylenalkenylene und polyheteroarylenalkenylene, 14. Synthesen und charakterisierung von poly(thieno[2′,3′:1,2]benzo[4,5-b]thiophen-2,6-diylvinylenarylenvinylen)en,poly(4,8-dimethoxythieno[2′,3′:1,2]benzo[4,5-b]thiophen-2,6-diylvinylenarylenvinylen)en und einigen modellverbindungen

Wittig-reactions of thieno[2′,3′:1,2]benzo[4,5-b]thiophene-2,6-dicarboxaldehyde (8a) with “mono- and bis-Wittig-salts” 12a–c and 9a–c poly(thieno[2′,3′:1,2]benzo[4,5-b]thiophene-2,6-diylvinylenearylenevinylene)s 10a–c and some model compounds 13a–c were obtained. Analogous reactions of 4,8-dimethoxythieno[2′,3′:1,2]benzo[4,5-b]thiophene-2,6-dicarboxaldehyde (8b) gave the corresponding poly(4,8-dimethoxythieno[2′,3′:1,2]benzol[4,5-b]thiophene-2,6-diylvinylenearylenevinylene)s 11a–c and their model compounds 14a–c . Wittig-reactions of benzo[b]thiophene-2-carboxaldehyde (15) with “mono- and bis-Wittig-salts” gave model compounds 16a–c and 17a, c . A new synthesis of thieno[2′,3′:1,2]benzo[4,5-b]thio-phene (4) was worked out. 4,8-Dimethoxythieno[2′,3′:1,2]benzo[4,5-b]thiophene (7) and dicarboxaldehydes 8a and 8b were synthesized for the first time. The structures of all compounds were confirmed by elemental analyses, IR and electronic spectra, those of the model compounds additionally by mass spectra, and in case of sufficient solubility by ¹H NMR spectra. The electrical conductivities of all polymers and their model compounds were investigated.     

Synthesis and properties of highly gas permeable poly(amide-imide)s

Seven dicarboxylic acids containing one or two preformed imide rings were prepared by condensation of trimellitic anhydride with 3-amino-4-methylbenzoic acid or with the diamines 2,4,6-trimethyl-1,3-phenylenediamine, 3,3′-dimethoxybenzidine, 3,3′,5,5′-tetramethyl-benzidine, 3,3′-dimethyl-1,1′-binaphthalene or by condensation of 2,2-hexafluoroisopropylidenebis(phthalic acid anhydride) (6FDA) with 2 mol of 3-aminobenzoic acid or 3-amino-4-methylbenzoic acid. Polycondensation was performed directly in N-methyl-2-pyrrolidone (NMP)/triphenyl phosphite/lithium chloride with oxydianiline, 2,2-bis(4-aminophenyl)-perfluoropropane or 3,3′,5,5′-tetramethylbenzidine. All the resulting polymers are soluble in NMP, some in tetrahydrofuran (THF) and could be cast to transparent, flexible and tough films. The helium permeability as a probe for diffusivity improves with increasing fluorine content and non-linearity in the repeating unit.     

Condensation polymerization of diphenyl 2,2′-diiodobiphenyl-4,4′-dicarboxylate with some di- and tetraamino compounds

In connection with the research for new thermostable high molecular weight materials several polybenzimidazoles were prepared by condensing diphenyl 2,2′-diiodobiphenyl-4,4′-dicarboxylate ( 1 ) with 3,3′-diaminobenzidine ( 2 ), bis(3,4-diaminophenyl) ether, 3,3′,4,4′-tetraaminobenzophenone, 1,2,5,6-tetraaminoanthraquinone, and 1,2,4,5-tetraaminobenzene. Depending on the reaction time and temperature, partial replacement of iodine atoms by phenoxy groups occurred in the polymers. Model compounds were prepared by condensation of ester 1 with o-phenylenediamine, 2,3-diaminopyridine, and 3,4-diaminopyridine. IR, UV, and ¹H NMR spectra of the model compounds were taken. The high thermostability of the polymers could be shown by thermogravimetry.     

Photochemical reactions and stabilizing properties of 2,6-Di-tert-butyl-4-methylphenol, 2. Photochemical processes of 2,6-Di-tert-butyl-4-methylphenol in polystyrene films

Photochemical reactions of 2,6-di-tert-butyl-4-methylphenol (BHT) were investigated in polystyrene films. It was found that the stabilizing effect of BHT on polystyrene photooxidation process consists in lowering the rate of the formation of low molecular weight carbonyl products and the yield of polymer chain scissions.     

New comb-like polymers with prospective nonlinear optical properties

New methacrylic copolymers with prospective second-order nonlinear optical effects are synthesized by radical copolymerization of methyl methacrylate with conjugated zwitterionic methacrylate monomers (2,6-di-tert-butyl-4-[1-(ω-methacryloyloxyalkyl)-4-pyridino]phenolates, 1a and 1b ). These monomers are obtained via a multi-step reaction. First, 4-(3,5-di-tert-butyl-4-hydroxyphenyl)pyridine ( 2 ) is electrosynthesized by an S_RN1 reaction in liquid ammonia. Then, this pyridine derivative is N-alkylated by an ω-bromoalkyl methacrylate ( 5a or 5b ) which, in its turn, is obtained by esterification of an ω-bromoalcohol and methacryloyl chloride.     

Synthesis,polymerization, copolymerization,and transition-metal coordination of 4-(2,2′:6′,2″-terpyridin-4′-yl)styrene and its polymers and copolymers

Homopolymer 5 from 4-(2,2′:6′,2″-terpyridin-4′-yl)styrene ( 4 ) and copolymers 6–8 from 4 and styrene, vinyl acetate, or acrylic acid were prepared by radical-initiated polymerization with 2,2′-azoisobutyronitrile. These polymers containing pendent 2,2′:6′,2″-terpyridinyl ligands readily formed monotridentate complexes with FeCl₂, NiCl₂, and CuCl₂. By reaction of copolymer 6 with 4′-(p-tolyl)-2,2′:6′,2″-terpyridyliron(III) trichloride or 4′-(p-tolyl-2,2′:6′,2″-terpyridylruthenium(III)) trichloride in the presence of ammonium hexafluorophosphate yielded polymer-metal complexes 11a, 11b containing the corresponding bistridentate complexes. A cyclic voltammogram of 11a containing a bis(2,2′:6′,2″-terpyridyl)iron(II) complex showed characteristic Fe²⁺/Fe³⁺ redox couples at + 1,12 V vs. saturated calomel electrode, which was also observed as a reversible color change between purple and colorless.     

Über polyarylenalkenylene und polyheteroarylenalkenylene, 13. Synthesen und charakterisierung von poly (dithieno[3,2-b: 2′, 2′,3′-d]thiophen-2, 6-diylvinylenarylenvinylen)en und einigen modellverbindungen

From Witting-reactions of dithieno[3,2-b: 2′, 3′-d]thiophene-2, 6-dicarboxaldephyde ( 1 ) with “mono-and bis-Wittig-salts” of the benzene and thiophene series poly(dithieno[3,2-b: 2′,3′-d]-thiophene-2,6-diylvinylenearylenevinylene)s 3a—c and some model compounds 5a—c were obtained. Wittig-reactions of dithieno[3,2-b: 2′,3-d]thiophene-2-carboxaldehyde ( 6 ) with “mono-and bis-Wittig-salts” gave model compounds 7a—c and 8a, c . The structures of all compounds were confirmed by elements analyses, IR-and electronic spectra, those of the model compounds additionally by mass spectra, and in case of sufficient solubility by ¹ H NMR spectra. The electrical conductivities of all compounds and the thermooxidactive degradation of the polymers 3a, c were investigated.     

Synthese und Reduktion des Tetra-tert-butyltetraoxocalix[4]arens

5,11,17,23-Tetra-tert-butyl-25,26,27,28-tetrahydroxy-2,8,14,20-tetraoxocalix[4]arene ( 4 ) was synthesized by oxidation of the tetraacetate of 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrahydroxycalix[4]arene ( 1 ). Compound 4 was characterized by chemical and spectroscopic methods. Reduction of 4 with hydrazine forms the starting material 1. 4 reacts with sodium borohydride to give 5,11,17,23-tetra-tert-butyl-2,8,14,20,25,26,27,28-octahydroxycalix[4]arene ( 6 ).     

Polymeric chiral crown ethers, 4. Substituent effects of methyl and phenyl groups in the 3,3′-positions on chiral recognition of poly(crown ether)s synthesized by cyclopolymerization of divinyl ethers derived from 1,1′-bi-2-naphthol

Chiral poly(crown ether)s were synthesized by cationic cyclopolymerization of (S)-2,2′-bis(2-vinyloxyethoxy)-3,3′-dimethyl-1,1′-binaphthyl [(S)- 1b ] and (R)-2,2′-bis[2-(2-vinyloxyethoxy)-ethoxy]-3,3′-dimethyl (or 3,3′-diphenyl)-1,1′-binaphthyl [(R)- 3b or (R)- 3c ]. The substituents in the 3,3′-positions of binaphthyl moiety disturb the intramolecular cyclization in the polymerization of monomer (S)- 1b , but have no influence on the cyclopolymerization tendency of monomers (R)- 3b and (R)- 3c . The polymers from (R)- 3b and (R)- 3c [(R)- 4b and (R)- 4c ] have a higher ability of chiral recognition towards a-amino acids, such as phenylglycine, phenylalanine, valine, and methionine, than the polymer from (R)- 3a [(R)- 4a ], which has no substituent in 3,3′-positions. The methyl and the phenyl substituents in the 3,3′-positions undoubtedly act as additional barrier causing an increase in the ability of chiral recognition, though the effect is less than expected from the result of model crown ethers.     

Electrochemical and chemical syntheses and doping of [poly(2,2′-dithienyl)-5,5′-diylvinylene]

The electroconductive polymer poly[(2,2′-dithienyl)-5,5′-diylvinylene] ( 1 ) was prepared by both electrochemical and chemical methods starting from trans-di(2-thienyl)ethylene ( 2 ). The electrochemically prepared material showed electrical conductivities of up to 40 Ω^?1 · cm^?1; the neutral, chemically prepared polymer was droped with iodine or arsenic pentafluoride but the conductivities were low. The experimental procedures are described and an interpretation of the results is given.     

Quenching of the excited state of membranes having polymerpendant tris(2,2′-bypyridine)ruthenium(II) groups by methylviologen and dioxygen

Quenching of the excited state of copolymer-pendant Ru(bpy) membranes by methylviologen (MV²⁺) and dioxygen was studied and its application proposed. The copolymers used were the copolymer of styrene (St) and 4-methyl-4′-vinyl-2,2′-bipyridine (Vbpy) and that of methyl methacrylate (MMA) and Vbpy. The copolymer-pendant complexes were prepared by reaction of the St- and MMA-copolymers with cis-Ru(bpy)₂Cl₂. The excited state of the St-copolymer complex membrane was not quenched by MV²⁺ solution in aqueous medium, but quenched in methanol. The excited state of the MMA-copolymer complex membrane was not quenched by MV²⁺ neither in water nor in water/methanol mixture. The excited state of St-copolymer complex membrane was not quenched by dioxygen in water, but in methanol. The excited state of MMA-copolymer complex membrane was quenched by dioxygen both in water and water/methanol mixture. The quenching by dioxygen can be used to measure the oxygen concentration in solutions.     

Living cationic polymerization of styrene by the bifunctional initiating system 1,4-bis(1-chloroethyl)benzene/SnCl4 in the presence of 2,6-di-tert-butylpyridine

The polymerization of styrene was studied by using a bifunctional initiator, 1,4-bis(1-chloroethyl)benzene ( 1 ). It was demonstrated that living polymerization can be achieved in the styrene/ 1 /SnCl₄ system in chloroform at ?15°C in the presence of 2,6-di-tert-butylpyridine. The number-average molecular weight of the obtained polymers increases with monomer conversion and with addition of a fresh feed of monomer at the end of the first-stage polymerization. The molecular weight distribution (MWD) of the obtained polymers is narrow ratio of weight- to number-average molecular weights (M _w/M _n < 1,2) throughout the polymerization. In the absence of 2,6-di-tert-butylpyridine, the initiating system results polystyrene with a bimodal MWD. Also a bimodal MWD was obtained with H₂O/SnCl₄ as initiating system. 2,6-Di-tert-butylpyridine in conjunction with H₂O/SnCl₄ does not lead to polymerization.     

Synthesis and properties of para-linked aromatic polycondensates containing 3,3′,4,4′-biphenyltetracarboxylic-N,N′-bis(4-amino-biphenyl) diimide units

Two new diamino monomers based on 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) were synthesized and used in a low temperature polyamide polycondensation. High molecular weight homopoly(amide-imide)s and copoly(amide-imide)s were synthesized via in-situ silylation and investigated with respect to their solution, thermal, and film forming properties. All polymers are soluble in strong acids and most in amide type solvents. Inherent viscosities up to 7.4 dl/g in N-methyl-2-pyrrolidone (NMP)/LiCl were achieved. A methyl substitution in ortho-position to the imide group resulted in polymers possessing improved solubility and good thermal stability up to 500°C. Isotropic films can be prepared from solution.     

Condensation polymerization of 2,2′-diiodobiphenyl-4,4′-dicarbonyl dichloride with some mono- and diamino compounds

Several potentially thermostable polyamides were prepared. 2,2′-Diiodobiphenyl-4,4′-dicarboxylic acid and its diacid chloride 1 were synthesized. The latter was condensed with several amines, e.g., aniline, p-toluidine, p-chloroaniline, and 2-aminopyridine, to prepare model compounds of polyamides testing the reactivity of the diacid dichloride 1 towards various amines, and to compare their spectra with those of the polymers. The polyamides themselves were prepared by solution and melt condensation of diacid chloride 1 with the following diamines: p-phenylenediamine, m-phenylenediamine, 2,6-diaminotoluene, benzidine, bis(4-aminophenyl)-methane, 4,4′-diaminobiphenyl sulfone, and 3,3′-diaminobenzophenone. The solubility of the polyamides in different solvents and their inherent viscosities were also measured. The values of the inherent viscosity were in the range of 0,1–1,9. The UV, IR, and ¹H NMR spectra of the prepared polyamides were recorded. The melting points of the polymers were found to be higher than 360°C and the thermogravimetric curves showed that the polymers are stable up to 400°C in air.     

Copolymerization of ethene with methyl acrylate and ethyl 10-undecenoate using a cationic palladium diimine catalyst

The cationic palladium catalyst [(ArN=C(Me)C(Me)N=Ar)Pd(CH₃)(NC—CH₃)]⁺BAr'₄^- (Ar = 2,6-C₆H₃(CH(CH₃)₂); Ar' = 3,5-C₆H₃(CF₃)₂) (DMPN/borate) was applied in ethene homopolymerization as well as ethene copolymerization with polar monomers such as methyl acrylate and ethyl 10-undecenoate. Both ethene homo- and copolymerization afforded amorphous, branched polyethenes with glass temperatures around –65°C and very similar high degree of branching (105 branched C/1000C), which was independent of temperature and ethene pressure. Copolymerization with polar comonomers gave polyethylene containing both alkyl and ester-functional alkyl side chains. The ratio of both types of short chain branches was influenced by the feed concentration of polar monomer. In the presence of sterically hindered phenols (e. g., 2,6-di-tert-butyl-4-methylphenol (BHT)) and tetramethylpiperidine-N-oxyl radical (TEMPO) acrylate homopolymerization was prevented. BHT addition promoted both catalyst activity and methyl acrylate incorporation significantly. Polymerization reaction, polymer microstructures and polymer properties of polar and non-polar branched polyethenes were investigated.     

Asymmetric induction in the cyclopolymerization of divinyl ethers derived from (R)- or (S)-3,3′-dimethyl-1,1′-bi-2-naphthol

Optically active divinyl ethers, (?)-(R)- and (+)-(S)-2,2′-bis[2-(2-vinyloxyethoxy)ethoxy]-3,3′-dimethyl-1,1′-binaphthyl [(R)- 1b and (S)- 1b ] were polymerized to produce chiral poly(crown ether)s. Their optical rotation was found to be profoundly influenced by the polymerization conditions. When increasing the monomer concentration from 0,1 to 0,3 mol · 1^?1, after polymerization with SnCl₄ in CH₂Cl₂ at 0°C, the optical rotation of the resulting polymers is drastically changed from +44,5° to ?17,3° for (R)- 1b and from ?35,6° to +20,9° for (S)- 1b . The analysis of ¹H NMR showed that the polymers have changed their optical rotation due to a configuration which has a tendency to be preferentially racemic diad at higher monomer concentrations in a nonpolar solvent. There are indications that the twist of 2,2′-binaphtyl moieties, the methyl groups in 3-, and 3′-positions as steric barrier, and the intramolecular solvation of the growing carbo-cation cooperatively control the propagation to induce the asymmetry in the main chain.