Polymers derived from 2,5-diamino-p-benzoquinone-diimide and related compounds

A number of new polymeric materials have been prepared by the self-condensation of 2,5-diamino-p-benzoquinonediimide and by its condensation with 2,5-diamino-p-benzoquinone, 2,5-dihydroxy-p-benzoquinone, and 2,5-dichloro-p-benzoquinone. Ladder polymers were expected, but in every case polymers with some open rings were obtained. 2,5-Diaminohydroquinone was condensed with 2,5-diamino-p-benzoquinonediimide and with 2,5-diamino-p-benzoquinone to produce heat stable polymers but the expected ladder structures were not obtained. Thermogravimetric analyses of the polymers in nitrogen all showed a weight loss at 100–150°C of 3–14% which was presumably due to loss of either chemically combined or absorbed water on the polymer and then only a 5% weight loss up to about 600°C with a final weight loss of 19% at 900°C.     

Reactions of poly(methyl methacrylate) radicals with some <Emphasis Type="Italic">p</Emphasis>-quinones in the presence of tri-<Emphasis Type="Italic">n</Emphasis>-butylboron in methyl methacrylate polymerization

The polymerization of methyl methacrylate initiated by dicyclohexyl peroxydicarbonate at 30 °C was studied in the presence of tri-n-butylboron and a series of quinones, namely, p-benzoquinone, chloranil, and 2,5-di-tert-butyl-p-benzoquinone, whose concentration changed from 0.25 to 2.00 mol.%. The initial polymerization rate and molecular weight of poly(methyl methacrylate) depend on the structure and concentration of quinone. The growth radicals react with p-benzoquinone and chloranil predominantly at the C=C bond, while they react at the C=O bond of 2,5-di-tert-butyl-p-benzoquinone. The terminal stable oxygen-centered radicals that formed react with alkylborane, terminating reaction chains and generating alkyl radicals into the bulk. The latter are involved in chain initiation.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2114–2119, October, 2004.     

Rigid-ladder polymers: Polymers containing anthraquinone recurring units

In an attempt to synthesize some processable ladder or partial ladder polymers containing anthraquinone recurring units, leucoquinalizarin was treated with 3,3′-diaminobenzidine. This polymer, which was a black powdery material, was slightly soluble in concentrated sulfuric acid and dimethylsulfoxide. Also, 1,5-diamino-2,6-dimercaptoanthraquinone was condensed with 2,5-dichloro-p-benzoquinone in pyridine to give a black powdery polymer. This was only partially soluble in concentrated sulfuric acid, but could be solubilized in alkali by reduction with sodium dithionite.     

2,5,-Dimethoxy- and 2,5-di-n-butoxy-1,4-benzoquinone reactions and polymerization with 1,6-hexanediamine

The serendipitous formation of 2,5-dimethoxy- 1,4-benzoquinone is reported from the reaction of 1,4-benzoquinone with methanol, DABCO, and paraformaldehyde. This monomer, and its di-n-butoxy analog, are also available from 2,5-dihydroxy-1,4-benzoquinone. These materials are capable of novel polycondensation reactions with diamines such as 1,6-hex-anediamine. Use of m-crexsol as polymerization solvent gave a dark, insoluble product while various amide solvents lead to orange or pink polymers that had average degrees of polymerization from 5 up to >30. These polymers, Plus model compounds obtained from 1-aminopropane and N,N'- dimethyl-1,6-hexanediamine, were characterized by FTIR, solution, and solid-state NMR.     

Photocrosslinking of polymers bearing epoxy or epithio groups by quinones in the solid state

Photocrosslinking of poly(glycidyl methacrylate) (PGMA) and a copolymer of 2,3-epithiopropyl methacrylate and methyl methacrylate [P(ETMA-co-MMA)] was studied in the solid state in the presence of various quinones. The efficiency of photocrosslinking was strongly dependent upon the structures of quinones and the kinds of polymers. For example, the alkyl-substituted quinones such as 2-ethyl-p-benzoquinone (EQ), 2-tert-butyl-p-benzoquinone (tBQ) and 2,5-di-tert-butyl-p-benzoquinone (2,5-dtBQ) did not induce photocrosslinking of poly(methyl methacrylate) (PMMA), whereas they acted as efficient photocrosslinking agents in PGMA and P(ETMA-co-MMA). The formation of charge transfer complexes did not play a principal role in this effective photocrosslinking, because the order of the photocrosslinking efficiency [EQ > tBQ > 2,5-dtBQ > p-benzoquinone (Q)] was not in agreement with that of the magnitude of the electron affinities of quinones, i.e., Q > EQ > tBQ > 2,5-dtBQ. Photopolymerization of propylene sulfide (PS) in the presence of tBQ or Q was also investigated. The presence of tBQ induced polymerization of PS upon UV irradiation. From these results, it was deduced that the photocrosslinking of P(ETMA-co-MMA) film containing tBQ proceeds via a cationic polymerization of epithio groups. A similar mechanism should be applicable to the photocrosslinking of PGMA film containing tBQ.     

The interaction between polymerization initiators and inhibitors in solution—IV: The reaction of benzoyl peroxide with hydroquinone in solution

The reaction between benzoyl peroxide and hydroquinone in a wide variety of solvents has been investigated by isolation and identification of the products. Benzoic acid, p-benzoquinone and benzoyloxy derivatives of p-benzoquinone are obtained under all conditions. Their relative amounts are largely determined by the molar ratios of the reactants and the nature of the solvent. In strongly polar solvents of high solvation power, p-benzoquinone is formed in preference to its derivatives. Nevertheless, the yield of 2,5-dibenzoyloxy p-benzoquinone reaches a maximum in acrylonitrile. Only in this solvent, at equal molar ratios of reactants, is full substitution in the hydroquinone nucleus achieved with the formation of tetrabenzoyloxy hydroquinone. These facts, together with the partial polymerization of acrylonitrile at room temperature at slightly higher peroxide/hydroquinone ratios and the complete suppression of the polymerization when perchloric acid is added, could be explained by a heterolytic mechanism involving the formation and controlled separation of ion pairs derived from the reactants.     

Uncontrolled pseudoliving free-radical polymerization of methyl methacrylate in the presence of butyl-<Emphasis Type="Italic">p</Emphasis>-benzoquinones

Polymerization of methyl methacrylate initiated by dicyclohexyl peroxydicarbonate in the presence of tri-n-butylboron and butyl-p-benzoquinone or 2,5-di-tert-butyl-p-benzoquinone occurred with no induction period. The yields and molecular masses of the polymers linearly increased with an increase in the conversion degree, which suggests the free-radical mechanism of “living” chain polymerization. The poly(methyl methacrylate) macrochains of the prepolymers contained sterically hindered aromatic structures with labile C-O bonds. The latter underwent reversible homolytic dissociation to give a growth-inducing radical and sterically hindered aryloxyls. Pseudoliving free-radical polymerization in the presence of the prepolymer (macroinitiator) was studied at 45, 60, and 80 °C. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1119–1122, June, 2007.     

Polymerization of methyl methacrylate in the presence of 2,5-di-tert-butyl-p-benzoquinone

Polymerization of methyl methacrylate in the presence of 2,5-di-tert-butyl-p-benzoquinone is a combination of two processes: inhibited and controlled radical polymerization. The adduct of chain propagation radicals and p-quinone formed due to the inhibited polymerization is a macroinitiator of controlled radical polymerization. The fraction of the pseudo-living process is determined by the concentration of p-quinone in the starting polymerized composition. Post-polymerization proceeds via the reversible inhibition mechanism.

     

New method for detection and spectrophotometric determination of quinones

The reaction between 3-phenylthiazolidine-2,4-dione (I) and p-benzoquinone (II), tetrachloro-p-benzoquinone (III), and 1,4-naphthoquinone (IV) in ammoniacal medium is applied for detection and spectrophotometric determination of quinones. The absorbance-concentration relationship is linear up to 18 μg/ml of quinone concentration. The lower limits of identification in the detection reaction are 2.5, 3.0, and 1 μg for (II), (III), and (IV), respectively, which reflect high sensitivity. The reaction between (I) and quinones is proved to be a condensation reaction and highly selective.     

醌型木素模型物的光学特性

为探索醌型木素化学结构与颜色的关系,以五种醌型木素模型物2-甲氧基-1,4-苯醌(I)、1,2-苯醌(II)、4-亚烯丙基-2-甲氧基-2,5-环己二烯酮(亚甲基醌)(III)、5-甲氧基-1,4-苯醌-2-氧负离子(IV)和5-甲基-1,4-苯醌-2-氧负离子(V)作为纸浆中醌型木素发色体的代表,在B3LYP/6-311++G(2d,p)水平上获得了它们在乙醇中的稳定基态构型,采用含时密度泛函理论(TD-DFT)在同等水平上计算了其在乙醇溶液中的电子光谱,并分析了它们在可见光范围内的吸收.结果发现:五种模型物在可见光范围内的吸收均源于电子的π→π*跃迁,它们的最大吸收波长顺序依次为IIIIIIIVV,吸光系数顺序依次为IVIVIIIII;漂白过程中生成的醌氧负离子以及邻醌类模型物具有中等大小的吸光系数(ε=1978-3197),吸收波长较长(445.47-552.36 nm),是漂白后纸浆具有颜色的重要原因.对醌类模型物吸收波长较小(414.91 nm),吸光系数大小为中等(ε=2094),亚甲基醌类模型物虽然吸光系数大(ε=31935),但吸收波长较小(407.90 nm),二者对漂白后纸浆的颜色影响较小.     

Synthesis of sterically hindered benzoquinone methacrylates

Sterically hindered p- and o-benzoquinone methacrylates, viz., 2,5-di(tert-butyl)-3,6-di-oxocyclohexa-1,4-dienyl methacrylate and 2,5-di(tert-butyl)-3,4-dioxocyclohexa-1,5-dienyl methacrylate, were synthesized by O-acylation of the lithium and tetrabutylammonium salts of 3,6-di(tert-butyl)-2-hydroxy-p-benzoquinone with methacryloyl chloride. The influence of the nature of cation and solvent on regioselectivity of the acylation was studied. The o-benzoquinone derivative obtained can serve as a paramagnetic ligand in metal complexes.     

Synthesis of aromatic polyesters and polyamides by alternating copolymerizations of 1,4-dicarbonyl-1,4-dihydronaphthalene with bezoquinones and benzoquinone diimines

1,4-Dicarbonyl-1,4-dihydronaphthalene ( 1 ) was synthesized by the dehydrochlorination reaction of 1,4-dihydronaphthalene-1,4-dicarbonyl chloride with triethylamine and obtained as its very dilute solution, but it easily polymerized in the concentration as high as 0.1 mol/L to give its polymer. 1 generated in situ by the dehydrochlorination reaction of 1,4-dihydronaphthalene-1,4-dicarbonyl chloride in a deoxygenated toluene polymerized alternatingly with benzoquinones such as 2-dodecylthio-p-benzoquinone, 2,5-di(tert-butyl)-p-benzoquinone, p-benzoquinone, and 2,3-dichloro-5,6-dicyano-p-benzoquinone, and with benzoquinone diimines such as N,N′-diethoxycarbonyl-p-benzoquinone diimine, N,N′-dibenzoyl-p-benzoquinone diimine, and N,N′-diphenyl-p-benzoquinone diimine to give aromatic polyesters and polyamides, respectively. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1929–1936, 1998     

Electron transfer and paramagnetic products of reactions of haloquinones with aliphatic amines

The reactions of chloranil (Cl₄Q) and bromanil (Br₄Q) with aliphatic amines in a DMF : H₂O (5 : 1, vol/vol) mixture were studied. The radical anions of 2,5-didimethylamino-3,6-chloro-p-benzoquinone and 2,5-didimethylamino-3,6-bromo-p-benzoquinone were identified by ESR spectra. The reaction rate constant of the replacement of two chlorine atoms by the amino groups in the radical anion of Cl₄Q at 288 K was estimated.     

Quinone copolymerization. I. Reactions of p-chloranil,p-benzoquinone,and 2,5-dimethyl-p-benzoquinone with vinyl monomers under free-radical initiation

The free-radical copolymerization reactions of p-chloranil, p-benzoquinone, and 2,5-di-methyl-p-benzoquinone with vinyl monomers were studied. Reactions of p-chloranil with styrene yielded copolymers of approximately 1:1 composition under a variety of reaction conditions. A copolymer containing a block of 1:1 of styrene:p-chloranil and a block of polystyrene was prepared. Several styrene-like monomers copolymerized with p-chloranil to yield copolymrs possessing considerable amounts of incorporated quinone. p-Benzoquinone copolymerized with 1,3-butadiene and 2-vinyl-pyridine to yield copolymers of significant molecular weights. Reactions of 2,5-dimethyl-p-benzoquinone with vinyl monomers did not yield any isolable polymeric products.     

Preparation and radical ring-opening polymerization of exo-methylene substituted cyclic ketene acetals

Preparation and radical ring-opening polymerization of the exo-methylene substituted cyclic ketene acetals, 2,4-dimethylene-1,3-dioxolane ( I ) and 2,5-dimethylene-1,3-dioxane ( II ), were carried out. Ketene acetals I and II were prepared by dehydrohalogenation of the corresponding cyclic haloacetal with potassium tert-butoxide in tetrahydrofuran at –78°C and ambient temperature, respectively. I underwent radical polymerization with essentially quantitative ring-opening with di-tert-butyl peroxide in dimethylformamide at 120°C. On the other hand, II underwent both ring-opening polymerization and vinyl polymerization under the same conditions of the polymerization of I . The differences of polymerization behavior between I and II were also discussed.     

Study of radiation-induced polymerization of vinyl monomers adsorbed on inorganic substances. V. Effects of p-benzoquinone and dose rate on methyl methacrylate–silica gel system

In order to elucidate the mechanism of radiation-induced polymerization of methyl methacrylate adsorbed on silica gel, the effects of p-benzoquinone addition and dose rate were studied in detail. Most of the polymerization is inhibited by p-benzoquinone at levels above 10^-2 mole/l. The GPC spectra of both graft polymers and homopolymers show two peaks. The high molecular weight material appears to have been formed by polymerization by a radical mechanism, because these peaks decrease as p-benzoquinone concentration increases; on the other hand, their low molecular weight polymers seem to be products of an ionic polymerization mechanism because those peaks are almost not affected by p-benzoquinone. The four GPC peaks differ in dose rate dependences of their polymerization rate. The dose-rate exponents of polymerization rate were obtained for the four GPC peaks. The behavior of the low molecular weight peaks of graft polymers and homopolymers were quite different, suggesting that the polymers differ considerably in formation mechanism.     

2-(N-Alkyl-p-hydroxyanilino)-1,4-benzochinone ausp-Benzochinonen und primären aliphatischen Aminen

In acetic (aqueous or chloroform) solutionp-benzoquinones yield with primary aliphatic amines mainly 2-(N-alkyl-p-hydroxy-anilino)-1,4-benzoquinones besides the 2-alkylamino- and 2,5-bis(alkylamino)-quinones. The methyl-, ethyl-,n-propyl-,n-butylhomologues ofp-benzoquinone and the isomer methylderivatives of toluquinone are described. Their structure were established by spectroscopic (UV/VIS, IR, NMR) methods and by synthesis of the methylderivative3 a fromp-benzoquinone andp-hydroxy-N-methylaniline. The influence of other acids on the reaction was studied.

Herrn Prof. Dr.G. Zigeuner, Universität Graz, mit den besten Wünschen zum 60. Geburtstag gewidmet.     

Polymerization and oxidation of pyrrole by organic electron acceptors

Simultaneous chemical polymerization and oxidation of pyrrole have been initiated by organic electron acceptors, 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and tetrachloro-o-benzoquinone(chloranil). The polypyrrole (PPY) complexes so produced are semiconductive and granular in nature. For the PPY–DDQ and PPY–chloranil complexes obtained from bulk polymerization, the respective electrical conductivities (σ) are of the order of 10^?1 and 10^?3 ohm^?1 cm^?1. However, σ is substantially lower for the complexes prepared in solvent media. Both complexes are relatively stable in the atmosphere. Thin uniform films of the PPY–organic acceptor complexes have also been synthesized on SnO₂ electrode by electrochemical polymerization in acetonitrile. The physicochemical properties of the PPY–organic acceptor complexes prepared chemically under the various experimental conditions are examined in detail.     

The reaction of 3,6-di-tert-butyl-1,2-benzoquinone and 3,6-di-tert-butylcatechol withtert-butyl hydroperoxide

Reaction of 3,6-di-tert-butyl-1,2-benzoquinone and 3,6-di-tert-butylcatechol withtert-butyl hydroperoxide in aprotic solvents leads to the generation of semiquinone (SQ^.H), alkylperoxy (ROO^.), and alkyloxy radicals. The reaction of SQ^.H and ROO^. produces 2,5-di-tert-butyl-6-hydroxy-1,4-benzoquinone, 3,6-di-tert-butyl-1-oxacyclohepta-3,5-diene-2,7-dione, and 2,5-di-tert-butyl-3,6-dihydroxy-1,4-benzoquinone. The radical generated from solvent attacks SQ^.H at position 4 with C−C bond formation. 4-Benzyl-2,5-di-tert-butyl-6-hydroxycyclohexa-2,5-diene-1-dione produced in this way is transformed into 4-benzyl-3,6-di-tert-butyl-1,2-benzoquinone under the reaction conditions. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 943–946, May, 1999.     

Preparation of soluble and fusible poly(2,5-dimethoxy-1,4-phenylene)

Poly(2,5-dimethoxy-1,4-phenylene) was prepared by oxidative polymerization of p-dimethoxybenzene with aluminum chloride and copper(II) chloride in nitrobenzene under reduced pressure. The polymers obtained were soluble in sulfuric acid and fusible at 320°C. The intrinsic viscosity of the polymer was ca. 0.07 in sulfuric acid. Demethylation of methoxy groups did not occur during the polymerization.