Oxidative Cyclization of Unsaturated Ketene Dithioacetals with Ceric Ammonium Nitrate to Form Bicyclic Lactones

Ceric ammonium nitrate oxidizes unsaturated ketene dithioacetals in wet MeCN to give cation radicals that cyclize to trisubstituted double bonds and styrenes by cation-like cyclizations leading to cyclic cation radicals that are transformed by further oxidation, hydrolysis and cyclization to bicyclic lactones in moderate to good yield.     

Oxidative polymerization of p-alkylphenols catalyzed by horseradish peroxidase

Enzymatic oxidative polymerization of p-alkylphenols using horseradish peroxidase as catalyst has been carried out in two polymerization solvent systems: a mixture of phosphate buffer (pH 7) and 1,4-dioxane, and a reverse micellar solution, yielding powdery polymeric materials. The polymer yield was much dependent upon the type of alkyl group in the monomer as well as the solvent type. In case of the polymerization of umbranched alkylphenols in the aqueous 1,4-dioxane, the polymer yield increased with increasing chain length of the alkyl group from 1 to 5, and the yield of the polymer from hexyl or heptylphenol was almost the same as that of the pentyl derivative. The relationship between the type of substituent and the polymer yield in the reverse micellar system was different from that in the aqueous 1,4-dioxane; the highest yield was achieved from ethylphenol. The resulting polymers had molecular weight of several thousands. The polymer was estimated to be composed from a mixture of phenylene and oxyphenylene units from IR analyses. TG measurement exhibited that the polymer had relatively high thermal stability. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1453–1459, 1997     

Oxidative polymerization of hydroquinone using deoxycholic acid supramolecular template

Polyhydroquinone (PHQ) is a redox-active polymer with quinone/hydroquinone redox active units in the main chain and may have potential applications as a mediator in biosensors and biofuel cells. By the oxidative polymerization of hydroquinone (HQ), PHQ can be easily synthesized, but the reaction lacks control over the structure of the product. Deoxycholic acid (DCA) was introduced as a supramolecular template to control the reaction. The reaction rate is 14 times of that in deionized water and twice of that in buffer. The DCA template increases not only the reaction rate, but also the molecular weight of the polymer obtained. The template effect of DCA was attributed to the supramolecular assemblies of DCA formed in the solution. Cyclic voltammetry study indicated the resulting PHQ was redox-active. While the supramolecular assemblies of DCA provided a template for the oxidative polymerization of HQ, the protons released as a by-product of the oxidative polymerization of HQ in turn enhanced the self-assembly of DCA. As a result, DCA microfibers form and separate out of the solution.     

Ceric(IV)-mediated Oxidative Addition of 1, 3-Dicarbonyl Compounds to MCPs: A Facile Access to Dihydrofuran Derivatives Incorporating Cyclopropyl Groups

A variety of simple cyclopropane-containing compounds have been of synthetic interest due to their biological activity1. The dihydrofuran ring system is found prevalently at the central position of diverse classes of naturally occurring and biologically a…     

Oxidative polymerization of phenylenediamines catalyzed by horseradish peroxidase

Ortho-, meta-, and para-phenylenediamines were polymerized using hydrogen peroxide as an oxidant and horseradish peroxidase as a catalyst in mixed solvents of 1,4-dioxane and water. The yield of the polymers was strongly dependent on solvent composition, and maximum yields were obtained at 15–30% 1,4-dioxane. The analysis of circular dichroic spectra of the enzyme suggested that enzyme structure was significantly modified at high 1,4-dioxane contents, which may be responsible for the decrease of catalytic activity of the enzyme. On the basis of IR and electronic spectra of the polymers, it was considered that o- and p-phenylenediamine polymers retain disubstituted benzene nuclei, which suggests that the polymerization proceeded mainly via N—N coupling. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2593–2600, 1998     

Electroinduced polymerization of acrylonitrile in the presence of Ce(IV)

Polymerization of acrylonitrile (AN) initiated by Ce(IV) was performed in an electrolytic cell. The precipitated polymer was formed in the cathodic compartment, and the reduced initiator was reoxidized in the anode, thus allowing for the continuation of the process. The effects of concentrations of the monomer, Ce(IV), and sulfuric acid (the electrolyte) were investigated as well as the potential and the temperature. The yield of the process, proceeding under mild conditions, was high. The study was augmented by voltametric and spectrophotometric investigation. The resulting polymer was characterized by FTIR and optical spectrometry, and its m.w. was determined by viscometric method. A possible mechanism of polymerization is suggested. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2319–2327, 1999     

Redox polymerization of methyl methacrylate with allyl alcohol 1,2-butoxylate-block-ethoxylate initiated by Ce(IV)/HNO3 redox system

Redox initiated free-radical polymerization of methyl methacrylate (MMA) with allyl alcohol 1,2-butoxylate-block-ethoxylate (AABE) was carried out using cerium(IV) ammonium nitrate/nitric acid (HNO₃) redox system to yield AABE-b-PMMA copolymers. The effects of MMA, AABE, Ce(IV) and HNO₃ concentrations on the polymerization rate and polymer yield were investigated. The effect of temperature on the rate of polymerization and polymer yield was also investigated in the temperature range of 25-70 °C. Copolymers were characterized using GPC, FT-IR, ¹H NMR and viscometry methods.     

CAN/PEG-400体系催化合成氧杂蒽二酮类衍生物

以硝酸铈铵(CAN)为催化剂,PEG-400为溶剂,芳香醛与β-环己二酮于85℃反应2.0 h～3.0 h合成了一系列氧杂蒽类衍生物,收率83%～96%,其结构经1H NMR和13C NMR确证。CAN/PEG-400可回收套用4次。     

Efficient synthesis of well-defined polycarbazoles via catalyst-transfer Kumada coupling polymerization

Polycarbazoles (PCZ) are well-studied class of polymers with good electrical and photoactive properties. Here, we have prepared the well-defined 3,6-PCZ with a molecular weight of 6148 and low polydispersities of 1.18. We also used 2,7-dibromo-9-(heptadecan-9-yl)-9H-carbazole as monomer to increase the solubility of the polymer. The 2,7-PCZ with a high molecular weight over 10,000 and low polydispersity of 1.27 was prepared successfully.     

N-取代环十二酮缩氨基硫脲的氧化环合反应

以环十二酮为起始物合成的一系列N-取代环十二酮缩氨基硫脲(Ⅰ)经二氧化锰氧化环合为2-(1,11-十一亚甲基)-5-取代亚氨基-△^3-1,3,4-噻二唑啉(Ⅱ)。Ⅱ的结构得到IR,13^CNMR和元素分析的确证。反应中同时分离到一个副产物,经IR,13^CNMR,EIMS和元素分析确定其结构为2-(1,11-十一亚甲基)-5-亚氨基△^3-1,3,4-噻二唑啉(Ⅲ)。据此提出了Ⅰ经二氧化锰氧化环合为Ⅱ的两步反应机制,此机制可以合理地解释Ⅱ和Ⅲ的生成。     

Asymmetric polymerization of N-vinylcarbazole with optically active anionic initiators

The anionic polymerization of N-vinylcarbazole(NVC) by using optically active anionic initiators such as the lithium salts of(S)-1-(9H-fluoren-2-yl)-4-isopropyl-4,5-dihydrooxazole((S)-1-FIDH) and(S)-2-(9H-fluoren-2-yl)-4-isopropyl-4,5-dihydrooxazole((S)-2-FIDH) and complexes of(-)-Sparteine with n-butylithium(n-Bu Li-(-)-Sp) or fluorenyl lithium(FILi-(-)-Sp) was achieved. The yield and specific rotation of poly(N-vinylcarbazole)s(poly(NVC)s) were considerably affected by the molar ratio of(S)-FIDH to NVC. The highest yield and specific rotation were obtained with Li-(S)-1-FIDH as an initiator, with a molar ratio of monomer and initiator [M]/[I] = 10/1. The effects of the chiral initiators, type of solvent and the polymerization temperature were investigated. The obtained optical activity of polymers was attributed to asymmetric induction of the chiral initiators.     

Bulk polymerization of N-vinylcarbazole initiated by C60

In this communication, we first used [60]fullerene as initiator to initiate the bulk polymerization of N-vinylcarbazole (NVC) monomer at 70°C (slightly higher than the melting point temperature, 65°C, of NVC). A reasonable polymerization reaction pathway via C₆₀-NVC ion-radical pairs is suggested. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3745–3747, 1999     

CAN引发S-DMDAAC-AM接枝共聚的研究

以硝酸铈铵(CAN)为引发剂,以淀粉(S)、二甲基二烯丙基氯化铵(DMDAAC)和丙烯酰胺(AM)为原料,通过反相乳液聚合,合成接枝共聚物。研究了加料顺序、引发剂浓度、单体与淀粉配比、油水体积比、乳化剂用量等因素对产品性能的影响。并用IR和1H-NMR对接枝产物进行了分析表征。     

Oxidative coupling polymerization of bishydrazide for the synthesis of poly(diacylhydrazine): Oxidative preparation of oxidatively degradable polymer

The oxidative coupling polymerization of bishydrazide is successfully performed to form poly(diacylhydrazine) (PDAH), which is an oxidatively degradable polymer. Oxone is an effective oxidant, and a mixture of an aprotic polar solvent, water, and acetonitrile or N,N‐dimethylacetamide is necessary as the solvent. On treatment of PDAH with sodium hypochlorite solution or hydrogen peroxide, the PDAH is rapidly oxidized and degraded to the corresponding dicarboxylic acid. When hydrogen peroxide is used as the oxidant, the addition of acetonitrile and potassium carbonate is necessary for effective degradation. PDAH exhibits high thermal stability in air and a high T_g value. No oxidation is observed in air. Thus, PDAH is an oxidatively degradable high‐performance polymer that is stable toward oxygen. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Radical polymerization of N-substituted itaconamic esters and itaconamides

Two kinds of itaconamic esters, α-substituted acrylate derivatives (IAE-I) and α-substituted acrylamide derivatives (IAE-II), as well as itaconamides (IAm) were prepared and polymerized with a radical initiator. It has been revealed that N,N-disubstituted IAE-I as an acrylate is more reactive in polymerization than N,N-disubstituted IAE-II as an acrylamide and that N,N′-dialkyl substituted IAm homopolymerizes but N,N,N′,N′;-tetraalkyl substituted one does not. In radical copolymerization with styrene, IAE-I showed a higher polymerization reactivity than IAE-II. The effects of the N-substituents on the polymerization reactivity were discussed on the basis of conformation of the monomers. The polymers obtained were also characterized. © 1994 John Wiley & Sons, Inc.     

Oxidative chemical polymerization of pyrrole

A reaction calorimeter has been used to determine at three different temperatures the enthalpy values for the polymerization of pyrrole dissolved in acetonitrile, by using FeCl₃ as the oxidative agent. From the calorimetric data it has been found that the reaction is first-order with respect to the pyrrole. The rate constants at the same temperatures have also been determined. By using the Arrhenius equation we have obtained the activation energy for the formation of this electroconducting polymer.Financial support from the italian National Research Council (CNR) is gratefully acknowledged.     

丝胶-甲基丙烯酸甲酯接枝共聚物的合成与表征

在酸性水介质中,以硝酸铈铵为引发剂合成了丝胶-甲基丙烯酸甲酯接枝共聚物,其结构经1H NMR,IR,SEM和GPC表征。用正交试验法考察了各因素对接枝共聚反应的影响,结果表明,单体浓度对接枝聚合反应的影响最大,反应时间的影响最小。     

Monomer-lsomerization Polymerization of Some Branched Internal Olefins with a Ziegler-Natta Catalyst

New examples for the monomer-isomerization polymerizations of some branched internal olefins, 4-methyl-2-pentene and 4-phenyl-2-butene, are presented. When these olefins are polymerized with A1(C₂ H₅)₃-TiCl₃ ([TiCl₃] = 120 mmole/liter, A1/Ti = 3.0) catalyst at 80°C, considerable amounts of high polymers [27.5%/60 hr ([η] = 0.68 d1/g) and 35.6%/100hr, respectively] were obtained. From the additional fact that the isomerization from these 2-olefins to the mixture of their positional isomers including 1-olefins was observed during the polymerization, it is assumed that the polymerizations from these 2-olefins are performed with the 1-olefins which isomerized from the starting 2-olefins.     

Ceric ammonium nitrate/acetic anhydride: A tunable system for the O-acetylation and mononitration of diversely protected carbohydrates

Esterification of a wide range of partially protected carbohydrate derivatives was achieved using acetic anhydride and a catalytic amount of ceric ammonium nitrate (CAN). Compatibility with the commonly used protecting groups was demonstrated, with the esterified products being furnished in good yields. Apart from affording the O-acetylated products, their mononitrated counterparts were also produced depending upon the reactivity of the starting material. Decreasing the molar equivalents of CAN afforded the O-acetylated products exclusively, while increasing it favored the mononitrated derivatives.     

Application of thermal analysis to study the macroredox polymerization of styrene with hydroxy-terminated polybutadiene

Ceric ammonium nitrate-hydroxy-terminated polybutadiene macroredox initiator has been investigated for the polymerization of styrene in nitric acid medium at 35 °C. Water inhibited the polymerization of styrene using this macroredox system. The products obtained were crosslinked and insoluble in water and organic solvents. A probable mechanism for the copolymerization reaction has been inferred from differential scanning calorimetry. Kinetic parameters for thermal degradation have been calculated by thermogravimetry (TG).