A novel synthetic method to phenyl-capped penta- and hexaaniline

A new convenient method is reported for the synthesis of the phenyl-capped pentamer and hexamer of aniline. The method was accomplished by the reaction of the parent aniline tetramer in the pernigraniline oxidation state with diphenylamine and N-phenyl-1,4-phenylenediamine in the leucoemeraldine oxidation state, respectively. The mechanism probably involves the formation of cation radicals and their coupling.     

Facile synthesis of phenyl-capped oligoanilines using pseudo-high dilution technique

Monodispersed phenyl-capped trianiline and tetraaniline were successfully synthesized by the reactions of diphenylamine with acetaldehyde-based Schiff's bases of N-phenyl-1,4-phenylenediamine and 1,4-phenylenediamine, respectively, in the presence of ammonium persulfate and hydrochloric acid, subsequent deprotonation and reduction with phenylhydrazine. The reaction mechanism probably involves the slow hydrolysis of the Schiff's bases and subsequent oxidative coupling reactions of the formed ammonium salts with diphenylamine at pseudo-high dilution condition of the salts.     

Preparation and characterization of polyaniline films in the presence of N-phenyl-1,4-phenylenediamine

The chemical oxidation of aniline to form polyaniline (PANI) films was made in the presence of N-phenyl-1,4-phenylenediamine (PPDA) in aqueous hydrochloric acid medium. The PANI films were monitored by using the quartz crystal microbalance (QCM) technique. The effect of PPDA and its concentration on the film formation was investigated. It was found that PPDA decreases the yield of the PANI film, the induction period and the depletion time of the polymerization. However, the growth rate of the film formation was found to increase by increasing PPDA concentration. These results were justified by measuring the UV-VIS absorption spectra for the in situ PANI films and the in situ UV-VIS absorption spectra for the polymer in the bulk during the polymerization. The conductivity for the PANI films at different concentrations of PPDA was measured. Also, the IR spectra, X-ray and the thermal gravimetric analysis for the PANI powder formed in the bulk in the presence of PPDA were measured and discussed.     

Electrochemical behavior of a new electroactive polyimide derived from aniline trimer

The electrochemical behavior of a soluble polyimide (Tani-polyimide) derived from an aniline trimer was investigated. Similar to processes observed in polyaniline, two typical redox processes involving protonation and ion insertion were observed. Due to the presence of an isolated, short quinonediimine or N,N′-diphenyl-p-phenylenediamine segment, Tani-polyimide displayed an electroactivity at higher potentials and did not undergo an electrochemical degradation reaction. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4295–4301, 1999     

Morphology studies of polyaniline lengthy nanofibers formed via dimers copolymerization approach

In this paper, two different aniline dimers, N-phenyl-1,2-phenylenediamine (2-PPD) and N-phenyl-1,4-phenylenediamine (4-PPD) were used as starting monomers in polyaniline (PANI) synthesis. It was found that 2-PPD dimer alone produced only an amorphous PANI oligomer with a flaky morphology, while the 4-PPD provided either linear nanofiber or a spaghetti-like hollow nanofiber structures comprising of worm-like fibril subunits. By adjusting the molar fed ratio of 4-PPD to 2-PPD in the copolymerization, long PANI nanofibers with length up to tens of microns, bundled together by single PANI fibrils with diameter ca. 3-5 nm, was formed. A possible formation mechanism was proposed taking account of the reactivity difference at positions 4 and 2 on the 4-PPD and 2-PPD, respectively.     

Theoretical study of the oxidative polymerization of aniline with peroxydisulfate: Tetramer formation

Semi‐empirical quantum chemical study of the oxidative polymerization of aniline with ammonium peroxydisulfate, in aqueous solutions without added acid, has been based on the MNDO‐PM3 computations of thermodynamic, redox, and acid–base properties of reactive species and the intermediates, combined with the MM2 molecular mechanics force‐field method and conductor‐like screening model of solvation. The main reaction routes of aniline tetramerization are proposed. The regioselectivity of the formation of aniline tetramers by redox and electrophilic aromatic substitution reactions is analyzed. It was proved that the linear N? C4 coupled tetra‐aniline is formed as a dominant product by three different pathways: comproportionation redox reaction between N‐phenyl‐1,4‐benzoquinonediimine and 4‐aminodiphenylamine, the one‐electron oxidation of aniline with its half‐oxidized N? C4 coupled trimer, and the electrophilic aromatic substitution reaction of aniline with fully oxidized N? C4 coupled trianiline nitrenium cation. The electrophilic aromatic substitution reaction of the N? C4 coupled aniline trimer with aniline nitrenium cation, as well as the oxidation of aniline with half‐oxidized branched trimer, lead to the branched aniline tetramers. The competing character of different tetramerization routes is highlighted. The oxidative intramolecular cyclization of branched oligoanilines and polyaniline, leading to the generation of substituted phenazine units, has been predicted to accompany the classical routes of the polymerization of aniline. Various molecular (branched vs. linear) oligomeric structures produced at different level of acidity during the course of polymerization and their impact on the formation of supramolecular structures of conducting polyaniline (nanorods and nanotubes vs. granular morphology), are discussed. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

New organosilicon derivatives of some analytical reagents: sorbents and metallochromic agents

A synthesis of organosilicon monomeric and polymeric derivatives of 1,4-phenylenediamine, 4-aminoantipyrine, and aniline, which are analytical agents possessing sorption properties, was accomplished. The synthesized organosilicon polymers were studied as sorbents of heavy metals Fe^III, Hg^II and noble metals Ag^I, Au^III, Rh^III, Pd^II, Pt^IV. Poly[(3-N-silsesquioxanylpropyl-4aminoantipyrine)] exhibited high sorption activity with respect to platinum group metals in comparison with poly[N,N´-bis(3-silsesquioxanylpropyl)-1,4-phenylenediamine]. The reaction of poly[(3-N-silsesquioxanylpropyl-4-aminoantipyrine)] practically with all the elements under study was accompanied by coloring. The starting monomer exhibited similar metallochromic properties.     

Oxidative polymerization of p-phenylenediamine

Oxidative polymerization of p-phenylenediamine in a hydrochloric acid solution yields not a polyquinoxaline polymer as described in the literature but a modified poly(1,4-benzoquinonediimine-N,N′-diyl-1,4-phenylene) analogous to polyaniline known as pernigraniline. A new scheme of oxidative polymerization of p-phenylenediamine was suggested.     

Kinetic parameters of radical reactions of 2-mercaptobenzothiazole with quinone imines

The chain reaction of N,N′-diphenyl-1,4-benzoquinone diimine with 2-mercaptobenzothiazole was studied by two methods developed earlier for the nonchain reaction of N-phenyl-1,4-benzoquinone monoimine with 2-mercaptobenzothiazole. In the methods used, the kinetic scheme of the reaction is simplified by creating conditions under which the rates of all stages except radical generation and decay can be neglected. One of the methods was updated. For the nonchain reaction of N-phenyl-1,4-benzoquinone monoimine with 2-mercaptobenzothiazole, both methods gave close results; for the chain reaction of N,N′-diphenyl-1,4-phenylenediamine with 2-mercaptobenzothiazole, the results differed by approximately one order of magnitude.     

Reactions of some arenes and pyrazoles in MeCN under conditions of undivided-cell electrolysis

As exemplified for the first time by pyrazole and its 4-nitro and 3,5-dimethyl derivatives, N-arylation of pyrazoles can be performed under conditions of undivided-cell amperostatic electrolysis (Pt electrodes, MeCN) of systems containing the pyrazolate anion and (or) pyrazole, arene (benzene, 1,4-dimethoxybenzene, or xylene), and a supporting electrolyte. In the case of electrolysis involving 1,4-dimethoxybenzene as arene, N-arylation followed simultaneously three routes to form an ortho-substitution product (1,4-dimethoxy-2-(pyrazol-1-yl)benzene), an ipso-substitution product (4-methoxy-1-(pyrazol-1-yl)benzene), and an ipso-bisaddition product (1,4-dimethoxy-1,4-di(pyrazol-1-yl)cyclohexa-2,5-diene) in a total current yield of up to 50%. The acid-base properties of the pyrazoles under study affect the ratio of the N-arylation products and govern the required composition of the starting reaction mixture. In the case of a stronger base, such as 3,5-dimethylpyrazole, N-arylation with 1,4-dimethoxybenzene occurred even in the pyrazole—arene—tetraalkylammonium perchlorate system, whereas N-arylation of 4-nitropyrazole (a weaker base) proceeded only in the presence of the pyrazolate anion or another base, viz., sym-collidine. Oxidation of arene to the radical cation is the key anodic reaction. Not only the pyrazolate anion, but also highly basic pyrazole or a solvate complex of weakly basic pyrazole with collidine can serve as a nucleophilic partner in subsequent transformations of these radical cations.     

Features of the synthesis of 1,1′-Phenylenebis(1H-tetrazoles) and their transformations in basic environment

Reactions of substituted 1,3- and 1,4-phenylenediamines with sodium azide and triethyl orthoformate in the presence of acetic acid led to the formation in high yields of the corresponding 1,12 -phenylenebis(1Htetrazoles). The presence of electron-acceptor groups in the molecules of the initial diamines reduces the yield of the target heterocycles. With 2-nitro-1,4-phenylenediamine the prevailing product was 2-nitro-4-(1H-tetrazol-1-yl)aniline. The obtained bistetrazoles in basic environment suffer an opening of one or both heterocycles forming cyanamides.     

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     

Synergistic interaction of epoxides and N‐vinylcarbazole during photoinitiated cationic polymerization

A kinetic study was conducted of the independent photoinitiated cationic polymerization of a number of epoxide monomers and mixtures of these monomers with N‐vinylcarbazole. The results show that these two different classes of monomers undergo complex synergistic interactions with one another during polymerization. It was demonstrated that N‐vinylcarbazole as well as other carbazoles are efficient photosensitizers for the photolysis of both diaryliodonium and triarylsulfonium salt photoinitiators. In the presence of large amounts of N‐vinylcarbazole, the rates of the cationic ring‐opening photopolymerization of epoxides are markedly accelerated. This effect has been ascribed to a photoinitiated free‐radical chain reaction that results in the oxidation of monomeric and polymeric N‐vinylcarbazole radicals by the onium salt photoinitiators to generate cations. These cations can initiate the ring‐opening polymerization of the epoxides, leading to the production of copolymers. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3697–3709, 2000     

Synthesis of phosphate‐pendant polymers and their application to thermally latent polymeric initiators

A novel phosphate monomer, O‐p‐(methacryloyloxymethyl)benzyl O,O‐diethyl phosphate (MDP) was synthesized by the reaction of diethyl phosphorochloridate with 1,4‐benzenedimethanol, followed by the reaction with methacryloyl chloride in the presence of triethylamine. The radical polymerization of MDP and copolymerization with methyl methacrylate were carried out in the presence of 2,2′‐azobisisobutyronitrile (3 mol %) in dimethylacetamide at 60 °C for 20 h to afford phosphate‐pendant polymers. The polymerization of glycidyl phenyl ether (GPE) was carried out with the phosphate‐pendant polymer as an initiator in the presence of ZnCl₂. The polymerization did not proceed below 90 °C but rapidly proceeded above 90 °C to afford polyGPE. The phosphate‐pendant polymer served as a good thermally latent polymeric initiator. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3365–3370, 2001     

Practical one-pot transformation of electron-rich aromatics into aromatic nitriles with molecular iodine and aq NH3 using Vilsmeier–Haack reaction

Various electron-rich aromatics could be efficiently transformed into the corresponding aromatic nitriles in good to moderate yields by treatment with DMF and POCl₃, followed by the reaction with molecular iodine or 1,3-diiodo-5,5-dimethylhydantoin (DIH) in aq NH₃. Some of less reactive aromatics, such as anisole, 1,2-dimethoxybenzene, 1,4-dimethoxybenzene, and mesityrene, could be also transformed into the corresponding aromatic nitriles in good to moderate yields using N-methylformanilide and O(POCl₂)₂, followed by the reaction with molecular iodine in aq NH₃. Moreover, propiophenone derivatives could be successfully transformed into the corresponding β-chlorocinnamonitriles by the reaction with DMF and POCl₃, followed by the reaction with molecular iodine and aq NH₃. These reactions are novel metal-free one-pot methods for the preparation of aromatic nitriles from electron-rich aromatics and β-chlorocinnamonitriles from propiophenones.     

Substituent effects on the polycondensation of quinones with aromatic amines to form poly(quinone imine)s

The effect of alkyl groups on the polycondensation of aromatic diamines and quinones to form poly(quinone imine)s was investigated. Models were synthesized under standard conditions: 1 equiv of quinone was reacted with 2 equiv of aniline in the presence of titanium tetrachloride and 1,4‐diazabicyclo[2.2.2]octane. Only modest yields of diimines were obtained when alkyl substituents were introduced. Likewise, alkyl substituents were harmful in the polycondensation of both anthraquinones and benzoquinones with aromatic diamines. As for fluorine substituents, model reactions with either 1,5‐difluoroanthraquinone or 1,4‐difluoroanthraquinone with aniline proceeded in high yields. These model compounds for aromatic poly(quinone imine)s were characterized with ¹H NMR spectroscopy, ¹⁹F NMR spectroscopy, variable‐temperature ¹H NMR spectroscopy, and X‐ray crystal structure determination. Polymers of the difluoroanthraquinones with aromatic diamines were obtained in high yields, although not in high molecular weights, and no stereocontrol was found. Both p‐benzoquinones and anthraquinones were used as monomers in these polymerizations, and a fundamental difference in reactivity was observed. With the former, the polymerization behaved as a classical polycondensation and demanded exact reagent equivalence. With the anthraquinones, however, the polymerization proceeded by a condensation chain polymerization and was much more forgiving. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 43–54, 2002     

N‐alkoxy pyridinium ion terminated polystyrenes: A facile route to photoinduced block copolymerization

Photoactive N‐alkoxy 4‐phenyl pyridinium and N‐alkoxy isoquinolinium ion terminated polystyrenes with hexafluoroantimonate counter anion were prepared and characterized. For this purpose, mono‐ and dibrominated polystyrenes were prepared by atom transfer radical polymerization (ATRP). The reaction of these polymers with silver hexafluoroantimonate in the presence of 4‐phenylpyridine N‐oxide and isoquinoline N‐oxide in dichloromethane produced desired polymeric salts with the corresponding functionalities. Irradiation of these photoactive polystyrenes produced alkoxy radicals at chain ends capable of initiating free radical polymerization of methyl methacrylate (MMA). This way, depending on the number of functionality, AB or ABA type block copolymers were formed which were characterized with the aid of gel permeation chromatography and ¹H NMR spectroscopy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 423–428, 2007.     

Synthesis of phosphate end‐functional polymers and application to thermally latent polymeric initiators

Novel phosphates, O‐p‐(hydroxymethyl)benzyl O,O‐diethyl phosphate ( 1 ) and O‐(2‐bromoisobutyryloxymethyl)benzyl O,O‐diethyl phosphate ( 2 ) were synthesized by the reaction of diethyl phosphorochloridate with 1,4‐benzenedimethanol and the successive reaction with 2‐bromoisobutyryl bromide in the presence of triethylamine and submitted to the polymerization of ?‐caprolactone and methyl methacrylate as the initiators. They afforded phosphate end‐functional poly(?‐caprolactone) and poly(methyl methacrylate) with controlled molecular weights and polydispersity ratios by living ring‐opening polymerization and samarium‐induced polymerization. The polymerization of glycidyl phenyl ether (GPE) was carried out with the phosphate end‐functional polymers as the latent polymeric initiators in the presence of ZnCl₂. The polymerization of GPE did not proceed below 90 °C, but it rapidly proceeded to afford poly(GPE) above the temperature. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3832–3840, 2001     

Synthesis of polypropylene graft copolymers by the combination of a polypropylene copolymer containing pendant vinylbenzene groups and atom transfer radical polymerization

This article discusses a facile and inexpensive reaction process for preparing polypropylene‐based graft copolymers containing an isotactic polypropylene (i‐PP) main chain and several functional polymer side chains. The chemistry involves an i‐PP polymer precursor containing several pendant vinylbenzene groups, which is prepared through the Ziegler–Natta copolymerization of propylene and 1,4‐divinylbenzene mediated by an isospecific MgCl₂‐supported TiCl₄ catalyst. The selective monoenchainment of 1,4‐divinylbenzene comonomers results in pendant vinylbenzene groups quantitatively transformed into benzyl halides by hydrochlorination. In the presence of CuCl/pentamethyldiethylenetriamine, the in situ formed, multifunctional, polymeric atom transfer radical polymerization initiators carry out graft‐from polymerization through controlled radical polymerization. Some i‐PP‐based graft copolymers, including poly(propylene‐g‐methyl methacrylate) and poly(propylene‐g‐styrene), have been prepared with controlled compositions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 429–437, 2005     

5,6-Dihydro-4H-pyrrolo[1,2-a][1,4]benzodiazepine-4,4-diacetic acid diethyl ester,an useful synthon for the synthesis of new polycyclic nitrogen systems of pharmacological interest

This report describes the synthesis of derivatives of two nitrogen tetracyclic ring systems, respectively 9H,11H-pyrimido[4,3-c]pyrrolo[1,2-a][1,4]benzodiazepine and spiro[piperidine-4,4′-[4H]pyrrolo[1,2-a][1,4]-benzodiazepine], by the use of the diethyl ester of 5,6-dihydro-4H-pyrrolo[1,2-a][1,4]benzodiazepine-4,4-diacetic acid as a synthon. This compound was obtained by condensation of 1-(2-aminomethylphenyl)-1H-pyrrole with diethyl 1,3-acetonedicarboxylate in acid medium. Pyrimidopyrrolobenzodiazepine derivatives were obtained by treating either the pyrrolobenzodiazepine 4,4-diacetate or the related 4-methyl-4-acetate with phenylisocyanate in boiling diethyl ether in the presence of sodium metal. The structure of 12,13-dihydro-11,13-dioxo-12-phenyl-9H,11H-pyrimido[4,3-c]pyrrolo[1,2-a][1,4]benzodiazepine, a product formed by loss of an acetate unit when 5,6-dihydro-4H-pyrrolo[1,2-a][1,4]benzodiazepine-4,4-diacetate, sodium metal and phenyl-isocyanate reacted in boiling xylene, was proved by catalytic reduction to 11,13-dioxo-12-phenyl-12,13,14,14a-tetrahydro-9H,11H-pyrimido[4,3-c]pyrrolo[1,2-a][1,4]benzodiazepine, which was synthesized by unambiguous pathway via 5,6-dihydro-4H-pyrrolo[1,2-a][1,4]benzodiazepine-4-acetate. The 2,6-dioxospiro[piperidine-4,4′-[4H]pyrrolo[1,2-a][1,4]benzodiazepine] derivatives were synthesized from the N-BOC derivative of 5,6-dihydro-4H-pyrrolo[1,2-a][1,4]benzodiazepine-4,4-diacetic acid diethyl ester, by hydrolysis followed by treatment with 2 equivalents of 1,1′-carbonyldiimidazole (CDI) and then with aniline or benzylamine. Removal of BOC from the N-phenyl-2,6-dioxopiperidine derivative was obtained by heating the related spiroderivative in toluene in the presence of p-toluenesulphonic acid. Similar reaction failed when the N-benzyl-2,6-dioxopiperidine analog was used as substrate.