Novel proton-type ionic liquid doped polyaniline for the headspace solid-phase microextraction of amines

A novel proton-type ionic liquid doped polyaniline (HIL-doped PANI) coating was presented, which was prepared on a stainless steel wire by electrodeposition in an aqueous solution containing aniline and 1-sulfobutyl-3-methylimidazolium hydrosulfate. The HIL-doped PANI coating showed granular nanostructure and had large specific surface. When it was applied to the headspace solid-phase microextraction of several amines (i.e., aniline, N-methylaniline, 3-methylaniline, 2-chloroaniline and 3-chloroaniline), it showed high extraction efficiency. The enrichment factors were 191.8–343.9 for different amines, much higher than those of common PANI and commercial polydimethylsiloxane/divinylbenzene coatings. Coupled with gas chromatographic analysis, the linear ranges were 0.097–100 μg/L with correlation coefficients above 0.9942, and the detection limits were 0.012–0.048 μg/L (S/N = 3) for different amines. The relative standard deviations (RSD) were smaller than 8.1% for five successive measurements with single fiber and the fiber-to-fiber RSDs were 8.6–13.8% (n = 5) for these amines. The proposed method was successfully applied to the extraction and determination of amines in organic waste water samples, and the recoveries were 78.3–112.8% for different analytes.     

The possibility of applying a titanium-magnesium nanocatalyst in the polymerization filling of polyolefins and some properties of the obtained composites

The possibility of applying a titanium-magnesium nanocatalyst during in situ polymerization of ethylene and propylene in the presence of organomodified aluminum silicates and diatomite under mild conditions is investigated. How the substantial (2- to 3-fold) increase in the catalytic activity of the system depends on the type and amount of filler is shown. The activity of the titanium-magnesium nanocatalyst-filler system during polymerization of propylene is 3–4 times higher than that during the polymerization of ethylene. Composites based on ultrahigh-molecular-mass polyethylene (M = (1.4–1.7) × 10⁶) with 3.5–13.0 wt % filler are obtained. According to DSC and X-ray structural-analysis data, the polyethylene matrix differs by its high crystallinity and a T _m of 143–144°C. The physicochemical characteristics of the composites are 1.5–2.0 times greater than those of unfilled polyethylene; the nanocomposite containing 11 wt % mont-morillonite modified with vinyltrimethoxysilane has the best properties. It is shown that during the propylene polymerization, the effect of the type of filler affects not only the catalytic activity of the system, increasing it three times in the case of diatomite, but also the stereospecificity of the effect. Isotactic high-molecularmass (up to 390 × 10³) polypropylene is obtained in the presence of montmorillonite containing vinyltrimethoxysilane, while a low-molecular-mass ((65–75) × 10³) polymer with lower isotacticity is formed on diatomite. The deformation-strength characteristics of composites based on polypropylene testify the formation of an elastomeric material with T _m = 156–158°C.     

Emulsion Polymerization Pathway for Preparation of Polyaniline‐Sulfate Salt,using Non Ionic Surfactant

In this work, aniline was polymerized directly to the polyaniline‐sulfate salt without using a protonic acid. The polyaniline‐sulfate salt was prepared by emulsion polymerization, using a non ionic surfactant such as poly(ethylene glycol)–block poly(propylene glycol)‐block poly(ethylene glycol). In the aniline oxidation process, to give the polyaniline salt by ammonium persulfate, the sulfate ion is generated from ammonium persulfate and doped on to the polyaniline. Ammonium persulfate acts both as an oxidizing agent, as well as the protonating agent in the aniline polymerization process, to give the polyaniline salt. This result indicates that the effect of sulfate ion, generated by ammonium persulfate during oxidation of aniline to the polyaniline salt, may be taken into consideration in the polymerization process of aniline.     

Chemoselective anti-Markovnikov hydroamination of α,β-ethylenic compounds with amines using montmorillonite clay

The catalytic activity of montmorillonite clays as a catalyst for the hydroamination of α,β-ethylenic compounds with amines was tested. Aniline and substituted anilines reacted with α,β-ethylenic compounds in the presence of catalytic amount of commercially available clay to afford exclusively anti-Markovnikov adduct in excellent yields. Aniline reacted with ethyl acrylate to yield only anti-Markovnikov adduct N-[2-(ethoxycarbonyl)ethyl]aniline (mono-addition product). No Markovnikov adduct (N-[1-(ethoxycarbonyl)ethyl]aniline and double addition product N,N-bis[2-(ethoxycarbonyl)ethyl]aniline were formed under selected reaction conditions. For a better exploitation of the catalytic activity in terms of increased activity and improved selectivity for the mono-addition product, the reaction parameters were optimized in terms of temperature, solvent, reactant mole ratio. Under optimized reaction conditions, montmorillonite clay K-10 showed a superior catalytic performance in the hydroamination of ethyl acrylate with aniline with a conversion of aniline to mono-addition product (almost 100% chemoselectivity) with a high rate constant 0.3414 min⁻¹ compared to the reported protocols. The dependence of conversion of aniline over different types of montmorillonite clays (K-10, K-20, K-30, Al-Pillared clay and untreated clay) has also been discussed. The activities of clay for the hydroamination of different aromatic and aliphatic amines have also been investigated. Under harsh reaction conditions (increased temperature and long reaction time) small amounts of di-addition products were observed. The kinetics data has been interpreted using the initial rate approach model.     

Electrochemical Polymerization of Aniline in Polyamide and Polyvinyl Alcohol Matrices

The electrochemical polymerization of aniline was studied in polymer matrices (polyamid-12 and polyvinyl alcohol) on an electrode in the potential cycling mode from –0.2 to +0.8 V vs. SCE. The indices of this process such as the potentials and currents of the polyaniline redox peaks, polymerization rate, and properties of the conducting composite formed depend on the nature of the matrix polymer and are a function of the extent of interaction of this matrix polymer with aniline and polyaniline.     

Synthesis of imines from nitrobenzene and TiO2 particles suspended in alcohols via semiconductor photocatalysis type B

UV irradiation on a non-aqueous suspension of titanium dioxide with nitrobenzene and different alcohols in deaerated conditions produces imines and aniline as main products. The conversion of nitrobenzene and the corresponding selectivity of imines or aniline depend on the type of alcohol used. A low conversion (3-12%) and selectivity close to 100% to imines were obtained with methyl, ethyl, or propyl alcohol. Otherwise, using i-propanol only aniline was detected with a conversion of 13%. Finally, a mixture of aniline and imines was formed employing n-butyl, n-amyl, and i-amyl alcohols with the higher conversion (∼50%).     

Electrochemical synthesis of a novel sulfonated polyaniline and its electrochemical properties

A novel N-substituted aniline, N-(4-sulfonicbutyryl)aniline was synthesized and subsequently to be electropolymerized to yield a new conductive polymer, poly(N-(4-sulfonicbutyryl)aniline). X-ray photoelectron spectrum (XPS) of the polymer film was examined to propose the polymer molecular structure. The sulfonated polyaniline was also characterized by ¹H NMR, TGA, DTA, FTIR, and UV–vis spectra. The sulfonated polyaniline showed high conductivity in neutral aqueous solutions, which is two orders of magnitude higher than that of poly(N-acetylaniline) (PNAANI).     

Enhancement of visible light-induced gelation of photocurable gelatin by addition of polymeric amine

We evaluated the effect of an electron donor on photogelation of photocurable gelatin, which is gelatin partially derivatized with eosin (eosin–gelatin). As an electron donor, ascorbic acid, 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA), and three kinds of radical polymerized amines such as poly(N,N-dimethylacrylamide-co-2-(N,N-dimethylamino)ethyl methacrylate) (poly(DMAAm-co-DMAEMA)), poly(N,N-dimethylacrylamide-co-3-(N,N-dimethylamino)propyl acrylamide) (poly(DMAAm-co-DMAPAAm)), and poly(3-(N,N-dimethylamino)propyl acrylamide) (polyDMAPAAm) were examined. Upon photo irradiation at the wavelength ranging from 400 to 520 nm with low illumination intensity (7.7 × 10³ lx), no gel was obtained from 20 wt.% of a viscous aqueous solution of the eosin–gelatin even by adding with ascorbic acid. Whereas in the presence of monomeric amine (DMAEMA, 3.0 wt.%), gel formation occurred by radical recombination between eosin groups incorporated into the gelatin. When the polymeric amines were added to the eosin–gelatin solution, gelation was markedly enhanced due to cross-linking of gelatins through polymeric amines in addition to direct bonding between gelatins. An increase in amine unit content in the polymeric amines resulted in increased gel yield and reduced swelling degree of water. In the presence of polyDMAPAAm, almost all gelatins were converted relatively rigid hydrogel. Application for a topical hemostatic glue was preliminary performed in rat injured model. A rat liver injured in laparotomy was coated with the aqueous eosin–gelatin solution containing polyDMAPAAm. Upon irradiation, the solution was immediately converted to a swollen gel, which was tightly adhered to the liver tissue and concomitantly hemostasis was completed with little tissue damage.     

Scope and limitations of montmorillonite K 10 catalysed opening of epoxide rings by amines

Montmorillonite K 10 efficiently catalyses the opening of epoxide rings by amines in high yields with excellent regio- and diastereo-selectivities under solvent-free conditions at room temperature affording an improved process for synthesis of 2-amino alcohols. Reaction of cyclohexene oxide with aryl/alkyl amines leads to the formation of trans-2-aryl/alkylaminocyclohexanols. For unsymmetrical epoxides, the regioselectivity is controlled by the electronic and steric factors associated with the epoxide and the amine. Selective nucleophilic attack at the benzylic carbon of styrene oxide takes place with aromatic amines, whereas, aliphatic amines exhibit preferential nucleophilic attack at the terminal carbon. Aniline reacts selectively at the less hindered carbon of other unsymmetrical epoxides. The difference in the internal strain energy of the epoxide ring in cycloalkene oxides and alkene oxides led to selective nucleophilic opening of cyclohexene oxide by aniline in the presence of styrene oxide. Due to the chelation effect, selective activation of the epoxide ring in 3-phenoxy propylene oxide takes place in the presence of styrene oxide leading to preferential cleavage of the epoxide ring in 3-phenoxy propylene oxide by aniline.     

Direct amidation of non-activated carboxylic acid and amine derivatives catalyzed by TiCp2Cl2

This paper described a mild and efficient direct amidation of non-activated carboxylic acid and amine derivatives catalyzed by TiCp₂Cl₂. Arylacetic acid derivatives reacted with different amines to afford the corresponding amides in good to excellent yield except of aniline. Aryl formic acids failed to react with aniline but smoothly reacted with aliphatic amines and benzylamine in moderate to good yield, fatty acids reacting with benzyl and aliphatic amines give amides in good to excellent yield. Chiral amino acids derivatives were transformed into amides without racemization in moderate yield. The possible mechanism of direct amidation catalyzed by TiCp₂Cl₂ was discussed. This catalytic method is very suitable for the amidation of low sterically hindered arylacetic acid, fatty acids with different low sterically hindered amines except aniline, as well as the amidation of aryl formic acid with benzyl and aliphatic amines.     

Synthesis of novel fluorescent molecule and its polymeric form with aniline as fluorescent and supercapacitor electrode materials

In this study, a fluorescent material, 2‐naphthyl‐4‐amino benzoate, is synthesized by the esterification of 4‐aminobenzoic acid with 2‐naphthol. This molecule is used in the bulk polymerization of aniline, which results in the formation of poly(aniline‐2‐naphthyl‐4‐aminobenzoate). For comparison, polyaniline and also poly(aniline‐4‐aminobenzoic acid) salts are prepared via bulk polymerization. Formation and properties of these polymeric materials are evaluated by Fourier‐transform infrared (FT‐IR), ¹³C nuclear magnetic resonance, matrix‐assisted laser desorption ionization, UV‐Vis, Fluorescence, X‐ray diffraction (XRD), Field emission‐scanning electron microscopy (FE‐SEM), Differential scanning calorimetry (DSC), thermogravimetric analysis, electrical resistance and electrochemical techniques. P(ANI‐2NA4ABA) is obtained in nanofiber morphology in 106 wt% yield with respect to the amount of aniline used with comparable conductivity of conventional polyaniline salts. This polymer salt is stable up to 220°C and indicates melting at 146°C on heating and crystal formation at 128°C on cooling. This polymer shows higher wavelength fluorescence compared to the conventional polyaniline salts. This polymer is used as an electrode material without binder, which shows a specific capacitance of 360 F g^?1 at 0.25 A g^?1.     

Specific features characterizing electrochemical synthesis of polyaniline conducted in the presence of poly(2-acrylamido-2-methyl-1-propanesulfonic acid) and the spectroelectrochemical characteristics of the obtained films

The electrochemical matrix polymerization of aniline in the presence of poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA) is performed in conditions that lead to the formation of an interpolymer complex comprising polyaniline and PAMPSA of the 1: 2 composition. The acceleration of the process of polymerization of aniline in the presence of PAMPSA as compared with traditional electropolymerization of aniline in hydrochloric acid is caused by the association of aniline molecules with the sulfo groups of PAMPSA and by a high concentration of hydrogen ions in the vicinity of a molecule of PAMPSA. It is established for the first time ever that, in the initial stages of synthesis for both polymeric and low-molecular-weight acids, the rate of polymerization is substantially greater at a smaller concentration of the acid. The distinguishing feature of the initial stage of electropolymerization of aniline at a low acidity of the environment is a non-autocatalytic character of the process, which may exert a discernible influence on a complex of physicochemical properties of polyaniline, including electric conduction. Studying spectroelectrochemical properties of the obtained films shows practical identity of their spectra with the spectra of standard polyaniline.     

Carbenium Ions in Substitution Reactions at the Amino Nitrogen Atom

Tropylium, xanthylium, and tritylium salts characterized by different stabilities differently reacted with biologically active amines. The reactions of tropylium perchlorate and tetrafluoroborate with 4-(cyclohepta-2,4,6-trien-1-yl)aniline was accompanied by hydrolysis of the N-(cyclohepta-2,4,6-trien-1-yl) derivative, the N-xanthenyl derivative underwent dehydrogenation, whereas tritylium perchlorate failed to react with 4-(cyclohepta-2,4,6-trien-1-yl)aniline. The reactions of pyrimidin-2-amine with tropylium, xanthylium, and tritylium salts afforded products of substitution of one hydrogen atom in the amino group with high yields. The N-substituted pyrimidin-2-amine derivatives were stable, and neither their dehydrogenation nor hydrolysis was observed.     

Simple Preparation of Sulfate Anion‐Doped Polyaniline‐Clay Nanocomposites by an Environmentally Friendly Mechanochemical Synthesis Route

Summary: Conducting polyaniline (PANI) and montmorillonite (MMT) nanocomposites were prepared from aniline sulfate and MMT by a mechanochemical synthesis route. X‐Ray diffraction analysis confirmed that, by controlling the aniline sulfate content, mechanochemical synthesis led to two types of different formations. After polymerization, the mechanochemical route synthesized much more PANI between the clay layers compared to a solution method. The electrical conductivities of the synthesized PANI‐MMT nanocomposites in pressed pellets ranged in the order of between 10⁻⁴ and 10⁻³ S · cm⁻¹.

X‐ray powder diffraction patterns of the intercalation products prepared by grinding montmorillonite with various amounts of Ani‐SO₄ in a mortar.     

Synthesis of polymers containing donor-acceptor Schiff base in side chain for nonlinear optics

The Schiff bases 4-(ω-hydroxyalkyloxy)-N-(5-nitro-2-thienylmethylene)aniline with 2, 6 and 8 methylenic units in their alkyl group in which a nitrothienyl group as acceptor and an oxyphenyl group as donor were synthesized by condensation of (ω-hydroxyalkyloxy)anilines with 5-nitro-2-thiophenecarboxaldehyde. The methacrylate monomers 4-(ω-methacryloyloxyalkyloxy)-N-(5-nitro-2-thienylmethylene)aniline with alkylene groups of different lengths were synthesized by two different routes and polymerized using a free radical initiator to produce low molecular weight polymers useful for nonlinear optics. All the obtained compounds were characterized by conventional spectroscopic methods. First-order hyperpolarizability (β) of 4-(2-hydroxyethyloxy)-N-(5-nitro-2-thienylmethylene)aniline typically was calculated using semiempirical method and the nonlinear optic properties of the same compound was studied by second harmonic generation.     

Transition-metal-free synthesis of aromatic amines via the reaction of benzynes with isocyanates

An unexpected reaction between benzynes and isocyanates to generate aromatic amines has been developed under transition-metal-free conditions. The in situ prepared anions formed through cleavage of the NC bond in isocyanates, reacted with aryne precursors to afford various aniline derivatives in moderate to excellent yield and tolerated various substituents on the o-silyl aryl triflate and the isocyanate.     

UV‐curing synthesis of sulfonated polyaniline‐silver nanocomposites by an in situ reduction method

Sulfonated polyaniline‐silver (SPAni‐Ag) hybrid nanocomposites have been synthesized by the in situ reduction using a UV‐curing polymerization method without using any reducing or binding agent. An aqueous solution of aniline and orthoanilinic acid (OA) comonomers, a free‐radical oxidant and silver metal salts were irradiated by UV rays. Reduction of the silver salt in aqueous aniline and OA leads to the formation of silver particles which in turn catalyze the oxidation of comonomers to sulfonated polyaniline (SPAni). The resultant SPAni‐Ag nanocomposites were characterized by using different spectroscopy analyses like UV–visible (UV–Vis), X‐ray diffraction (XRD) and infrared spectroscopy. The absorption bands were revealed to be optically active and the peaks blue‐shifted due to the presence of metallic silver within the SPAni matrix. The XRD patterns displayed both the broad amorphous polymeric and sharp metallic peaks. Scanning electron microscopy and transmission electron microscopy of the nanocomposites showed a uniform size distribution with spherical and granular morphology. Thermogravimetric analysis revealed that the nanocomposites had a better thermal stability than the bulk SPAni. Copyright © 2008 John Wiley & Sons, Ltd.     

Silica‐Polyaniline Based Bienzyme Cholesterol Biosensor: Fabrication and Characterization

In the present investigation, silica‐polyaniline based bienzyme cholesterol biosensor is fabricated through a simple one‐step electrochemical method. The one‐step fabrication process involves electrochemical polymerization of N[3‐(trimethoxysilyl)propyl]aniline to result poly(N[3‐(trimethoxysilyl)propyl]aniline) (PTMSPA) and simultaneous immobilization of two enzymes, horseradish peroxidase (HRP) and cholesterol oxidase (ChOx) into PTMSPA matrix. The modified electrode is designated as PTMSPA‐HRP/ChOx‐ME. PTMSPA facilitates direct electron transfer between the electrode surface and the active redox centers of HRP. This enables the operation of a biosensor at a low working potential of about ?150 mV (vs. Ag/AgCl) for the detection of hydrogen peroxide. The PTMSPA‐HRP/ChOx‐ME demonstrates excellent analytical performance for the detection of cholesterol between 1 and 25 mM with high sensitivity and selectivity. PTMSPA possesses features suited for the fabrication of third‐generation biosensors.     

Synthesis and electrochemical properties of nanocomposites containing poly(3,6-bis(phenylamino)-2,5-dichlorobenzoquinone and multiwalled carbon nanotubes

The method of synthesizing nanocomposites based on multiwalled carbon nanotubes and a new polymer poly(3,6-bis(phenylamino)-2,5-dichlorobenzoquinone) containing polyaniline chains with electroactive substituents in the N-position is developed, and the electrochemical properties of the composites are studied. The in situ oxidative polymerization of N-substituted aniline performed in the presence of multiwalled carbon nanotubes makes it possible to design an organized, effective structure of the conducting composite material with enhanced electrochemical capacity and stable capacity parameters during long cycling in protic (1 mol/L H₂SO₄) and aprotic (1 mol/L LiClO₄ in propylene carbonate) electrolytes.     

Electrochemical Template Synthesis of an Polyaniline Composite with Polymeric Perfluorinated Sulfo Cationite

Combining a tracer technique with electrochemical measurements offers a unique opportunity to study the mechanism of anodic synthesis of a composite based on an electron-conducting polymer (polyaniline) and a polymeric perfluorinated sulfo cationite (Nafion, MF-4SK). The composite formation involves two steps. First, the monomer (aniline) is intercalated into the solid-cationite matrix probably with the formation of a template phase, after which postintercalation polymerization of the template occurs.