Cationic cyclization of neoprene with a diethylaluminum chloride and organic chloride catalyst system

The cyclization of neoprene was achieved with the aid of a cationic catalyst system based on diethylaluminum chloride (Et2AlCl) and an organic chloride, allyl chloride (CH2=CHCH2Cl) or benzyl chloride (C6H5CH2Cl). The main parameters of the cyclization process were investigated. Elastomers with low intrinsic viscosity, ready solubility and some gelling were obtained. Xylene was a good solvent for the cyclization process, which took place in a very short time (less than or equal to5 min). The products were characterized with IR, H-1-NMR, differential scanning calorimetry, and gel permeation chromatography. The polycyclic structure was determined. The degree of cyctization and the incorporated solvent content were estimated with a H-1-NMR method.

Fabrication and electrochemical behaviors of multilayers composed of heteropholyanions and poly(diallyldimethylammonium chloride) on 4-aminothiophenol modified gold electrodes

Multilayer films composed of heteropolyanions (HPAS, SiMo11 VO405-) and cationic polymer poly(diallyldimethylammonium chloride) on 4-aminothiophenol self-assembled-monolayer were fabricated by electrochemical growth. Growth processes of the composite films were characterized by cyclic voltammetry. The results prove the third redox peak of Mo increases more rapidly, otherwise the other Mo redox peaks increase very slowly when the number of layers of heteropolyanions is greater. The peak potentials of composite films shift linearly to negative position with higher pH, which implies that protons are involved in the redox processes of HPA. The investigation of electrocatalytic behaviors of composite films shows a good catalytic activity for the reductions of HNO2 and BrO3-. Catalytic currents increase with increasing number of layers of heteropolyanions, moreover, the catalytic currents have a good linear relationship with the concentrations of BrO3-.

The LB films of dansyl chloride labeled octadecylamine and its fluorescence lifetime

Octadecylamine was derivatized with dansyl chloride (5-dimethylaminonaphthalene-1-sulfonyl chloride) In order to simplify and understand the LB films of fluorescent probe labeling proteins. its monolayer and multilayers in the absence and presence of stearic acid were deposited by LB technique. Fluorescence spectra and lifetimes of the fluorescent products were studied to elucidate the microenvironment of molecules in the LB films.

Synthesis of bis [bis (tert-butylcyclopentadienyl) neodymium chloride] and structural trend of bis[bis(tertbutylcyclopentadienyl) lanthanide chloride]

The reaction of NdCl3 with 2 equiv. of Na-(BuC5H4)-C-t in THF(tetrahydrofuran) gives blue crystals [((BUC5H4)-C-t)(2)NdCl](2), C36H52Cl2Nd2(M-r = 844.11) Which crystallizes in the triclinic system with space group . The crystal data are a=11.978 (1), b=12.671(4), c=12.706(2)Angstrom, alpha=105.47(2), beta=99.38(1)? gamma=93.15 (2)degrees, V=1825 (3) Angstrom(3), Z = 2 , D-c = 1.53g/cm(3), F(000) = 450 , T = 298K , lambda(MoK alpha) = 0.71069 Angstrom, , mu = 14.97cm(-1). Final R = 0.0390, R-w = 0.0376 for 4329 reflections with I greater than or equal to 3 sigma(I-o). The molecule has a dimer structure with two certrosymmetrical chlorine bridges. The structural trend of these analogous complexes is discussed.

Phase transition and transition kinetics of a thermotropic poly(amide-imide) derived from 70% pyromellitic dianhydride, 30% terephthaloyl chloride, and 1,3-bis[4-(4 '-aminophenoxy)cumyl]benzene

The phase transition and transition kinetics of a liquid crystalline copoly(amide-imide) (PAI37), which was synthesized from 70 mol% pyromellitic dianhydride, 30 mol% terephthaloyl chloride, and 1,3-bis[4-(4'-aminophenoxy)cumyl]benzene, was characterized by differential scanning calorimetry, polarized light microscopy, X-ray diffraction, and rheology. PAI37 exhibits a glass transition temperature at 182 degreesC followed by multiple phase transitions. The crystalline phase starts to melt at similar to 220 degreesC and forms smectic C (S-C) phase. The Sc phase transforms into smectic A (S-A) phase when the temperature is above 237 degreesC. The S-C to S-A transition spans a broad temperature range in which the S-A phase vanishes and forms isotropic melt. The WARD fiber pattern of PAI37 pulled from the anisotropic melt revealed an anomalous chain orientation, which was characterized by its layer normal perpendicular to the fiber direction. The transition kinetics for the mesophase and crystalline phase formation was also studied.

Barrier properties of vinylidene chloride methyl acrylate copolymer

A series of vinylidene dichloride (VDC) copolymers with methyl acrylate (MA) as comonomer (3-12wt%), was prepared by free-radical suspension copolymerization. The permeability coefficients of the copolymers to oxygen and carbon dioxide were measured at 1.0 MPa and at 30 degrees C, and those to water vapor were measured at 30 degrees C and 100% relative humidity. All the VDC/MA copolymers studied are semicrystalline. As the MA content increases, the permeability coefficients of the copolymers to oxygen, carbon dioxide, and water vapor are progressively increased, caused by decrease in crystalline fraction and increase in free volume of VDC/MA copolymers.

Crystal structure and mechanism of (Z)-1-[2-(phenyl-bromide-chloride)vinyl]-1-cyclohexanol

The crystal structure and mechanism of the title molecule are described. This crystal is orthorhombic, belonging to space group PC21/B with a=1,002 1(2) nm, b=1.483 0(3) nm, c=2.173 6(4) nm, V=3.230 39(2) nm(3), Z=2, D-c=1.80 g/cm(3), R=0.069 3. The structure was solved by direct method. The tin atom of the title compound exists in two distorted-trigonal-bipyramidal geometry, defined by two carbon, one bromide, one chloride and one oxygen atoms leading to a five-membered chelate ring. In the structure, the five-membered ring containing the intermolecular O-->Sn has a half chair conformation.

The transfer of chloride ion across an anion exchange membrane

The transfer of chloride ions into a low resistance anion exchange membrane (AEM) was investigated by cyclic voltammetry (CV) and electrochemical impedance spectra. In all cases, concentration polarization of Cl- ions is exterior to the membrane. It controls the flux and produces the limiting currents: either steady state or transient (peak type) current. In CV experiments, when the size of the holes in the membrane was much smaller than the distance between membrane holes, the Cl- anion transfer showed steady state voltammetric behavior. Each hole in the membrane can be regarded as a microelectrode and the membrane was equivalent to a microelectrode array in this condition. When the hole in the membrane was large or the distance between membrane holes was small, the CV curve of the Cl- anion transfer across the membrane showed a peak shape, which was attributed to linear diffusion. In AC impedance measurement, the impedance spectrum of the membrane system was composed of two semicircles at low DC bias, corresponding to the bulk characteristics of the membrane and the kinetic process of ion transfer, respectively. The bulk membrane resistance increases with increasing DC bias and only one semicircle was observed at higher DC bias. The parameters related to kinetic and membrane properties were discussed.

The miscibility of homopolymer random copolymer blends .4. Poly(vinylidene chloride-co-acrylonitrile) poly(methyl methacrylate) blends

The miscibility of blends of poly(vinylidene chloride-co-acrylonitrile) (VDC-AN) and poly(methyl methacrylate) (PMMA) has been studied with DSC, FT-IR, and NMR methods. The results indicate that the VDC-AN/PMMA blends are miscibile on a molecular level, and the dipole-dipole interactions between C=O and C-Cl-2 and/or interpolymer hydrogen bondings between COOCH3 and CN and CCl groups play the role on the miscibility of the blends. It is found that the -CCl2- groups have two different chemical environments in the pure VDC-AN copolymer, which may result from the different configurations of the copolymer, such as -CCl2- groups in the ''alternating'' segments and -CCl2- groups in the ''blocky'' segments as proposed. It is the -CCl2- group in the ''alternating'' segment that takes part in the dipole-dipole interaction with C=O group in PMMA.

Structure and thermal properties of vinylidene chloride/acrylics copolymers

A series of vinylidene chloride (VDC) copolymers with methyl acrylate (MA) or butyl acrylate (BA) as comonomer (not more than 10%) was prepared by free-radical suspension copolymerization. The effects of comonomer structure, copolymer composition, and reaction condition (such as polymerization temperature on crystallinity) and thermal properties (such as melting temperature and decomposition temperature) were investigated. All VDC/acrylics copolymers studied here are semicrystalline and have more than one crystalline structure. The melting temperature of MA/VDC copolymers is decreased progressively with increase in MA content. The decomposition temperature of MA/VDC copolymers is slight increased gradually with increase in MA content. MA/VDC copolymers have lower melting temperature compared with BA/VDC copolymers with same VDC composition. The melting temperature of VDC copolymers increases with increase in polymerization temperature and decomposition temperature of those is almost independent of polymerization temperature. (C) 1996 John Wiley & Sons, Inc.

Barrier properties of vinylidene chloride copolymers

The permeability coefficients of a series of copolymers of vinylidene chloride (VDC) with methyl acrylate (MA), butyl acrylate (BA) or vinyl chloride (VC) (as comonomer) to oxygen and carbon dioxide have been measured at 1.0 MPa and 30 degrees C, while those to water vapor have been measured at 30 degrees C and 100% relative humidity. All the copolymers are semicrystalline. VDC/MA copolymers have lower melting temperature compared with VDC/BA copolymers, while that melting temperature of VDC/VC copolymer is higher than that of VDC/acrylate copolymers with the same VDC content. The barrier property of the copolymers is predominantly controlled by crystallite, free volume fraction, and cohesive energy. The permeability coefficients of VDC/MA copolymers to oxygen, carbon dioxide, and water vapor were successfully correlated with the ratio of free volume to cohesive energy.

Preparation of Pb-Ca-Na master alloy using molten chloride salt electrolysis

An electrolysis technique for co-deposition of Ca2+ and Na+ at the liquid lead cathode was put forward. The experiment was carried out at an electrolysis temperature below 650 degrees C and had a current efficiency of 98%, which are respectively 100 similar to 300 degrees C lower and 15% similar to 30% higher than those reported both at home and abroad.

Relationship between the dissolution behaviours and current efficiencies of La, Ce, Pr and Nd in their chloride molten salts

The dissolution behaviours of La and Nd in their chloride molten salts were studied by means of the see-through cell, electrochemical weak polarization and quantum chemistry (extended Huckel molecular orbital). The reasons for the low current efficiencies of rare earth metals and the difference between La and Nd in their own chloride electrolytes on the basis of the solubility, rate of dissolution, and existing state of the metals dissolved as well as the structure of the melts, are discussed.

ELECTROOXIDATION OF A CHLORIDE COMPLEX OF PLATINUM(II) AT A GLASSY-CARBON ELECTRODE

The electro-oxidation of PtCl42- was studied on a glassy carbon (GC) electrode. A Pt(IV) complex was formed on the electrode surface through coordination to the oxygen atom of an oxide functional group on the electrode, which results in its deactivation. The ferri/ferrocyanide redox couple was used as a probe to examine the activity of the GC electrode. X-ray photoelectron spectroscopy was employed to characterize the platinum on the electrode surface, and showed that the oxidation state of the Pt element changes depending on the electrochemical treatment of GC electrode. The platinum complex on the surface of the GC electrode can be transformed to Pt-0 by cycling the electrode between -0.25 and +1.65 V/SCE in 0.1 M H2SO4 solution. The above procedure can be used to disperse platinum ultramicroparticles on the surface of a GC electrode.

ELECTROCHEMICAL AND IN-SITU SPECTROELECTROCHEMICAL STUDY OF (TETRAPHENYLPORPHINATO)MANGANESE(III) PERCHLORATE IN THE PRESENCE OF CHLORIDE ANIONS .2. OXIDATION PROCESSES

An investigation of electrode oxidation processes of (tetra-phenylporphinato) manganese (III) Perchlorate, (TPS)Mn(III)ClO4, was carried out during the titration of chloride anions by conventional cyclic voltammetry, thin-layer cyclic voltammetry and spectroelectrochemistry. It was demonstrated that in the presence of one equivalent amount of Cl-, the first one electron oxidation reaction corresponds to the Mn(III)I cation radical oxidation, and the second one electron oxidation corresponds to the cation radical/dication generation followed by an iso-porphyrin formation reaction, however in the presence of two equivalent amount of Cl-, the first one electron oxidation of Mn(III) gives Mn(IV) porphyrin and the second one electron oxidation generates cation radicals of Mn(IV) followed by an iso-porphyrin formation reactions. Mechanisms of these redox processes are postulated.