Presence Of LiClO4 Research Articles

Влияние полисульфидов лития на циклирование литиевого электрода в 1М LiClO4 в сульфолане

The effect of lithium polysulphides on the cyclic deposition/and dissolution of lithium metal on an inert stainless steel electrode and on a lithium metal electrode in sulfolane solutions has been studied. It has been shown that the addition of lithium polysulphides to sulfolane solutions leads to a significant increase in the cycle life (2 or more times) and cycling efficiency of a lithium metal electrode and a lithium metal on inert stainless steel electrode. It also results in the reduction of the corrosion rate of the lithium cathodic deposits. The positive influence of lithium polysulphideson the electrochemical behaviour of the lithium electrode is explained by the formation, in the presence of lithium polysulphides, of a «sulphide» surface film, which has a higher lithium-ion conductivity and better protection properties in comparison to the surface film formed on the lithium in the presence of LiClO4.

Effect of Metal Ions on the Reactions of the Cumyloxyl Radical with Hydrogen Atom Donors. Fine Control on Hydrogen Abstraction Reactivity Determined by Lewis Acid–Base Interactions

A time-resolved kinetic study on the effect of metal ions (M(n+)) on hydrogen abstraction reactions from C-H donor substrates by the cumyloxyl radical (CumO(•)) was carried out in acetonitrile. Metal salt addition was observed to increase the CumO(•) β-scission rate constant in the order Li(+) > Mg(2+) > Na(+). These effects were explained in terms of the stabilization of the β-scission transition state determined by Lewis acid-base interactions between M(n+) and the radical. When hydrogen abstraction from 1,4-cyclohexadiene was studied in the presence of LiClO(4) and Mg(ClO(4))(2), a slight increase in rate constant (k(H)) was observed indicating that interaction between M(n+) and CumO(•) can also influence, although to a limited extent, the hydrogen abstraction reactivity of alkoxyl radicals. With Lewis basic C-H donors such as THF and tertiary amines, a decrease in k(H) with increasing Lewis acidity of M(n+) was observed (k(H)(MeCN) > k(H)(Li(+)) > k(H)(Mg(2+))). This behavior was explained in terms of the stronger Lewis acid-base interaction of M(n+) with the substrate as compared to the radical. This interaction reduces the degree of overlap between the α-C-H σ* orbital and a heteroatom lone-pair, increasing the C-H BDE and destabilizing the carbon centered radical formed after abstraction. With tertiary amines, a >2-order of magnitude decrease in k(H) was measured after Mg(ClO(4))(2) addition up to a 1.5:1 amine/Mg(ClO(4))(2) ratio. At higher amine concentrations, very similar k(H) values were measured with and without Mg(ClO(4))(2). These results clearly show that with strong Lewis basic substrates variations in the nature and concentration of M(n+) can dramatically influence k(H), allowing for a fine control of the substrate hydrogen atom donor ability, thus providing a convenient method for C-H deactivation. The implications and generality of these findings are discussed.

ChemInform Abstract: Intramolecular Electrophilic Cyclization of Functional Derivatives of Unsaturated Compounds. Part 2. Synthesis and Transformation of N‐{(2Z)‐5‐ [(Arylsulfanyl)methyl]dihydrofuran‐2(3H)‐ylidene}‐N‐alkyl(aryl)aminium Perchlorates.

AbstractThe cyclization of amides (I) with arylsulfenyl chlorides (II) in the presence of LiClO4 gives rise to perchlorates (III), which are used as starting compounds in the synthesis of lactones (V), amides (VII), and sulfones (VIII).

A new approach for synthesis of electroactive phenol based polymer: 4-(2,5-Di(thiophen-2-yl)-1H-pyrrol-1-yl)phenol and its oxidative polymer

In this study, the 4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)phenol (4-DTPP) was synthesized by the reaction of 1,4-di(2-thienyl)-1,4-butanedione and 4-aminophenol. This monomer was electrochemically polymerized in the presence of LiClO4 as the supporting electrolyte in acetonitrile (AN). The copolymerization were achieved in the presence of thiophene (Th) with 3,4-ethylenedioxythiophene (EDOT) in 0.1M LiClO4/AN electrolyte-solvent couple. The polymer of 4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)phenol was synthesized by oxidative polycondensation reaction in an aqueous alkaline medium using NaOCl (30%) as oxidant. The structures of compounds were confirmed by FT-IR, UV–vis, and 1H-NMR techniques. The characterizations of compounds were made by TG–DTA, DSC, gel permeation chromatography (GPC) and solubility tests. Electrical conductivities of the synthesized monomer and polymer were measured by four-point probe technique using a Keithley 2400 electrometer. Fluorescence measurements were carried out in various solvents.

Optically pure trans-1-benzyl-4-aminopiperidin-3-ols. Synthesis and absolute configuration

Enantiomerically pure trans-(3R,4R)-4-aminopiperidin-3-ols, which are convenient precursors for making natural and synthetic aminohydroxylated piperidine alkaloid analogs, were efficiently synthesized through the reaction of enantiomerically pure (3R,4S)-3,4-epoxypiperidine with amines in the presence of LiClO4 in CH3CN at room temperature. The absolute stereochemistry of the resultant amino alcohols was determined by the stereochemical correlation method and single-crystal X-ray analysis.

Three-component synthesis of new unsymmetrical oxindoles via Friedel–Crafts type reaction

The synthesis of 2-(3-(4-(dimethylamino)phenyl)-2-oxoindolin-3-yl)-1 H-indene-1,3(2 H)-diones as new unsymmetrical oxindoles via a Friedel–Crafts type three-component reaction of 1,3-indandion, N, N-dimethylaniline and isatins in ethanol in the presence of LiClO 4 is reported.

ChemInform Abstract: Cyclofunctionalization of 6‐Alkenylsulfanylpyrazolo[3,4‐d]pyrimidin‐4(5H)‐ones with Arenesulfenyl Chlorides.

AbstractReactions of the title alkenyl thioethers with arenesulfenyl chlorides in CHCl3 affords products of addition at the exocyclic double bond, while analogous reactions in acetic acid in the presence of LiClO4 are accompanied by an intramolecular electrophilic cyclization involving the N7 atom.

Cyclofunctionalization of 6-alkenylsulfanylpyrazolo[3,4-d]-pyrimidin-4(5H)-ones with arenesulfenyl chlorides

Reactions of 6-allylsulfanylpyrazolo[3,4-d]pyrimidin-4(5H)-one with arenesulfenyl chlorides in chloroform gave products of addition of the latter at the exocyclic double bond, while analogous reactions in acetic acid in the presence of LiClO4 were accompanied by intramolecular electrophilic cyclization involving the N7 atom. 6-Cinnamylsulfanylpyrazolo[3,4-d]pyrimidin-4(5H)-one reacted with arenesulfenyl chlorides in acetic acid in the absence of electrolyte to produce fused pyrazolo[4′,3′: 5,6]pyrimido[2,1-b][1,3]thiazine derivatives. Introduction of a bulky phenyl group into position 1 of the pyrazolo[3,4-d]pyrimidine system reduces the yield of the corresponding intramolecular cyclization product at N7 as a result of concurrent formation of acyclic addition product. DOI

A highly conductive organic–inorganic hybrid electrolyte based on co-condensation of di-ureasil and ethylene glycol-containing alkoxysilane

Organic–inorganic hybrid electrolytes based on di-ureasil backbone structures by reacting poly(propylene glycol)- block-poly(ethylene glycol)- block-poly(propylene glycol) bis(2-aminopropyl ether) (ED2000) with 3-(triethoxysilyl)propyl isocyanate (ICPTES), followed by co-condensation with methoxy(polyethylenoxy)propyl trimethoxysilane (MPEOP) in the presence of LiClO 4 were prepared and characterized by a variety of techniques. The hybrid electrolytes showed good resistance to crystallization and excellent conductivity for use in lithium-ion batteries, as determined by differential scanning calorimetry (DSC) and impedance measurements, respectively. The temperature dependence of the ionic conductivity exhibited a VTF (Vogel–Tamman–Fulcher)-like behavior for all the compositions studied and a maximum ionic conductivity value of 6.9 × 10 −5 S cm −1, a relatively high value for solid polymer electrolytes, was achieved at 30 °C for the hybrid electrolyte with a [O]/[Li] ratio of 16. A microscopic view of the dynamic behavior of the polymer chains ( 13C) and the ionic species ( 7Li) was provided by the 1H and 7Li line widths measured from 2D 1H– 13C WISE (Wideline Separation) and variable temperature 7Li static NMR, respectively, to elucidate the influence of the mobility of the polymer chains and the charge carriers on the observed ionic conductivity. The present salt-free hybrid electrolyte after plasticization with 1 M LiClO 4 in EC/PC solution exhibited a swelling ratio of 275% and reached an ionic conductivity value up to 8.3 × 10 −3 S cm −1 at 30 °C, which make it a good candidate for the further development of advanced rechargeable lithium-ion batteries.

Totally Selective Synthesis of Enantiopure (3S,5S)- and (3R,5R)-4-Amino-3,5-dihydroxypiperidines from Aminodiepoxides Derived from Serine

The transformation of enantiopure (2R,4R)- and (2S,4S)-N,N-dibenzyl-1,2:4,5-diepoxypentan-3-amine, 1 and 2, into the corresponding enantiopure (3S,5S)- and (3R,5R)-3,5-dihydroxy-3-aminopiperidines, 3 and 4 respectively, is described. The opening of the two epoxide rings with a range of amines takes place with total regioselectivity and high yields, in the presence of LiClO4. A mechanism to explain this transformation is proposed.

Effect of LiClO4 on the thermal and morphological properties of organic/inorganic polymer hybrids

This paper describes the thermal properties, morphologies, and interactions within the binary and ternary blends of poly(methyl methacrylate) (PMMA), octa(phenol)octasilsesquioxane (OP-POSS), and LiClO4. In the binary PMMA/OP-POSS blends, the OP-POSS molecules tend to aggregate and result in a decrease (19°C) in the glass transition temperature. In the ternary PMMA/LiClO4/OP-POSS blends, however, the OP-POSS molecules form small sphere-like domains (20nm) leading to the composite's glass transition temperature increasing by up to 30°C. Based on these FT-IR spectra, the addition of LiClO4 influenced the probability of hydrogen bonds formed between PMMA and OP-POSS and these SEM micrographs, DSC, and XRD data indicated that the addition of LiClO4 is a convenient and simple approach toward dispersing the OP-POSS nanoparticles within PMMA, where the presence of LiClO4 changes the physical effect of OP-POSS from that of a diluent role to a cross-linker role.

Synthesis of amphiphilic poly(methyl methacrylate‐ b‐ethylene oxide) copolymers from monohydroxy telechelic poly(methyl methacrylate) as macroinitiator

AbstractThe synthesis of well‐defined poly(methyl methacrylate)‐block‐poly(ethylene oxide) (PMMA‐b‐PEO) dibock copolymer through anionic polymerization using monohydroxy telechelic PMMA as macroinitiator is described. Living anionic polymerization of methyl methacrylate was performed using initiators derived from the adduct of diphenylethylene and a suitable alkyllithium, either of which contains a hydroxyl group protected with tert‐butyldimethylsilyl moiety in tetrahydrofuran (THF) at −78 °C in the presence of LiClO4. The synthesized telechelic PMMAs had good control of molecular weight with narrow molecular weight distribution (MWD). The 1H NMR and MALDI‐TOF MS analysis confirmed quantitative functionalization of chain‐ends. Block copolymerization of ethylene oxide was carried out using the terminal hydroxyl group of PMMA as initiator in the presence of potassium counter ion in THF at 35 °C. The PMMA‐b‐PEO diblock copolymers had moderate control of molecular weight with narrow MWD. The 1H NMR results confirm the absence of trans‐esterification reaction of propagating PEO anions onto the ester pendants of PMMA. The micellation behavior of PMMA‐b‐PEO diblock copolymer was examined in water using 1H NMR and dynamic light scattering. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2132–2144, 2008

Ion Conduction and Polymer Dynamics of Poly(2-vinylpyridine)-Lithium Perchlorate Mixtures

Ion conduction and polymer dynamics of homogeneous mixtures of poly(2-vinylpyridine) (P2VPy) with 0.1 to 10 mol % lithium perchlorate (LiClO(4)) were investigated using broadband dielectric spectroscopy. Interpretation of the relaxation behavior was assisted by findings from differential scanning calorimetry, Fourier transform infrared spectroscopy, dynamic mechanical analysis, and wide-angle and small-angle X-ray scattering experiments. Five dielectric relaxations were observed: a local beta-process in the glassy state, a segmental relaxation, a slow segmental process, an ion-mode relaxation, and electrode polarization. The local P2VPy beta-relaxation was strongly suppressed with increasing LiClO(4) content arising from the formation of transient crosslinks, which lead to a subsequent decrease in the number of free pyridine groups and/or a reduction in the local free volume in the presence of LiClO(4). Ion conduction at low LiClO(4) concentrations (<10 mol %) is governed by the diffusion of anions through the matrix, which is strongly coupled with the segmental relaxation. At relatively high LiClO(4) concentration (10 mol %), partial decoupling between ion motion and the segmental relaxation was observed, leading to increased conductivity.

Electrolyte-Concentration and Ion-Size Dependence of Excited-State Intramolecular Charge-Transfer Reaction in (Alkylamino)benzonitriles: Time-Resolved Fluorescence Emission Studies

Time-resolved studies with three intramolecular charge-transfer molecules 4-(1-azetidinyl)benzonitrile (P4C), 4-(1-pyrrolidinyl)benzonitrile (P5C), and 4-(1-piperidinyl)benzonitrile (P6C) in ethyl acetate in presence of LiClO(4) indicate that the average reaction time for LE --> CT conversion increases at low electrolyte concentration and then decreases to become comparable and even lower than that in the pure solvent. Except for Mg(2+), the average reaction time decreases linearly with the ion size in perchlorate solutions of ethyl acetate. The observed electrolyte-concentration dependence of the average reaction time for these molecules agrees well with the predictions from the theory of Zwan and Hynes [Chem. Phys. 1991, 152, 169] in the broad barrier overdamped limit with barrier frequency, omega(b) approximately 2 x 10(12) s(-1).

A soluble conducting polymer of 4-(2,5-di(thiophen-2-yl)-1 H-pyrrol-1-yl)benzenamine and its multichromic copolymer with EDOT

Here we report the synthesis of a monomer, 4-(2,5-di(thiophen-2-yl)-1 H-pyrrol-1-yl)benzenamine (SNS-NH 2) produced by the reaction of 1,4-di(2-thienyl)-1,4-butanedione and benzene-1,4-diamine. This monomer was electrochemically polymerized in the presence of LiClO 4, NaClO 4 (1:1) as the supporting electrolyte in acetonitrile. Copolymerization in the presence of 3,4-ethylenedioxythiophene (EDOT) was achieved in acetonitrile NaClO 4/LiClO 4 (0.1 M:0.1 M) solvent–electrolyte couple. Resulting homopolymer and copolymer were characterized by means of cyclic voltammetry, Fourier transform infrared spectroscopy, nuclear magnetic resonance, scanning electron microscopy and ultraviolet–visible spectroscopy. Spectroelectrochemistry analysis of homopolymer, P(SNS-NH 2), reflected electronic transitions at 376 and 650 nm indicating π–π ∗ transition and polaron band formation, respectively. The polymer has an electronic bandgap of 2.12 eV with a yellow color in the fully reduced form and a blue color in the fully oxidized form. Switching ability of the homopolymer was evaluated by kinetic studies upon measuring the % T as 20.7% at the maximum contrast point. Copolymer revealed multichromic property with five different colors at different applied potentials. Colorimetry studies for P(SNS-NH 2-co-EDOT) proved that it is possible to provide fine tuning of these colors by varying applied potential during synthesis. Dual-type complementary colored electrochromic devices (ECD) using P(SNS-NH 2-co-EDOT)/poly(3,4-ethylenedioxythiophene) (PEDOT) in sandwich configuration were constructed. Spectroelectrochemistry, switching ability and optical memory of the electrochromic devices were investigated.

Efficient One‐Pot Synthesis of Enantiomerically Pure 2‐(Hydroxymethyl)morpholines.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Development and characterisation of a novel composite electrode material consisting of poly(3,4-ethylenedioxythiophene) including Au nanoparticles

Composite material consisting of poly(3,4-ethylenedioxythiophene) (PEDOT), including Au nanoparticles encapsulated by N-dodecyl- N, N-dimethyl-3-ammonium-1-propanesulphonate (SB12) is synthesised by constant-current method on ITO glass, in aqueous medium, leading to an electrode coating. The synthesis process is followed by UV–vis spectroelectrochemistry, both in normal-beam and in parallel-beam configurations. Under the same experimental conditions PEDOT is also synthesised by electropolymerisation only in the presence of LiClO 4 supporting electrolyte, as well in solutions also containing SB12. The data relative to the electrosynthesis of the three materials are compared. The composite material based on the conductive polymer matrix including Au nanoparticles has been characterised by SEM, TEM, ICP, Raman and UV–vis spectroscopies. The behaviour of the three different electrode coatings with respect to p-doping process has been studied by conventional electrochemical techniques and by potentiostatic and potentiodynamic UV–vis spectroelectrochemical methods. Conclusions are drawn out about the effect of the presence of the surfactant and of Au nanoparticles on the electrochemical properties of the electrode system.

Stereodivergent Baylis-Hillman Reaction of a Chiral Acryloyl Imide Exploiting Ion-Chelation Effect: Mechanistic Insight on the Rearrangement of Trichloroacetimidates of the Baylis-Hillman Adducts to Trichloroacetamides

In the presence of DABCO, ethyl glyoxalate and (4S,5R)-1,5-dimethyl-3-acryloyl-4-phenylimidazolidin-2-one gave mixtures of the corresponding Baylis-Hillman adducts enriched in either isomer, depending on the absence or the presence of LiClO4 in the reaction mixture. A diastereomeric mixture in 10:90 dr allowed to definitively establish the mechanism of the reaction leading to trichloroacetamides starting from trichloroacetimidates of the Baylis-Hillman adducts.

A soluble conducting polymer of 2,5-di(thiophen-2-yl)-1- p-tolyl-1 H-pyrrole and its electrochromic device

A monomer 2,5-di(thiophen-2-yl)-1- p-tolyl-1 H-pyrrole was synthesized via reaction of 1,4-di(2-thienyl)-1,4-butanedione and p-toluidine in the presence of catalytical amount of p-toluenesulfonic acid. Chemical polymerization of the monomer yielded a soluble polymer. The average molecular weight was determined by gel permeation chromatography as number average molecular weight (Mn) 2.5 × 10 3 g/mol. The monomer was also electrochemically polymerized in the presence of LiClO 4, NaClO 4 (1:1) as the supporting electrolyte in acetonitrile. Cyclic Voltammetry, Fourier Transform Infra Red, Nuclear Magnetic Resonance, Scanning Electron Microscopy and Ultraviolet–Visible Spectroscopy were employed for the characterization of the polymer. Spectroelectrochemistry analysis of homopolymer revealed an electronic transition at 428 nm which corresponds to π–π⁎ transition. Switching ability of the homopolymer was evaluated by kinetic studies upon measuring the percent transmittance (% T) at the maximum contrast point, indicating that poly(2,5-di(thiophen-2-yl)-1- p-tolyl-1 H-pyrrole) is a suitable material for electrochromic devices.

Physical and electrochemical properties of low molecular weight poly(ethylene glycol)‐bridged polysilsesquioxane organic–inorganic composite electrolytes via sol–gel process

AbstractA new class of ionic conducting organic/inorganic hybrid composite electrolyte with high conductivity, better electrochemical stability and mechanical behavior was prepared through the sol–gel processing between ethylene‐bridged polysilsesquioxane and poly(ethylene glycol) (PEG). The composite electrolyte with 0.05 LiClO4 per PEG repeat unit has the best conductivity up to 10−4 S/cm at room temperature with the transference number up to 0.48 and an electrochemical stability window as high as 5.5 V versus Li/Li+. Moreover, the effect of the PEG chain length on the properties of the composite electrolyte has also been studied. The interactions between ions and polymer have also been investigated for the composite electrolyte in the presence of LiClO4 by means of FTIR, DSC, and TGA. The results indicated the interaction of Li+ ions with the ether oxygen of the PEG, and the formation of transient crosslinking with LiClO4, resulting in an increase of the Tg of the composite electrolyte. The VTF‐type behavior of the ionic conductivity implied that the diffusion of the charge carriers was assisted by the segmental motions of the polymer chains. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2752–2758, 2007