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Tetraalkylammonium Salts (tetraalkylammonium + salt)

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Chemistry66%

Selected Abstracts

Tetraalkylammonium Salts of Weakly Coordinating Aluminates: Ionic Liquids, Materials for Electrochemical Applications and Useful Compounds for Anion Investigation

CHEMISTRY - A EUROPEAN JOURNAL, Issue 8 2009
Ines Raabe Dr.
Abstract Weak and robust? Tetraalkylammonium salts of weakly coordinating fluorinated alkoxyaluminates are easily accessible, chemically robust materials that show interesting physico-chemical properties like low melting points, high electrochemical stability and electric conductivity in weakly polar solvents such as CH2Cl2, Ph-F and toluene. In this study, we investigated the tetraalkylammonium salts of the weakly coordinating fluorinated alkoxyaluminates [pftb], ([Al(O(C(CF3)3)4],), [hfip], ([Al(OC(H)(CF3)2)4],) and [hftb], ([Al(OC(CH3)(CF3)2)4],) in order to obtain information on their undisturbed spectral and structural properties, as well as to study their electrochemical behavior (i.e., conductivities in non-polar solvents and electrochemical windows). Several of the compounds qualify as ionic liquids with melting points as low as 42,°C for [NBu4]+[hfip],. Simple and almost quantitative metathesis reactions yielding these materials in high purity were developed. These [NR4]+ salts serve as model compounds for undisturbed anions and their vibrational spectra,together with simulated spectra based on quantum chemical DFT calculations,were used for the clear assignment of the anion bands. Besides, the ion volumes of the anions (Vion([pftb],)=0.736,nm3, Vion([hftb],)=0.658,nm3, Vion([hfip],)=0.577,nm3) and their decomposition pathways in the mass spectrometric measurements have been established. The salts are highly soluble in non-polar solvents (up to 1.09,mol,L,1 are possible for [NBu4]+[hftb], in CH2Cl2 and 0.41,mol,L,1 for [NBu4]+[hfip], in CHCl3) and show higher molar conductivities if compared to [NBu4]+[PF6],. The electrochemical windows of CH2Cl2, CH3CN and 1,2-F2C6H4 using the [NBu4]+ aluminate electrolytes are up to +0.5,V/,0.7,V larger than those using the standard [NBu4]+[PF6],. [source]

Tetraalkylammonium salt as photoinitiator of vinyl polymerization in organic and aqueous media: A mechanistic and laser flash photolysis study

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2002
María L. Gómez
Abstract N -Dimethyl- N -[2-(N,N -dimethylamino)ethyl]- N -(1-methylnaphthyl)ammonium tetrafluoroborate (I) was synthesized with the aim of obtaining a versatile photoinitiator for vinyl polymerization in organic solvents and water. Salt I was able to trigger the polymerization of acrylamide, 2-hydroxyethylmethacrylate and styrene even at very low concentrations of the salt (,1.0 × 10,5 M). Using laser flash photolysis and fluorescence techniques and analyzing the photoproduct distribution, we were able to postulate a mechanism for the photodecomposition of the salt. With irradiation, I undergoes an intramolecular electron-transfer reaction to form a radical ion pair (RIP). The RIP intermediate decomposes into free radicals. The RIP and the free radicals are active species for initiating the polymerization. Depending on the concentration of the vinyl monomers studied, the initiation mechanism of the polymerization reaction changes. At large monomer concentrations, the RIP state is postulated to trigger the reaction by generating the anion radical of the olefin substrate. At a low monomer concentration, the free radicals produced by the decomposition of I are believed to start the chain reaction. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 901,913, 2002; DOI 10.1002/pola.10166 [source]

Recoverable Phase-Transfer Catalysts with Fluorinated Anions: Generation and Reactions of Dichlorocarbene and CCl3 Anion in the Heterogeneous System KOH(s)/CHCl3/nBu4NPF6

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2008
Galina V. Kryshtal
Abstract Tetraalkylammonium salts bearing PF6, and BF4, anions have been recognized as recoverable phase-transfer catalysts for the synthesis of 1,1-dichlorocyclopropane and ,-(trichloromethyl)carbinol derivatives from alkenes or aldehydes in the heterogeneous system KOH(s)/CHCl3. The catalysts retained their catalytic activity over several reactioncycles.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

Tetraalkylammonium Salts of Weakly Coordinating Aluminates: Ionic Liquids, Materials for Electrochemical Applications and Useful Compounds for Anion Investigation

CHEMISTRY - A EUROPEAN JOURNAL, Issue 8 2009
Ines Raabe Dr.
Abstract Weak and robust? Tetraalkylammonium salts of weakly coordinating fluorinated alkoxyaluminates are easily accessible, chemically robust materials that show interesting physico-chemical properties like low melting points, high electrochemical stability and electric conductivity in weakly polar solvents such as CH2Cl2, Ph-F and toluene. In this study, we investigated the tetraalkylammonium salts of the weakly coordinating fluorinated alkoxyaluminates [pftb], ([Al(O(C(CF3)3)4],), [hfip], ([Al(OC(H)(CF3)2)4],) and [hftb], ([Al(OC(CH3)(CF3)2)4],) in order to obtain information on their undisturbed spectral and structural properties, as well as to study their electrochemical behavior (i.e., conductivities in non-polar solvents and electrochemical windows). Several of the compounds qualify as ionic liquids with melting points as low as 42,°C for [NBu4]+[hfip],. Simple and almost quantitative metathesis reactions yielding these materials in high purity were developed. These [NR4]+ salts serve as model compounds for undisturbed anions and their vibrational spectra,together with simulated spectra based on quantum chemical DFT calculations,were used for the clear assignment of the anion bands. Besides, the ion volumes of the anions (Vion([pftb],)=0.736,nm3, Vion([hftb],)=0.658,nm3, Vion([hfip],)=0.577,nm3) and their decomposition pathways in the mass spectrometric measurements have been established. The salts are highly soluble in non-polar solvents (up to 1.09,mol,L,1 are possible for [NBu4]+[hftb], in CH2Cl2 and 0.41,mol,L,1 for [NBu4]+[hfip], in CHCl3) and show higher molar conductivities if compared to [NBu4]+[PF6],. The electrochemical windows of CH2Cl2, CH3CN and 1,2-F2C6H4 using the [NBu4]+ aluminate electrolytes are up to +0.5,V/,0.7,V larger than those using the standard [NBu4]+[PF6],. [source]

Electrochemical synthesis and stabilization of cobalt nanoparticles

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2006
A. Ledo-Suárez
Abstract Cobalt nanoparticles (NPs) were synthesized via an electrochemical method in the presence of tetraalkylammonium salt. The nanometer dimensions of the NPs can be controlled in a simple way by adjustment of the current density. From these particles stable colloidal suspensions are prepared in the presence of a fatty acid (oleic acid) and triphenylphosphine. The colloidal system is stable against oxidation when they are kept in heptane (C7H16). Transmission electron microscopy (TEM) was employed to determine the core size and the shape of metal nanoparticles. The chemical interaction of the surfactant with the Co nanoparticles was studied by using Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). Thermogravimetric analysis (TGA) was used to study the thermal stability and the composition of the capped cobalt nanoparticles. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Tetraalkylammonium Salts of Weakly Coordinating Aluminates: Ionic Liquids, Materials for Electrochemical Applications and Useful Compounds for Anion Investigation

CHEMISTRY - A EUROPEAN JOURNAL, Issue 8 2009
Ines Raabe Dr.
Abstract Weak and robust? Tetraalkylammonium salts of weakly coordinating fluorinated alkoxyaluminates are easily accessible, chemically robust materials that show interesting physico-chemical properties like low melting points, high electrochemical stability and electric conductivity in weakly polar solvents such as CH2Cl2, Ph-F and toluene. In this study, we investigated the tetraalkylammonium salts of the weakly coordinating fluorinated alkoxyaluminates [pftb], ([Al(O(C(CF3)3)4],), [hfip], ([Al(OC(H)(CF3)2)4],) and [hftb], ([Al(OC(CH3)(CF3)2)4],) in order to obtain information on their undisturbed spectral and structural properties, as well as to study their electrochemical behavior (i.e., conductivities in non-polar solvents and electrochemical windows). Several of the compounds qualify as ionic liquids with melting points as low as 42,°C for [NBu4]+[hfip],. Simple and almost quantitative metathesis reactions yielding these materials in high purity were developed. These [NR4]+ salts serve as model compounds for undisturbed anions and their vibrational spectra,together with simulated spectra based on quantum chemical DFT calculations,were used for the clear assignment of the anion bands. Besides, the ion volumes of the anions (Vion([pftb],)=0.736,nm3, Vion([hftb],)=0.658,nm3, Vion([hfip],)=0.577,nm3) and their decomposition pathways in the mass spectrometric measurements have been established. The salts are highly soluble in non-polar solvents (up to 1.09,mol,L,1 are possible for [NBu4]+[hftb], in CH2Cl2 and 0.41,mol,L,1 for [NBu4]+[hfip], in CHCl3) and show higher molar conductivities if compared to [NBu4]+[PF6],. The electrochemical windows of CH2Cl2, CH3CN and 1,2-F2C6H4 using the [NBu4]+ aluminate electrolytes are up to +0.5,V/,0.7,V larger than those using the standard [NBu4]+[PF6],. [source]