Trimethylsilyl Chlorosulfonate Research Articles

Sulfonated poly(bis-A)-sulfones as proton exchange membranes for direct methanol fuel cell application

Sulfonated poly(bis-A)-sulfone (SPSF) samples were prepared by a mild postsulfonation method using trimethylsilyl chlorosulfonate as sulfonation agent, and their thermal and mechanical properties were evaluated. The serials of SPSF membranes are thermally stable up to 450°C in air. When compared with the poly(bis-A)-sulfone membrane, the hydrophilicity and water uptake of the SPSF membranes are enhanced. A microphase-separated structure comprised of hydrophilic and hydrophobic polymer backbone was observed from atomic force microscopy phase images. The hydrophilic ionic clusters become continuous to form channels when ion exchange capacity (IEC) reached 1.47 mequiv/g. Moreover, the membranes showed very good proton conductivities (20°C, 0.01–0.11 S/cm) and low-methanol permeability (0.09–3.06 × 10−6 cm2/s), and the methanol diffusion coefficients were lower than that of Nafion112 (1.35 × 10−6 cm2/s) with IEC values from 0.70 to 1.47 mequiv/g. However, the Fenton's reagent test revealed that the membranes exhibited very poor oxidation stability, which is the main defect limiting the application of SPSF for proton exchange membranes. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers

Crosslinked Sulfonated Polysulfone-Based Polymer Electrolyte Membranes Induced by Gamma Ray Irradiation

Sulfonated aromatic polymers generally show high swelling at high proton conductivity. This disadvantage makes many of them unfit for proton exchange membrane applications. Crosslinking of the polymer is one way to overcome this problem. In this study, radiation-induced crosslinking was performed on a sulfonated polysulfone membrane, with doses ranging from 2.5 to 25.0 kGy (dose rate: 45 Gy/min) using gamma rays from a 60Co source. The pristine sulfonated polysulfones was obtained by mild sulfonation of bisphenol-A-polysulfone with trimethylsilyl chlorosulfonate as sulfonating agent. The proton conductivity of the membranes was characterized by means of electrical impedance spectroscopy techniques. Ion-exchange capacity, degree of sulfonation, water content and chemical stability membrane properties were characterized before and after irradiation. The results show that the mechanical, chemical and thermal stability of the membrane improve after irradiation. The degree of sulfonation and the proton conductivity exhibit a tendency to decrease with increasing irradiation total dose.

Anhydrous state proton conduction in sulfonated bisphenol a polyetherimide with 1H‐1,2,4 triazole as proton solvent

AbstractIn this study, bisphenol A polyetherimide was sulfonated to various degrees (22, 48, and 62%) by trimethylsilylchlorosulfonate (TMSCS). Novel anhydrous proton conducting polyelectrolytes were prepared by the incorporation of 1H‐1,2,4‐triazole (Taz) as proton solvent in sulfonated polyetherimide (SPEI) matrix. The conductivity reached about 2 × 10–3 S/cm at 80 °C and 10–2 S/cm at 140 °C. The temperature dependence proton conductivity of the polyelectrolytes followed Arrhenius equation. The conductivity improved considerably at a temperature close to the triazole melting temperature in SPEI(X)H matrix. It was proposed that the high mobility of the triazolium ions (vehicle diffusion), in addition to structure diffusion, contribute to the high conductivity of these proton conducting electrolytes above the melting temperature of triazole. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2178–2187, 2009

Preparation and characterization of sulfonated polysulfone/titanium dioxide composite membranes for proton exchange membrane fuel cells

In the present study, sulfonated polysulfone (sPS)/titanium dioxide (TiO2) composite membranes for use in proton exchange membrane fuel cells (PEMFCs) were investigated. Polysulfone (PS) was sulfonated with trimethylsilyl chlorosulfonate in 1,2 dichloroethane at ambient temperatures. It was shown that the degree of sulfonation is increased with the molar ratio of the sulfonating agent to PS repeat unit. The degree of sulfonation was determined by elemental analysis and 1H NMR was performed to verify the sulfonation reaction on the PS. Sulfonation levels from 15 to 40% were easily achieved by varying the content of the sulfonating agent. Composite membranes were prepared by blending TiO2 with sPS solution in DMAC (5 wt.%) by the solution casting procedure. The membranes have been characterized by thermal analysis, water uptake, proton conductivity measurements and single cell performance. The addition of TiO2 increased the thermal stability but high filler concentrations decreased the miscibility of the composite component, and resulted in brittle membranes. The conductivity values in the range of 10−3–10−2 S/cm were obtained for composite membranes. The conductivities of the membranes show similar increasing trend as a function of operating temperature. The membranes were tested in a single cell operating at 60–85 °C in humidified H2/O2. Single fuel cell tests performed at different operating temperatures indicated that sPS/TiO2 composite membrane is more hydrodynamically stable and also performed better than sPS membranes. The highest performance of 300 mA/cm2 was obtained for sPS/TiO2 membrane at 0.6 V for an H2–O2/PEMFC working at 1 atm and 85 °C. The results show that sPS/TiO2 is a promising membrane material for possible use in proton exchange membrane fuel cells.

Proton conducting sol–gel sulfonated membranes produced from 2-allylphenol, 3-glycidoxypropyl trimethoxysilane and tetraethyl orthosilicate

An important research area in proton exchange membrane fuel cells (PEMFC) is devoted to the development of low cost membranes able to work at temperatures higher than 100 °C. In this work, homogeneous, transparent and crack-free hybrid membranes have been synthesized using tetraethyl orthosilicate (TEOS), 3-glycidoxipropyl trimethoxysilane (GPTMS) and 2-allylphenol (AP) as precursors. The synthesis of proton conducting membranes was performed by a post-sulfonation method using trimethylsilyl chlorosulfonate as a mild sulfonating agent. The water retention properties provided by sulfonate and hydroxyl groups and the high porosity leads to relatively high proton conductivity (maximum values around 1.3 × 10 −3 S cm −1 at 140 °C and 100% RH) for membranes treated at 180 °C and sulfonated for 2 h.

Polymer electrolytes based on sulfonated polysulfone for direct methanol fuel cells

This paper reports the development and characterization of sulfonated polysulfone (SPSf) polymer electrolytes for direct methanol fuel cells. The synthesis of sulfonated polysulfone was performed by a post sulfonation method using trimethyl silyl chlorosulfonate as a mild sulfonating agent. Bare polysulfone membranes were prepared with two different sulfonation levels (60%, SPSf-60 and 70%, SPSf-70), whereas, a composite membrane of SPSf-60 was prepared with 5 wt% silica filler. These membranes were investigated in direct methanol fuel cells (DMFCs) operating at low (30–40 °C) and high temperatures (100–120 °C). DMFC power densities were about 140 mW cm −2 at 100 °C with the bare SPSf-60 membrane and 180 mW cm −2 at 120 °C with the SPSf-60-SiO2 composite membrane. The best performance achieved at ambient temperature using a membrane with high degree of sulfonation (70%, SPSf-70) was 20 mW cm −2 at atmospheric pressure. This makes the polysulfone-based DMFC suitable for application in portable devices.

Development and characterization of sulfonated polysulfone membranes for direct methanol fuel cells

The development of a direct methanol fuel cell based on composite polysulfone membranes modified with silica filler is reported. The synthesis of sulfonate polysulfone samples was carried out by a mild sulfonation process using trimethyl silyl chlorosulfonate as sulfonating agent. Composites membranes with 5 wt% of silica filler were prepared and characterized. A composite membrane tested in direct methanol/oxygen fuel cell gave a maximum power density of about 180 mWcm −2 at 120°C.

Proton Conducting Organic/Inorganic Sol–Gel Membranes Produced from Phenyltriethoxysilane and 3-Methacryloxypropyl Trimethoxysilane

The increase of the operation temperature in Proton Exchange Membrane Fuel Cells (PEMFC) above 100∘C would be an important breakthrough for the application of this type of fuel cell in electric vehicles. Hybrid organic-inorganic membranes with nano-sized interfaces can combine all the properties to meet this objective. Membranes using phenyltriethoxysilane and 3-methacryloxypropyl trimethoxysilane have been synthesised by polymerisation of methacrylate groups and inorganic condensation of silanol groups. Sulfonation process to provide proton conductivity affects both proton conductivity and chemical stability of hybrid membranes. Liquid sulfonation during the sol preparation and chlorosulfonic acid as sulfonating agent leads to chain cleavage while trimethylsilyl chlorosulfonate does not affect the polymer backbone. The increase of temperature (up to 120–130∘C) and relative humidity leads to an increase of proton conductivity close to 10− 3 S/cm.

A novel method for the synthesis of regiospecifically sulfonated porphyrin monomers and dimers

A novel method has been developed to regiospecifically synthesize water-soluble sulfonated porphyrin monomers tetrakis(4′-sulfonatophenyl)porphyrin, tetrakis(3′-sulfonatophenyl)porphyrin, tetrakis(2′-sulfonatophenyl)porphyrin, tetrakis(2′,5′-dimethyl-4′-sulfonatophenyl)porphyrin, the dimers of 1,2-bis[5,10,15-tri(4′-sulfonatophenyl)porphyrinyl]benzene and 1,2-bis[5,10,15-tri(2′,5′-dimethyl-4′-sulfonatophenyl)porphyrinyl]benzene in high yields through introduction of the trimethylsilyl group on the phenyl rings and reaction with trimethylsilyl chlorosulfonate in CCl 4 solvent.

ChemInform Abstract: Improved Simple Synthesis of Cyclic Sulfates from Trimethylsilyl Chlorosulfonate.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Improved simple synthesis of cyclic sulfates from trimethylsilyl chlorosulfonate

Reaction of iodosobenzene and trimethylsilyl chlorosulfonate followed by removal of the solvent and trimethylchlorosilane gives phenyliodosulfate. This can be used without further purification to prepare cyclic sulfates from alkenes, including vinylsilanes. Previous results have shown that if the trimethylchlorosilane is not removed, sultones are formed and a possible explanation of this behaviour is given.Key words: silicon, vinylsilanes, cyclic sulfate, phenyliodosulfate.

Revisit to the sulfonation of pyrroles: is the sulfonation position correct?

Sulfonation of pyrrole and its 1-methyl derivatives with a sulfur trioxide–pyridine complex was found to give 3-sulfonated pyrroles, but not 2-sulfonates as described in textbooks. The replacement of 1-methyl-2-tri- n-butylstannylpyrrole with trimethylsilyl chlorosulfonate, followed by quenching with aq. NaHCO 3 also generated sodium 1-methylpyrrole-3-sulfonate, not 2-sulfonate.

Improved simple synthesis of cyclic sulfates from trimethylsilyl chlorosulfonate

Reaction of iodosobenzene and trimethylsilyl chlorosulfonate followed by removal of the solvent and trimethylchlorosilane gives phenyliodosulfate. This can be used without further purification to prepare cyclic sulfates from alkenes, including vinylsilanes. Previous results have shown that if the trimethylchlorosilane is not removed, sultones are formed and a possible explanation of this behaviour is given.Key words: silicon, vinylsilanes, cyclic sulfate, phenyliodosulfate.

ChemInform Abstract: Tin for Organic Synthesis. Part 12. Synthesis of Aromatic and Olefinic Sodium Sulfonates by Electrophilic Destannylation with Trimethylsilyl Chlorosulfonate.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Tin for Organic Synthesis, 12. Synthesis of Aromatic and Olefinic Sodium Sulfonates by Electrophilic Destannylation with Trimethylsilyl Chlorosulfonate

AbstractA mild and effective method for the preparation of a variety of aromatic, olefinic, and acetylenic sodium sulfonates is described. The reaction of trialkylaryl‐ (2a‐k) and ‐heteroarylstannanes (4a‐d), bis‐(1‐alkenyl)dibutylstannanes (6a‐f), or trialkylalkynylsta manes with trimethylsilyl chlorosulfonate (1) followed by hydrolysis with aqueous NaHCO3 provides the sodium sulfonates in an ipso‐specific and in the case of vinylic stannanes stereospecific manner. A comparison of the reactivity of stannylated and silylated olefinic compounds 13 and 14 underlines the greater leaving ability of the stannyl moiety. The in situ preparation of the stannanes makes it possible to apply the synthetic method to natural products such as N‐substituted apocodeine (17).

Preparation of silica-based cation-exchangers for use in ion chromatography

A low exchange-capacity, silica-based cation-exchanger for use in ion chromatography has been synthesized. (p-Trimethylsilyl)benzyl-dimethylchlorosilane (TBDCS) reacts with trimethylsilyl chlorosulfonate (TMCS) to produce a compound sulfonated in the para position of the type ArSO2OSi (CH3)3, which is bonded to 5 μm porous silica beads and hydrolysed to the corresponding arylsulfonic acid. The product is hydrophilic and has a high degree of sulfonation, efficiencies of packed columns reaching about 40,000–50,000 plates per meter for the separation of the Mn2+ ion. The new stationary phase has been applied to the ion chromatography of some organic and inorganic ions. It is notable that 14 lanthanides can be separated by isocratic elution about one hour on a 150×4·6 mm column, with 4 mM ethylenediamine and 6 mM α-hydroxyl-isobutanoic acid (pH 3.67) as mobile phase.

Nouvelles fonctionnalisations a partir de cyclopropanes silicies

cis- and trans-1,2-Bis(trimethylsilyl)cyclopropane react with trimethylsilyl chlorosulfonate or acetyl chloride/aluminium chloride to afford the trans-sulfonyl or -acetyl derivatives resulting from substitution of one trimethylsilyl group without ring opening. The results confirm the effect of the trimethylsilyl group previously observed for trimethylsilylcyclopropane. In contrast cis- and trans-1-trimethylsilyl 2-(trimethylsilylmethyl)cyclopropane undergo facile diacylation with ring opening. This reaction offers a new, competitive acces to bifunctional butenes and especially to diacyl derivatives.

Poly(trimethylsilyl)benzenes: Synthese, sulfonation

The system Me 3SiCl/Mg/hexamethylphosphorotriamide (HMPT) reacts with some di- or poly-chlorobenzenes leading directly to the corresponding di- or poly-trimethylsilyl derivatives (yields 70-85%). Reaction of trimethylsilyl chlorosulfonate with these compounds gives in a first step trimethylsilyl arylsulfonic esters, Ph(SiMe 3)SO 3SiMe 3. An excess of sulfonating reagent leads to sulfonation either at the PhSi bond (SiMe 3 group in meta or para position) or, mainly, at the MeSi bond (SiMe 3 group in ortho position). By this process new silylated sulfonic compounds can be synthesized.

Sulfonation de dérivés siliciés acétyléniques et alléniques fonctionnels

Sulfonating agents such as trimethylsilyl chlorosulfonate and “dioxane, SO 3”, react with silylalkynes (ΣCH 2CCSiMe 3) in which Σ is a functional group, to yield silylacetylene sulfonates (Σ = OMe, Cl), acetylenic sulfates (Σ = OH, OSiMe 3) or SO 3 nitrogen adduct (Σ = NR 2). Allenoxysilanes Me 3Si(Σ 1)CCC(Σ 2)OSiMe 3 yield either allenic sulfate (Σ 1 = Me 3Si, Σ 2 = t-Bu) or silyl ketonic sulfonate (Σ 1 = n-Bu, Σ 2 = t-Bu). A mechanism is proposed for these reactions.

Sultones organométalliques : IV. Réactions de sulfonation en série silacyclobutanique

The behaviour of some substituted silacyclobutanes with respect to sulfur trioxide and other sulfonating agents (SO 3/dioxane, trimethylsilyl chlorosulfonate) is studied. The 1,1-dialkylated derivatives of silacyclobutane, 2-methylsilacyclobutane and 3-methylsilacyclobutane as well as the spiranes of the type (CH 2) n Si(CH 2) 3 ( n = 4 or 5) react with sulfur trioxide to give 4-sila-1,4-butanesultones. On the other hand, the alkoxylated or dialkylaminated derivatives fix SO 3 via the functional group, thus giving silacyclobutanyl sulfates or amidosulfates of the type XSO 2O(R)Si(CH 2) 3 (X = OR′, NR′ 2). The sulfonation of 1-methyl-1-phenylsilacyclobutane leads mainly to 1-methyl-1-silacyclobutylbenzenesulfonate, besides the expected sultone. The structure of the insertion products of SO 3 in the SiC, SiN, SiO and SiCl bonds is deduced from their infrared and protonic resonance spectra. Reaction mechanisms, permitting to ascertain the role of the substituents on the mode of insertion of sulfur trioxide and the reactivity of the cyclobutane SiC bond, are considered.