Presence Of Chlorosulfonic Acid Research Articles

Microstructural evolution effects on the density of carbon nanotube fibers

In this study, we investigate structural change in wet-spun carbon nanotube (CNT) fibers and explore the resulting changes in density and tensile strength. Given the presence of chlorosulfonic acid (CSA) inside the fiber and the evolution of tubular shape, the difference between the experimental density of CNT fibers and the theoretical density of individual CNTs can be reasonably approximated. During the heat treatment of pristine CNT fibers at 1400 °C, the capillary force induced by removal of CSA between or inside CNTs leads to the polygonization of the circumference of individual nanotubes. This morphological transformation results in the improved tensile strength and increased density by enlarging the contact area between CNTs and reducing the occupied volume. The demonstration of correlation between CNT structure and density can offer insights into the manufacturing and applications of high-performance CNT fibers.

Preparation and application of sulfonated polysulfone in an electrochemical hydrogen storage system

Storage of hydrogen in/on solid-state materials is predicted from their tendency to adsorb-desorb hydrogen. It is crucial to find a new class of materials that can reversibly store hydrogen at high rates under reasonable temperature, pressure, and cost conditions. Polymeric materials have recently come to the fore of hydrogen storage technologies because of their reversible capacity, approximately high surface area, and thermomechanical stabilities. Here, we report, for the first time, a polymer for hydrogen storage based on sulfonated polysulfone (SPSU) of above 500 mAh g−1 (~1.8 wt% H) of discharge capacity. Primarily, the SPSU have polymerized from polysulfone (PSU) in the presence of chlorosulfonic acid (ClSO3H). The spectroscopic and elemental analyses confirm the successful sulfonation of PSU. The electrochemical properties of the sample illustrate at high frequency, the resistance is small with slopes of around zero. Cyclic voltammetry affirms a quick ion transfer ability of the host polymer owing to the ion diffusion reaction within the working electrodes. The charge-discharge efficiency of this system exhibits a stable sequence with around 93% efficiency, comparable with many benchmark commercial batteries. The results clearly emphasize that the SPSU can be individually assigned for hydrogen storage. This study will promote the technology of hydrogen sorption on organic polymers.

Characterization and Molecular Docking Study of New 4-Acetamidoalkyl Pyrazoles As B-Raf /Cox-2 Inhibitors

Several new 4-acetamidoalkyl pyrazoles are synthesized by an efficient, one-pot three-component reaction of 3,5-dimethyl-1-phenyl-1H-pyrazole or 3-methyl-1-phenyl-1H-pyrazol-5-ol, aromatic aldehydes, and acetonitrile in the presence of chlorosulfonic acid at room temperature. The products are characterized based on IR, 1H and 13C NMR data and evaluated as potential COX-2 and B-Raf inhibitors by molecular docking studies. All the products showed the potency of B-Raf and COX-2 inhibitory effects with a greater binding affinity to B-Raf than COX-2 protein.

Characterization and molecular docking study of new 4-acetamidoalkyl pyrazoles as B-Raf/COX-2 inhibitors

Several new 4-acetamidoalkyl pyrazoles are synthesized by an efficient, one-pot three-compo­nent reaction of 3,5-dimethyl-1-phenyl-1H-pyrazole or 3-methyl-1-phenyl-1H-pyrazol-5-ol, aromatic aldehydes, and acetonitrile in the presence of chlorosulfonic acid at room temperature. The products are characterized based on IR, 1H and 13C NMR data and evaluated as potential COX-2 and B-Raf inhibitors by molecular docking studies. All the products showed the potency of B-Raf and COX-2 inhibitory effects with a greater binding affinity to B-Raf than COX-2 protein.

Synthesis of 3-[(acetylamino)(aryl)Methyl]-4-Hydroxy-6-Methyl-2H-Pyran-2-Ones

A one-pot, three-component reaction between aryl aldehydes, 4-hydroxy-6-methyl-2H-pyran-2-one, and acetonitrile in the presence of chlorosulfonic acid affords 3-[(acetylamino)(aryl)methyl]-4-hydroxy-6-methyl-2H-pyran-2-ones in excellent yields.

Coating and lamination of Nafion117 with partially sulfonated PVdF for low methanol crossover in DMFC applications

Sulfonation of PVdF was carried out in the presence of chlorosulfonic acid at 60°C. The presence of characteristic peaks of sulfonic acid in the FT-IR spectra confirmed the successful sulfonation of PVdF. X-ray diffraction was conducted to analyze the effect of sulfonation on the crystallinity of PVdF. On sulfonation for a period of 2h, the maximum DS value achieved was 33%. This sulfonated PVdF resin was utilized as a laminate and/or coating material for the modification of Nafion-117. The laminated and coated Nafion-117 as polymer electrolyte membranes in direct methanol fuel cell (DMFC) exhibited significantly lower methanol crossover by magnitude of two orders, leading to their respective higher membrane selectivities and OCV (open circuit voltage) over prisine Nafion-117 membrane. By operating the DMFC with highly concentrated methanol (5M), the cell efficiency (maximum power density) for the laminated and coated Nafion 117 membranes was found to be superior over that of pristine Nafion-117.

New Ion Exchangers Based on Copolymers: 2,3-(2-Hydroxy-3-Methacryloyloxypropoxy)Naphthalene–Styrene

Synthesis and characterization of the new polymeric ion exchangers with thiol and sulfonyl hydroxide groups are presented. These new sorbents were also compared with polymeric microspheres possessing methylenethiol groups on the surface presented previously. The polymeric cation ion exchangers in the form of microspheres were obtained by the suspension-emulsion polymerization tetrafunctional monomer: 2,3-(2-hydroxy-3-methacryloyloxypropoxy)naphthalene (2,3-NAF.DM) with styrene (St). Next, multistage modification introducing sulfur-containing group (thiol or sulfonyl hydroxide or methylenethiol) on the surface of polymeric matrices was made. In order to obtain sulfonyl hydroxide derivatives the matrices were performed as follows: the parent microspheres were treated by H2SO4 (Method I) or with the addition of oleum (Method II). The thiol groups were introduced in a two-stage reaction. In the first stage chlorosulfonation of parent microspheres in the presence of chlorosulfonic acid was carried out. Finally, the reduction of modified microspheres by using SnCl2·2H2O was conducted. The sulfur group content (elemental analysis, scanning electron microscope EDX SEM), thermal properties (thermogravimetric analysis), porous structure as well as the swelling characteristics of the functional beads were examined. The surface texture was also visualized by the AFM method.

Synthesis and characterization of sulfonated graphene as a highly active solid acid catalyst for the ester-exchange reaction

A new synthesis methodology of sulfonated graphene was developed. In this process, the number of hydroxyl groups in graphene was initially increased with n-BuLi. Then, in the presence of chlorosulfonic acid, sulfonic acid groups could be covalently immobilized to hydroxyl groups under mild conditions. Sulfonated graphene as a solid catalyst was applied for the reactions between various alcohols and ethyl acetate. The experimental results indicate that sulfonated graphene can catalyze the ester-exchange reaction efficiently.

Three-Component Reaction of 5,5-Dimethylcyclohexan-1,3-dione, Aromatic Aldehydes, and Acetonitrile in the Presence of Chlorosulfonic Acid Forming N-[(2-Hydroxy-4,4-dimethyl-6-oxocyclohexene-1-yl)-aryl-methyl]-acetamides

A three-component reaction between 5,5-dimethylcyclohexan-1,3-dione (dimedone), aromatic aldehydes, and acetonitrile in the presence of chlorosulfonic acid afforded N-[(2-hydroxy-4,4-dimethyl-6-oxocyclohexene-1-yl)-aryl-methyl]-acetamides in good yields. The temperature-dependent 1H NMR of one of the products has been investigated.

ChemInform Abstract: Synthesis of Symmetrical Bisamides by Reaction Between Aromatic Aldehydes and Alkyl Nitriles in the Presence of Chlorosulfonic Acid

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 of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis of Symmetrical Bisamides by Reaction between Aromatic Aldehydes and Alkyl Nitriles in the Presence of Chlorosulfonic Acid

Reaction between aromatic aldehydes and alkyl nitriles in the presence of chlorosulfonic acid leads to N-[alkanoylamino-(aryl)-methyl]- amide derivatives in excellent yields.

Three-Component reaction between 2-naphthol, Aromatic Aldehydes and Acetonitrile in the Presence of Chlorosulfonic Acid Yields 1-(Acetylamino (Aryl)Methyl)-2-Naphthols

The one-pot, three-component reaction between aryl aldehydes, 2-naphthol, and acetonitrile in the presence of chlorosulfonic acid affords 1-[acetylamino(aryl)methyl]-2-naphthols in excellent yields.

Highly Efficient Beckmann Rearrangement and Dehydration of Oximes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Highly efficient Beckmann rearrangement and dehydration of oximes

Under mild conditions, Beckmann rearrangement of a variety of ketoximes could proceed in the presence of chlorosulfonic acid using toluene as a solvent with excellent conversion and selectivity. This procedure could also be applied in the dehydration of aldoximes for obtaining the corresponding nitriles.

Preparation and electrochemical characterization of sulfonated interpolymer of polyethylene and styrene–divinylbenzene copolymer membranes

Preformed interpolymer films of polyethylene and styrene–divinylbenzene copolymer subjected to chemical treatment for various time intervals, in the presence of chlorosulfonic acid and ethylene dichloride mixture of different composition, have been used as membranes in these investigations. Membrane potential and conductance measurements have been carried out in sodium chloride solutions of different concentrations, to investigate the relationship between the concentration of the fixed ionic site and the electrochemical characteristics of these sulfonated membranes. Counter-ion transport numbers and thus permselectivity of these treated membranes were found to be proportional to the concentration of the fixed sulfonic acid groups. Membrane conductance data, along with values of concentration of fixed ionic site in the membrane, were used for the estimation of the tortuosity factor, salt permeability coefficient and frictional coefficient between solute and membrane matrix employing non-equilibrium thermodynamic principles. Furthermore, the transport properties are discussed in relation to the hydrophilic nature and thus the extent of sulfonation of these membranes.

Acid catalytic effects in the chlorination of propanoic acid

Selective α-chlorination of propanoic acid to form 2-monochloropropanoic (MCA) and 2,2-dichloropropanoic acid (DCA) was investigated in a laboratory-scale, semibatch reactor at 90–130 °C at atmospheric total pressure and in the presence of chlorosulfonic acid (ClSO3H) and 2,2-dichloroethanoic acid (DCA′) as catalytic agents and oxygen as a radical scavenger. The decomposition of the catalyst was investigated with sulfur analysis and UV-spectrometry. The studies revealed that the majority of sulfur remains in the reaction mixture, but is converted to an inactive form during the chlorination. The reasons may be the decomposition of ClSO3H and its reaction with propanoic acid. The kinetic experiments revealed autocatalytic and parallel formation of MCA and DCA, the selectivity being independent of Cl2 concentration in the liquid phase. The experiments with DCA′ also demonstrated that DCA′ has a catalytic effect on the chlorination The experiments confirmed the validity of a previously proposed reaction scheme for α-chlorination, which comprises the formation of the reaction intermediate (propanoyl chloride) from propanoic acid and ClSO3H, the acid-catalyzed enolization of the acid and a hydroxyl-chlorine exchange reaction. The acid-catalyzed enolization is the rate determining step in the reaction sequence. The kinetic data were fitted to rate equations based on the reaction scheme. © 2000 Society of Chemical Industry

Chlorosulfonic Acid Promotes Unusually Selective Chlorination of 2‐Alkanones with Sulfuryl Chloride. Synthesis of 3,3‐Dichloro‐and 1,1,3,3‐Tetrachloro‐4‐Methyl‐2‐Pentanone

AbstractChloride ions formed during the chlorination of ketones with sulfuryl chloride catalyze the production of chlorine. The phenomenon can be suppressed by addition of chlorosulfonic acid, causing a significant change in the regioselectivity of chlorination of 2‐alkanones. Thus from 4‐methyl‐2‐pentanone in the presence of chlorosulfonic acid and the N,N‐dime‐thyloctylammonium salt the 3,3‐dichloroketone was obtained with 76‐78% selectivity (70% isolated) at 40 ± 7°C. After 24h at 90‐105°C the 1,1,3,3‐tetrachloroketone was formed with 90‐92% selectivity and isolated in 80% yield after haloform cleavage of the 1,1,1,3‐isomer. In the absence of chlorine the chlorination involves equilibrated mixtures of enolic intermediates due to competing C‐protonation.

Kinetics of the Chlorination of Acetic Acid with Chlorine in the Presence of Chlorosulfonic Acid and Thionyl Chloride

The chlorination of acetic acid with molecular chlorine in the presence of chlorosulfonic acid and thionyl chloride as catalytic agents was studied in a laboratory-scale semibatch reactor operating at atmospheric pressure. Monochloroacetic acid was the main product, and dichloroacetic acid was formed in parallel as a byproduct. Chlorosulfonic acid was a more active catalytic agent than thionyl chloride owing to its acid catalytic effect in enolization of the real catalytic intermediate, acetyl chloride. When the whole amount of the catalytic agent was introduced in the beginning of the reaction decreasing chlorination rates were observed, whereas autocatalytic kinetics appeared when stepwise addition of the catalytic agents was applied. In the former case the decreasing reaction rates were explained by the decomposition of the catalytic agents following first-order kinetics. The autocatalytic effects were explained by a kinetic model involving acid-catalyzed enolization of acetyl chloride and chlorination of the enols as rate-determining steps. The kinetic model provided a good description of the experimental results

Condensation of Aliphatic Alcohols with Aryl Hydrocarbons in the Presence of Chlorosulfonic Acid1

Condensation of Aliphatic Alcohols with Aryl Hydrocarbons in the Presence of Chlorosulfonic Acid¹