Sulfonyl Research Articles

Synthesis of Poly(styrene sulfonyl chloride) via reversible addition-fragmentation chain transfer polymerization and characterization thereof for membrane applications

Reversible addition-fragmentation chain transfer (RAFT) polymerization has been examined for the synthesis of poly (styrene sulfonyl chloride) (PSSC) of high molecular weight and narrow polydispersity index (PDI). PSSC, contains reactive sulfonyl chloride that can allow use of organic solvent for membrane casting, and chemical modification through reactive sulfonyl groups. For PSSC preparation, end-capped styrene i.e. styrene sulfonyl chloride (SSC) is used as a monomer, which is derived from sodium 4-vinylbenzenesulfonate by chlorination with thionyl chloride. Fourier transform infrared spectroscopy, Raman spectroscopy and Proton nuclear magnetic resonance spectroscopy, have been successfully used to confirm the polymer architecture. End-group of PSSC containing RAFT agent (Cyanomethyl N-methyl-N-phenylcarbamodithioate), is also confirmed by fragmentation analysis using Gas chromatography-mass spectroscopy. Evaluation of PSSC by X-ray diffraction and differential scanning calorimetry showed that resulting polymer is predominantly amorphous in nature and has a glass transition temperature of 119 ​°C. Gel permeation chromatography data reveals formation of high molecular weight (84 ​kDa) PSSC with and low PDI (1.4). Moreover, PSSC can be converted to polyelectrolyte and can be crosslinked by interfacial polymerization concept; hence, it would have considerable prospective for membrane preparation for fuel cell and water purification.

Bench-Stable Electrophilic Fluorinating Reagents for Highly Selective Mono- and Difluorination of Silyl Enol Ethers.

Efficient methods for the synthesis of fluorinated compounds have been intensively studied, recently. Development of practical fluorinating reagents is indispensable for this purpose. Herein, bench-stable electrophilic fluorinating reagents were synthesized as N-fluorobenzenesulfonimide (NFSI) substitutes. Reagents obtained by replacing one of the NFSI sulfonyl groups with an acyl group led to the highly selective monofluorination of silyl enol ethers with suppression of undesired overreaction, that is, difluorination. On the other hand, reagents bearing electron-withdrawing substituents at NFSI benzenesulfonyl groups efficiently facilitated the difluorination of silyl enol ethers under base-free conditions. Thus, both mono- and difluorinated target materials were prepared from the same substrate.

Photoacid Generators Activated through Sequential Two-Photon Excitation: 1-Sulfonatoxy-2-alkoxyanthraquinone Derivatives.

Two sulfonate ester derivatives of anthraquinone, 1-tosyloxy-2-methoxy-9,10-anthraquinone (1a) and 1-trifluoromethylsulfonoxy-2-methoxy-9,10-anthraquinone (1b), were prepared and their ability to produce strong acids upon photoexcitation was examined. It is shown that these compounds generate acid with a yield that increases with light intensity when the applied photon dose is held constant. Additional experiments show that the rate of acid generation increases fourfold when visible light (532 nm) laser pulses are combined with ultraviolet (355 nm) compared with ultraviolet alone. Continuous wave diode laser photolysis also affects acid generation with a rate that depends quadratically on the light intensity. Density functional theory calculations, laser flash photolysis, and chemical trapping experiments support a mechanism, whereby an initially formed triplet state (T1) is excited to a higher triplet state which in turn undergoes homolysis of the RS(O2)-OAr bond. Secondary reactions of the initially formed sulfonyl radicals produce strong acids. It is demonstrated that high-intensity photolysis of either 1a or 1b can initiate cationic polymerization of ethyl vinyl ether.

A Divergent Strategy for Site-Selective Radical Disulfuration of Carboxylic Acids with Trisulfide-1,1-Dioxides.

The direct conversion of carboxylic acids into disulfides is described. The approach employs oxidative photocatalysis for base-promoted decarboxylation of the substrate, which yields an alkyl radical that reacts with a trisulfide dioxide through homolytic substitution. The trisulfide dioxides are easily prepared by a newly described approach. 1°, 2°, and 3° carboxylic acids with varied substitution are good substrates, including amino acids and substrates with highly activated C-H bonds. Trisulfide dioxides are also used to achieve the γ-C(sp3 )-H disulfuration of amides through a radical relay sequence. In both reactions, the sulfonyl radical that results from substitution propagates the reaction. Factors governing the selectivity of substitution at S2 versus S3 of the trisulfide dioxides have been explored.

A Divergent Strategy for Site‐Selective Radical Disulfuration of Carboxylic Acids with Trisulfide‐1,1‐Dioxides

AbstractThe direct conversion of carboxylic acids into disulfides is described. The approach employs oxidative photocatalysis for base‐promoted decarboxylation of the substrate, which yields an alkyl radical that reacts with a trisulfide dioxide through homolytic substitution. The trisulfide dioxides are easily prepared by a newly described approach. 1°, 2°, and 3° carboxylic acids with varied substitution are good substrates, including amino acids and substrates with highly activated C−H bonds. Trisulfide dioxides are also used to achieve the γ‐C(sp3)−H disulfuration of amides through a radical relay sequence. In both reactions, the sulfonyl radical that results from substitution propagates the reaction. Factors governing the selectivity of substitution at S2 versus S3 of the trisulfide dioxides have been explored.

Synthetic resin acid derivatives selectively open the hKV 7.2/7.3 channel and prevent epileptic seizures.

About one third of all patients with epilepsy have pharmacoresistant seizures. Thus there is a need for better pharmacological treatments. The human voltage-gated potassium (hKV ) channel hKV 7.2/7.3 is a validated antiseizure target for compounds that activate this channel. In a previous study we have shown that resin acid derivatives can activate the hKV 7.2/7.3 channel. In this study we investigated if these channel activators have the potential to be developed into a new type of antiseizure drug. Thus we examined their structure-activity relationships and the site of action on the hKV 7.2/7.3 channel, if they have unwanted cardiac and cardiovascular effects, and their potential antiseizure effect. Ion channels were expressed in Xenopus oocytes or mammalian cell lines and explored with two-electrode voltage-clamp or automated patch-clamp techniques. Unwanted vascular side effects were investigated with isometric tension recordings. Antiseizure activity was studied in an electrophysiological zebrafish-larvae model. Fourteen resin acid derivatives were tested on hKV 7.2/7.3. The most efficient channel activators were halogenated and had a permanently negatively charged sulfonyl group. The compounds did not bind to the sites of other hKV 7.2/7.3 channel activators, retigabine, or ICA-069673. Instead, they interacted with the most extracellular gating charge of the S4 voltage-sensing helix, and the effects are consistent with an electrostatic mechanism. The compounds altered the voltage dependence of hKV 7.4, but in contrast to retigabine, there were no effects on the maximum conductance. Consistent with these data, the compounds had less smooth muscle-relaxing effect than retigabine. The compounds had almost no effect on the voltage dependence of hKV 11.1, hNaV 1.5, or hCaV 1.2, or on the amplitude of hKV 11.1. Finally, several resin acid derivatives had clear antiseizure effects in a zebrafish-larvae model. The described resin acid derivatives hold promise for new antiseizure medications, with reduced risk for adverse effects compared with retigabine.

Propargylamines in Pd/Cu-catalyzed tandem coupling-cyclization-N-deprotection in a single pot: Construction of N-unsubstituted vs N-sulfonyl indole ring

The Pd/Cu-catalyzed tandem coupling–cyclization-N-deprotection in a single pot (Method a) vs sequential coupling–cyclization under similar conditions (Method b) has been studied using propargylamine as a terminal alkyne under environmentally friendly conditions. The first sequence (Method a) was followed to afford the N-unsubstituted indoles when 2,2,2-trifluoro-N-(2-iodophenyl)acetamides were employed as halides whereas N-sulfonyl indoles were obtained following the second path (Method b) when 2-iodo sulfanilides were used as halides. A number of compounds based on either the framework indolo[2,3–b]quinoxaline-indole or a similar framework possessing a sulfonyl group at the indole nitrogen were obtained in good yield employing the Method a or b, respectively. While the study was carried out with the goal of accessing a library of indolo[2,3–b]quinoxaline-indole based small molecules of potential biological interest (especially as anti-tubercular agents) the generality/scope of Method a was expanded further via the synthesis of simpler indole derivatives using various other propargylamines as terminal alkynes.

Enantioselective Catalyzed Synthesis of Amino Derivatives Using Electrophilic Open‐Chain N‐Activated Ketimines

AbstractN‐Activated ketimines are characterized by the presence of acyl, sulfonyl, and phosphinoyl groups linked to the nitrogen atom of the azomethine system. These electron‐withdrawing groups enhance the electrophilic character of the imino moiety allowing the addition of even weak nucleophilic reagents. The presence of the oxygen atoms in these activating groups with its coordinating and Lewis or Brønsted properties is of paramount importance in asymmetric catalyzed reactions. This review collects the results that have appeared in the literature during the last two decades on the utilization of open‐chain N‐activated ketimines for the synthesis of optically active α‐disubstituted and α‐trisubstituted amino derivatives including nitrogen‐containing heterocyclic compounds.magnified image

Sulfonated carbon-catalyzed deamination of alanine under hydrothermal conditions

Here, the catalytic effects of sixteen types of solid acid/base additives on the deamination of alanine under hydrothermal conditions at 90–150 °C were examined. As a result, porous sulfonated carbon (FCC-P) showed the highest catalytic activity, which was attributed to the high contents of multiple functional groups like sulfonyl and oxygen functional groups. Using FCC-P as the catalyst, the parameters including the additive amount and alanine solution concentration were optimized to be 0.5 g and ≥ 50 mmol/L, respectively, and the effects of temperature and time were studied detailedly. At 150 °C for 60 min, the deamination yield and alanine conversion achieved to 20.0% and 51.0%, respectively, with the production yield of ammonium at 7.6%. The reusability of two types of sulfonated carbon catalysts was examined. Finally, FCC-P was applied to amino acids including glycine, valine, leucine, and serine, and showed high catalytic activity for each hydrothermal deamination reaction.

The competition between solvent–solvent and solute–solvent act on the nucleation process of 4-(methylsulfonyl)benzaldehyde

The role of solvent in the process of crystal nucleation is crucial for crystallization process investigate, design and control. In this work, the influence of solvents on the nucleation of 4-(Methylsulfonyl)benzaldehyde (MSBZ) has been studied. An array of induction time experiments covering a range of supersaturations were carried out in four solvents. Given the same induction time, the driving forces of MSBZ for nucleation was found ranking as toluene (1784.56 J‧mol−1) > methanol (1653.93 J‧mol−1) > acetonitrile (1309.89 J‧mol−1) > acetic acid (1052.09 J‧mol−1), which is consistent with the order of the pre-exponential factor A calculated by classical nucleation theory. The binding energies of solute–solvent at site 1 increase according to the following order: acetonitrile (−19.89 kJ‧mol−1) < methanol (−26.21 kJ‧mol−1) < toluene (−27.78 kJ‧mol−1) < acetic acid (−42.09 kJ‧mol−1), which confirm that the stronger the binding of solvent and solute, the more difficult for nucleation except for acetic acid. By comparing the binding energy of solute–solvent at site 3 and the solution infrared spectroscopy, it was found that the larger the binding energy, the smaller the location of asymmetrical stretching peaks of sulfonyl group except acetic acid. The anomalous excursion of infrared spectra (1322 cm−1), the maximum attachment frequency (26.59 ln(m−3‧s−1)) and the strongest solvent–solvent interaction (−42.09 kJ‧mol−1) in acetic acid solution suggest that the competition of molecular interactions between the solvent–solvent and solute–solvent may play a big role in the nucleation process.

Substitution of a nitro group by diazonium salts in σH-Adducts of carbanions to mono-nitrobenzenes. Formation of substituted azobenzenes and indazoles

σ H -Adducts formed at low temperature from nitrobenzene derivatives and carbanions stabilized by cyano, alkoxycarbonyl or sulfonyl groups react with benzenediazonium salts as nucleophiles, forming a new C–N bond preferentially at carbon atom bearing the nitro group. The so-formed intermediates eliminate HNO 2 molecule under action of base, yielding substituted azobenzenes. Adducts of secondary carbanions, stabilized by cyano or sulfonyl groups to the ortho positions of nitrobenzenes, cyclize in situ to substituted indazoles. Some ortho σ H -adducts of 1-chloroethyl phenyl sulfone carbanion add diazonium cations at meta position to the nitro group. In this case, the subsequent elimination of HCl leads to azo compounds retaining the nitro group in its original position.

Novel Sulfonyl Piperzine Antibiotics Targeting the Lipid A Biosynthetic Enzyme LpxH in Gram‐negative Bacteria

The UDP-2,3-diacylglucosamine pyrophosphatase, LpxH, is an essential enzyme in the biosynthesis of the lipid A, which functions as the hydrophobic anchor of lipopolysaccharides or lipooligosaccharides in the outer leaflet of the outer membrane of Gram-negative bacteria. This enzyme is conserved in the majority of Gram-negative bacterial pathogens and is an excellent novel antibiotic target. Here we report the development of a coupled, nonradioactive and colorimetric LpxH assay suitable for high-throughput analysis of LpxH inhibition and screening. Using this new assay, we have established a pharmacophore model for the recently reported LpxH inhibitor by AstraZeneca (dubbed as AZ1 below). Our crystal structure of Klebsiella pneumoniae LpxH (KpLpxH) in complex with AZ1 shows that AZ1 fits snugly into the L-shaped acyl chain-binding chamber of LpxH with its indoline ring situating adjacent to the active site, its sulfonyl group adopting a sharp kink, and its N-CF3-phenyl substituted piperazine group reaching out to the far side of the LpxH acyl chain-binding chamber. Our solution NMR investigation later revealed the presence of a second ligand conformation that was unseen in the crystalline state, delineating a cryptic inhibitor envelope that expands the observed footprint of AZ1 in the LpxH-bound crystal structure. Utilizing these discoveries, we designed new AZ1-derivatives that display striking improvement in antibiotic activity over AZ1 against wild-type K. pneumoniae. Co-administration with outer membrane permeability enhancers profoundly sensitizes E. coli to our designed LpxH inhibitors. As none of these first sulfonyl piperazine compounds occupied the active site of LpxH, we designed a new series of sulfonyl piperazine analogs and discovered an extended N-acyl chain analog that additionally occupied the untapped polar binding pocket near the manganese cluster of the LpxH active site. We expect that this work will provide guiding design principles for new LpxH inhibitors and establish important frameworks for the future development of antibiotics against multi-drug resistant Gram-negative pathogens

Asymmetric Diels–Alder reaction between furans and propiolates

We report the first asymmetric Diels–Alder reaction between furan and propiolates. Propiolate, a dienophile, was equipped with an Evans’ auxiliary and a sulfonyl group to control and facilitate diastereoselective cycloaddition. Treatment with furan as a diene and aluminium Lewis acid afforded a 7-oxabicyclo[2.2.1]heptadiene skeleton diastereoselectively. The origin of diastereoselectivity can be explained by chelation of aluminium center to carbonyl groups and oxygen of furan. Friedel–Crafts-type products were obtained when pyrrole was used as diene.

A Series of new Urea‐MOFs Obtained via Post‐synthetic Modification of NH2‐MIL‐101(Cr): SO2, CO2 and H2O Sorption

AbstractThe amino group in the MOF NH2‐MIL‐101(Cr) was post‐synthetically converted into urea‐groups partially using either ethyl isocyanatoacetate, furfuryl isocyanate, p‐toluenesulfonyl isocyanate or 3‐(triethoxysilyl)propyl isocyanate in acetonitrile. The derived four novel urea‐MOFs exhibit the expected lower BET surface areas and pore volumes than MIL‐101(Cr) and NH2‐MIL‐101(Cr) MOFs but the partially p‐toluenesulfonyl‐urea‐modified MOF exhibits an outstanding SO2 adsorption capacity of 823 cm3 g−1 (corresponding to 36.7 mmol g−1 or 70 wt.% at T=0 °C and 0.9 bar), which is the second highest SO2 uptake of any known material today – surprisingly even better than for highly porous MIL‐101(Cr) with an uptake of 645 cm3 g−1 SO2 under the same conditions. The high uptake is linked to the favorable dipole interactions of SO2 with the sulfonyl group of the p‐toluenesulfonyl‐modified MOF.

3-B-RUT, a derivative of RUT, protected against alcohol-induced liver injury by attenuating inflammation and oxidative stress

Alcoholic liver disease (ALD) is the most common chronic liver disease worldwide. Currently, there is no definitive treatment for alcohol-induced liver injury (ALI). Inflammatory response and oxidative stress play a crucial role in ALI. Cyclooxygenase 2 (COX-2) can be induced by inflammation and it has been reported that the enhanced expression of COX-2 in alcoholic liver injury. Rutaecarpine (RUT) was extracted from evodia rutaecarpa. RUT has a wide range of pharmacological activities. In order to increase its anti-inflammatory activity, our group introduced sulfonyl group to synthesized the 3-[2-(trifluoromethoxy)benzenesulfonamide]-rutaecarpine (3-B-RUT). In this study, we explored the protective effect of 3-B-RUT on alcoholic liver injury in vivo and in vitro and preliminarily explore its mechanism. Mice ALI model was established according to the chronic-plus-binge ethanol model. Results showed that 3-B-RUT (20 μg/kg) attenuated alcohol-induced liver injury and suppressed liver inflammation and oxidative stress, and the effect was comparable to RUT (20 mg/kg). In vitro results are consistent with in vivo results. Mechanistically, the 3-B-RUT might suppress inflammatory response and oxidative stress by regulating activation of NF-κB/COX-2 pathway. In summary, 3-B-RUT, a derivative of RUT, may be a promising clinical candidate for ALI treatment.

Heavy oil viscosity reduction at mild temperatures using palladium acetylacetonate

Metal-ligand compounds (“MLCs”) have been shown to reduce heavy oil viscosity and upgrade oil quality. However, MLCs generally require high treatment temperatures (around 250 °C), which is undesirably energy-intensive. We identified palladium(II) acetylacetonate (“PdA”) as a model MLC that can operate at mild temperatures (<200 °C). We studied its effectiveness on heavy oil viscosity reduction in the range of 80–300 °C using viscometry, SARA analysis, GC–MS, XPS, and XRD to characterize Peace River oil samples thermally treated with and without PdA. This MLC effectively lowered oil viscosity at all treatment temperatures, whereas thermal-only treatments did not reduce viscosity below 160 °C. The thermal treatment with PdA in the 130–250 °C range reduced viscosity by up to ~35% more than the thermal treatment alone. GC–MS and TGA results indicated the PdA partially decomposed at 80 °C and higher temperatures, releasing acetylacetone (“HA”), which lowered oil viscosity. The temperature and HA effects did not completely account for the observed viscosity reduction from thermal treatment with PdA, indicating there were other significant effects. In the 80–130 °C range, the asphaltene fraction increased due to PdA or its decomposition products intercalating into the asphaltene clusters. At temperatures around 250 °C, the resin fraction decreased, correlating to in situ formed metallic Pd that catalytically hydrogenate the resin sulfonyl groups to aliphatic sulfur. This new understanding of the temperature-dependent impact – acetylacetonate ligand, MLC-asphaltene attraction, and palladium metal catalyst formation – on oil viscosity changes provides an improved approach to developing new MLCs for field-relevant conditions.

P&lt;i&gt;K&lt;/i&gt;&lt;sub&gt;a&lt;/sub&gt; Determination of Strongly Acidic C-H Acids Bearing a (Perfluoroalkyl)sulfonyl Group in Acetonitrile by Means of Voltammetric Reduction of Quinone

A voltammetric method has been developed for the determination of the acid dissociation constant (pKa) of (RfSO2)2CHR (Rf = perfluoroalkyl), which is a strongly acidic molecule that serves as an acid catalyst. In acetonitrile solution containing small quantity of the acid, the reduction peak potential of quinone caused by the acid shifted to a more positive side accompanied by an increase in the acidity of the acid. This relationship was in good agreement with an equation derived from the Nernst equation. The present finding has been successfully applied to the determination of the pKa of the acids in acetonitrile with values ranging from 7 to 17.

Decatungstate as Direct Hydrogen Atom Transfer Photocatalyst for SOMOphilic Alkynylation.

A versatile approach for the alkynylation of a variety of aliphatic hydrogen donors, including alkanes, is reported. We used tetrabutylammonium decatungstate as photocatalyst to generate organoradicals from C–H/Si–H bonds via hydrogen atom transfer. The latter intermediates underwent SOMOphilic alkynylation by methanesulfonyl alkynes to afford internal alkynes upon loss of a sulfonyl radical. The effect of different radicofugal groups on the reaction outcome was evaluated and rationalized via a combined experimental and computational approach.

Surface water treatment for production of potable water by coagulation/filtration/nanofiltration membranes hybrid system.

Providing potable water will be a challenge for humanity over the next years. In this research, water samples from the Gamasiab River (Iran) were purified to achieve drinking water by applying coagulation, conventional filtration in combination with the nanofiltration process. By using poly aluminum chloride as a coagulant, the turbidity decreased by 96.4%. The turbidity and COD decreased by 98.82% and 32.7%, respectively, via passing the effluent through the activated carbon. Membranes were made of polyethersulfone (PES). Cesium hydrogen phosphotungstic acid (Cs0.5 H2.5 PW12 O40 as CsPW) nanoparticles were incorporated into the polymer matrix to improve the hydrophilicity. The morphology of membranes was studied using the FE-SEM and AFM. The pure water flux and contact angle for the sulfonated PES with 1.5 wt.% CsPW were 51.9kg/m2 h and 55.49 °, respectively. The percentage of the turbidity, conductivity, TDS, and COD removal was found to be 99.9, 89.3, 89.3, and 86.6%, respectively, after the hybrid process. The removal of calcium, magnesium, nitrate, chloride, sodium, sulfate, and bicarbonate ions was 90.5, 83.4, 87.9, 60.7, 49, 86, and 80.5%, respectively. Based on these results, the river water meets the standards for drinking water after being purified by applying the aforementioned coagulation/filtration and nanofiltration processes. PRACTITIONER POINTS: The treatment of the Gamasiab River (Iran) was selected for this study to produce potable water. A hybrid systematic coagulation/filtration/nanofiltration (NF) was considered. Water quality parameters were measured and compared with the standard values. The cesium hydrogen phosphotungstic acid was incorporated into the NF to increase the hydrophilicity and water flux. Polyethersulfone was sulfonated to add the sulfonyl group to the polymer.

Transition Metal‐Free Synthesis of Sulfonyl‐ and Bromo‐Substituted Indolo[2,1‐α]isoquinoline Derivatives through Electrochemical Radical Cascade Cyclization

AbstractA tunable electrosynthesis of sulfonyl‐ and bromo‐substituted indolo[2,1‐α]isoquinoline derivatives has been disclosed. In this reaction, a variety of easily available 2‐aryl‐N‐acryloyl indoles can readily react with sulfonyl and/or bromine radicals, which are generated from arylsulfonyl hydrazides and potassium bromide respectively, to furnish the valuable sulfonyl‐ and bromo‐substituted benzindolo‐fused polycyclic compounds in moderate to good yields. Control experiment indicated that the reaction proceeds via a radical cascade cyclization pathway. This protocol features broad substrate scope and good functional group tolerance under transition metal‐free and oxidant‐free conditions.magnified image