Sulfite Anion Research Articles

Fe-Catalyzed Fluorosulfonylation of Alkenes via Sulfur Dioxide Insertion: Synthesis of Lactam-Functionalized Alkyl Sulfonyl Fluorides.

A novel Fe-catalyzed fluorosulfonylation of alkenes with Na2S2O4 and N-fluorobenzenesulfonimide (NFSI) for assembling various lactam-functionalized alkyl sulfonyl fluorides is disclosed. In this reaction, Na2S2O4 acts as both an SO2 source and a reductant. Furthermore, the resulting products can be efficiently transformed into valuable chemicals, including sulfonyl esters and sulfonamides, via the sulfur(VI) fluoride exchange (SuFEx) click reaction. Preliminary mechanistic studies suggest that the transformation proceeds through intramolecular radical cyclization, SO2 insertion, sulfite anion formation, and fluorination.

Investigation on special reactivity of sulfite as an electron acceptor for the attenuated Fenton reaction and the abatement mechanism

Sulfur(IV) as a ubiquitous substance in the atmosphere and water bodies can be deliberately involved in different redox reactions based on the known ability to donate electrons, but the inhibition effect on the advanced oxidation processes (AOPs) especially the Fenton reaction, which played a vital role in aerosol aging and pollution treatment, still stayed fuzzy. In this work, it was first found that sulfite had an unexpected reactivity to accept electrons from Fe(II) monitored by the chemiluminescence (CL) method to reduce Fe(II) seriously. Dynamics calculation, UV–vis absorption, HPLC, and CL analysis indicated that sulfite anions can be transferred into SO2·- or dimer S2O42- through reacting with Fe(II). The direct consumption of Fe(II) in Fenton reaction only happened by sulfite among other inorganic anions during degrading different organic pollution, and the produced S2O42- showed an overpowering inhibitory ability on hydroxyl radical especially at pH 5.3, both resulting in a strong inhibition effect on the Fenton reaction. In contrast at pH 3.1, the fast depletion of sulfite by H2O2 and decomposition of S2O42- fell off the inhibition effect. Furthermore, abatement experiments showed that the effect of sulfite could be circumvented by using a non-iron-based oxidation system with other metal ions, additionally clarifying the reaction of Fe(II)-sulfite played the primary role in the inhibition. Significantly, this inhibition effect of sulfite on the Fenton reaction was demonstrated to take place both in the natural wastewater and degrading two acids from biomass burning in the atmosphere, identifying the attenuated Fenton reaction in the presence of sulfur(IV) in the environment.

INTERACTION OF 7,7´-DIOXO-7H, 7´ H-3, 3´ -BENZIMIDAZO[2,1-a]BENZO[de]ISOQUINOLINE-4, 4´ -DICARBOXYLIC ACID WITH SODIUM DITHIONITE IN WATER-ALKALINE SOLUTION

Using the spectrophotometric method, the interaction of 7,7´-dioxo-7H, 7´ H-3, 3´ -benzimidazo[2,1-a]benzo[de]isoquinoline-4, 4´ -dicarboxylic acid with sodium dithionite in an aqueous-alkaline solution in aerobic and anaerobic conditions has been studied. It is found, that in the initial stage of process very rapidly formation of a tetraanion is observed due to the addition of two electrons. In the future, depending on the conditions of the reaction (aerobic, anaerobic atmosphere, small or large concentrations of the reducing agent), the tetraanion transition to the initial compound is observed due to its oxidation with air oxygen or sulfite anion formed from dithionite anions, as well as at sufficiently high concentrations of the reducing agent. A subsequent chemical stage of cyclization is possible with the cleavage of two carboxyl groups from the reduced form of the initial compound. It has also been established that the cyclization product is N,N'-di(benzimidazole)diimides of perilen-tetracarboxylic acid, which is isolated from a solution in a solid state. Its elemental composition is analyzed, IR- and electronic absorption spectra were obtained. The reversible nature of the initial stage of the interaction of 7, 7´-dioxo-7H, 7' H-3, 3´-benzimidazo[2,1-a]benzo[de]isoquinoline-4,4´-dicarboxylic acid with sodium dithionite is indicated by the fact that under aerobic conditions the concentration of the intermediate product present in the form of tetraanion decreases faster than the anaerobic atmosphere. The transition of the reduced form of the initial compound to the original, non-restored one is also observed during bubbling of air through the reaction mixture. It has been established by cyclic voltammetry that reversible reduction of the initial compound is also possible due to an electrochemical reaction occurring on a carbon-metal electrode in an aqueous-alkaline solution. The analysis of the voltage dependences showed that two electrons participate in the electrode reaction. For citation: Polenov Yu.V., Egorova E.V. Interaction of 7,7´-dioxo-7H, 7´ H-3, 3´ -benzimidazo[2,1-a]benzo[de]isoquinoline-4, 4´ -dicarboxylic acid with sodium dithionite in water-alkaline solution. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 6. P. 80-87. DOI: 10.6060/ivkkt.20246706.7056.

Copper Immobilized over 2D Hexagonal SBA-15 for Electrochemical and Colorimetric Sulfite Sensing.

Sulfite (SO32-) is considered a highly toxic anion for living organisms. Herein, we report the synthesis of copper immobilized over a 2D hexagonally ordered mesoporous silica material CuMS as an electrochemical and colorimetric dual-technique-based sensing platform for sulfite detection. The immobilization of copper on silica was achieved through the bis[3-(triethoxysilyl)propyl]tetrasulfide (TEPTS) ligand. Morphological and physical properties of the material were confirmed by several characterization techniques, including scanning electron microscopy, transmission electron microscopy, X-ray diffraction, N2 sorption, and X-ray photoelectron spectroscopy. The CuMS material retained mesoporosity with a narrow pore size distribution (D ≈ 5.4 nm) and a high Brunauer-Emmett-Teller surface area of 682 m2 g-1 after the immobilization of copper. The prepared catalyst shows promising electrocatalytic activity toward sulfite oxidation. A linear variation in the peak current was obtained for SO32- oxidation in the 0.2-15 mM range with a high sensitivity of 62.08 μA cm-2, under optimum experimental conditions. The limit of detection (LOD) was found to be 1.14 nM. CuMS also shows excellent activity toward colorimetric detection of sulfite anions with an LOD of 0.4 nM. The proposed sensor shows high selectivity toward the sulfite anion, even in the presence of common interferents. The detection of sulfite in white wine with excellent recovery demonstrates the practical applicability of this sensor.

Experimental and computational study of polystyrene sulfonate breakdown by a Fenton reaction

Experimental studies and ab initio quantum chemistry calculations were combined to investigate the process by which a Fenton reaction breaks down polystyrene sulfonate. The experimental results show that both molecular weight reduction and loss of aromaticity occur nearly simultaneously, a finding that is supported by the calculations. The results show that more than half of the material is broken down to low molecular weight compounds (< 500 g/mol) with two molar equivalents of H2O2 per styrene monomer. The calculations provide insights into the reaction pathways and indicate that at least two hydroxyl radicals are required to cleave backbone CC bonds or to eliminate aromaticity. The calculations also show that, of the aromatic carbons, hydroxyl radical is most likely to add to the carbon bonded to sulfur. This finding explains the loss of hydrogen sulfite anion early in the process and also the efficient reduction of Fe(III) to Fe(II) through semiquinone formation. Taken together the experimental and computational results indicate that the reaction is very efficient and that very little H2O2 is lost to unproductive reactions. This high efficiency is attributed to the close association of Fe atoms with the sulfonate group such that hydroxyl radicals are generated near the polymer chains.

Rational design of composite supporting electrolyte required for achieving high performance aqueous organic redox flow battery

Although aqueous organic redox flow batteries (AORFBs) have many benefits, their organic active materials have the limitations in solubility and chemical instability. To overcome the problems, efforts to develop new organic active materials is usually made. However, these efforts have still limitations in some prospects. Thus, in this study, instead of developing new organic active materials, a rationally designed composite supporting electrolyte is suggested to improve energy density, power density, life-cycle, and efficiency of AORFB using 2-hydroxy-1,4-naphthoquinone (Lawsone) and potassium ferrocyanide as redox couple. The composite supporting electrolyte consists of potassium hydroxide (KOH) and potassium sulfite and is optimized by density functional theory (DFT). DFT predicts that sulfite anions help the solubility and stability of Lawson to improve, while hydroxide anions promote reactivity. The predictions are proved by electrochemical evaluations. With that, when the optimal composite supporting electrolyte is used, high capacity and excellent retention of AORFB (90 % at 100th cycle (from 20.27 to 18.42 Ah·L−1)) are achieved, while high power of 12.4 W is produced by AORFB short stack.

SO2 pollutant conversion to sulfuric acid inside a stand-alone photoelectrochemical reactor: A novel, green, and safe strategy for H2SO4 photosynthesis

Instead of performing the risky gas-phase oxidization of SO2, to produce sulfuric acid, this noxious gas can be first dissolved in water and then the resulting sulfite (SO32-) anions could be safely oxidized through a green photoelectrochemical route upon an environmentally-friendly, affordable photoanode. In this article, the authors deal with this environmentally/industrially important issue and conduct the sulfite-to-sulfate conversion process upon an n-type semiconducting hematite thin-film, deposited electrochemically on a commercially available tin-oxide substrate. The investigations revealed an excellent photoelectrochemical response and a fair oxidizing ability for the fabricated photodevice/reactor, to convert sulfite to sulfate in a two-electrodic standalone setup [no external potential was applied]. Furthermore, a superior activity was achieved for the production of sulfate upon the Co (II) impregnated photoanode. By drawing the system's energy diagram and noticing the reactions which occur during the photoconversion process, the phenomenon was also interpreted from a physicoelectrochemical mechanistic perspective.

The Peroxymonocarbonate Anion HCO4- as an Effective Oxidant in the Gas Phase: A Mass Spectrometric and Theoretical Study on the Reaction with SO2.

The peroxymonocarbonate anion, HCO4-, the covalent adduct between the carbon dioxide and hydrogen peroxide anion, effectively reacts with SO2 in the gas phase following three oxidative routes. Mass spectrometric and electronic structure calculations show that sulphur dioxide is oxidised through a common intermediate to the hydrogen sulphate anion, sulphur trioxide, and sulphur trioxide anion as primary products through formal HO2-, oxygen atom, and oxygen ion transfers. The hydrogen sulphite anion is also formed as a secondary product from the oxygen atom transfer path. The uncommon nucleophilic behaviour of HCO4- is disclosed by the Lewis acidic properties of SO2, an amphiphilic molecule that forms intermediates with characteristic and diagnostic geometries with peroxymonocarbonate.

Reactive Blue 19 dye removal by UV-LED/chlorine advanced oxidation process.

In recent years, advanced oxidation processes (AOPs) have indicated the greatest potential in the removal of stable organic compounds, including dyes. In this study, the ultraviolet light-emitting diodes (UV-LEDs) combined with chlorine was evaluated to remove Reactive Blue 19 (RB19) dye from aqueous solution. The effect of key experimental parameters including pH, initial chlorine concentration, initial dye concentration, and reaction time on the performance of UV-LED irradiation, UV-LED/chlorine, and the chlorination method for the removal of RB19 was studied in this research. Results showed that, more than 99% of RB19 was removed after 30 min of reaction time under optimized conditions (pH = 5, [chlorine] = 300 μM, and [RB19] = 20 mg L-1) with apparent kinetic rate constant (kapp) of 17.1 × 10-2 min-1 in UV-LED/chlorine process. However, for the chlorination method, removal efficiency was 64.7% (kapp = 3.41 × 10-2 min-1) with an apparent kinetic rate constant of 0.0341 min-1. Results also showed that UV-LED irradiation is not effective at all in removing RB19. The scavenging assay showed that OH• radicals (67.23%) had the highest contribution in RB19 removal in UV-LED/chlorine process while Cl• (17.82%) and [Formula: see text] (8.56%) had a minor role in the degradation of the dye. The RB19 degradation kinetics analysis revealed that the processes of UV-LED/chlorine and chlorination degradation followed the pseudo-first-order kinetic model. In this study, the impact of chloride, nitrate, bicarbonate, carbonate, sulfate, and sulfite anions on the performance of the process was investigated. It indicated that sulfite anion has the most negative impact on the RB19 removal process. By evaluating the synergistic effect between UV-LED lamp and chlorine, a synergy index of 5.0 was obtained for the UV-LED/chlorine process. The results presented that the UV-LED/chlorine process has a better performance than each of them alone and has the necessary efficiency for RB19 removal. Measuring COD reported its removal efficiency of 98% during the UV-LED/chlorine process under optimized conditions. Experiments continued with textile factory wastewater and indicated 30.9% of its COD removed after treatment when 1.0 μM chlorine was used.

TDDFT study on the ESPT and ICT mechanism of a bifunctional fluorescent probe for detecting fluoride and sulphite

TDDFT method was applied to study the excited-state mechanism of a reported fluorescent probe for fluoride and sulfite. Theoretical results showed the excitation of the probe molecule involved an intramolecular charge transfer process. Based on potential energy scanning and frontier orbital analysis, the excited-state proton-transfer process of the fluoride-probe product resulted in the significant red-shifted fluorescence. In contrast, the intramolecular charge transfer process was inhibited by sulfite anions. Due to the curtailing of the conjugated system, a blue-shifted emission was observed in the fluorescence spectrum. By exploiting the difference in fluorescence wavelengths,fluoride and sulfite anions could be recognized.

Multifunctional diphenyl ether-based, cross-linked polyisocyanide for efficient iodine capture and NO2-/SO32- electrochemical probing

Compared with the extensively reported Schiff base-type polyimine (their backbones are connected by CN bond) porous organic polymers (POPs), there are rare reports regarding the exploration of polyisocyanide (PIC)-based, C1-type polyimine POPs. Herein, a kind of diphenyl ether-based, cross-linked PIC derivative (POBI) was successfully prepared. Fundamental properties of POBI as chemical structure, morphology, porosity, and thermal stability, were characterized. N, O-heteroatoms, aromatic motif and porous framework contained in the structure of POBI make it useful as a new type of iodine capture platform. Experimental results told that POBI can adsorb iodine in both vapor (under 75 °C and normal pressure) and solution (under 25 °C in cyclohexane) states. The maximum adsorption capacities in two states reached ~ 2.29 g g−1 and ~ 239 mg g−1, respectively. At the same time, the POBI-modified electrode (POBI/CS/GCE) illustrated stronger electrochemical response toward hazardous nitrite (NO2-) and sulfite (SO32-) anions relative to that of controlling electrodes (pristine glassy carbon electrode (GCE) and chitosan (CS)/GCE). The corresponding detection limits reached ~ 0.40 μmol L−1 (NO2-) and ~ 16.50 μmol L−1 (SO32-), respectively. We envisage that this work could play a positive role in further broadening the functional applications of polyisocyanide compounds.

Aqueous Organic Redox Flow Battery Using Lawsone Dissolved in Co-Supporting Electrolyte Containing Hydroxide and Sulfite Anions

Aqueous Organic Redox Flow Battery Using Lawsone Dissolved in Co-Supporting Electrolyte Containing Hydroxide and Sulfite Anions

Elevated risk of haloacetonitrile formation during post-chlorination when applying sulfite/UV advanced reduction technology to eliminate bromate

The formation of haloacetonitriles (HANs) during chlorination after sulfite/ultraviolet (UV) treatment of bromate (BrO3−) in the presence of amino acids (AAs) was investigated. During sulfite/UV treatment, the primary species hydrated electrons (eaq−) and hydrogen atom radicals (H) dominated the reduction of BrO3− to bromide (Br−), whereas the sulfite anion radicals (SO3−) and H degraded AAs to produce the intermediates HN=C(CH3)–COOH, CH3–CH=NH, and CH3–C≡N via α‑hydrogen abstraction and NH2–hydrogen abstraction mechanisms. During post-chlorination, Br− was converted to HBrO/BrO-, and the HN=C(CH3)–COOH, CH3–CH=NH, and CH3–C≡N groups featured higher bromine utilization factor (BUF) and chlorine utilization factor (CUF) values than AAs, enhancing the formation of dibromoacetonitrile (DBAN) and dichloroacetonitrile (DCAN). The energetic feasibility of the transformation pathway, that is, HN=C(CH3)–COOH, CH3–CH=NH, and CH3–C ≡ N formation via hydrogen abstraction by SO3− and H and their further conversion to HANs, was proved by density functional theory calculations, which showed stepwise negative Gibbs free energy changes (ΔG < 0). The effects of pH and water matrices (e.g., HCO3−, Cl−, Fe3+, and natural organic matter) were comprehensively evaluated. Although 72% of BrO3− was removed by sulfite/UV treatment in the presence of AAs, the cytotoxicity index (CTI) and genotoxicity index (GTI) during post-chlorination increased by 213% and 125%, respectively, due to the formation of 24 CX3R-type disinfection by-products (DBPs), especially brominated DBPs. Accordingly, more attention should be given to the formation of brominated DBPs during post-chlorination when using sulfite/UV processes to remove BrO3− in the presence of AAs. As a solution, using monochloramine instead of chlorine as a disinfectant after the sulfite/UV process could significantly lower the CTI and GTI values by alleviating the formation of brominated DBPs.

Absorption characteristic of carbon dioxide in Ionic Liquids based sulfite anion in the pre-combustion condition

Absorption characteristic of carbon dioxide in Ionic Liquids based sulfite anion in the pre-combustion condition

Reaction mechanism catalyzed by the dissimilatory adenosine 5′-phosphosulfate reductase. Adenosine 5′-monophosphate inhibitor and key role of arginine 317 in switching the course of catalysis

The present research is a continuation of our work on dissimilatory reduction pathway of sulfate - involved in biogeochemical sulfur turnover. Adenosine 5′-phosphosulfate reductase (APSR) is the second enzyme in the dissimilatory pathway of the sulfate to sulfide reduction. It reversibly catalyzes formation of the sulfite anion (HSO3−) from adenosine 5′-phosphosulfate (APS) - the activated form of sulfate provided by ATP sulfurylase (ATPS). Two electrons required for this redox reaction derive from reduced FAD cofactor, which is suggested to be involved directly in the catalysis by formation of FADH-SO3− intermediate. The present work covers quantum-mechanical (QM) studies on APSR reaction performed for eight models of APSR active site. The cluster models were constructed based on two crystal structures (PDB codes: 2FJA and 2FJB), differing in conformation of Arg317 active site residue. The described results indicated the most feasible mechanism of APSR forward reaction, including formation of FADHN-SO3− adduct (with proton on N5 atom of isoalloxazine), tautomerization of FADHN-SO3− to FADHO-SO3− (with proton on CO moiety of isoalloxazine), and its reductive cleavage to oxidized FAD and sulfite anion. The reverse reaction proceeds in the backward direction. It is suggested that it requires two AMP molecules, one acting as a substrate and another as an inhibitor of forward reaction, which forces change of Arg317 conformation from “arginine in” (2FJA) to “arginine out” (2FJB). Important role of Arg317 in switching the course of the APSR catalytic reaction is revealed by changing the direction of thermodynamic driving force. The presented research also shows the importance of the protonation pattern of the reduced FAD cofactor and protein residues within the active site.

Sodium sulfite heptahydrate and its relation to sodium carbonate heptahydrate.

The monoclinic crystal structure of Na2SO3(H2O)7 is characterized by an alternating stacking of (100) cationic sodium-water layers and anionic sulfite layers along [100]. The cationic layers are made up from two types of [Na(H2O)6] octahedra that form linear 1∞[Na(H2O)4/2(H2O)2/1] chains linked by dimeric [Na(H2O)2/2(H2O)4/1]2 units on both sides of the chains. The isolated trigonal-pyramidal sulfite anions are connected to the cationic layers through an intricate network of O-H...O hydrogen bonds, together with a remarkable O-H...S hydrogen bond, with an O...S donor-acceptor distance of 3.2582 (6) Å, which is about 0.05 Å shorter than the average for O-H...S hydrogen bonds in thiosalt hydrates and organic sulfur compounds of the type Y-S-Z (Y/Z = C, N, O or S). Structural relationships between monoclinic Na2SO3(H2O)7 and orthorhombic Na2CO3(H2O)7 are discussed in detail.

Microwave-Assisted Synthesis of Cobalt Oxide/Reduced Graphene Oxide (Co3O4–rGo) Composite and its Sulfite Enhanced Photocatalytic Degradation of Organic Dyes

Abstract One-pot synthesis of Co3O4 nanocrystals on reduced graphene oxide (rGO) was carried out by reacting cobalt nitrate, L-arginine, extract of Laportae aestuans as oxidant, fuel and reducing agent, respectively, in a domestic microwave. Morphologies of Co3O4–rGo (RGCO) composite was elucidated using UV-Vis, FT-IR, TEM, SEM, EDX, XRD and photoluminescence spectroscopies. The synthesized RGCO composite was applied as heterogeneous photocatalyst in the activation of Na2SO3 (sulfite) as sacrificial agent to degrade cationic dyes: rhodamine B (RhB) and methylene blue (MB), under visible light, at neutral pH 7.0. Photocatalytic performance of as-prepared RGCO was significantly enhanced in the presence of Na2SO3. Enhanced photocatalytic activity of RGCO was attributed to the synergistic effects between sulfite radicals generated in situ, and reduced graphene oxide, in which rGO served as electron sink to suppress recombination of photogenerated charge carriers. Plausible mechanistic pathways responsible for the activation of sulfite anions in situ are presented in this paper.

Synthesis, Structure, and Electrochemical Properties of [Na(SO3)2(RPO3)4MoV4MoVI14O49]5− (R = Propyl or t-Butyl)

Abstract New mixed-valence polyoxometalate (POM)-organic hybrids, i.e., [Na(SO3)2(PrPO3)4MoV4MoVI14O49]5− and [Na(SO3)2(t-BuPO3)4MoV4MoVI14O49]5−, were synthesised and studied using crystallography, solution-phase 31P NMR, and electrochemistry. These species comprise four organic phosphonates bonded to a metal oxide cage. Derivatization was achieved by considering the pKa of the organic phosphonates and sulfite anions that acted as templates for the self-assembly of molybdate with POM. All the clusters were prepared in a water-acetonitrile mixed solvent system by a one-pot procedure and showed multi-step redox cycles, revealing that [Na(SO3)2(RPO3)4MoV4MoVI14O49]5− comprised a unique set of covalently grafted POM-organic hybrids with high redox activity.

Degradation and COD removal of trichlorophenol from wastewater using sulfite anion radicals in a photochemical process combined with a biological reactor: Mechanisms, degradation pathway, optimization and energy consumption

This study proposes the combination of UV/sulfite with a biological reactor (USPB) for the degradation, dechlorination and mineralization of 2, 4, 6-trichlorophenol (TCP). The effects of pH, sulfite dosage, co-existing water anions and quenchers on the performance of the UV/sulfite process (USP) were investigated. The rate of degradation, dechlorination and mineralization of TCP under optimum experimental conditions of pH, 7.0; [sulfite]/[TCP] = 3.13; UV irradiation, 87 μW cm−2; dissolved oxygen (DO), 2 mg L-1 and an 80 min reaction time, were 100, 98 and 30.2%, respectively (initial TCP concentration was 250 mg L-1 and initial COD was 363 mg L-1). Investigation of the reaction mechanism revealed the superiority of sulfite radicals (SO3-) in the degradation and dechlorination of TCP. The co-existing water anions did not significantly affect the performance of TCP degradation. The intermediates derived from TCP degradation included: 1,3-cyclohexadiene, 2-chloro-1-benzoquinone, 2-chlorophenol, benzene, 2-hydroxy benzoquinone and cyclohexene. The (BOD5)/(COD) ratio (the solution biodegradability index) was obtained as 0.57 after 80 min of UV/sulfite reaction time. The effluent obtained from UV/sulfite after 80 min of reaction time (with COD of 253 mg L-1) was efficiently post-treated in a batch biological reactor (MLSS = 5000 mg L-1), and the COD reduced to 37 mg L-1 after 720 min (12 h) of aeration. Therefore, it was found that the combination of the UV/sulfite with a biological process might be an efficient method for the treatment of wastewater containing high concentrations of toxic compounds.

An AIE fluorescent switch with multi-stimuli responsive properties and applications for quantitatively detecting pH value, sulfite anion and hydrostatic pressure

An AIE fluorescent switch exhibited multi-parameter detection properties for pH, sulfite anion and pressure with good linear relationships.