Thiourea Dioxide Research Articles

A Simple Conversion of Aldoximes to Nitriles Using Thiourea Dioxide

Thiourea dioxide (TDO) has been demonstrated to be an efficient reagent for the transformation of aromatic, heteroaromatic, alkenyl and aliphatic aldoximes to respective nitriles in excellent yields. Furthermore, this method has been applied to the synthesis of fungicide cyazofamid from a commercial precursor using TDO as a pivotal dehydrating and reducing reagent. This new procedure offers simple and easily reproducible technique for nitrile synthesis and highlights the synthetic utility of TDO as a versatile reagent in organic chemistry.

Palladium-Catalyzed Amino-Sulfonylation of Aryl Iodide Derivatives via the Insertion of Sulfur Dioxide: One-Pot Synthesis of Aryl Primary Sulfonamides with Thiourea Dioxides

AbstractA palladium-catalyzed one-pot amino-sulfonylation of aryl iodide derivatives with thiourea dioxide, PdCl2dppf, and one-pot added hydroxylamine-O-sulfonic acid is presented. This amino-sulfonylation gave structure diversity to aryl primary sulfonamides and features good functional group compatibility, mild reaction conditions, excellent regioselectivity, and moderate to good yields. The robustness and potential of this method have also been successfully demonstrated by late-stage elaboration and gram-scale reaction. This approach achieves the divergent construction of the complex core structures that are prevalent in highly valuable natural products such as Sulpiride, Venetoclax, and Furosemide­.

Thiourea Dioxide Catalyzed Sustainable Synthesis of Diverse Quinoxaline and Pyrazine Derivatives in Aqueous Medium at Ambient Temperature

AbstractAn eco‐conscious, metal‐free protocol has been developed to synthesize a diverse collection of biologically and pharmacologically active quinoxaline and pyrazine derivatives. The protocol involves a one‐pot condensation of various 1,2‐diamines with 1,2‐diones using thiourea dioxide as a catalyst and water as a solvent at ambient temperature. Notably, the catalyst can be reused up to five times without any significant loss of efficacy. The green aspects of this method involved milder reaction conditions, higher yields with shorter reaction times, simple work‐up, non‐chromatographic separations, good reusability, and easy catalyst recovery by simple filtration. Moreover, the reaction is successfully accelerated to a multigram scale, making it favourable for production at a larger scale.

Unlocking high-efficiency decontamination by building a novel heterogeneous catalytic reduction system of thiourea dioxide/biochar

Herein, we reported a new contaminant purification paradigm, which enabled highly efficient reductive denitration and dechlorination using a green, stable reducing agent thiourea dioxide (TDO) coupled with biochar (BC) over a wide pH range under anoxic conditions. Specifically, BC acted as both activators and electron shuttles for TDO decomposition to achieve complete anoxic degradation of p-nitrophenol (PNP), p-nitroaniline, 4-chlorophenol and 2,4-dichlorophenol within 2 h. During this process, multiple strongly reducing species (i.e., SO22-, SO2•- and e-/H•) were generated in BC/TDO systems, accounting for 13.3%, 9.7% and 75.5% of PNP removal, respectively. While electron transfer between TDO and H+ or contaminants mediated by BC led to H• generation and contaminant reduction. These processes depended on the electron-accepting capacity and electron-conducting domains of biochar. Significantly, the BC/TDO systems were highly efficient at a pH of 2.0–8.0, especially under acidic conditions, which performed robustly in common natural water constituents.

Molecular mechanism of the metal-independent production of hydroxyl radicals by thiourea dioxide and H2O2

It is well-known that highly reactive hydroxyl radicals (HO•) can be produced by the classic Fenton system and our recently discovered haloquinone/H2O2 system, but rarely from thiol-derivatives. Here, we found, unexpectedly, that HO• can be generated from H2O2 and thiourea dioxide (TUO2), a widely used and environmentally friendly bleaching agent. A carbon-centered radical and sulfite were detected and identified as the transient intermediates, and urea and sulfate as the final products, with the complementary application of electron spin-trapping, oxygen-18 isotope labeling coupled with HPLC/MS analysis. Density functional theory calculations were conducted to further elucidate the detailed pathways for HO• production. Taken together, we proposed that the molecular mechanism for HO• generation by TUO2/H2O2: TUO2 tautomerizes from sulfinic acid into ketone isomer (TUO2-K) through proton transfer, then a nucleophilic addition of H2O2 on the S atom of TUO2-K, forming a S-hydroperoxide intermediate TUO2-OOH, which dissociates homolytically to produce HO•. Our findings represent the first experimental and computational study on an unprecedented new molecular mechanism of HO• production from simple thiol-derived sulfinic acids, which may have broad chemical, environmental, and biomedical significance for future research on the application of the well-known bleaching agent and its analogs.

Going Green for Blue - An Indigo Approach

Introduction: Dominating use of chemical processes for reducing indigo at several small-scale production houses formed the ground for initiating this study. Conventional textile processing hubs still use sodium hydrosulphite as a reducing agent irrespective of the source of indigo, whether natural or synthetic ignoring the unfavourable consequences of their disposal and elimination from effluent Method: The paper addresses the critical environmental issues related to the conventional reduction of indigo and studies already undertaken. It examines the indigo dyeing process of cotton using natural, chemical and eco-friendly reducing agents in combination with calcium hydroxide for a comparative study. Identification of natural indigo through High-Performance Liquid Chromatography was undertaken for further experimentation. Under specific parameters, the study examined the effect of Thiourea dioxide and natural reducing agents in indigo dyeing replacing Sodium hydrosulphite. The difference in weight, strength, and colour parameters such as K/S (HUNTERLAB), CIELab values and colourfastness are measured. The experimental results showed weight gain in all fabrics after indigo dyeing. There is a decrease in weft strength only in tamarind, iron, jaggery and dextrose vats. Iron vat showed a higher colour yield out of all reducing agents due to forming metal complexes with the cotton fabric, which influenced colour depth and highest relative colour strength % (114.11) and ΔC (8.48). Result: Thiourea dioxide showed the next highest relative colour strength % (96.59) and lowest ΔH values (8.54) concerning the values of the hydro process. Structural changes of fiber were studied by using SEM (Scanning Electron Microscope) after using different reducing agents, which revealed superior surface topography of samples dyed using thiox. The colour difference showed no significant effect on the colourfastness of alternative reducing agents. Conclusion: Thiox can be a perfect substitution for hydro in indigo dyeing as it was found practical and feasible for implementation even by small-scale units in India.

INTERACTION OF THIOUREA DIOXIDE WITH n-BUTYLAMINE

The influence of n-butylamine on the stability and reducing activity of thiourea dioxide (TDO, aminoiminomethanesulfinic acid, formamidinesulfinic acid) in the reaction with azo dye Orange II has been studied. The addition of an excess of n-butylamine leads to the increase in reducing activity of thiourea dioxide in the reaction with the azo dye Orange II in strongly alkaline solutions, whereas the stability of thiourea dioxide decreases under these conditions. It has been shown that with an excess of n-butylamine, N,N'-di-n-butylthiourea dioxide is formed. N-n-butylthiourea dioxide was synthesized and isolated in the solid state as a product of the reaction of thiourea dioxide with n-butylamine in an acidic medium (pH 5) at a molar ratio of reagents 1:1. This compound was characterized by IR, 1Н and 13С NMR spectroscopy. N-n-butylthiourea dioxide has a higher solubility in water than the thiourea dioxide, but lower reducing activity in the reaction with azo dye Orange II in the range of pH 6.9–11.8. The formation of active reducing agent sulfoxylate in course of TDO decomposition leads to its high reducing activity in alkaline aqueous solutions. It has been shown that the rates of decomposition of the studied compounds increase with increasing pH. It has been established that N-n-butylthiourea dioxide is more stable in alkaline media than thiourea dioxide. Based on the previous data and data obtained in this work the following sequence of reducing activity of thioureas dioxides in strongly alkaline media was proposed: N,N'-dialkylthiourea dioxides > thiourea dioxide > N-alkylthiourea dioxides. The stability of thiourea dioxides in strongly alkaline aqueous solutions increases in reverse order.

Development of chemiluminescent systems and devices for analytical applications.

Chemiluminescence (CL) refers to the light-emitting phenomenon resulting from chemical reactions. Due to its simplicity in terms of instrumentation and high sensitivity, CL plays a critical role in analytical chemistry and has developed rapidly in recent years. In this review, we discuss the efforts made by our group in the field of CL. This includes exploring new luminophores that function under neutral pH conditions, developing oxidant- and reactive oxygen species-based coreactants (e.g. artemisinin and thiourea dioxide) for luminol and lucigenin CL, utilizing nanomaterial-based CL signal amplification and employing innovative ultrasound devices for CL and their analytical applications. We discussed the CL amplification mechanisms of these systems in detail. Finally, we summarize the challenges and prospects for the future development of CL.

Zwitterion Reduces Open‐Circuit Voltage Loss in Wide‐Bandgap Perovskite Solar Cells with 22% Efficiency and Its Application in Tandem Devices

Wide‐bandgap (WBG) perovskite solar cells (PSCs) can be combined with other narrow‐bandgap cells to form tandem solar cells (TSCs), which have excellent commercialization prospects. However, the component of WBG perovskite is complex, and the crystallization process is difficult to control. Various bulk and surface defects in polycrystalline films lead to severe nonradiative recombination of photogenerated carriers, resulting in severe open‐circuit voltage (VOC) loss in WBG PSCs. Herein, a zwitterionic additive is introduced to alleviate the VOC deficit. The sulfinyl group (–SO) in formamidine sulfinic acid (FSA) has a robust interaction with Pb2+, which retards the crystallization and improves the crystal quality in perovskite films. Furthermore, FSA has negatively charged centers (–SO2−) and positively charged centers (–C(NH2)2+), which can passivate the halogen and cation vacancies, respectively. The improved crystalline quality and passivated defects reduce the capture of carriers by defects and facilitate higher VOC. With this strategy, the 1.68 eV bandgap PSCs achieve a champion efficiency of 22.06% and a high VOC of 1.25 V (VOC loss = 0.43 V). Moreover, the 2‐terminal perovskite/silicon TSCs are fabricated with an extraordinary power conversion efficiency of 28.81%.

A Titration Method for Standardization of Aqueous Sodium Chlorite Solutions Using Thiourea Dioxide.

Accurate and cost-effective methods for the analysis of oxychlorine compounds in water are critical to modern chlorine-based water treatment. With alternatives to elemental chlorine and hypochlorite bleaches growing in popularity, simple quantification methods for the disinfectant chlorine dioxide (ClO2) in water, as well as chlorite (ClO2-) and chlorate (ClO3-), which are commonly used precursors in ClO2 generation, are required. However, currently, regulated standard methods require specialized equipment and do not effectively discriminate between molecular and ionic species. In this contribution, we present a simple titration-based method for chlorite determination in water using commercially available and easy-to-handle reagents. Specifically, chlorite is reduced with a slight excess of thioureadioxide (TUD). The remaining reductant is then back-titrated against a known amount of potassium permanganate, affording calculatable chlorite concentrations through measured consumption of a reductant and a clear visual endpoint upon accumulation of excess KMnO4. Straightforward methods for chlorite standardization with reasonable error and accuracy for field and/or lab application have the potential to greatly enhance quality assurance and therefore assist in resource deployment in water treatment.

Effective reduction and recovery of As(III) and As(V) from alkaline wastewater by thiourea dioxide: Efficiency and mechanism.

For alkaline wastewater with high arsenic concentration, the traditional lime precipitation inevitably produces large amounts of hazardous waste. Herein, a heat-activated reduction method employing thiourea dioxide (TDO) as the reductant was proposed to efficiently remove and recover As(III)/As(V) from alkaline wastewater in the form of valuable As(0). More than 99.9% of As(III)/As(V) (2-400mM) were reduced to As(0) with a high purity of more than 99.5 wt% by TDO within 30min. The highly reductive eaq- and SO2- radical generated during TDO decomposition contribute to the arsenic reduction, and the contribution ratios of eaq- and SO2- radical were estimated to be approximately 57.6% and 42.4% for As(III) removal and 62.2% and 37.8% for As(V) removal, respectively. The arsenic reduction was greatly improved by increasing pH and temperature, which could accelerate the cleavage of C-S bond in TDO for the eaq- and SO2- formation. The presence of dissolved oxygen, which can not only scavenge eaq-/SO2- but also directly oxidize SO22-, had a negative effect on the arsenic removal. The presence of CO32- slightly suppressed the arsenic removal due to the eaq- scavenging effect while SiO32-, PO43-, Cl-, SO42- and NH4+ had negligible effects. The proposed method was a potential technology for the efficient removal and reduction of arsenic in alkaline wastewater.

Production of bio-indigo dye by surmounting its physical and chemical insoluble nature

Indigo is a natural blue dye that has been in use for centuries. However, its insolubility in water and most organic solvents limits its application in various fields. In this study, we aimed to enhance the indigo production by surmounting its physical and chemical insolubility. To achieve this, a combination of genetic engineering, biotransformation optimization, and solubilization techniques has been employed. First, the indole-converting enzymes, flavin-containing monooxygenase (MaFMO) from Methylophaga aminisulfidivorans and toluene monooxygenase from Pseudomonas mendocina (PmT4MO), were tested and their expression was optimized, which allowed for the efficient conversion of indole to indigo via indoxyl. Next, to overcome the insolubility of indigo and facilitate indole/indigo transport through the cell membrane, organic solvents and detergent mixing were optimized. Genetic modification was attempted by introducing caveolae complex structures into the membrane to create a permanent indole/indigo transport system. Finally, inspired by wastewater treatment and indigo solubilization during the indigo-dyeing process, indigo adsorption and reduction were applied using an Amberlite XAD4 adsorption bead and thiourea dioxide reducing agent to achieve enhanced production of indigo, respectively. These counteracting strategies against the insoluble nature of indigo resulted in a significant increase in bio-indigo production, with 1.5 g/L produced from 15 mM indole, representing an increase of more than 300% compared with that of the initial production titer. This study provides valuable insights into the optimization of indigo bioproduction and could lead to the development of more efficient methods for bio-dye production.

Versatility of thiourea dioxide as redox agent in globins: Case study with myoglobin

This work focuses on understanding the versatile chemical properties of thiourea dioxide (TDO). The electronic structure of TDO is clarified, based on DFT and NBO population analysis calculations. We demonstrate that the most probable structure is the carbenoid one, with charge delocalization. The reduction of myoglobin with TDO was studied under different conditions in the pH range between 5 and 13, anaerobic/aerobic conditions and in the presence/absence of cysteine. Depending on the conditions, deoxy-, oxy-, carboxy-, and, in some cases, sulf-Mb species were obtained. To understand the influence of compounds containing S, N, and O functional groups on the decomposition kinetics of TDO in basic media, experiments and DFT calculations were performed. Adducts of cysteine and glycine with TDO identified in these investigations are deemed unlikely to be involved in protein reduction by TDO in short-term room-temperature UV–vis experiments.

Multidentate Molecule Anchoring Halide Perovskite Surface and Regulating Crystallization Kinetics toward Efficient Light‐Emitting Diodes (Small 11/2023)

Efficient Light-Emitting Diodes In article number 2205336, Yue-Min Xie, You-Yong Li, Man-Keung Fung, and co-workers introduce a novel multidentate molecule (Formamidine Sulfinic Acid, FSA) to heal perovskite defects, where the intense bonding strength of the S≐O and –NH2 groups of the multidentate molecule to the undercoordinated Pb defects can effectively facilitate the passivation of the perovskites, thus leading to modified perovskite crystallization properties with enhanced passivation durability.

Mechanochemistry Frees Thiourea Dioxide (TDO) from the ‘Veils’ of Solvent, Exposing All Its Reactivity

The synthesis of nitrogen-based heterocycles has always been considered essential in developing pharmaceuticals in medicine and agriculture. This explains why various synthetic approaches have been proposed in recent decades. However performing as methods, they often imply harsh conditions or the employment of toxic solvents and dangerous reagents. Mechanochemistry is undoubtedly one of the most promising technologies currently used for reducing any possible environmental impact, addressing the worldwide interest in counteracting environmental pollution. Following this line, we propose a new mechanochemical protocol for synthesizing various heterocyclic classes by exploiting thiourea dioxide (TDO)'s reducing proprieties and electrophilic nature. Simultaneously exploiting the low cost of a component of the textile industry such as TDO and all the advantages brought by a green technique such as mechanochemistry, we plot a route towards a more sustainable and eco-friendly methodology for preparing heterocyclic moieties.

Thiourea dioxide as a green reductant for selective depolymerization of lignin to guaiacol

Selective depolymerization of lignin is a key strategy for realizing high-value utilization of this natural renewable aromatic biopolymer. Degradation of lignin by the traditional technologies usually requires costly metal complex catalysts, and encounters poor monomer selectivity at present. Herein, a novel eco-friendly reduction system for high selectivity production of guaiacol directly from technical lignin by thiourea dioxide (TDO) assisted sodium hydroxide was reported. The experimental results of lignin and 2-phenoxy-1-phenylethanol depolymerization confirmed that the addition of TDO effectively promoted the cleavage of C-O bond of β-O-4-alcohols, and lignin was completely converted with minimal char formation of 2.73 wt% under relatively mild conditions. In addition, 4.91 wt% of phenolic monomers and 55.29 wt% of re-lignin were generated, and all with improved yields compared to the environment in the absence of TDO. Notably, the selectivity of guaiacol could amount to 64.77% in this reduction system, which is significantly higher than most reports of lignin depolymerization using noble metals, enabling value-increment utilization of technical lignin by means of low cost.

One-step removal of hexavalent chromium in wide pH range using thiourea dioxide: the role of reactive species.

One-step removal of hexavalent chromium in a wide pH range is of great significance. In this paper, a single thiourea dioxide (TD) and two-components thiourea dioxide/ethanolamine (MEA) were used as a green reducing agent for the efficient removal of Cr(vi), respectively. The reduction of Cr(vi) and the precipitation of Cr(iii) were carried out simultaneously under this reaction system. The experimental results proved that TD was activated by amine exchange reaction with MEA. In other words, MEA promoted the generation of an active isomeride of TD by changing the equilibrium position of the reversible reaction. After adding MEA, the removal rate of Cr(vi) and total Cr could reach industrial water discharge standards in a wide pH range of 8-12. The change of pH, reduction potential and the decomposition rate of TD were investigated in the reaction processes. Meanwhile, reductive and oxidative reactive species were produced simultaneously during this reaction process. Further, oxidative reactive species (O2˙- and 1O2) were beneficial for the decomplexation of Cr(iii) complexes and the formation of Cr(iii) precipitation. The experimental results also demonstrated that TD/MEA was effective in practical industrial wastewater. Hence this reaction system has a significant industrial application prospect.

Multidentate Molecule Anchoring Halide Perovskite Surface and Regulating Crystallization Kinetics toward Efficient Light-Emitting Diodes.

Functional passivators are conventionally utilized in modifying the crystallization properties of perovskites to minimize the non-radiative recombination losses in perovskite light-emitting diodes (PeLEDs). However, the weak anchor ability of some commonly adopted molecules has limited passivation ability to perovskites and even may desorb from the passivated defects in a short period of time, which bring about plenty of challenges for further development of high-performance PeLEDs. Here, a multidentate molecule, formamidine sulfinic acid (FSA), is introduced as a novel passivator to perovskites. FSA has multifunctional groups (S≐O, C≐N and NH2 ) wherethe S≐O and C≐N groups enable coordination with the lead ions and the NH2 interacts with the bromide ions, thus providing the most effective chemical passivation for defects and in turn the formation of highly stable perovskite emitters. Moreover, the interaction between the FSA and octahedral [PbBr6 ]4- can inhibit the formation of unfavorable low-n domains to further minimize the inefficient energy transfer inside the perovskite emitters. Therefore, the FSA passivated green-emitting PeLED exhibits a high external quantum efficiency (EQE) of 26.5% with fourfold enhancement in operating lifetime as compared to the control device, consolidating that the multidentate molecule is a promising strategy to effectively and sustainably passivate the perovskites.

Effect of cellulose fiber graft copolymerization with glycidyl methacrylate on the papermaking process retention and drainage aid performance

Abstract Improving the retention and drainage aid performance of high speed papermaking processes is an important and challenging issue. In this study, fiber modification was used to improve the papermaking retention and drainage aid performance. The graft copolymerization of glycidyl methacrylate (GMA) with cellulose fibers was initiated using Fe2+-thiourea dioxide(TDO)-H2O2 in a mild aqueous medium; the synthesized polyglycidyl methacrylate grafted cellulose (CPGMA) was used to replace softwood bleached kraft pulp(SBKP) and hardwood bleached kraft pulp(HBKP), to study their retention and drainage aid behavior in the cationic polyacrylamide (CPAM)/colloidal SiO2/ anionic polyacrylamide (APAM) system. Graft copolymerization significantly enhanced the fiber hydrophobicity. Additionally, the papermaking process drainage aid performance and retention rate of the filler increased significantly with an increase in the CPGMA substitution rate. A small amount of CPGMA (0.5 %) significantly improved the dewatering ability and some improved the retention performance of the wet end of papermaking. SBKP-polyglycidyl methacrylate grafted cellulose (S-CPGMA) exhibited better retention and drainage aid performance than HBKP-polyglycidyl methacrylate grafted cellulose (H-CPGMA). Thus, introducing Fe2+-thiourea dioxide(TDO)-H2O2 initiated graft copolymerized S-CPGMA (in mild aqueous media) into pulp could improve the retention and drainage aid performance of the wet part of paper production.

Recyclable and dual active catalyst of copper nanocluster-bound graphitic carbon nitride for the photo-induced synthesis of arylsulfones

A photocatalytic system of Cu(0) nanocluster-bound graphitic carbon nitride (Cu(0)-g-C3N4) was developed for three-component arylsulfonylation reactions. The Cu(0)-g-C3N4 nanocomposite has a structure in which 2–5 nm metallic Cu nanoclusters are anchored on the surface of g-C3N4 nanosheets. The Cu(0) clusters were synthesized by reducing Cu2+ ions with ascorbic acid in the presence of g-C3N4 nanosheets. Cu(0)-g-C3N4 was designed to exhibit dual catalytic activity involving the transfer of photo-induced electrons from g-C3N4 to Cu(0) for the reduction of arylhalides, while the holes in g-C3N4 oxidize the sulfur dioxide anion. The structure of the catalyst was confirmed by electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The well-defined, air-stable Cu(0)-g-C3N4 catalyst effectively promotes the sulfonylation of aryl iodides, thiourea dioxide, and electrophiles to afford the corresponding arylsulfonyl compounds in moderate to good yields. The reusability of the catalyst was also evaluated, and it could be reused up to ten times in arylsulfonylation without the loss of its activity.