Reaction Of Dimethyl Sulfoxide Research Articles

Reduction of CO2 in the presence of light via excited-state hydride transfer reaction in a NADPH-inspired derivative.

The photo-catalytic reduction of CO2 into chemical feedstocks using solar energy has attracted vast interest in environmental science because of global warming. Based on our previous study on the CO2 complex with one of the benzimidazoline (BI) derivatives, we explore the photochemical reduction of CO2 in one of the benzimidazoline derivatives (1,3-dimethyl-5,6-diol-2,3-dihydro-1H-benzimidazole) by quantum-chemical methods. Our results reveal that carbon dioxide can be reduced to formate (HCOO-) by a hydride transfer reaction in the excited state of this complex of benzimidazoline derivative and CO2. While the ground-state hydride transfer reaction in this complex exhibits a substantial barrier, a charge-transfer can occur in the first singlet excited state of the complex in the UV-A region (326 nm), and after overcoming a moderate barrier (∼0.4 eV) the system can have access to the products. The interaction with a polar solvent decreases further the barrier such that the reaction in dimethyl sulfoxide can proceed with a negligibly small barrier (∼0.1 eV) or in a nearly barrierless manner. Our results show that this benzimidazoline derivative may act as a catalyst in the photoreduction of CO2.

Benzannulation and N‐Annulation of β‐Ketoenamines for Synthesizing Aniline and Pyridine Derivatives Using DMSO as a Methine Source

AbstractBenzannulation and N‐annulation of β‐ketoenamines by the in‐situ generated methyl(methylene)sulfonium ion from the reaction of dimethyl sulfoxide (DMSO) and 1,2‐dibromoethane (DBE) was achieved. The β‐ketoenamines underwent N‐annulation to pyridine derivatives, while the N‐alkylated enamines were benzannulated to afford substituted anilines. The utility of the intermediate methyl(methylene)sulfonium ion was further extended for synthesizing methylene‐bridged bis‐1,3‐dicarbonyl compounds.magnified image

Potassium tert-Butoxide-Promoted Tandem Cyclization of Organoselenium Alkynyl Aryl Propargyl Ethers.

Base-promoted cyclization of 3-organoselenyl-methylene-2-alkynyl aryl propargyl ethers has been developed for the synthesis of 3-butylselanyl-methylene benzofurans, 3-methyl-2-alkynyl-benzofurans, and 4-iodo-benzo[b]furan-fused selenopyrans. Under potassium tert-butoxide as the base and tetrahydrofuran as the solvent, at room temperature, 3-organoselenyl-methylene-2-alkynyl aryl propargyl ethers were converted into 3-butylselanyl-methylene benzofurans via a 5-exo-dig mode. Using the same substrate, changing the solvent to dimethylsulfoxide, 3-methyl-2-alkynyl-benzofurans were selectively obtained in good yields. From 3-butylselanyl-methylene benzofurans, 4-iodo-benzo[b]furan-fused selenopyrans were prepared through a nucleophilic cyclization promoted by molecular iodine. The optimization of the reaction conditions showed that the solvents governed the regioselectivity of this cyclization and the initial formation of the dimsyl anion by the reaction of dimethylsulfoxide with potassium tert-butoxide was crucial for the 3-methyl-2-alkynyl-benzofuran preparation. We also proposed the mechanism for the formation of the products, demonstrated that the methodology can be scaled up, and showed the application of the prepared compounds as substrate in further transformations.

Efficient Visible-Light-Driven RAFT Polymerization Mediated by Deep Eutectic Solvents under an Open-to-Air Environment

In this work, we investigate the effects of deep eutectic solvents (DESs) on a facile reversible addition–fragmentation chain-transfer (RAFT) polymerization driven by visible light. A DES composed of tetrabutylammonium chloride (TBACl) and ethylene glycol served as a nonvolatile medium for a variety of monomers, including methyl methacrylate, methyl acrylate, dimethylacrylamide, and styrene. We first employed the polymerization-through pathway to overcome oxygen inhibition in an open-to-air environment using methyl methacrylate as the model compound. The photoiniferter polymerization using trithiocarbonates as the chain transfer agent (CTA) in DESs exhibited enhanced polymerization rates and achieved a narrow molecular weight distribution. Interestingly, even dithiobenzoate, the CTA with low efficiency for photoiniferter polymerization, exhibited a nearly 4.5-fold increase in the apparent polymerization rate constants when compared to the reaction in dimethyl sulfoxide. Moreover, the stability of the CTAs was increased in DESs for efficient control of molecular weight distribution and preservation of functional chain ends. We then surveyed photocatalysts for photoelectron/energy transfer (PET) RAFT polymerization and found that eosin Y was compatible with DESs. The PET-RAFT polymerization using dithiobenzoate in DESs showed even higher polymerization rates than the photoiniferter polymerization and enabled the polymerization under natural sunlight. Besides methyl methacrylate, other monomers also exhibited an increased polymerization rate in DESs, comparable to reactions in ionic liquids. These results suggest that DESs are effective and green media to facilitate photo-induced RAFT polymerization without additives or tedious degassing processes.

Sulfation of wheat straw soda lignin: Role of solvents and catalysts

Sulfation of wheat straw soda lignin by the sulfamic acid–urea mixture in different solvents has been investigated for the first time. The effect of a catalyst used in the lignin sulfation process on the yield of the lignin sulfates and sulfur content in them has been explored. It has been found that the optimal medium for the lignin sulfation with sulfamic acid is dioxane and, in the presence of a catalyst, urea. Although the sulfated lignins obtained using the reaction in dimethyl sulfoxide and diglyme have the maximum sulfur contents (11.2% and 9.9%, respectively), these products are difficult to isolate and purify, which complicates the use of these solvents. Sulfated lignin obtained in the dioxane medium has a high (10.1%) sulfur content and is easy to isolate and purify. The incorporation of sulfate groups into the lignin structure has been confirmed by the infrared and nuclear magnetic resonance spectroscopy investigations. In the infrared spectra of sulfated lignin, characteristic absorption bands at 800–860 and 1260–1200 cm−1 appear. The dominant substitution of aliphatic hydroxyl groups has been confirmed by the nuclear magnetic resonance spectroscopy study. It has been found that, during the modification and purification of lignin, the latter is fractionated, which results in the redistribution of molecular weights toward the high molecular-weight region, as well as the removal of some low-molecular-weight components, which is reflected in a decrease in the number of signals in the nuclear magnetic resonance spectra.

Solution and Solid-State Characterization of PbSe Precursors.

The addition of lead to diphenyl diselenide in ethylenediamine (en) or pyridine (py) allowed for the observation of the solvento complexes, (en)Pb(SePh)2 or (py)2Pb(SePh)2, respectively. Performing this reaction in dimethyl sulfoxide and subsequent crystallization was found to afford Pb(SePh)2. Inductively coupled plasma optical emission spectroscopy revealed a 1:2 lead to selenium ratio for all three complexes. Nuclear magnetic resonance spectroscopy confirms that Pb(SePh)2 is readily solubilized by ethylenediamine, and electrospray ionization mass spectrometry supports the presence of Pb(SePh)2 moieties in solution. Single-crystal X-ray diffraction analysis of the pyridine adduct, (py)2Pb(SePh)2, revealed a seesaw molecular geometry featuring equatorial phenylselenolate ligands. Crystals of Pb(SePh)2 grown from dimethyl sulfoxide revealed one-dimensional polymeric chains of Pb(SePh)2. We believe that the lead(II) phenylselenolate complexes form via an oxidative addition reaction.

Effect of solvent polarity on the regioselective hydroxyalkylation of indole with trifluoroacetaldehyde hemiacetals

The effect of solvents has been found as a crucial factor in determining the regioselectivity of the hydroxyalkylation of indole with trifluoroacetaldehyde hemiacetals. The appropriate selection of the solvent ensured to achieve absolute N1 or C3 regio/chemoselectivity of the reaction depending on the polarity and dielectric constant of the medium. Reaction conditions were optimized considering the effect of solvent, including temperature, time, and molar ratio of reactants to base. In order to rationalize this effect, density functional theory has been employed in which implicit as well as explicit role of solvent was studied, which were further validated with in situ 1H NMR spectroscopy experiments. The comparison of transition states derived from the implicit calculations revealed that the lowest energy path of the reaction in dimethyl sulfoxide (DMSO) leads to product formation with N-selectivity. Further DFT calculations on explicit interactions of indole with DMSO indicated enhanced nucleophilicity on the N atom compared to that of C3 atom, which is evident from the calculated electrostatic potential (ESP) fit charges of these complexes. These findings appear to support the experimental data and explain the N-selectivity in DMSO.

Case study—Characterizing and averting risk of catastrophic vessel failure for a reaction in dimethyl sulfoxide

AbstractProcess safety testing performed on a batch process for making a pharmaceutical intermediate revealed that one process stream, a reaction in dimethyl sulfoxide, had a significant undesired reaction that could lead to catastrophic vessel failure as a result of a single process deviation. Comprehensive testing identified the worst case process stream with the lowest exotherm initiation temperature and most severe pressure consequences, for which corrective actions must be taken. With this information in hand, hazard assessments were performed to support processing, to determine the appropriate safeguards needed to mitigate the consequences, and to reduce the likelihood of reaching this activity to a tolerable level.

Functional dextran amino acid ester particles derived from N-protected S-trityl-L-cysteine

This work describes the derivatization of dextran using N-(tert-butyloxycarbonyl)-S-(trityl)-L-cysteine in the presence of N,N′-carbonyldiimidazole (CDI) as a coupling agent. Homogeneous reactions in dimethyl sulfoxide allowed for an efficient coupling of the amino acid derivative to the polymer backbone. Derivatization was confirmed by infrared and 13C NMR spectroscopy, size exclusion chromatography and elemental analysis. The presence of hydrophobic protecting groups resulted in a product that can be shaped into water-insoluble particles stable in an aqueous environment and non-toxic for lung epithelial cells. It is suggested that materials composed of ester bonds between amino acids and polysaccharides are useful for targeted drug delivery, bio-imaging or surface functionalization.

Heterogenized Cu (II) salen complex grafted on graphene oxide nanosheets as a precursing catalyst for the Pd‐free Sonogashira coupling

Cu (II) salen complex immobilized on graphene oxide nanosheets [Cu (II) salen@GO] was synthesized with 3‐chloropropyltrimethoxysilan as a linker and wholly characterized using various techniques like X‐ray diffraction, Fourier‐transform infrared, scanning electron microscopy/energy‐dispersive X‐ray spectroscopy, transmission electron microscopy, as well as atomic absorption spectroscopy (AAS). Cu (II) salen@GO as an effective heterogeneous catalyst has been investigated for the Sonogashira coupling reaction in dimethylsulfoxide with good to high yield (98%) in 4 hr at 110°C when the loading of Cu was 0.7 mmol g−1 based on Cu element analysis by AAS. It was understood that heterogeneous catalyst was as active as its homogeneous analog, and presented good recoverability and no significant loss in activity within successive runs.

Spectral study of the reactions of dimethyl sulfoxide with the nitrite complexes of Co-porphyrins

It is revealed by FTIR and electron absorption spectroscopy that the reactions of dimethyl sulfoxide with the nitro complexes of Co-porphyrins both in the solid phase and an inert solvent afford six-coordinate complexes with the general formula (DMSO)Со(Por)(NO2) (Por is meso-tetraphenyl- and meso-tetra-p-tolylporphyrinato dianions). These compounds are stable in the solid state, whereas they partially decompose in an inert solvent to form five- and six-coordinate complexes. The ambident nitrite and dimethyl sulfoxide ligands are coordinated to the metal atom through the N and O atoms, respectively, which was confirmed by the application of isotope-containing compounds 15NO2 and DMSO-d6.

Solvothermal evolution of red palygorskite in dimethyl sulfoxide/water

Abstract Red clay deposit with palygorskite (Pal) as the main component is abundant on the earth, but it is not yet fully utilized in industrial fields because of its deep color. In this paper, we employed a facile one-step solvothermal process to treat red Pal using water, dimethyl sulfoxide (DMSO) and DMSO/water as solvents and studied the effect of this process on the structure, physico-chemical characteristics and color of red Pal. It was revealed that the brick-red Pal still remain its color unchanged after solvothermal reaction in water or DMSO solvent, but it converted to white after reaction in dimethyl sulfoxide (DMSO)/water mixture. When the volume ratio of DMSO to water is 2:1, the product has the best whiteness of 83.3%. The associated minerals such as quartz, feldspar and muscovite did not change significantly and the rod-like crystalline morphology of Pal still remains intact after solvothermal reaction. The leaching of Fe(III) in Pal, the dissolution of α-Fe 2 O 3 and the reduction of Fe(III) by the dimethyl sulfide (the reaction product of DMSO with water) to Fe(II) contributed to the conversion of red Pal to white one. The conversion of brick-red Pal to white would lay a foundation for the applications of deep-colored clay minerals in the fields of chemical industries and composite materials.

The impact of solvent properties on the performance of oxygen reduction and evolution in mixed tetraglyme-dimethyl sulfoxide electrolytes for Li-O2 batteries: Mechanism and stability

The instability of the electrolyte and the sluggish kinetics of the reactions hinder the application of Li-O2 batteries. In this study, we aim to better understand the behavior of oxygen reduction (ORR) and evolution (OER) reactions in dimethyl sulfoxide (DMSO), Tetraglyme (G4) and their blend DMSO-G4, with emphasis on the role of solvent nature in the mechanism and reaction route, using rotating ring-disc electrode (RRDE) and differential electrochemical mass spectrometry (DEMS). Interestingly, RRDE results showed that the stability and the ratio of the formed O2−·: Li2O2 increase with addition of DMSO to G4. A proposed mechanism for ORR is discussed. Depending on the solvation ability of the solvent, which primarily determines the lifetime and solubility of the superoxide intermediate in solution, a solution or a surface-based pathway is followed: in highly solvating solvents (e.g. those with high donor or acceptor number) such as DMSO, superoxide is stabilized in solution; while in low solvating solvent, it is further reduced to Li2O2, blocking the surface. The results of the scan rate variation under defined mass transport in DMSO suggest a sequential formation of monolayers of Li2O2 during reduction. In G4-solutions, despite of the reversible formation of Li2O2, deactivation of the electrode takes place, as evidenced by DEMS. This could arise from a reduction products-induced decomposition of the electrolyte, forming a deactivating film on the surface during ORR, which is only partially removed at higher potentials evolving CO2. Also, we found that DMSO is more active towards OER than G4. The electrode material as well influences the kinetics, in particular of OER. These findings could have implications for the development of Li-air battery.

Crystal structures of tetrakis (hydroxyacetato)bis(dimethylsulfoxide) dirhodium(II)

Tetrakis(hydroxyacetato)bis(dimethyl sulfoxide)dirhodium(II) (1) is synthesized by the reaction of dimethyl sulfoxide (DMSO) with Rh2(OOCCH2OH)4. The complex is characterized by elemental analysis, FT-IR, ESI+-MS, 1H and 13C NMR, along with single crystal X-ray diffraction. The ambidentate DMSO ligands are bound to the rhodium center of 1 through their sulfur atoms, which is firstly predicated by its orange color, then confirmed by the observation of an increase in the S–O stretching frequencies, and finally, unambiguously determined by single crystal X-ray diffraction. The structure of 1 contains two similar but crystallographically independent molecules. Both molecules contain lantern dirhodium units, joined equatorially by four bidentate hydroxyacetate ligands and two monodentate DMSO axial ligands. Four hydrogen bonds link the molecules together with d(O⋯O) of 2.767(4)-2.824(4) A to form a three dimensional network.

Novel polyurethanes from xylan and TDI: Preparation and characterization

ABSTRACTXylan is a hemicellulose, which is found abundantly in nature. In this work, a novel polyurethane was developed involving xylan and tolylene-2,4-diisocyanate (TDI). Polymer synthesis was achieved through conventional heat or microwave-assisted reaction in dimethyl sulfoxide. Because xylan has multiple OH groups on each polymer chain, the TDI/xylan molar ratio had to be adjusted to produce a soluble polymeric product. The reaction products were characterized by 13C NMR, FTIR, thermogravimetric analysis, and differential scanning calorimetry. The xylan polyurethane was shown to exhibit improved thermal stability over xylan.

An Efficient Aromatization of 2-Amino-4,5,6,7-tetrahydrobenzo-[b]thiophene-3-carboxylates in Dimethyl Sulfoxide Catalyzed by p-Toluenesulfonic Acid

A novel oxidation–aromatization of alkyl 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylates is reported. The Gewald product, obtained from three-component condensation reaction between a cyclohexanone, an alkyl cyanoacetate, and sulfur, underwent an oxidation reaction in dimethyl sulfoxide in the presence of a catalytic amount of p-toluenesulfonic acid to give the corresponding alkyl 2-aminobenzo[b]thiophene-3-carboxylate in excellent yield.

Synthesis of 3-aminomethyl-4-hydroxycoumarins and their retro-Mannich reaction in dimethyl sulfoxide

Hydrogenation of 3-formyl-4-hydroxycoumarin aliphatic imines leads to 3-aminomethyl-4-hydroxycoumarins, which undergo a retro-Mannich reaction in dimethyl sulfoxide containing even traces of water.

Simplified continuum solvent model with a smooth cavity based on volumetric data.

We present a continuum solvent model (CSM) with a smooth cavity for the application in grid-based electronic structure methods. The cavity is identified with the inherently smooth distribution function of a binary mixture at infinite dilution. We obtain a cavity model based on atomic van der Waals radii and one free parameter controlling the overall size. This single parameter is sufficient to adequately reproduce experimental partial molar volumes. The CSM based on this cavity is of similar accuracy in the prediction of aqueous solvation Gibbs energies of small neutral molecules and ions as other CSMs with a smooth cavity. We apply the model to systems in non-aqueous solution, i.e., spiropyran/merocyanin energetics, a proton transfer reaction in dimethyl sulfoxide, and the electrostatic screening of charged gold clusters in an ionic liquid.

Probing the Lithium–Sulfur Redox Reactions: A Rotating-Ring Disk Electrode Study

Detailed mechanistic understanding of sulfur redox reactions is critical for developing efficient and stable lithium–sulfur batteries. Here, we employ the rotating-ring disk electrode technique to probe the reaction kinetics and reaction mechanism of lithium–sulfur redox reactions in dimethyl sulfoxide and 1,3-dioxolane:1,2-dimethoxyethane. We quantitatively determine the number of electrons involved in the reduction reactions and the specific activity of sulfur reduction reactions. We show that the electrochemical steps of sulfur reduction exhibit fast reaction kinetics and only account for approximately one-quarter of the total capacity (i.e., ≈4 e–/S8) within the short reaction time in RRDE experiments (seconds). The complete conversion of sulfur to Li2S can only be accomplished via chemical (i.e., potential-independent) polysulfide recombination/dissociation reactions that generate electrochemically reducible polysulfides with long reaction time (hours) in a closed battery cell. The influence of the s...

Free energy landscape for glucose condensation and dehydration reactions in dimethyl sulfoxide and the effects of solvent

The mechanisms and free energy surfaces (FES) for the initial critical steps during proton-catalyzed glucose condensation and dehydration reactions were elucidated in dimethyl sulfoxide (DMSO) using Car–Parrinello molecular dynamics (CPMD) coupled with metadynamics (MTD) simulations. Glucose condensation reaction is initiated by protonation of C1OH whereas dehydration reaction is initiated by protonation of C2OH. The mechanisms in DMSO are similar to those in aqueous solution. The DMSO molecules closest to the C1OH or C2OH on glucose are directly involved in the reactions and act as proton acceptors during the process. However, the energy barriers are strongly solvent dependent. Moreover, polarization from the long-range electrostatic interaction affects the mechanisms and energetics of glucose reactions. Experimental measurements conducted in various DMSO/Water mixtures also show that energy barriers are solvent dependent in agreement with our theoretical results.