Showing papers on "Reagent published in 2020"
TL;DR: It was determined that the as-synthesized AuNPs between 15 nm and 30 nm exhibit well-defined size and shape, and narrow size distribution, but became more polydispersed and less spherical in shape as the particle size increased.
Abstract: Gold nanoparticles (AuNPs) exhibit unique size-dependent physiochemical properties that make them attractive for a wide range of applications. However, the large-scale availability of precision AuNPs has been minimal. Not only must the required nanoparticles be of precise size and morphology, but they must also be of exceedingly narrow size distribution to yield accurate and reliable performance. The present study aims to synthesize precision AuNPs and to assess the advantages and limitations of the Turkevich method-one of the common chemical synthesis technique. Colloidal AuNPs from 15 nm to 50 nm in diameter were synthesized using the Turkevich method. The effect of the molar ratio of the reagent mixture (trisodium citrate to gold chloride), the scaled-up batch size, the initial gold chloride concentration, and the reaction temperature was studied. The morphology, optical property, surface chemistry, and chemical composition of AuNPs were thoroughly characterized. It was determined that the as-synthesized AuNPs between 15 nm and 30 nm exhibit well-defined size and shape, and narrow size distribution (PDI < 0.20). However, the AuNPs became more polydispersed and less spherical in shape as the particle size increased.
113 citations
82 citations
TL;DR: The findings of this study suggest that sewage sludge derived Fe-rich biochar could be utilized as an efficient Fenton catalyst for recalcitrant organics degradation.
82 citations
TL;DR: Ce-AlOOH were investigated to develop as an adsorbent for removing fluoride and modification of oxalic acid exhibited a new easier way to quickly increase M-OH content, which contributed to the dominated adsorption sites.
78 citations
TL;DR: Mechanistic studies indicate that the reaction proceeds through a borrowing hydrogen pathway involving metal–ligand cooperation at the Mn‐pincer complex, providing a convenient, economical, and environmentally benign pathway for the selective C−C bond formation.
Abstract: Highly selective β-methylation of alcohols was achieved using an earth-abundant first row transition metal in the air stable molecular manganese complex [Mn(CO)2 Br[HN(C2 H4 Pi Pr2 )2 ]] 1 ([HN(C2 H4 Pi Pr2 )2 ]=MACHO-i Pr). The reaction requires only low loadings of 1 (0.5 mol %), methanolate as base and MeOH as methylation reagent as well as solvent. Various alcohols were β-methylated with very good selectivity (>99 %) and excellent yield (up to 94 %). Biomass derived aliphatic alcohols and diols were also selectively methylated on the β-position, opening a pathway to "biohybrid" molecules constructed entirely from non-fossil carbon. Mechanistic studies indicate that the reaction proceeds through a borrowing hydrogen pathway involving metal-ligand cooperation at the Mn-pincer complex. This transformation provides a convenient, economical, and environmentally benign pathway for the selective C-C bond formation with potential applications for the preparation of advanced biofuels, fine chemicals, and biologically active molecules.
76 citations
TL;DR: An improved phenol-sulfuric acid method was developed for the determination of carbohydrates in the presence of persulfate and showed that Na2SO3 was the best reagent for chemical pretreatment due to redox reaction, high selectivity and colorless oxidation product, and the others were not suitable as pretreatment reagents.
75 citations
TL;DR: The application of isoimpratorin in the synthesis of nano-metallic electro and photocatalysts, especially silver nanoparticles, is a simple, cost-effective and efficient approach.
Abstract: In the current study, isoimperatorin, a natural furanocoumarin, is used as a reducing reagent to synthesize isoimperatorin mediated silver nanoparticles (Iso-AgNPs), and photocatalytic and electrocatalytic activities of Iso-AgNPs are evaluated. Iso-AgNPs consisted of spherically shaped particles with a size range of 79–200 nm and showed catalytic activity for the degradation (in high yields) of New Fuchsine (NF), Methylene Blue (MB), Erythrosine B (ER) and 4-chlorophenol (4-CP) under sunlight irradiation. Based on obtained results, Iso-AgNPs exhibited 96.5%, 96.0%, 92%, and 95% degradation rates for MB, NF, ER, and 4-CP, respectively. The electrochemical performance showed that the as-prepared Iso-AgNPs exhibited excellent electrocatalytic activity toward hydrogen peroxide (H2O2) reduction. It is worth noticing that the Iso-AgNPs were used as electrode materials without any binder. The sensor-based on binder-free Iso-AgNPs showed linearity from 0.1 µM to 4 mM with a detection limit of 0.036 μM for H2O2. This binder-free and straightforward strategy for electrode preparation by silver nanoparticles may provide an alternative technique for the development of other nanomaterials based on isoimperatorin under green conditions. Altogether, the application of isoimpratorin in the synthesis of nano-metallic electro and photocatalysts, especially silver nanoparticles, is a simple, cost-effective and efficient approach.
75 citations
TL;DR: A review of recent advances in difluoroalkylation reactions using different substrates can be found in this paper, where RCF2X is reduced by metal, photocatalyst or bases to RCF 2 radical.
Abstract: This review describes recent advances in difluoroalkylation reactions using different substrates. Generally speaking, RCF2 radical is generally proposed in the mechanism of these reactions. At present, the most used difluoroalkylation reagent is RCF2X, which can be reduced by metal, photocatalyst or bases to RCF2 radical. Various substrates such as alkenes, alkynes, amines and so on could well be applied to these difluoroalkylation reactions.
72 citations
TL;DR: The satisfactory recovery values found in river and drinking water samples demonstrated the suitability of this sensor for screening analyses in water samples and revealed the attractiveness of this paper-based device thanks to the synergic combination of paper and carbon black as cost-effective materials.
70 citations
TL;DR: A boron compound has been shown to mediate the one-pot binding, cleavage and reduction of N 2 to ammonium salts under mild conditions through a complex cascade mechanism involving multiple reduction–protonation sequences.
Abstract: The industrial reduction of dinitrogen (N2) to ammonia is an energy-intensive process that consumes a considerable proportion of the global energy supply. As a consequence, species that can bind N2 and cleave its strong N-N bond under mild conditions have been sought for decades. Until recently, the only species known to support N2 fixation and functionalization were based on a handful of metals of the s and d blocks of the periodic table. Here we present one-pot binding, cleavage and reduction of N2 to ammonium by a main-group species. The reaction-a complex multiple reduction-protonation sequence-proceeds at room temperature in a single synthetic step through the use of solid-phase reductant and acid reagents. A simple acid quench of the mixture then provides ammonium, the protonated form of ammonia present in fertilizer. The elementary reaction steps in the process are elucidated, including the crucial N-N bond cleavage process, and all of the intermediates of the reaction are isolated.
69 citations
TL;DR: In this article, a 2D heterostructured composite material by substituting hexagonal boron nitride (h-BN) with polyaniline (Pani), h-BN@x%Pani, via an in situ chemical oxidative method was synthesized.
TL;DR: Investigations on the applicability of this photochemical transformation show that a broad variety of acidic alcohols can be subjected to this transformation and thus demonstrate the feasibility of this concept for O‐H functionalization reactions (54 examples, up to 98 % yield).
Abstract: Hexafluoroisopropanol is typically considered as an unreactive solvent and not as a reagent in organic synthesis. Herein, we report on a mild and efficient photochemical reaction of aryl diazoacetates with hexafluoroisopropanol that enables, under stoichiometric reaction conditions, the synthesis of fluorinated ethers in excellent yield. Mechanistic studies indicate there is a preorganization of hexafluoroisopropanol and the diazoalkane acts as an unreactive hydrogen-bonding complex. Only after photoexcitation does this complex undergo a protonation-substitution reaction to the reaction product. Investigations on the applicability of this photochemical transformation show that a broad variety of acidic alcohols can be subjected to this transformation and thus demonstrate the feasibility of this concept for O-H functionalization reactions (54 examples, up to 98 % yield).
TL;DR: In this article, the microstructure of sulfidated nanoscale zero-valent iron (S-nZVI) and the reaction mechanism with cadmium (Cd) were investigated.
TL;DR: The use of FhBC as an adsorbent for arsenic represents a new strategy of using the Fenton reaction while reducing secondary contamination, and avoiding the risk of secondary contamination.
TL;DR: The present reaction could be accomplished through the trifluoroalkylation of quinoxalin-2(1H)-ones with unactivated alkenes and Langlois' reagent (CF3SO2Na), which provided a highly attractive approach to access a series of biologically important 3-trifluoalkylated quin oxalin-1H-ones.
Abstract: A K2S2O8-mediated three-component protocol has been developed for the construction of 3-trifluoroalkylated quinoxalin-2(1H)-ones under metal-free conditions. The present reaction could be accomplis...
TL;DR: Mechanist-ically, a combination of quantum chemical and experimental observations suggest that the reaction proceeds via exchange of the NR and O substituents through intermediates featuring an aluminium-bound isocyanate fragment.
Abstract: Anionic molecular imide complexes of aluminium are accessible via a rational synthetic approach involving the reactions of organo azides with a potassium aluminyl reagent. In the case of K2 [(NON)Al(NDipp)]2 (NON=4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethyl-xanthene; Dipp=2,6-diisopropylphenyl) structural characterization by X-ray crystallography reveals a short Al-N distance, which is thought primarily to be due to the low coordinate nature of the nitrogen centre. The Al-N unit is highly polar, and capable of the activation of relatively inert chemical bonds, such as those found in dihydrogen and carbon monoxide. In the case of CO, uptake of two molecules of the substrate leads to C-C coupling and C≡O bond cleavage. Thermodynamically, this is driven, at least in part, by Al-O bond formation. Mechanistically, a combination of quantum chemical and experimental observations suggests that the reaction proceeds via exchange of the NR and O substituents through intermediates featuring an aluminium-bound isocyanate fragment.
TL;DR: A novel synthesis of 3-Nitrosoindoles starting from easily available N-nitrosoanilines and sulfoxonium ylides via Rh(III)-catalyzed acylmethylation and trifluoroacetic acid (TFA)-mediated nitroso transfer/cyclization cascade reaction in one pot has been developed.
TL;DR: In this article, a three-component annulation-halosulfonylation of 1,6-enynes has been developed for stereoselective synthesis of 33 examples of 1-indanones with generally good yields under environmentally benign conditions.
TL;DR: An unprecedented electrochemical trifluoromethylation/SO 2 -insertion/cyclization process has been achieved in an undivided cell in an atom-economic fashion.
Abstract: An unprecedented electrochemical trifluoromethylation/SO2 insertion/cyclization process has been achieved in an undivided cell in an atom-economic fashion. The protocol relies on tandem cyclization of N-cyanamide alkenes by using Langlois' reagent as a source of both CF3 and SO2 under direct anodically oxidative conditions, in which two C-C bonds, two C-X bonds (N-S and S-C), and two rings were formed in a single operation. This transformation enabled efficient construction of various trifluoromethylated cyclic N-sulfonylimines from readily accessible materials.
TL;DR: SF6 was applied as pentafluorosulfanylation reagent to prepare ethers with a vicinal SF5 substituent through a one‐step method involving photoredox catalysis, and toxic reagents are completely avoided.
Abstract: SF6 was applied as pentafluorosulfanylation reagent to prepare ethers with a vicinal SF5 substituent through a one-step method involving photoredox catalysis. This method shows a broad substrate scope with respect to applicable alcohols for the conversion of α-methyl and α-phenyl styrenes. The products bear a new structural motif with two functional groups installed in one step. The alkoxy group allows elimination and azidation as further transformations into valuable pentafluorosulfanylated compounds. These results confirm that non-toxic SF6 is a useful SF5 transfer reagent if properly activated by photoredox catalysis, and toxic reagents are completely avoided. In combination with light as an energy source, a high level of sustainability is achieved. Through this method, the proposed potential of the SF5 substituent in medicinal chemistry, agrochemistry, and materials chemistry may be exploited in the future.
TL;DR: In this article, a microwave-activated H2O2/PS double oxidants system was developed for NO removal from flue gas, and several experiments and characterization were conducted to study several fundamental issues of NO removal using the developed microwave activated H 2O2 /PS oxidation system (e.g., optimizing technological parameters, determining free radicals and products, and revealing NO removal mechanism).
TL;DR: Novel green nanocomposite from mesoporous MCM-41 and Co3O4 was synthesized from rice husk based silica gel and using the green extract of Peach leaves as reducing reagent and characterized by different techniques as green photocatalyst in the degradation of Acephate pesticide under visible light illumination.
TL;DR: In this article, a radical 1,3-trifluoromethylation/alkynylation of various allylboronic esters with concomitant 1,2-boron shift with alkynyl triflones is reported.
TL;DR: Ultrasonic-assisted electrochemical treatment for phenolic wastewater shows that microwave can accelerate the reaction rate, reduce the number of metal ions, save the process cost and reduce the difficulty of post-treatment.
TL;DR: Correlation analysis showed that the electricity generation of the TC-MFC was linearly related to the removal efficiency of heavy metals from soil (R2 = 0.9296).
TL;DR: The first Pd-catalyzed enantioselective azidation of unactivated alkenes using readily accessible 1-azido-1,2-benziodoxol-3(1H)-one (ABX) as an azidating source has been established herein, which affords a wide variety of structurally diverse 3-N3-substituted piperidines in good yields with excellent enantiOSElectivities.
Abstract: The first Pd-catalyzed enantioselective azidation of unactivated alkenes has been established by using readily accessible 1-azido-1,2-benziodoxol-3(1H)-one (ABX) as an azidating reagent, which affords a wide variety of structurally diverse 3-N3 -substituted piperidines in good yields with excellent enantioselectivity. The reaction features good functional-group compatibility and mild reaction conditions. Notably, both an electrophilic azidating reagent and the sterically bulky chiral pyridinyl-oxazoline (Pyox) ligand are crucial to the successful reaction.
TL;DR: The design and synthesis of hypervalent trifluoromethylthio-iodine(III) reagent 1 is reported and the elucidation of its structure by NMR spectroscopy and X-ray crystallography is elucidated.
TL;DR: This chemistry represents the first general use of iodo‐BCPs as electrophiles in cross‐coupling, and the first Kumada coupling of tertiary iodides, and enables the synthesis of a wide range of 1,3‐C‐disubstituted BCPs including various drug analogues.
Abstract: 1,3-Disubstituted bicyclo[1.1.1]pentanes (BCPs) are important motifs in drug design as surrogates for p-substituted arenes and alkynes. Access to all-carbon disubstituted BCPs via cross-coupling has to date been limited to use of the BCP as the organometallic component, which restricts scope due to the harsh conditions typically required for the synthesis of metallated BCPs. Here we report a general method to access 1,3-C-disubstituted BCPs from 1-iodo-bicyclo[1.1.1]pentanes (iodo-BCPs) by direct iron-catalyzed cross-coupling with aryl and heteroaryl Grignard reagents. This chemistry represents the first general use of iodo-BCPs as electrophiles in cross-coupling, and the first Kumada coupling of tertiary iodides. Benefiting from short reaction times, mild conditions, and broad scope of the coupling partners, it enables the synthesis of a wide range of 1,3-C-disubstituted BCPs including various drug analogues.
TL;DR: This finding allows the treatment of plasmonic excitation as a reagent in chemical reactions; the chemical potential of this reagent is tunable by the light intensity.
Abstract: By the photoexcitation of localized surface plasmon resonances of metal nanoparticles, one can generate reaction equivalents for driving redox reactions. We show that, in such cases, there is a chemical potential contributed by the plasmonic excitation. This chemical potential is a function of the concentration of light, as we determine from the light-intensity-dependent activity in the plasmon-excitation-driven reduction of CO2 on Au nanoparticles. Our finding allows the treatment of plasmonic excitation as a reagent in chemical reactions; the chemical potential of this reagent is tunable by the light intensity.