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1.
Mohsin Javed Muhammad Azam Qamar Sammia Shahid Hashem O. Alsaab Salma Asif 《RSC advances》2021,11(59):37254
The photocatalytic activity of photocatalysts is severely hampered by limited visible light harvesting and unwanted fast recombination of photogenerated e− and h+. In the current study, the photocatalytic efficiency of Cu–ZnO/S-g-C3N4 (CZS) nanocomposites was investigated against MB dye. The composite materials were designed via chemical co-precipitation method and characterised by important analytical techniques. Distinctive heterojunctions developed between S-g-C3N4 and Cu–ZnO in the CZS composite were revealed by TEM. The synthesized composites exhibit a huge number of active sites, a large surface area, a smaller size and better visible light absorption. The considerable enhancement in the photocatalytic activity of CZS nanocomposites might be accredited to the decay in the e–h pair recombination rate and a red shift in the visible region, as observed by PL and optical analysis, respectively. Furthermore, the metal (Cu) doping into the S-g-C3N4/ZnO matrix created exemplary interfaces between ZnO and S-g-C3N4, and maximized the photocatalytic activity of CZS nanocomposites. In particular, CZS nanocomposites synthesized by integrating 25% S-g-C3N4 with 4% Cu–ZnO (CZS-25 NCs) exhibited the 100% photocatalytic degradation of MB in 60 minutes under sunlight irradiation. After six cycles, the photocatalytic stability of CZS-25 NCs was excellent. Likewise, a plausible MB degradation mechanism is proposed over CZS-25 NCs based on photoluminescence and reactive species scavenger test observation. The current research supports the design of novel composites for the photocatalytic disintegration of organic contaminants.The photocatalytic activity of photocatalyst is severely hampered by limited visible light harvesting and unwanted fast recombination of photogenerated e− and h+. 相似文献
2.
In this study, the synthesis of nitrogen-doped zinc oxide nanoparticles with a cabbage like morphology (N-ZnONCBs) by a hydrothermal method using zinc acetate dihydrate as a precursor and hydrazine monohydrate as a nitrogen source is reported. N-ZnONCB were characterized using UV-visible Spectroscopy (UV-Vis), Fluorescence Spectroscopy, Fourier Transmittance Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Raman Spectroscopy, Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Electron Dispersive Spectroscopy (EDS) and EDX elemental mapping. N-ZnONCBs were tested for their photocatalytic capabilities in the degradation of methylene blue (MB) under UV-light and visible light irradiation for about 0 to 80 minutes and 0 to 50 min respectively. The N-ZnONCB catalyst demonstrated improved photodegradation efficiency (98.6% and 96.2%) and kinetic degradation rates of MB (k = −0.0579 min−1 and k = −0.0585 min−1) under UV light and visible light irradiation at different time intervals. The photodegradation study was also evaluated with different dosages of N-ZnONCB catalyst, different initial concentrations of MB and variation in the pH (3, 5, 9 and 11) of the solution of MB under UV light and visible light irradiation. The photocatalytic degradation intermediate products were obtained by liquid chromatography mass spectra (LC-MS) and also complete mineralization was determined by using Total Organic Carbon (TOC) studies. This photocatalyst was also tested with 2,4-dichlorophenol (2,4-DCP) under visible light irradiation at different time intervals. Fluorescence and quenching studies were performed for the binding interaction between the N-ZnONCB catalyst and MB dye. A Zetasizer was used to find the charge and average size of the N-ZnONCB catalyst and also the charge of the N-ZnONCB catalyst before and after MB dye solution adsorption. The N-ZnONCB catalyst was also tested for its photostability and reusability with a percentage degradation rate of MB (93.2%) after 4 cycle experiments. These results have clearly demonstrated that the N-ZnONCB catalyst can be applied for the photocatalytic degradation of MB from wastewater samples.In this study, the synthesis of nitrogen-doped zinc oxide nanoparticles with a cabbage like morphology (N-ZnONCBs) by a hydrothermal method using zinc acetate dihydrate as a precursor and hydrazine monohydrate as a nitrogen source is reported. 相似文献
3.
A novel ZnO–GO/CGH composite was prepared using an in situ synthesis process for photodegradation of methylene blue under visible light illumination. The chitin–graphene composite hydrogel (CGH) was used to provide uniform binding of the nano ZnO–GO composite to the hydrogel surface and prevent their agglomeration. GO provides multi-dimensional protons and electron transport channels for ZnO with a flower-like structure, which possessed improved photo-catalytic activity. SEM analysis indicates that the hydrogel has good adsorption properties with rougher surfaces and porous microstructure, which enables it to adsorb the dyes effectively. Under synergetic enhancement of adsorption and photo-catalysis, catalytic activity and nano ZnO–GO/CGH recycling improved greatly. Synthesized nano ZnO–GO/CGH showed high dye removal efficiency of 99%, about 2.2 times that of the pure chitin gel under the same condition. This suggests the potential application of the new photocatalytic composites to remove organic dyes from wastewater.A novel ZnO–GO/CGH composite was prepared using an in situ synthesis process for photodegradation of methylene blue under visible light illumination. 相似文献
4.
Liyan Wang Yangwen Hou Shanshan Xiao Fei Bi Li Zhao Yingqi Li Xiaojia Zhang Guangqing Gai Xiangting Dong 《RSC advances》2019,9(67):39304
A facile template-free one-step synthesis method of ultrathin g-C3N4 nanosheets was developed through thermal polycondensation of melamine. The higher temperature, prolonged time and tightly sealed crucible reaction system contributed to the formation of ultrathin g-C3N4 nanosheets. The as-synthesized g-C3N4 nanosheets were applied to the visible light photocatalytic degradation of RhB. The photocatalytic activity was significantly enhanced with increased calcination temperature from 500 °C to 650 °C and prolonged calcination time from 4 h to 10 h. Interestingly, the obtained ultrathin g-C3N4 nanosheets simultaneously possess high yield and excellent photocatalytic activity. Moreover, g-C3N4 nanosheets can maintain photochemical stability after five consecutive runs. The remarkably enhanced photocatalytic activity can be interpreted as the synergistic effects of the enhanced crystallinity, the large surface area, the reduced layer thickness and size and the reduced number of defects. A new layer exfoliation and splitting mechanism of the formation of the ultrathin nanosheets was proposed. This work provides a new strategy to develop a facile eco-friendly template-free one-step synthesis method for potential large-scale synthesis of ultrathin nanosheets with high yield, high photocatalytic efficiency and stable activity for environmental and energetic applications.g-C3N4 with enhanced photocatalytic activity and high yield is synthesized by a one-step pyrolysis method of melamine in a sealed crucible. 相似文献
5.
Rooha Khurram Zhan Wang Muhammad Fahad Ehsan Song Peng Maryam Shafiq Bushra Khan 《RSC advances》2020,10(73):44997
The leading challenge towards environmental protection is untreated textile dyes. Tailoring photocatalytic materials is one of the sustainable remediation strategies for dye treatment. Hematite (α-Fe2O3), due to its favorable visible light active band gap (i.e. 2.1 eV), has turned out to be a robust material of interest. However, impoverished photocatalytic efficiency of α-Fe2O3 is ascribable to the short life span of the charge carriers. Consequently, the former synthesized heterostructures possess low degradation efficiency. The aim of the proposed endeavor is the synthesis of a novel zinc telluride-modified hematite (α-Fe2O3/ZnTe) heterostructure, its characterization and demonstration of its enhanced photocatalytic response. The promising heterostructure as well as bare photocatalysts were synthesized via a hydrothermal approach. All photocatalysts were characterized by the X-ray diffraction technique (XRD), scanning electron microscopy (SEM), and electron diffraction spectroscopy (EDX). Moreover, the selectivity and activity of the photocatalyst are closely related to the alignment of its band energy levels, which were estimated by UV-Vis diffuse reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). Nanomaterials, specifically α-Fe2O3 and α-Fe2O3/ZnTe, were used for the degradation of Congo red (97.9%), methyl orange (84%) and methylene blue (73%) under light irradiation (>200 nm) for 60 min. The results suggested that with the aforementioned optimized fabricated heterostructure, the degradation efficiency was improved in comparison to bare hematite (α-Fe2O3). The key rationale towards such improved photocatalytic response is the establishment of a type-II configuration in the α-Fe2O3/ZnTe heterostructure.Effective generation and transportation of electron–hole pairs in the presence of light leads to efficient degradation of textile pollutants over an α-Fe2O3/ZnTe nanocomposite compared to the individual components. 相似文献
6.
Liyana Labiba Zulfa Ratna Ediati Alvin Romadhoni Putra Hidayat Riki Subagyo Nuhaa Faaizatunnisa Yuly Kusumawati Djoko Hartanto Nurul Widiastuti Wahyu Prasetyo Utomo Mardi Santoso 《RSC advances》2023,13(6):3818
Mesoporous heterojunction MOF-derived α-Fe2O3/ZnO composites were prepared by a simple calcination of α-Fe2O3/ZIF-8 as a sacrificial template. The optical properties confirm that coupling of both the modified pore and the n–n heterojunction effectively reduces the possibility of photoinduced charge carrier recombination under irradiation. The mesoporous Fe(25)ZnO with 25% loading of α-Fe2O3 exhibited the best performance in MB degradation, up to ∼100% after 150 minutes irradiation, higher than that of pristine ZnO and α-Fe2O3. Furthermore, after three cycles reusability, mesoporous Fe(25)ZnO still showed an excellent stability performance of up to 95.42% for degradation of MB. The proposed photocatalytic mechanism of mesoporous Fe(25)ZnO for the degradation of MB corresponds to the n–n heterojunction system. This study provides a valuable reference for preparing mesoporous MOF-derived metal oxides with an n–n heterojunction system to enhance MB photodegradation.Mesoporous heterojunction MOF-derived α-Fe2O3/ZnO composites were prepared by a simple calcination of α-Fe2O3/ZIF-8 as a sacrificial template. 相似文献
7.
Miku Nomura Zubeda Begum Chigusa Seki Yuko Okuyama Eunsang Kwon Koji Uwai Michio Tokiwa Suguru Tokiwa Mitsuhiro Takeshita Hiroto Nakano 《RSC advances》2023,13(6):3715
Catalytic functionality of new optically active thiourea fused γ-amino alcohols was examined in the asymmetric Mannich reaction of β-keto active methylene compounds with imines to afford chiral Mannich products, β-amino keto compounds, with continuous chiral centers, that are versatile synthetic intermediates for deriving various biologically active compounds. In particular, the thiourea fused γ-amino alcohols showed satisfactory catalytic activity in this reaction and afforded chiral Mannich products in excellent chemical yield (up to 88%) and stereoselectivities (up to syn : anti/93 : 7 dr, up to 99% ee).Catalytic functionality of new optically active thiourea fused γ-amino alcohols was examined in the asymmetric Mannich reaction of β-keto active methylene compounds with imines to afford chiral Mannich products, β-amino keto compounds.. 相似文献
8.
Haicheng Li Linlin Zang Fengtong Shen Libin Wang Liguo Sun Fulong Yuan 《RSC advances》2021,11(30):18519
The preparation of high-efficiency, pollution-free photocatalysts for water treatment has always been one of the research hotspots. In this paper, a carbon framework formed from waste grapefruit peel is used as the carrier. A simple one-step chemical vapor deposition (CVD) method allows tubular g-C3N4 to grow on the carbon framework. Tubular g-C3N4 increases the specific surface area of bulk g-C3N4 and enhances the absorption of visible light. At the same time, the carbon framework can effectively promote the separation and transfer of charges. The dual effects of static adsorption and photodegradation enable the g-C3N4/carbon (CNC) framework to quickly remove about 98% of methylene blue within 180 min. The recyclability indicates that the tubular g-C3N4 can stably exist on the carbon framework during the photodegradation process. In the dynamic photocatalytic test driven by gravity, roughly 77.65% of the methylene blue was degraded by the CNC framework. Our work provides an attractive strategy for constructing a composite carbon framework photocatalyst based on the tubular g-C3N4 structure and improving the photocatalytic performance.Tubular g-C3N4 grown on a carbon framework increased the surface area of bulk g-C3N4, enhanced the absorption of visible light and promoted the photocatalytic performance. 相似文献
9.
Information on the turnover and lifespan of murine γ/δ cells was obtained by administering the DNA precursor, bromodeoxyuridine (BrdU), in the drinking water and staining lymphoid cells for BrdU incorporation. For TCR-γ/δ (Vγ2) transgenic mice, nearly all γ/δ thymocytes became BrdU+ within 2 d and were released rapidly into the peripheral lymphoid tissues. These recent thymic emigrants (RTEs) underwent phenotypic maturation in the periphery for several days, but most of these cells died within 4 wk. In adult thymectomized (ATx) transgenic mice, only a small proportion of γ/δ cells survived as long-lived cells; most of these cells had a slow turnover and retained a naive phenotype. As in transgenic mice, the majority of RTEs generated in normal mice (C57BL/6) appeared to have a restricted lifespan as naive cells. However, in marked contrast to TCR transgenic mice, most of the γ/δ cells surviving in ATx normal mice had a rapid turnover and displayed an activated/memory phenotype, implying a chronic response to environmental antigens. Hence, in normal mice many γ/δ RTEs did not die but switched to memory cells. 相似文献
10.
Marie Malissen Pablo Pereira David J. Gerber Bernard Malissen James P. DiSanto 《The Journal of experimental medicine》1997,186(8):1277-1285
We have investigated the role of common γ chain (γc)-signaling pathways for the development of T cell receptor for antigen (TCR)-γ/δ T cells. TCR-γ/δ–bearing cells were absent from the adult thymus, spleen, and skin of γc-deficient (γc−) mice, whereas small numbers of thymocytes expressing low levels of TCR-γ/δ were detected during fetal life. Recent reports have suggested that signaling via interleukin (IL)-7 plays a major role in facilitating TCR-γ/δ development through induction of V-J (variable-joining) rearrangements at the TCR-γ locus. In contrast, we detected clearly TCR-γ rearrangements in fetal thymi from γc− mice (which fail to signal in response to IL-7) and reduced TCR-γ rearrangements in adult γc thymi. No gross defects in TCR-δ or TCR-β rearrangements were observed in γc− mice of any age. Introduction of productively rearranged TCR Vγ1 or TCR Vγ1/Vδ6 transgenes onto mice bearing the γc mutation did not restore TCR-γ/δ development to normal levels suggesting that γc-dependent pathways provide additional signals to developing γ/δ T cells other than for the recombination process. Bcl-2 levels in transgenic thymocytes from γc− mice were dramatically reduced compared to γc+ transgenic littermates. We favor the concept that γc-dependent receptors are required for the maintenance of TCR-γ/δ cells and contribute to the completion of TCR-γ rearrangements primarily by promoting survival of cells committed to the TCR-γ/δ lineage. 相似文献
11.
Komal Harmandeep Kaur Money Kainth Sher Singh Meena Tejwant Singh Kang 《RSC advances》2019,9(71):41803
Inspired by the nano-segregation of ionic liquids (ILs) into bi-continuous structures constituting of arrays of ionic and non-ionic components, herein, a new and sustainable strategy for preparation of mesh-like nano-sheet α-Fe2O3 nanoparticles and their photo-catalytic activity under sunlight, is presented. For the purpose, metal (iron) containing ionic liquids (MILs), 1-alkyl-3-methylimidazolium tetrachloroferrates, [Cnmim][FeCl4], (n = 4, 8 and 16), which not only act as precursors and solvents but also as structure directing agents have been used. Thus prepared NPs show MIL dependent structural, photophysical and magnetic properties. The catalytic efficiency of NPs has been tested for the photo-degradation of organic dyes (Rhodamine B) in aqueous solution under sunlight. The NPs are found to exhibit comparable catalytic efficiency under sunlight as compared to that observed under high intensity visible lamplight, without showing a decline in their catalytic efficiency even after 4 catalytic cycles. It is anticipated that the present work will provide a new platform for preparation of sunlight active nanomaterials for photo-catalytic applications with control over the structural and physical properties via varying the molecular structure of MILs.Inspired by nanosegregation of ionic liquids into bicontinuous structures of arrays of ionic and non-ionic components, we present a new sustainable strategy for preparation of mesh-like nano-sheets of α-Fe2O3 nanoparticles and their photocatalytic activity under sunlight. 相似文献
12.
In this article, the catalyst Au/γ-Fe2O3@hydroxyapatite (Au/γ-Fe2O3@HAP) consisting of Au nanoparticles supported on the core–shell structure γ-Fe2O3@HAP was prepared through a deposition–precipitation method. The catalyst was characterized by transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, N2 adsorption–desorption and atomic absorption spectrometry. The as-prepared Au/γ-Fe2O3@HAP exhibited excellent performance for the reduction of 4-nitrophenolate (4-NP) to 4-aminophenolate (4-AP) in the presence of NaBH4 at room temperature. Thermodynamic and kinetic data on the reduction of 4-NP to 4-AP catalyzed by the as-prepared catalyst were studied. The as-prepared catalyst could be easily separated by a magnet and recycled 6 times with over 92% conversion of 4-NP to 4-AP. In addition, the as-prepared catalyst showed excellent catalytic performance on other nitrophenolates. The TOF value of this work on the reduction of 4-NP to 4-AP was 241.3 h−1. Au/γ-Fe2O3@HAP might have a promising potential application on the production of 4-AP and its derivatives.In this article, the catalyst Au/γ-Fe2O3@hydroxyapatite (Au/γ-Fe2O3@HAP) consisting of Au nanoparticles supported on the core–shell structure γ-Fe2O3@HAP was prepared through a deposition–precipitation method. 相似文献
13.
Ajay Kumar Adepu Srinath Goskula Suman Chirra Suresh Siliveri Sripal Reddy Gujjula Venkatathri Narayanan 《RSC advances》2019,9(42):24368
In the present study, we synthesized several high-surface area V2O5/TiO2–SiO2 catalysts (vanado titanium silicate, VTS). The synthesized materials were characterized by PXRD, FE-SEM/EDAX, TEM, FTIR, UV-Vis, XPS, fluorescence and photocatalytic activity studies. The small-angle powder X-ray diffraction pattern shows that the 110 and 200 planes are merged to become a single broad peak. Field-emission scanning electron microscopy shows that the titanosilicate is spherical in shape and V2O5 has a hexagonal rod-shaped morphology. The presence of various metal ions, such as V, Ti, Si and O, was observed by energy dispersive X-ray analysis and X-ray photoelectron spectroscopy. The transmission electron microscopy image shows clear hexagonal mesoporous fringes with V2O5 distribution. The BET surface area analysis shows that the VTS catalysts have higher surface areas than pure V2O5. Fourier transform infrared spectroscopic analysis shows the presence of Ti4+ ions connected to the silanol groups. The bandwidths of pure titanosilicate, V2O5 and their composites were calculated from their diffuse reflectance ultraviolet-visible spectra. The bandwidth was tuned by heterojunctions in the studied catalysts. The photoluminescence spectra of the VTS catalysts show a distinct behaviour as compared to those of the pure components. The photocatalytic activity of methylene blue degradation was determined with pure constituents and catalysts. VTS-1 (TS and VO weight ratio 2 : 1) shows higher conversion than other catalysts, pure titanosilicate and V2O5. This is probably due to the heterojunctions and higher surface area in VTS-1. Kinetic studies reveal that direct sunlight shows higher activity than pure visible light. A plausible physical and chemical mechanism for the photocatalytic activity is proposed.In the present study, we synthesized several high-surface area V2O5/TiO2–SiO2 catalysts (vanado titanium silicate, VTS). The synthesized materials are characterized by PXRD, FE-SEM/EDAX, TEM, BET-surface area, FT-IR, UV-Vis, XPS, fluorescence and photocatalytic studies. 相似文献
14.
Graphdiyne (GD), a novel two dimensional (2D) carbon material, has earned a lot of attention in recent years. Constructing a novel hybrid nanomaterial based on GD, macrocyclic host and Au nanoparticles is an effective strategy for heterogeneous catalysis applications. While tremendous advancements in the preparation of two dimensional (2D) materials anchoring Au nanoparticles have been made, it is an urgent requirement to explore a green, efficient and facile approach for obtaining small-sized Au nanoparticles. The use of the 2D material graphdiyne (GD) presents more-promising candidates for constructing excellent sites for loading metal nanoparticles. In this study, a novel 2D heterogeneous hybrid nanomaterial (P5A-Au-GD) based on GD and pillar[5]arene (P5A)-reduced Au nanoparticles (P5A-Au) was successfully prepared. In this strategy, the P5A can reduce HAuCl4 with the aid of NaOH in the dispersion of GD. Accordingly, the generated P5A-Au can immediately interact with GD to form the P5A-Au-GD hybrid nanomaterial without any harsh reduced materials or other energies. The Au nanoparticles with average diameter of 2–3 nm are homogeneously dispersed on the surface of GD. The heterogeneous 2D catalyst of P5A-Au-GD shows high catalytic performances in the reduction of 4-nitrophenol and methylene blue by comparing commercial Pd/C catalyst. Meanwhile, the unique 2D heterogeneous hybrid material P5A-Au-GD exhibits durable recyclability and stability during the catalytic reaction. Considering the outstanding merits of the heterogeneous 2D catalyst of P5A-Au-GD as well as the simple and green preparation, this study might not only present enormous opportunities for the stabilized, high-performance and sustainable catalysts but also be applied in other frontier studies of sustainable functionalized nanocomposites and advanced materials.Application of a novel 2D heterogeneous hybrid nanomaterial based on graphdiyne and pillar[5]arene-reduced Au nanoparticles in catalyzing the reduction of 4-nitrophenol and methylene blue. 相似文献
15.
The inefficiency of conventional photocatalytic treatment for removing rhodamine B is posing potential risks to ecological environments. Here, we construct a highly efficient photocatalyst consisting of Ag3PO4 and α-Fe2O3 hybrid powders for the treatment of rhodamine B. Ag3PO4 nanoparticles (nanoparticles, about 50 nm) are uniformly dispersed on the surface of α-Fe2O3 microcrystals (hexagonal sheet, about 1.5 μm). The Ag3PO4-deposited uniformity on the α-Fe2O3 surface first increased, then decreased on increasing the hybrid ratio of Ag3PO4 to α-Fe2O3. When the hybrid ratio of Ag3PO4 to α-Fe2O3 is 1 : 2, the distribution of Ag3PO4 particles on the sheet α-Fe2O3 is more uniform with excellent Ag3PO4/α-Fe2O3 interface performance. The catalytic degradation efficiency of hybrids with the introduction of Ag3PO4 nanoparticles on the α-Fe2O3 surface reached 95%. More importantly, the hybrid material exhibits superior photocatalytic stability. Ag3PO4/α-Fe2O3 hybrids have good reusability, and the photocatalytic efficiency could still reach 72% after four reuses. The excellent photocatalytic activity of the as-prepared hybrids can be attributed to the heterostructure between Ag3PO4 and α-Fe2O3, which can effectively inhibit the photoelectron–hole recombination and broaden the visible light response range.We construct a highly efficient photocatalyst consisting of Ag3PO4 and α-Fe2O3 hybrid powders for the treatment of rhodamine B. The catalytic degradation efficiency reached 95% after 10 min. 相似文献
16.
γ-Keto sulfones are versatile building blocks and valuable intermediates in organic synthesis and pharmaceutical chemistry. Motivated by their excellent properties, we herein report a green, convenient, metal-free hydrosulfonylation method for a variety of ynones, vinyl ketones, and sodium sulfinates in the absence of stoichiometric oxidants. This operationally simple protocol provides straightforward and practical access to a wide range of γ-keto sulfones with broad functional group tolerance from easily available starting materials. Moreover, the β,γ-unsaturated keto sulfones could further react with 2,3-butadienoate to generate cyclopentenes in phosphine-mediated [3 + 2] cycloaddition.The methodology features a convenient, mild, efficient, C–S sulfonylation approach without the use of any metal catalysts and stoichiometric oxidants.As a useful common structural fragment in a broad number of pharmaceuticals1 and functional materials,2 keto sulfones are usually present in promising biologically active molecules such as Casodex,3VCAM-1 (ref. 4) and anti-HIV-1 (ref. 5) (Fig. 1). Furthermore, a valuable synthetic impression is associated with the role of reactive intermediates in various high-demand synthetic transformations,6 including total synthesis.7 Owing to their excellent properties, and efficient and practical synthesis methods keto sulfones are in high demand.Open in a separate windowFig. 1Representative biologically active γ-keto sulfones.In the past decades, a variety of protocols have been developed to construct β-keto sulfones.8 Whereas succinct synthetic routes toward structurally related γ-keto sulfones are scarce,9 traditionally, γ-keto sulfones were synthesized via the nucleophilic substitution of sodium sulfinates by 2-chlorovinyl ketones,10 the elimination of the bromo derivatives of saturated keto sulfones11 and the oxidation of the corresponding sulfides or sulfoxides.12 However, the principal drawback is that these procedures were strongly limited by multiple steps, narrow substrate scope, or poor stereoselectivity.Indeed, several streamlined strategies for the preparation of γ-keto sulfones involves addition reaction of alkenes or alkynes have been developed.13 Li''s group14 reported the synthesis of (E)-vinyl sulfones through Pd-catalyzed conjugate additions of alkynes with 1,2-bis(phenylsulfonyl)ethane. In 2013 Jiang and co-workers15 showed that a Pd-catalyzed sulfonylation of alkynoates with sodium sulfinates affords γ-keto sulfones (Scheme 1a). Li and coworkers16 reported that BPO triggered the hydrosulfonylation of chalcones with arylsulfonyl hydrazides producing γ-keto sulfones. Subsequently, Bi''s group17 developed a Ag2CO3-promoted sulfonylation of allyl/propargyl alcohols with sodium sulfinates for the preparation of γ-keto sulfones (Scheme 1b). Nevertheless, most cases still have to use large excess oxidants, noble metal catalysts, or require high temperatures. Accordingly, an efficient, mild and practical method to furnish γ-keto sulfones is worthwhile studying.Open in a separate windowScheme 1Methods for the synthesis of γ-keto sulfones.With growing demand for sustainable chemistry, an “ideal” reaction system for such transformations would be “metal-free” due to cost efficiency and possible advantages regarding toxicity, as well as selectivity. With this intent, we herein describe a simple and efficient acid-mediated sulfonylation of sodium sulfinates and α,β-unsaturated ketones for the selective synthesis of γ-keto sulfones (Scheme 1c). The significant advantages of this method are high efficiency, metal-free and mild reaction conditions, thus providing a potential application in natural product synthesis and medicinal chemistry.Further studies were commenced with the optimization of the conditions for the hydrosulfonylation of the ynone 1f with sodium benzosulfonate 2a (13e and acetyl chloride/H2O,19 as used in the previous study, were completely ineffective due to several unknown complex products being formed (entry 1). Gratifyingly, the desired γ-keto sulfone 3fa was isolated in a 49% yield (E/Z = 90 : 10) as the major product for the reaction mediated by AcOH (entry 3). Encouraged by this initial result, we screened an array of acids. The results showed that 4-chlorobenzoic acid (PCBA) gave the best result, leading to the isolation of γ-keto sulfone 3fa in a yield of 80% (E/Z = 98 : 02) (entries 4–15). Solvent screening indicated that mesitylene could improve the yield to 85% (E/Z = 95 : 05) (entry 21). Further investigations on the reduced usage of PCBA to 2.0 equivalents, the yield of 3fa was slightly reduced (entry 22, 83% yield, E/Z = 95 : 05). The amounts of sodium benzosulfonate 2a and the reaction temperature have deleterious effects on the reaction yields (entries 23–27). Thus, the optimized reaction conditions were successfully established as 1f (1.0 equiv.), 2a (2.5 equiv.), PCBA (2.0 equiv.), and mesitylene (2.0 mL) at 30 °C in this process.Optimization of the reaction conditionsa
Open in a separate windowaReaction conditions: 1f (0.1 mmol), 2a (0.25 mmol), acid (x equiv.), solvent (1.0 mL), 30 °C, 48 h.bIsolated yields.cDetermined by RP-HPLC.dWith 2.0 equiv. 2a.e50 °C.f80 °C. PCBA = 4-chlorobenzoic acid. PNBA = p-nitrobenzoic acid.We then sought to explore the generality of the method for the synthesis of α,β-unsaturated γ-keto sulfones, using various ynones in reactions with 2a under the optimized conditions (Scheme 2). The reaction of the 1-phenylprop-2-yn-1-one 1a with 2a proceeded reasonably to provide an excellent yield of the corresponding γ-keto sulfone 3aa (97% yield, E/Z = 98 : 02). To our delight, the reaction worked successfully with a range of ynones 1 bearing various substituents on the aromatic ring. Substituents such as methyl, thiomethylmethoxy, phenyl, halogen and dimethylamino atoms could be tolerated and gave the corresponding products 3ba–3ja with high to excellent yields (71–98% yield) and stereoselectivity (E/Z = 82 : 18 to 98 : 02). Trifluoromethyl and nitro substituents on the aromatic ring were also compatible and products 3ka and 3la were afforded 95% and 71% yields, respectively. 9-Anthracenee-derived ynone successfully afforded 3ma in a 94% yield (E/Z = 98 : 02). The methyl group in the ortho or meta positions of the aromatic ring gave the desired γ-keto sulfones in 82% and 94% yield, respectively. The desired product 3pa bearing a pitavastatin unit could be readily prepared in a yield of 87%. When alkyl terminal alkynone 1q was subjected to the reaction, affording the desired product 3qa in 65% yield (E/Z = 97 : 03).1Open in a separate windowScheme 2Sulfonylation reaction of various terminal alkynones with 2a. All reactions were carried on 0.2 mmol scale in mesitylene (2.0 mL) and used 2.5 equiv. of 2a, 2.0 equiv. PCBA, at 30 °C. Yields of isolated products are reported. E/Z ratios were determined by RP-HPLC.Inspired by the above results, the nonterminal alkyne was used as the substrate to react with PhSO2Na at 30 °C for 36 h. The reaction provided E and Z-β-sulfonyl-α,β-unsaturated carbonyl mixed compounds 3qa13e (86% yield, E/Z = 1 : 1).The results of ynone 1a reacting with a number of sodium sulfinates under the optimized condition are depicted in Scheme 3. Gratifyingly, no matter whether the phenyl ring of sodium sulfinate was substituted with either a sterically hindered, electron-donating, or electron-withdrawing group, all of them smoothly furnished the corresponding products in moderate to excellent yields with a high range of E/Z ratios from 52 : 48 to 97 : 03 (3ab–3an). Likewise, 2-napthyl and cyclopropyl substituted sodium sulfinates were both effective in this reaction with a yield of 87% and 85%, respectively (3ao and 3ap). Additionally, l-10-camphorsulfonyl sulfinate 2q was also suitable for this reaction.Open in a separate windowScheme 3Sulfonylation reaction of terminal alkynone (1a) with sodium Sulfinates. All reactions were carried on 0.2 mmol scale in mesitylene (2.0 mL) and used 2.5 equiv. of 2, 2.0 equiv. PCBA, at 30 °C. Yields of isolated products are reported. E/Z ratios were determined by RP-HPLC.Interestingly, the treatment of the vinyl ketone 4a with PhSO2Na (2a) under the standard conditions furnished sulfone 5aa (Scheme 4). The substrate scope was also explored in Scheme 4. Delightfully, it was perfectly tolerable to introduce both electron-donating (OCH3 and Ph) and electron-withdrawing (F, Cl, and CN) groups at the para position of the phenyl ring, affording the corresponding products (5ba–5fa) in excellent yields. 4-Toluene sulfonate and cyclopropane sulfonate also reacted well with substrate 2a to form γ-keto sulfone in excellent yields. We were pleased to find that the β-trifluoromethylated enone 4h and trans-chalcone (4i–4j) could be successfully employed to give desired products (5ha–5ja, 55–61% yields). Unfortunately, no reaction occurred for 2-cyclopentenone.Open in a separate windowScheme 4Sulfonylation reaction of vinyl ketone with sodium sulfinates. All reactions were carried on 0.2 mmol scale in mesitylene (2.0 mL) and used 2.0 equiv. of 2a, 2.0 equiv. PCBA, at 30 °C. Yields of isolated products are reported. aAt 80 °C for 72 h.Additionally, the synthetic utility of the γ-keto sulfones obtained by the present method was explored (Scheme 5). Gram-scale ynone 1a was reacted with sodium benzosulfonate 2a to form product 3aa with an excellent E/Z ratio (A). Lu''s [3 + 2] cycloaddition of 2,3-butadienoate with α,β-unsaturated γ-keto sulfones 3 mediated by phosphine produced cycloadducts 6 (ref. 18) in good yields (B). Moreover, pyrazole derivative 6b could be efficiently obtained from 3aa under ultrasound (US) irradiation conditions (C). Next, γ-keto sulfone 3pa derived from the biologically active pitavastatin could also react with hydrazine to give a high yield of 6c (D).Open in a separate windowScheme 5Gram-scale preparation and further synthetic utilization.To understand the reaction mechanism, control reactions of 1a with 2a were examined (Scheme 6a). When 1a and 2a was subjected to the standard reaction conditions except using deuterated 4-chlorobenzoic acid system, the 3a were detected with 80% yield. An attempt to run the reaction of 1a and 2a in a anhydrous solvent system under an N2 atmosphere also successfully delivered 3a in 97% yield.20 The results unambiguously disclosed that the incorporated hydrogen atoms in 3a originated from acid rather than water. The reaction using 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and 2,4-di-tert-butyl-4-methylphenol (BHT) as the radical scavengers showed no observable radical intermediates and unaffected desired products formation, which suggests that the radical process could be ruled out.20 On the basis of the results presented above and previous reports, we propose the following mechanism in Scheme 6b. The 4-chlorobenzoic acid activates the carbonyl group in α,β-unsaturated ketones 1 (4) to afford intermediate I or tautomerize to intermediate II. Finally, sulfonyl anion can add to the unsaturated bond of intermediate II to afford the products 3 (5).Open in a separate windowScheme 6Mechanistic studies. 相似文献
Entry | Acid (x equiv.) | Solvent | Yieldb (%) | E/Zc |
---|---|---|---|---|
1 | Buffer (pH = 3.5) | DMF | NR | — |
2 | Acetyl chloride/H2O | CHCl3 | NR | — |
3 | AcOH (3.0) | Toluene | 49 | 90 : 10 |
4 | HCO2H (3.0) | Toluene | 23 | 85 : 15 |
5 | HCl (3.0) | Toluene | 36 | 80 : 20 |
6 | HNO3 (3.0) | Toluene | 36 | 87 : 13 |
7 | Benzoic acid (3.0) | Toluene | 66 | 96 : 04 |
8 | p-Toluic acid (3.0) | Toluene | 52 | 96 : 04 |
9 | 4-Acetylbenzoic acid (3.0) | Toluene | 57 | 96 : 04 |
10 | 4-Fluorobenzoic acid (3.0) | Toluene | 73 | 98 : 02 |
11 | PCBA (3.0) | Toluene | 80 | 98 : 02 |
12 | 4-Bromobenzoic acid (3.0) | Toluene | 72 | 95 : 05 |
13 | PNBA (3.0) | Toluene | 57 | 88 : 12 |
14 | 2-Naphthoic acid (3.0) | Toluene | 48 | 94 : 06 |
15 | 2-Nitrobenzoic acid (3.0) | Toluene | 29 | 94 : 06 |
16 | PCBA (3.0) | o-Xylene | 73 | 92 : 08 |
17 | PCBA (3.0) | p-Xylene | 70 | 90 : 10 |
18 | PCBA (3.0) | m-Xylene | 72 | 96 : 04 |
19 | PCBA (3.0) | DMF | NR | — |
20 | PCBA (3.0) | MeOH | 68 | 89 : 11 |
21 | PCBA (3.0) | Mesitylene | 85 | 95 : 05 |
22 | PCBA (2.0) | Mesitylene | 83 | 95 : 05 |
23 | PCBA (1.2) | Mesitylene | 76 | 91 : 09 |
24 | PCBA (0.5) | Mesitylene | 44 | 73 : 27 |
25d | PCBA (2.0) | Mesitylene | 79 | 90 : 10 |
26e | PCBA (2.0) | Mesitylene | 80 | 95 : 05 |
27f | PCBA (2.0) | Mesitylene | 53 | 97 : 03 |
17.
Jiandong Liu Xiaohong Ma Lina Yang Xingliang Liu Aixia Han Haitang Lv Chao Zhang Shiai Xu 《RSC advances》2018,8(13):7142
A simple in situ green oxidation synthesis route was developed to prepare Ti3+ and N self-doped SrTiOxNy nanoparticles using TiN and H2O2 as precursors. X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) were used to characterize the crystallinity, structure and morphology. X-ray photoelectron spectroscopy (XPS) tests confirmed the presence of Ti3+ and N in the prepared SrTiOxNy nanoparticles. The resultant nanoparticles were shown to have strong absorption from 400 to 800 nm using UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The formation mechanism of the Ti3+ and N self-doped SrTiOxNy nanoparticles was also discussed. Under visible light irradiation, the obtained Ti3+ and N self-doped samples showed higher photocatalytic activity for the degradation of the model wastewater, methylene blue (MB) solution. The most active sample T-130-Vac, obtained at 130 °C under vacuum, showed a 9.5-fold enhancement in the visible light decomposition of MB in comparison to the commercial catalyst nano-SrTiO3. The sample also showed a relatively high cycling stability for photocatalytic activity.A simple in situ green oxidation synthesis route was developed to prepare Ti3+ and N self-doped SrTiOxNy nanoparticles using TiN and H2O2 as precursors. 相似文献
18.
An efficient synthesis of imides using metal-free photoredox-catalyzed direct α-oxygenation of N,N′-disubstituted anilines in the presence of 9-mesityl-10-methylacridinium [Acr+-Mes]BF4 as a photoredox catalyst and molecular oxygen as a green oxidant under visible light was developed. This photochemical approach offered operational simplicity, high atom economy with a low E-factor, and functional group tolerance under mild reaction conditions. Control and quenching experiments confirmed the occurrence of a radical pathway and superoxide radical anion α-oxygenation reactions, and also provided strong evidence for the reductive quenching of [Acr+-Mes]BF4 based on a Stern–Volmer plot, which led to the proposed mechanism of this reaction.A visible-light-mediated direct α-oxygenation of N,N-dibenzylanilines to imides in the presence of [Acr+-Mes]BF4 as a metal-free photocatalyst and O2 as a green oxidant. 相似文献
19.
Nanocomposites of tetraaniline (TAN) nanostructures/silver nanoparticles (Ag NPs) were synthesized by an interfacial polymerization method using N-phenyl-1, 4-phenylenediamine (NPPD), AgNO3 and ammonium persulphate (APS) as monomer, oxidizing agent in immiscible solvent toluene–water respectively. The structure and morphology of the as-prepared TAN and Ag NPs were investigated by UV-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and thermogravimetry (TG). The results of FTIR spectroscopy confirmed the formation of TAN and Ag NPs and those of XRD showed the presence of the face centred cubic (fcc) phase of Ag NPs. The FESEM and TEM images gave direct evidence that Ag NPs stabilized with the TAN nanostructures. TGA indicated the enhanced thermal stability of the nanocomposites (NCs). The catalytic activity of TAN/Ag NCs was investigated for the model reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of excess sodium borohydride.Nanocomposites of tetraaniline/silver nanoparticles were synthesised using an interfacial polymerisation method. The catalytic activity was investigated for the model reduction of 4-nitrophenol to 4-aminophenol in the presence of excess sodium borohydride. 相似文献
20.
Development of γG, γA, γM, β1C/β1A, C′1 esterase inhibitor, ceruloplasmin, transferrin, hemopexin, haptoglobin, fibrinogen, plasminogen, α1-antitrypsin, orosomucoid, β-lipoprotein, α2-macroglobulin, and prealbumin in the human conceptus
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The synthesis of γG, γA, γM, β1C/β1A, C′1 esterase inhibitor, ceruloplasmin, transferrin, hemopexin, haptoglobin, fibrinogen, α1-antitrypsin, orosomucoid, β-lipoprotein, α2-macroglobulin, and prealbumin was studied in 15 normal human embryos and fetuses of 29 days to 18 wk gestation and in the yolk sacs of four embryos from 5.5 to 11.5 wk gestation using tissue culture in 14C-labeled amino acids followed by radioimmunoelectrophoresis. The human embryo as early as 29 day gestation synthesized β1C/β1A, C′1 esterase inhibitor, transferrin, hemopexin, α1-antitrypsin, β-lipoprotein, α2-macroglobulin, and prealbumin in culture. At 32 days gestation ceruloplasmin and orosomucoid were also synthesized, but synthesis of fibrinogen was not observed before 5.5 wk. Synthesis of γM occurred as early as 10.5 wk gestation, and γG synthesis was found in cultures as early as 12 wk gestation; γA synthesis was not detected in any of the tissue cultures. With the exception of the γ-globulins, each of the proteins studied was synthesized by the liver, but additional sites of synthesis for some of these proteins were also found. Synthesis of γG and γM occurred primarily in the spleen, but other sites of synthesis were noted as well. 相似文献