scholarly journals Combustion-Synthesized Porous CuO-CeO2-SiO2 Composites as Solid Catalysts for the Alkenylation of C(sp3)-H Bonds Adjacent to a Heteroatom via Cross-Dehydrogenative Coupling

Catalysts ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1252
Author(s):  
Ha V. Le ◽  
Vy B. Nguyen ◽  
Hai H. Pham ◽  
Khoa D. Nguyen ◽  
Phuoc H. Ho ◽  
...  
Keyword(s):  
Mixed Oxides ◽  
Coupling Reaction ◽  
Catalytic Performance ◽  
Composite Catalyst ◽  
High Porosity ◽  
One Pot ◽  
General Validity ◽  
Solid Catalysts ◽  
Surface Areas ◽  
Dehydrogenative Coupling

A series of mixed oxides of CuO, CeO2, and SiO2 were prepared by gel combustion and employed for the first time as efficient solid catalysts in a solvent-less liquid-phase cross-dehydrogenative coupling. The facile one-pot catalyst synthesis resulted in highly porous materials presenting large specific surface areas and strong metal–support interactions. The interaction with highly dispersed CeO2 enhanced the redox properties of the CuO species. The CuO-CeO2-SiO2 composites exhibited excellent catalytic performance for the selective coupling between 1,1-diphenylethylene and tetrahydrofuran with a yield up to 85% of 2-(2,2-diphenylvinyl)-tetrahydrofuran in the presence of di-tert-butyl peroxide (DTPB) and KI. Albeit both CuO and CeO2 species are proved to be responsible for the catalytic conversion, a great synergistic improvement in the catalytic activity was obtained by extended contact between the oxide phases by high porosity in comparison with the reactions using individual Cu or Ce catalysts. The activity of the composite catalyst was shown to be highly stable after five successive reaction cycles. Furthermore, the study scope was extended to the synthesis of different derivatives via composite-catalyzed coupling of C(sp2)-H with C(sp3-H) adjacent to a heteroatom. The good yields recorded proved the general validity of this composite for the cross-dehydrogenative coupling reaction rarely performed on solid catalysts.

Effect of Different Silicate Supports on the Catalytic Performance of MoVTeO Mixed Oxides in Partial Oxidation of Isobutane

2014 ◽  
Vol 12 (1) ◽  
pp. 623-628
Author(s):  
Jing Hu ◽  
Zhifang Li ◽  
Xiaoyuan Yang ◽  
Wenli Ding ◽  
Jingqi Guan
Keyword(s):  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Partial Oxidation ◽  
Mixed Oxides ◽  
Supported Catalysts ◽  
Catalytic Performance ◽  
Surface Areas ◽  
Specific Surface Areas ◽  
Mcm 41

Abstract A series of 5% MoV0.3Te0.25 supported on different silicates (i.e. SiO2, HMS, MCM-41, and MCM-48) have been prepared, characterized, and tested as catalysts in the partial oxidation of isobutane to methacrolein. Characterization results showed that the supports almost kept intact structures after supporting 5 wt.% MoV0.3Te0.25 and the supported catalysts had large specific surface areas. Catalytic tests showed that the specific surface area played a key role in the catalytic activity for the supported catalysts.

Synthesis of imidazopyridine-fused indoles via one-pot sequential Knoevenagel condensation and cross dehydrogenative coupling

2018 ◽  
Vol 16 (33) ◽  
pp. 6123-6132 ◽  
Author(s):  
Vikki N. Shinde ◽  
Shiv Dhiman ◽  
Rangan Krishnan ◽  
Dalip Kumar ◽  
Anil Kumar
Keyword(s):  
Knoevenagel Condensation ◽  
Coupling Reaction ◽  
One Pot ◽  
Dehydrogenative Coupling ◽  
Palladium Catalyzed

Synthesis of imidazopyridine-fused indoles has been developed via one-pot sequential Knoevenagel condensation followed by palladium-catalyzed intramolecular cross-dehydrogenative coupling reaction.

scholarly journals A Systematic Study on Bio-Based Hybrid Aerogels Made of Tannin and Silica

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5231
Author(s):  
Ann-Kathrin Koopmann ◽  
Wim J. Malfait ◽  
Thomas Sepperer ◽  
Nicola Huesing
Keyword(s):  
Specific Surface ◽  
Processing Parameters ◽  
Water Soluble ◽  
High Porosity ◽  
Mesopore Volume ◽  
One Pot ◽  
Surface Areas ◽  
Hybrid Aerogels ◽  
Highly Porous ◽  
Silica Hybrid

Tannin-silica hybrid materials are expected to feature excellent mechanic-chemical stability, large surface areas, high porosity and possess, after carbothermal reduction, high thermal stability as well as high thermal conductivity. Typically, a commercially available tetraethoxysilane is used, but in this study, a more sustainable route was developed by using a glycol-based silica precursor, tetrakis(2-hydroxyethyl)orthosilicate (EGMS), which is highly water-soluble. In order to produce highly porous, homogeneous hybrid tannin-silica aerogels in a one-pot approach, a suitable crosslinker has to be used. It was found that an aldehyde-functionalized silane (triethoxysilylbutyraldehyde) enables the covalent bonding of tannin and silica. Solely by altering the processing parameters, distinctly different tannin-silica hybrid material properties could be achieved. In particular, the amount of crosslinker is a significant factor with respect to altering the materials’ properties, e.g., the specific surface area. Notably, 5 wt% of crosslinker presents an optimal percentage to obtain a sustainable tannin-silica hybrid system with high specific surface areas of roughly 800–900 m2 g−1 as well as a high mesopore volume. The synthesized tannin-silica hybrid aerogels permit the usage as green precursor for silicon carbide materials.

scholarly journals Catalytic performance of Ce1-xLnxOy of nanocrystalline Ln (III-IV)-substituted ceria

2019 ◽  
Vol 2 (3) ◽  
Author(s):  
Eduardo Arístides Poggio-Fraccari1 ◽  
Mariño F1 ◽  
Sorbello C2 ◽  
Jobbagy M2
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Co Oxidation ◽  
Surface Segregation ◽  
Mixed Oxides ◽  
Catalytic Performance ◽  
High Yield ◽  
Good Activity ◽  
Reactor Operation ◽  
Surface Areas

The activity of several lanthanide promoted Ceria in CO oxidation was studied. Samples were obtained by a high yield and sustainable method by urea thermal decomposition. Precursors basic carbonates, Ce1-xLnx(OH)CO3, being Ln = La (III), Sm(III), Gd(III), Pr(III) were prepared in the range of compositions 0 to 30 at.%. These precursors were annealed to moderate temperature obtain Ln-Ce mixed oxides, at 450ºC. These exhibit large surface areas up to 120 m2/g. Their catalytic performance revealed good activity towards CO oxidation  (COOX) for all samples. However, a different behavior may be observed for Ln content higher than 20 at.%. By the reactor operation in differential conditions, the activation energy for COOX were obtained for all samples. The rise of activation energy as a function of Ln(III-IV) content is analyzed in the frame of phase stability and surface segregation.

Copper-Mediated One-Pot Synthesis of Indoles through Sequential Hydroamination and Cross-Dehydrogenative Coupling Reaction

Synthesis ◽  
2019 ◽  
Vol 52 (01) ◽  
pp. 75-84 ◽  
Author(s):  
Peng Sun ◽  
Jiaojiao Yang ◽  
Zirui Song ◽  
Yichao Cai ◽  
Yajie Liu ◽  
...  
Keyword(s):  
Mixed Solvents ◽  
Coupling Reaction ◽  
One Pot ◽  
One Pot Synthesis ◽  
Dehydrogenative Coupling ◽  
High Yields

Starting from simple anilines and ester arylpropiolates, an efficient one-pot synthesis of 2-arylindole-3-carboxylate derivatives has been developed through copper-mediated sequential hydroamination and cross-dehydrogenative coupling (CDC) reaction. The initial hydroamination of anilines to ester arylpropiolates in benzene can proceed in a stereoselective manner to give ester (Z)-3-(arylamino)acrylates in the presence of CuCl2/phenanthroline, KMnO4, and KHCO3 at 120 °C. Sequentially, these in situ functionalized adducts can undergo direct intramolecular oxidative alkenylation of aromatic C–H bond in mixed solvents (benzene/DMSO 1:1) at 130 °C affording multi-substituted­ indoles in good to high yields.

Enhanced catalytic performance of Pd–Pt nanodendrites for ligand-free Suzuki cross-coupling reactions

RSC Advances ◽  
2015 ◽  
Vol 5 (36) ◽  
pp. 28467-28473 ◽  
Author(s):  
Zheng-Jun Wang ◽  
Jing-Jing Lv ◽  
Jiu-Ju Feng ◽  
Ningbo Li ◽  
Xinhua Xu ◽  
...  
Keyword(s):  
Coupling Reaction ◽  
Cross Coupling ◽  
Catalytic Performance ◽  
Coupling Reactions ◽  
Wet Chemical Method ◽  
One Pot ◽  
Cross Coupling Reactions ◽  
Cross Coupling Reaction ◽  
Ligand Free ◽  
Wet Chemical

The Pd–Pt NDs were synthesized by a one-pot wet-chemical method, which showed enhanced catalytic activity toward Suzuki cross-coupling reaction.

scholarly journals Facile Synthesis of Iron-Based MOFs MIL-100(Fe) as Heterogeneous Catalyst in Kabachnick Reaction

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1451
Author(s):  
Noura Elsayed Elharony ◽  
Ibrahim El Tantawy El Sayed ◽  
Abdullah G. Al-Sehemi ◽  
Ahmed A. Al-Ghamdi ◽  
Ahmed S. Abou-Elyazed
Keyword(s):  
Heterogeneous Catalyst ◽  
Condensation Reaction ◽  
Aromatic Aldehydes ◽  
Catalytic Performance ◽  
Bet Surface Area ◽  
High Yield ◽  
Ferric Nitrate ◽  
One Pot ◽  
Solid Catalysts ◽  
Recyclable Heterogeneous Catalyst

An effective technique was proposed for the synthesis of novel α-aminophosphonates: a three-component one-pot condensation reaction of aniline, aromatic aldehydes, and triphenyl phosphite in the presence of (MIL-100(Fe)) as a heterogeneous catalyst. Initially, MIL-100(Fe) was synthesized using H3BTC and ferric nitrate at low temperature and atmospheric pressure. Further, MIL-100(Fe) was characterized using various techniques such as XRD, BET surface area, scanning electron microscopy (SEM), Fourier-transform infrared (FT-IR), and thermogravimetric analysis (TGA). Herein, MIL-100(Fe) showed exceptional catalytic performance for the synthesis of α-aminophosphonate and its derivatives compared with conventional solid catalysts, and even homogeneous catalysts. The study demonstrated that MIL-100(Fe) is an ecofriendly and easily recyclable heterogeneous catalyst in Kabachnick reactions for α-aminophosphonate synthesis, with high yield (98%) and turnover frequency (TOF ~ 3.60 min−1) at room temperature and a short reaction time (30 min).

scholarly journals A novel composite of W18O49 nanorods on reduced graphene oxide sheets based on in situ synthesis and catalytic performance for oxygen reduction reaction

RSC Advances ◽  
2017 ◽  
Vol 7 (4) ◽  
pp. 2051-2057 ◽  
Author(s):  
Jiahao Guo ◽  
Yantao Shi ◽  
Huawei Zhou ◽  
Xuchun Wang ◽  
Tingli Ma
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Catalytic Performance ◽  
Reduction Reaction ◽  
In Situ Synthesis ◽  
Composite Catalyst ◽  
One Pot ◽  
Reduced Graphene ◽  
Graphene Oxide Sheets

A novel composite catalyst based on in situ synthesis of W18O49 nanorods on reduced graphene oxide sheets was successfully fabricated through a one-pot solvothermal route.

scholarly journals Simultaneous Adsorption and Reduction of Cr(VI) to Cr(III) in Aqueous Solution Using Nitrogen-Rich Aminal Linked Porous Organic Polymers

2021 ◽  
Vol 13 (2) ◽  
pp. 923
Author(s):  
Muhammad A. Sabri ◽  
Ziad Sara ◽  
Mohammad H. Al-Sayah ◽  
Taleb H. Ibrahim ◽  
Mustafa I. Khamis ◽  
...  
Keyword(s):  
Active Sites ◽  
Condensation Reaction ◽  
Significant Loss ◽  
Single Step ◽  
High Porosity ◽  
Organic Polymers ◽  
Porous Organic Polymers ◽  
One Pot ◽  
Surface Areas ◽  
Redox Active

Two novel nitrogen-rich aminal linked porous organic polymers, NRAPOP-O and NRAPOP-S, have been prepared using a single step-one pot Schiff-base condensation reaction of 9,10-bis-(4,6-diamino-S-triazin-2-yl)benzene and 2-furaldehyde or 2-thiophenecarboxaldehyde, respectively. The two polymers show excellent thermal and physiochemical stabilities and possess high porosity with Brunauer–Emmett–Teller (BET) surface areas of 692 and 803 m2 g−1 for NRAPOP-O and NRAPOP-S, respectively. Because of such porosity, attractive chemical and physical properties, and the availability of redox-active sites and physical environment, the NRAPOPs were able to effectively remove Cr(VI) from solution, reduce it to Cr(III), and simultaneously release it into the solution. The efficiency of the adsorption process was assessed under various influencing factors such as pH, contact time, polymer dosage, and initial concentration of Cr(VI). At the optimum conditions, 100% removal of Cr(VI) was achieved, with simultaneous reduction and release of Cr(III) by NRAPOP-O with 80% efficiency. Moreover, the polymers can be easily regenerated by the addition of reducing agents such as hydrazine without significant loss in the detoxication of Cr(VI).

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