scholarly journals Pickering Interfacial Catalysis—Knoevenagel Condensation in Magnesium Oxide-Stabilized Pickering Emulsion

ACS Omega ◽  
2020 ◽  
Vol 5 (21) ◽  
pp. 12224-12235
Author(s):  
Amid L. Sadgar ◽  
Tushar S. Deore ◽  
Radha V. Jayaram
Keyword(s):  
Magnesium Oxide ◽  
Knoevenagel Condensation ◽  
Pickering Emulsion ◽  
Interfacial Catalysis

Magnetic-responsive Pickering emulsion and its catalytic application at the water–oil interface

2021 ◽  
Author(s):  
Shenghua Ma ◽  
Wei Zong ◽  
Xiaojun Han
Keyword(s):  
Pickering Emulsion ◽  
Schematic Diagram ◽  
Catalytic Application ◽  
Interfacial Catalysis

Schematic diagram of interfacial catalysis reactions by MRGO–Pd Pickering emulsion.

Single-step fabrication of multi-compartmentalized biphasic proteinosomes

2017 ◽  
Vol 53 (61) ◽  
pp. 8537-8540 ◽  
Author(s):  
Lei Wang ◽  
Ping Wen ◽  
Xiaoman Liu ◽  
Yuting Zhou ◽  
Mei Li ◽  
...  
Keyword(s):  
Pickering Emulsion ◽  
Single Step ◽  
Interfacial Catalysis ◽  
Self Assembled

Multi-compartmentalized biphasic proteinosomes were self-assembled using a single-step double Pickering emulsion procedure, and exploited for enzyme-mediated interfacial catalysis, polysaccharide shell templating, and hydrogel functionalization.

scholarly journals pH-Responsive Pickering emulsion stabilized by polymer-coated silica nanoaggregates and applied to recyclable interfacial catalysis

RSC Advances ◽  
2020 ◽  
Vol 10 (69) ◽  
pp. 42423-42431
Author(s):  
Ruidong Luo ◽  
Jinfeng Dong ◽  
Yunbai Luo
Keyword(s):  
Diblock Copolymer ◽  
Trifluoroacetic Acid ◽  
Fumed Silica ◽  
Pickering Emulsion ◽  
Emulsion System ◽  
Ph Responsive ◽  
Interfacial Catalysis

We synthesized a diblock copolymer and grafted it onto fumed silica in the presence of trifluoroacetic acid to obtain a pH-responsive Pickering emulsion system stabilized by polymer-coated nanoaggregates, P-Si.

scholarly journals Solvent-free Knoevenagel condensation over supported mixed metal oxides catalysts

2017 ◽  
Author(s):  
◽  
Nokubonga Prudence Makhanya
Keyword(s):  
Magnesium Oxide ◽  
Heterogeneous Catalysts ◽  
Knoevenagel Condensation ◽  
Ethyl Cyanoacetate ◽  
Product Yield ◽  
Magnesium Nitrate ◽  
Solvent Free ◽  
Secondary Amines ◽  
Side Reactions ◽  
Vanadium Concentration

Knoevenagel condensation reaction is a useful protocol for the formation of C=C bond in organic synthesis. This protocol is extensively utilized by synthetic chemist to generate dynamic intermediates or end-products such as perfumes, polymers, pharmaceuticals and calcium antagonists. The reaction is catalyzed by bases such as ammonia, primary and secondary amines, quaternary ammonium salts, Lewis acids, catalysts containing acid-base sites, which are carried out under homogeneous conditions. This necessitates the use of organic solvent which generate the large volumes of solvent waste. From green chemistry perspective, solvent free heterogeneous catalysts have received considerable attention. Since, these heterogeneous catalysts not only avoid the use of organic solvents but also suppress side reactions such as self-condensation and oligomerisation leading in better selectivity and product yield. In recent years, therefore, the use of heterogeneous catalyst, their recovery and reusability are in demand in industry. The use of cobalt, iridium and platinum hydroxyapatites, MgO/ZrO2, MgO/HMCM- earlier been reported in the literature, and used as heterogeneous catalysts for the Knoevenagel condensation of aldehydes and esters. Based on these evidences, we envisioned that MgO and VMgO could also be used as heterogeneous catalysts for this reaction. Magnesium oxide was synthesized from three precursors, viz. magnesium nitrate, magnesium carbonate and magnesium acetate. Magnesium oxide prepared from magnesium nitrate precursor was found to be the optimum giving an 81 % product yield. Vanadium-magnesium oxide catalysts with different vanadium loadings; 1.5, 3.5 and 5.5 wt. %, were synthesized by wet impregnation of magnesium oxide with aqueous ammonium metavanadate solution. The synthesized catalysts were characterized by ICP-AES, FTIR, Powder XRD, SEM-EDX and TEM. The Knoevenagel condensation reactions between benzaldehyde and ethyl cyanoacetate were carried out in a 100 mL two-necked round bottom flask equipped with a reflux condenser, magnetic stirrer and a CaCl2 guard tube. An equimolar quantity (10 mmol) of substrates and 0.05g of catalyst were added to the flask and heated at 60 °C, stirred vigorously for the required time. The yields were determined using GC-FID equipped with a capillary column. Elemental composition of the catalysts (vanadium and MgO) was determined by ICP-AES. IR spectra of MgO showed that magnesium oxide was the only phase present in the catalysts prepared from different precursors. The 1.5 and 5.5 wt. % VMgO showed weak bands attributed to pyrovanadate and orthovanadate phases present in small quantities. The phases manifested more with the increase in the vanadium concentration (3.5 and 5.5 wt. % VMgO). The diffraction patterns of all the catalysts showed the existence of MgO and magnesium orthovanadate. The morphology of the catalysts with increasing vanadium was more affected by precursor treatment rather than chemical differences. Electron microscopy showed that the VMgO surface is only sparingly covered with vanadium and MgO showed stacked with large rounded particles. Good to excellent yields were obtained for the MgO catalysts: MgO(1) 68 %, MgO(2) 65 %, MgO(3) 72 %, MgO(P) 73 % and MgO(DP) 82 %. Excellent yields were obtained for the VMgO catalysts: 1.5VMgO 83 %, 3.5VMgO 91 % and 5.5VMgO 97 %. The 5.5VMgO catalyst was found to be the optimum catalyst and was further tested for it activity using different aldehyde substrates. Excellent yields of the products were obtained for benzaldehyde 97 %, nitrobenzaldehyde 94 %, bromobenzaldehyde 96 %, chlorobenzaldehyde 93 % and methoxybenzaldehyde 95%.

Preparation of a Pickering emulsion by modification of an amine-functionalized graphene oxide surface with organosilane: efficient catalyst for the Knoevenagel condensation of malononitrile with aldehydes at mild temperature

2020 ◽  
Vol 44 (15) ◽  
pp. 5995-6002 ◽  
Author(s):  
Bingxu Qian ◽  
Fei Wang ◽  
Dongsheng Li ◽  
Yongxin Li ◽  
Bo Zhang ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Knoevenagel Condensation ◽  
Pickering Emulsion ◽  
Oxide Surface ◽  
Functionalized Graphene ◽  
Pickering Emulsions ◽  
Efficient Catalyst ◽  
Functionalized Graphene Oxide ◽  
Amine Functionalized ◽  
Mild Temperature

In this study, a series of Pickering emulsions for catalysis of Knoevenagel condensations of malononitrile with aldehydes were prepared by surface modification of amine-functionalized graphene oxide (GO-NH2) with trimethoxymethylsilane (MTMS).

scholarly journals Tramadol Encapsulation in Aqueous Phase of Water/Oil Pickering Emulsion Stabilized by Magnesium Oxide Particles

2018 ◽  
Vol 6 (2) ◽  
pp. 37-43 ◽  
Author(s):  
Papa Mady SY ◽  
Sidy Mouhamed Dieng ◽  
Louis Augustin Diaga Diouf ◽  
Alphonse Rodrigue Djiboune ◽  
Mamadou Soumboundou ◽  
...  
Keyword(s):  
Magnesium Oxide ◽  
Aqueous Phase ◽  
Pickering Emulsion ◽  
Oxide Particles
Sign in / Sign up

Export Citation Format

Share Document