Novel magnetic lignosulfonate-supported Pd complex as an efficient nanocatalyst for N-arylation of 4-methylbenzenesulfonamide

Novel lignin-supported copper complex as a highly efficient and recyclable nanocatalyst for Ullmann reaction

In this work, we prepared polyhydroxylated lignin by demethylation and hydroxylation of lignin, and grafted phosphorus-containing groups by nucleophilic substitution reaction, the resulting material could be used as a carrier for the preparation of heterogeneous Cu-based catalysts (PHL-CuI-OPR₂). The optimal PHL-CuI-OP^tBu₂ catalyst was characterized by FT-IR, TGA, BET, XRD, SEM-EDS, ICP-OES, XPS. The catalytic performance of PHL-CuI-OP^tBu₂ in the Ullmann CN coupling reaction was evaluated using iodobenzene and nitroindole as model substrates under nitrogen atmosphere with DME and H₂O as cosolvent at 95 °C for 24 h. The applicability of modified lignin-supported copper catalyst was investigated of various aryl/heteroaryl halides with indoles under optimal conditions, the corresponding products were obtained with high yield. Additionally, it could be easily recovered from the reaction medium by an easy centrifugation and washing.

N,N′-Dimethylurea as an efficient ligand for the synthesis of pharma-relevant motifs through Chan–Lam cross-coupling strategy

The combination of copper and N,N′-dimethylurea is used to showcase the Chan–Lam N-arylation of three different nitrogen nucleophiles. The synthesized catalyst is cheap, chemoselective, and also found to be effective in the N-arylation of target APIs.

Heteropolyacid coupled with cyanoguanidine decorated magnetic chitosan as an efficient catalyst for the synthesis of pyranochromene derivatives

In this study, a novel nanocatalyst was successfully prepared by heteropolyacid immobilization of magnetic chitosan-cyanoguanidine composite and fully characterized by different analysis methods, including FTIR, XRD, TGA, SEM, and EDS. The catalytic activity of fabricated composite was examined in a one-pot three-component reaction, involving the diverse active methylene compounds, various aryl aldehydes, and malononitrile in water. The results revealed the efficient catalytic performance of composite, while all reactions proceeded smoothly and led to the formation of the corresponding pyranochromene derivatives in high to excellent yields.

Influence of starch with different degrees and order of gelatinization on the microstructural and mechanical properties of pectin cryogels: A potential pore morphology regulator

The applications of cryogels are defined by their porous morphology as well as mechanical properties. To achieve efficient regulation of porous properties for pectin cryogels, we selected starch as a potential polysaccharide regulator. Pectin/starch composite cryogels with different degrees of gelatinization were formulated, and two ways of starch gelatinization were considered: starch gelatinization occurred before or after pectin crosslinking during forming the hydrogel network. The results showed that high gelatinized starch (73.8 %-100.0 %) rendered pectin cryogels with denser pore morphology and higher mechanical strength. The pore diameter transferred from 160-200 μm to 40-60 μm with the degree of gelatinization, while the total porosity decreased by about 15 % and the specific surface area increased by about 100 m²/g. When starch gelatinization occurred before pectin crosslinking, the hydrogen bond interactions between gelatinized starch and pectin were formed to accelerate the gelation rate of the pectin Ca²⁺-dependent network. When gelatinization occurred after pectin crosslinking, the pre-formed pectin network delayed the breakdown of the starch crystalline structure during gelatinization. The qualitative regulation of the pore morphology in pectin cryogels by incorporating starches with varying degrees of gelatinization was confirmed.

Palladium-Supported Polydopamine-Coated NiFe2O4@TiO2: A Sole Photocatalyst for Suzuki and Sonogashira Coupling Reactions under Sunlight Irradiation

The effective utilization of solar energy in synthetic organic chemistry has gained extensive attention owing to its enormous energy and environmentally benign nature. In this context, we designed and synthesized a magnetically retrievable, sole palladium (Pd)-supported polydopamine-coated core@shell (NiFe₂O₄@TiO₂) heterogeneous nanophotocatalyst for Suzuki and Sonogashira coupling reactions under sunlight irradiation. The synthesized catalyst was characterized by powder X-ray diffraction (PXRD), Fourier-transform infrared, UV-vis, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and vibrating sample magnetometer analysis. The photocatalytic activity of the synthesized nanocatalyst under sunlight irradiation was assessed for both Suzuki and Sonogashira coupling reactions, where it worked excellently well with a high yield of the product up to 98 and 96%, respectively. Its efficacy was also investigated in the conversion of substituted substrates in both the coupling reactions into desired biaryls and diarylacetylenes. Unique features of the synthesized catalyst are (i) its effective performance for both the aforesaid coupling reactions under ambient reaction conditions for a short reaction time in polar protic solvents (ethanolic water/EtOH) with good yield without any byproduct, (ii) magnetic retrieval of the catalyst from the reaction mixture employing an external magnet is an added advantage, and (iii) the retrieved catalyst could potentially be reutilized for up to five consecutive runs without appreciable diminution of catalytic efficacy, and its stability was confirmed by inductively coupled plasma optical emission spectroscopy analysis and XRD.

Wood-Sourced Polymers as Support for Catalysis by Group 10 Transition Metals

Despite providing interesting solutions to reduce the number of synthetic steps, to decrease energy consumption or to generate less waste, therefore contributing to a more sustainable way of producing important chemicals, the expansion of the use of homogeneous catalysis in industrial processes is hampered by several drawbacks. One of the most important is the difficulty to recycle the noble metals generating potential high costs and pollution of the synthesized products by metal traces detrimental to their applications. Supporting the metals on abundant and cheap biosourced polymers has recently appeared as an almost ideal solution: They are much easier to recover from the reaction medium and usually maintain high catalytic activity. The present bibliographical review focuses on the development of catalysts based on group 10 transition metals (nickel, palladium, platinum) supported on biopolymers obtained from wood, such as cellulose, hemicellulose, lignin, and their derivatives. The applications of these catalysts in organic synthesis or depollution are also addressed in this review with examples of C-C couplings, oxidation, or hydrogenation reactions.