Design and Development of Magnetically Retrievable Nanohybrid Catalyst for the Green Synthesis of Paracetamol

As ecological and environmental demands for sustainability are one of the most strategic landscapes in the green chemistry, recent chemical researches have been directed toward eco‐friendly catalysts. Further advancement in this area has presented magnetically recoverable nanocatalyst. Herein, Cu‐based nanocatalyst was synthesized via reaction of picolinaldehyde and amine group of immobilized chitosan on the magnetic nanosupport, and followed by metallation. The prepared nanocatalyst was characterized by a variety of techniques. FT‐IR analysis demonstrated the favored coating of chitosan‐based Cu complex over Fe3O4 nanoparticles. The scanning electron microscopy and transmission electron microscope techniques confirmed nano‐sized of the catalyst. Fe3O4 nanoparticles and the nanocatalyst fit the X‐ray diffraction pattern of standard magnetite. High thermal stability of the nanocatalyst was determined by the TGA analysis. The inductively coupled plasma atomic emission analysis technique specified content of Cu was 0.62 mmol/g. Magnetic properties were analyzed by the vibrating sample magnetometer study. Regarding green chemistry goals, the applicability of this nanocatalyst was tested in the oxidation of sulfides derivatives. The nanocatalyst exhibited high catalytic activity and selectivity in the oxidation of sulfides to the corresponding sulfoxide (without over‐oxidation of sulfides to sulfones) under green conditions. Based on the magnetic properties (alluded to the Fe3O4 component), the nanocatalyst could be easily recovered from the reaction mixture using an external magnet, and reused up to four times without noticeable deterioration in its performance. Moreover, the other merits such as high yields, mild reaction condition, use of stable and green oxidant and eco‐friendly procedure made this nanocatalyst as a valuable catalyst in practical synthesis. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 1626–1631, 2018

The novel acid-base magnetic recyclable catalyst prepared through carbon disulfide trapping process: Applied for green, one-pot, and efficient synthesis of 2,3-dihydroquinazolin-4 (1H) -ones and bis(indolyl)methanes in large-scale

In this study, a PVAm-bearing SO3H groups/Fe3O4 nanocomposite was prepared via a simple and in situ polymerization of acrylamide onto the surface of magnetic nanoparticles without using organosilane precursors. In order to obtain amine-functionalized magnetic, Hofmann degradation was carried out. In the following, sulfonated-polyvinyl amine coated on Fe3O4 nanoparticles was prepared by covalent grafting of chlorosulfonic acid on amine groups. The introduction of polymer to the surface of magnetic nanoparticles increases the loading content with functional groups extremely. The resulting hybrid material was effectively employed as an unprecedented acid magnetic catalyst for the one-pot synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles under solvent-free conditions. High yields, mild reaction conditions, short reaction times, operational simplicity with reusability are the notable features of the catalyst. The structure of the newly developed catalyst was characterized using TGA, FT-IR, SEM, TEM, VSM, EDX, CHNS, and XRD analysis. Magnetic separation and recycling of the catalyst for at least 8 runs is possible without any significant deterioration in catalytic activity. This work is the first report of employing PVAm as a linker for immobilizing liquid acid on a support.

Co‐immobilization of an Enzyme and a Metal into the Compartments of Mesoporous Silica for Cooperative Tandem Catalysis: An Artificial Metalloenzyme

Three novel Pd (II), Cu (II), and Fe (III) complexes were prepared from thiazole ligand through bidentate chelating mode. Alternative spectral and analytical tools were applied to elucidate their structural and molecular formulae. This study was extended to investigate stability and stoichiometry of complexes in solution, using standard methods. In addition, the best atomic distribution within structural forms was obtained by Material Studio Package via the density functional theory (DFT) method. This computational study fed us with significant physical characteristics for differentiation. Also, crystal surface properties in the packing system were studied using the Crystal explorer program, to evaluate the extent of contact between surfaces. Computational data discriminate Pd (II)‐thiazole (HYHPd) complex by some physical features, which may be promising in the catalytic field. This complex was selected to play a catalytic function to synthesize polyfunctionalized pyrrole derivatives using ultrasonic irradiation in a one‐pot reaction. The catalyst was selected for this application based on the history of Pd (II) complexes and the properties expected theoretically. A condensation reaction for aromatic aldehyde, aromatic amine, acetylacetone, and nitromethane was carried out under mild reaction conditions by ultrasonic irradiation. All reaction conditions were optimized among that variable Lewis acid catalysts in comparison to our new complexes. HYHPd catalyst displayed superiority in overall trials with high yield, short time, and green conditions (solvent H2O/EtOH). Also, the recovery of hetero‐catalyst was succeeded and reused by the same efficiency up to five times after that the efficiency was reduced. The mechanism of action was proposed based on the ability of Pd (II) for adding extra‐bonds overzaxis and supported by theoretical aspects.

1-Methyl-3-(2-oxyethyl)-1H-Imidazol-3-ium-Borate Sulfonic Acid ([MOEI]-BSA) was easily prepared and used as a new and highly efficient solid acid catalyst for the synthesis of benzimidazole derivatives with high isolated yields. Various substituted benzimidazoles were synthesized by a combination of o-phenylenediamines and aldehydes in the presence of [MOEI]-BSA with excellent yields in water and under a mild and green reaction conditions. This method is also applicable for precursors such as aromatic and unsaturated aldehydes and o-phenylenediamines. Addition of organic part to BSA and synthesis of [MOEI]-BSA as a new Bronsted acidic ionic liquid (BAIL) improved the efficiency of this catalyst. 1-Methyl-3-(2-oxyethyl)-1H-Imidazol-3-ium-Borate Sulfonic Acid ([MOEI]-BSA) was easily prepared and used as a new and highly efficient solid acid catalyst for the synthesis of benzimidazole derivatives with high isolated yields. Various substituted benzimidazoles were synthesized by a combination of o-phenylenediamines and aldehydes in the presence of [MOEI]-BSA with excellent yields in water and under a mild and green reaction conditions. This method is also applicable for precursors such as aromatic and unsaturated aldehydes and o-phenylenediamines. Addition of organic part to BSA and synthesis of [MOEI]-BSA as a new Bronsted acidic ionic liquid (BAIL) improved the efficiency of this catalyst.

A mild and efficient method for the one-pot synthesis of functionalized dihydro-2-oxopyrroles is described via four-component domino reaction of amines, dialkyl acetylenedicarboxylates, and formaldehyde in the presence of super magnetic nano iron oxide (nano Fe3O4) in EtOH at room temperature. The major advantages of the present method are mild and green reaction conditions, high yields, short reaction times, clean reaction, magnetically recyclable catalyst, atom economy (63–76 %), operational simplicity, and no need for column chromatography. It is found that the catalyst is recyclable and can be used up to six times without significant loss of its activity.

β-Cyclodextrin-propyl sulfonic acid: a new and eco-friendly catalyst for one-pot multi-component synthesis of 3,4-dihydropyrimidones via Biginelli reaction

Polyaniline, polyaniline/SiO2, and poly(4-vinylpyridine) are highly effective base catalysts for the synthesis of tetrahydrobenzo[b]pyran and 3,4-dihydropyrano[c]chromene derivatives by the one-pot three-component condensation reaction of aryl aldehydes, malononitrile and α-hydroxy or α-amino activated C–H acids such as 1,3-cyclohexanedione, dimedone, 4-hydroxy-6-methylpyrone, 4-hydroxycoumarin, 1,3-dimethylbarbituric acid, and 1,3-dimethyl-6-amino uracil. The remarkable advantages of this new procedure are high yields, short experimental time, mild reaction condition, low cost and easy preparation of the catalysts, and no need for any workup and purification after completion of the reaction. In addition, these catalysts exhibited excellent recoverability without a negligible decrease of their activities after at least six cycles of reaction.

A hybrid nanobiocatalyst with in situ encapsulated enzyme and exsolved Co nanoclusters for complete chemoenzymatic conversion of methyl parathion to 4-aminophenol

DABCO (1,4-diaza-bicyclo[2,2,2]octane) was applied as an efficient catalyst for the one-pot three-component synthesis of highly functionalized cyclohexenones: 2-oxo-N,4,6-triarylcyclohex-3-enecarboxamides via the condensation between acetophenone/4-methylacetophenone, aromatic aldehydes, and acetoacetanilide in ethanol at ambient condition. This methodology has a number of advantages such as high yields, short reaction times, clean work-up (just simple filtration), and mild reaction conditions.

Levulinic acid is one of the potential and versatile biomass-derived chemicals. Product analysis via HPLC revealed that the heterogeneous dehydration of glucose over hybrid nanocatalyst exhibited better performance compared to single catalyst. Hybrid nanocatalyst containing H-Y zeolite and CrCl3 could substitute homogenous acid catalyst for attaining high levulinic acid yield. Different CrC3 and H-Y zeolite weight ratios of 1:1, 1:2 and 2:1 were prepared according to the wetness impregnation method. The hybrid catalyst with a 1:1 weight ratio performed better compared to others with the highest levulinic acid yield reported (93.5%) at 140 °C, 180 min reaction time, 0.1 g catalyst loading and 0.1 g glucose feed. Characterization results revealed that properties such as surface area, mesoporosity and acidic strength of the catalyst have significant effects on glucose dehydration for levulinic acid production.

The catalytic efficiency of silver nanoparticles supported on chitosan as a green, robust, and efficient nanocatalyst for the direct synthesis of biologically active compounds, such as: imidazole derivatives as well as pyrazine scaffolds through multi-component reactions strategy, have been demonstrated. In this work, imidazole derivatives were achieved via pseudo four-component reactions by utilization of benzaldehydes, benzils, anilines, and ammonium acetate under solvent-free conditions. Moreover, pyrazine scaffolds were synthesized through a three-component reaction of phenylenediamine derivatives, isocyanides and various ketones in water. The main advantages of this protocol are the reusability of the catalyst, operational simplicity, mild reaction conditions, and high-yielding.

A bioinorganic nanohybrid catalyst was synthesized by combining esterase with a platinum nanoparticle (PtNP). The combination of two catalysts resulted in enhanced catalytic activities, esterase hydrolysis, and hydrogenation in PtNPs, as compared to each catalyst alone. This hybrid catalyst can be successfully used in the multistep synthesis of acetaminophen (paracetamol), an analgesic and antipyretic drug, in a one-pot reaction with high yield and efficacy within a short time, demonstrating that the nanobiohybrid catalyst offers advantages in the synthesis of fine chemicals in industrial applications.

Abstract: New coumarin chalcones 3j–p were conveniently obtained in high yields via Claisen-Schmidt condensation reaction, when acetyl coumarin 1 reacted with 3-aryl-1-phenyl pyrazole-4-carbaldehydes 2j–p in boiling ethanol in the presence of triethyl amine as a catalyst. Also, two synthetic pathways were afforded for the synthesis of novel tetrazolo[1,5-a]pyrimidinyl-2H-chromen-2-ones 5a-p. The first pathway is a multistep process including formation and separation of chalcones, which then were allowed to react with 5-aminotetrazole 4. While, the second pathway is a highly efficient one-pot three-component condensation reaction of 3-acetyl coumarin 1, aromatic aldehydes 2a-p and 5-aminotetrazole 4 under green and mild reaction conditions by using acetic acid (AcOH) as a catalyst and solvent. The molecular structure of products was established on the basis of their NMRs, IR and elemental analysis data. Solvent optimization was carried out in the reaction producing 3-(5-Phenyl-4,5-dihydrotetrazolo[1,5-a]pyrimidin-7-yl)-2H-chromen-2-one (5a). The advantages to using environmental-friendly acetic acid are simple operation, short reaction time, high efficient (97%), operationally facile and wide tolerance of starting materials. objective: The advantages of using environmental-friendly AcOH are simple operation, short reaction time, high efficient (97%), operationally facile and wide tolerance of starting materials.