An efficient synthesis of ampicillin on magnetically separable immobilized penicillin G acylase

<正>Penicillin G acylase(PGA) was immobilized on the magnetic hydrophilic polymer microspheres with average pore size of 17.1 nm,specific surface area of 128.2 m~2/g and saturate magnetization of 6.4 emu/g.The 96.7%ampicillin yield with 1.60 of the synthesis/hydrolysis(S/H) ratio from 6-aminopenicillanic acid(6-APA) and D-(-)-alpha-phenylglycine methyl ester(D-PGME) can be achieved using the resultant magnetic biocatalyst in ethylene glycol,where only 82.1%yield with 1.40 of the S/H ratio was obtained using the free PGA under the identical reaction conditions.The immobilized PGA can be separated magnetically and recycled for five times without obvious loss of its catalytic activity.     

Tetrazole derivatives synthesis using Fe3O4@fibroin-SO3H as a magnetically separable green solid acid nanocatalyst under solvent-free conditions

Research on Chemical Intermediates - In the present study, a magnetically separable potent solid acid nanocatalyst with a facile preparation technique was fabricated via incorporation of fibroin as...     

Sulfamic acid: an efficient, cost-effective and recyclable solid acid catalyst for the Friedlander quinoline synthesis

o-Aminoaryl ketones undergo smooth condensation with α-methylene ketones in the presence of sulfamic acid (NH₂SO₃H) (SA) under mild reaction conditions to afford the corresponding polysubstituted quinolines in excellent yields. The catalyst can be recovered by simple filtration and can be recycled in subsequent reactions. The method is simple, cost-effective and environmentally benign.     

A simple synthesis of magnetic nanoparticles-supported 4-aminomethylbenzoic acid as a highly efficient and reusable catalyst for synthesis of 2-amino-4H-chromene derivatives

Research on Chemical Intermediates - A new 4-aminomethylbenzoic acid-functionalized Fe3O4 magnetic nanoparticles as a hybrid heterogeneous catalyst was synthesised and characterized by FT-IR, XRD,...     

Reduced graphene oxide/iron oxide hybrid composite material as an efficient magnetically separable heterogeneous catalyst for transfer hydrogenation of ketones

Reduced graphene oxide was synthesized and functionalized with FeSO₄⋅7H₂O to form a reduced graphene oxide/iron oxide hybrid composite. The hybrid composite was extensively characterized using various techniques. Its application for transfer hydrogenation of various ketones was studied. The investigation showed that it serves as a good catalyst for transfer hydrogenation of aromatic and some aliphatic ketones resulting in excellent isolated yields (97–99%) of products. It is magnetically separable showing good reusability. The products were characterized and compared with authentic ones.     

Nano-Fe3O4@silica sulfuric acid as a reusable and magnetically separable potent solid acid catalyst in Biginelli-type reaction for the one-pot multicomponent synthesis of fused dihydropyrimidine derivatives: A greener NOSE and SFRC approach

An efficient, highly product selective, eco-friendly, one-pot multicomponent synthesis of dihydropyrimidine derivatives via Biginelli reaction has been described. The reaction was developed by greener nanoparticle-catalyzed organic synthesis enhancement (NOSE) chemistry and solvent free reaction condition (SFRC) approaches, which helped us in making the procedure greener. The reaction went smoothly with a diverse range of aromatic, aliphatic, hetero-aromatic aldehydes, different amine sources, as well as various β-dicarbonyl compounds, showing the flexibility of this methodology. Magnetically separable nano-Fe₃O₄@SiO₂@SO₃H, which acts as a potent solid acid catalyst, was characterized by FT-IR, SEM, EDX and TEM, VSM, and TGA analyses. The catalyst was recycled from the reaction mixture easily by an external magnet and reused in five more consecutive runs without much decrease in catalytic activity. Its catalytic efficiency was compared to other nano and bulk solid acid catalyst in order to ascertain the best combination for the conversion.     

Sulfamic acid: an efficient, cost-effective and recyclable solid acid catalyst for the three-component synthesis of α-amino nitriles

α-Amino nitriles are synthesized by the three-component coupling reaction of aldehydes, amines and trimethylsilyl cyanide using sulfamic acid as a heterogeneous solid acid catalyst, under solvent-free conditions in excellent yields. The catalyst was recovered by simple filtration and was recycled in subsequent reactions.     

Nano-Fe3O4-encapsulated silica particles bearing sulfonic acid groups as a magnetically separable catalyst for green synthesis of 1,1-diacetates

Sulfonic acid-functionalized silica-coated nano-Fe₃O₄particles (Fe₃O₄@SiO₂–SO₃H) serve as a novel heterogeneous catalyst for the synthesis of acylals by direct condensation of aldehydes with acetic anhydride under solvent-free conditions at room temperature in short reaction times and excellent yields. The catalyst could be easily separated from the final product using an external magnet and reused several times without consequential loss of reactivity.     

Phospho sulfonic acid as an efficient and recyclable solid acid catalyst for the solvent-free preparation of acylals

Phospho sulfonic acid (PSA) acts as a highly effective and reusable catalyst for the chemo-selective protection of aldehydes with acetic anhydride under solvent-free conditions. The desirable features of this new catalytic methodology include its sustainability, effectiveness in the absence of solvent, a facile work-up procedure, and economic viability. PSA is fully characterized by Fourier transform infrared spectroscopy, wide-angle X-ray scattering analysis, and scanning electron microscopy with energy dispersive X-ray spectroscopy. The catalyst can be reused several times without significant loss of activity. In addition, no chromatographic separations are needed to obtain the desired products.     

Dithiocarbamate as an efficient intermediate for the synthesis of 2-amino-1,3,4-thiadiazoles in water

A new and facile protocol for the synthesis of 2-amino-1,3,4-thiadiazoles in water is described. Reaction of acid hydrazides with easily prepared dithiocarbamates gives the corresponding thiadiazoles in moderate to excellent yields. 2-Amino-1,3,4-oxadiazoles were not observed as side products using this procedure.     

Nanocrystalline sulfated zirconia as an efficient solid acid catalyst for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones

The condensation reaction of 2-aminobenzamide and aldehydes or ketones was investigated in the presence of nanocrystalline sulfated zirconia (SO₄ ^2?/ZrO₂) as solid acid catalyst. SO₄ ^2?/ZrO₂ nanoparticles with different calcination temperatures were prepared and characterized by XRD, FT-IR and SEM techniques. The results confirm good stabilization of tetragonal phase of zirconia in the presence of sulfate. The reusability experiments show partial deactivation of the catalyst due to leaching of the sulfate and coke deposition on the catalyst.     

Phosphomolybdic acid: a highly efficient solid acid catalyst for the synthesis of trans-4,5-disubstituted cyclopentenones

The furan-2-yl(phenyl)methanol undergoes smooth aza-Piancatelli rearrangement with aryl amines in the presence of 0.03 mol % phosphomolybdic acid in acetonitrile under reflux conditions to afford the corresponding trans-4,5-disubstituted cyclopentenone derivatives in good yields with high selectivity in short reaction time.     

Organic reactions in water: an efficient method for the synthesis of 1,2,4-oxadiazoles in water

A simple and efficient process has been developed for the synthesis of 1,2,4-oxadiazoles in good yields through the reaction of amidoximes with anhydrides under catalyst-free conditions in water.     

The Vilsmeier reagent as an efficient acid activator for the synthesis of β-lactams

The Vilsmeier reagent (chloromethylenedimethylammonium chloride) has been used as an efficient and cheap acid activator for the one-step Staudinger reaction of substituted acetic acids and imines under mild conditions. This reaction is clean and the by-products are DMF and triethylamine hydrochloride which were removed by simple aqueous work-up.     

Nanocomposites with different metals as magnetically separable nanocatalysts for oxidation of aldehydes

In this study, two metals were chosen for composing two different nanocatalysts. Zinc acetate and nickel chloride were used to prepare two nanocatalysts from acetanilide anchored to functionalized silica-coated Fe₃O₄ magnetic nanoparticles. They were identified using scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and gas chromatography–mass spectrometry. These nanocatalysts were used for the oxidation of the following aldehydes: 3-hydroxybenzaldehyde, 4-methoxybenzaldehyde, and 3-nitrobenzaldehyde. High efficiency, stability, recoverability, recyclability, and selectivity were achieved using these nanocatalysts.     

β-Cyclodextrin as an efficient catalyst for the one-pot synthesis of 1-aminophosphonic esters in water

A simple, efficient, and general method has been developed for the one-pot synthesis of α-aminophosphonic esters in water using β-cyclodextrin as an efficient catalyst. α-Aminophosphonic esters were obtained in good yields (45-82%) and purity under mild conditions by the reaction of diethyl phosphite with a mixture of aldehyde and amine in water at reflux.     

Fe3O4-supported N-pyridin-4-amine-grafted graphene oxide as efficient and magnetically separable novel nanocatalyst for green synthesis of 4H-chromenes and dihydropyrano[2,3-c]pyrazole derivatives in water

Research on Chemical Intermediates - Fe3O4-magnetized N-pyridin-4-amine-functionalized graphene oxide [Fe3O4@GO-N-(pyridin-4-amine)] was readily prepared via a three-step procedure. The synthesized...     

Boric acid as an efficient catalyst for the synthesis of 1,1-diacetate under solvent-free condition

Boric acid (BO₃H₃) is an inexpensive, efficient and mild catalyst for the synthesis of 1,1-diacetate (acylal) from the various aromatic and heteroaryl aldehydes with acetic anhydride at room temperature under solvent-free condition. The present method does not involve any hazardous organic solvents or catalysts. This method gives notable advantages such as excellent chemoselectivity, mild reaction condition, short reaction times and excellent yield.     

Phosphated tungstate: An efficient new solid phosphoric acid catalyst for the synthesis of heterocyclic nitrones

Phosphated tungstate as a new, reusable and efficient solid phosphoric acid catalyst was synthesized and used to promote the reaction of diaminoglyoxime with various aromatic aldehydes. The prepared phosphated tungstate was characterized using various techniques including X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy and thermal analysis. A wide variety of heterocyclic nitrones were obtained under mild reaction conditions and in high yields by using the prepared catalyst.