Catalyst For Solvent-free Synthesis Research Articles

Homoleptic phenoxy-imine pyridine zinc complexes: efficient catalysts for solvent free synthesis and chemical degradation of polyesters

Robust homoleptic zinc catalysts offer new opportunities for recycling polyesters such as poly(lactic acid) and poly(ethylene terephthalate) to obtain platform molecules in a plastics circular economy approach.

Tri Oxometallic Zeolite Composite Nanostructures: New and Efficient Catalyst for Solvent Free Synthesis of Bis (Dihydropyrimidinone) Derivatives

The facile chemical synthesis method was used for preparing Bis (dihydropyrimidinone) derivatives through Biginelli condensation reaction of terephthalic aldehyde, 1,3-dicarbonyl compounds and (thio) urea or guanidine with tri metallic Fe–Co–V/Zeolite and Fe–Co–Mo/Zeolite composite nanostructures. The structural functionalities and morphological observations of catalyst were obtained using characterization techniques of field emission scanning electron microscopy, X-ray diffraction, Fourier transfer infrared (FT-IR) spectroscopy and transmission electron microscope. The Bis (dihydropyrimidinone) derivatives confirmed by FT-IR, NMR and mass spectroscopy. Excellent yields of the biginelli products and simple work-up are attractive features of this effective protocol.

New Tetradentate Acidic Catalyst for Solvent-Free Synthesis of 1- Amidoalkyl-2-Naphthols and 4,4′-(Arylmethylene)-Bis(3-Methyl-1-Phenyl-1H-Pyrazol-5-ol)s

In this work, a tetradentate acidic catalyst based on pentaerythritol tetrabromide and methylimidazole was designed and synthesized. The catalyst was characterized by Fourier transform infrared, 1H NMR, 13C NMR, and thermogravimetric analysis and its catalytic activity in the synthesis of 1-amidoalkyl-2-naphthols (from 2-naphthol, aryl aldehydes, and amide) and 4,4′-(arylmethylene)-bis(3-methyl-1-phenyl-1H-pyrazole-5-ol)s (from aryl aldehydes, phenylhydrazine, and ethyl acetoacetate), two important classes of compounds, was investigated. The catalyst has multiple interesting properties such as hydrogen bonding interactions, high catalytic activity, heterogeneous feature, and ability to be useful under solvent-free condition.

MWCNTs@NHBut/PTA: New efficient solid acid catalyst for solvent free synthesis of benzochromenopyrimidines

In this study, a novel and eco‐friendly synthesis of benzochromenopyrimidines catalyzed by phosphotugstic acid immobilized on aminated multiwalled carbon nanotubes (MWCNTs@NHBut/PTA) is reported. New solid acid catalyst was prepared through a simple process with good percentage of organo metallic groups and characterized with FTIR, TEM, SEM, EDX and TGA techniques. Reusable catalytic system provides a convenient, safe and green pathway to generate a variety of benzochromenopyrimidines under mild conditions.

SnCl4 grafted on silica gel: an efficient catalyst for solvent-free synthesis of coumarins via the Pechmann condensation

A facile synthesis of substituted coumarins via Pechmann condensation catalyzed by SnCl4 grafted on silica gel is described, which was conducted under solvent-free condition in high yields. The catalyst is noncorrosive and can be easily prepared and separated from the reaction mixture. This methodology offers some advantages with regard to yield of products, simplicity in operation and green aspects.

Synthesis, Characterization and Catalytic Activity of Molybdenum Oxide Supported Zirconia Catalysts for Solvent-free Synthesis of Chalcones

Solvent-free Claisen-Schmidt condensation (CSC) for the synthesis of chalcone has been studied using MoO3/ZrO2 material as solid acid catalyst. A series of MoO3/ZrO2 catalysts with various MoO3 loadings (10-30 wt%) were prepared using modified precipitation method. The catalysts were extensively characterized using various techniques viz., TG-DTA, XRD, N2 Sorption, BET-surface area, NH3-TPD, Raman and FT-IR spectroscopies, AAS, EDX, TEM and SEM. The detailed parametric studies were carried out to optimize the reaction parameters in order to achieve maximum selectivity with high % yield of chalcones. Substituted benzaldehyde and acetophenone were used as reactants to study the effect of electron withdrawing and electron donating groups on the activity of catalyst. 15 wt% MoO3/ZrO2 catalyst pre- pared using modified preparation technique proved to be an excellent heterogeneous catalyst for solvent free synthesis of chalcone with yield as high as 93 %, by using only 1.5 wt% of catalyst.

Preparation of Mg/Al layered double hydroxide (LDH) with structurally embedded molybdate ions and application as a catalyst for the synthesis of 2-adamantylidene(phenyl)amine Schiff base

Preparation of MoO42−-containing Mg/Al layered double hydroxide (LDH) using co-precipitation method has been suggested. The possibility of introduction of molybdate ions from solutions with different concentrations of molybdate to the structure of LDH has been investigated. For this purpose, the mixture of magnesium and aluminium nitrates was added to the solution of molybdate or vice versa. The XRD patterns of obtained specimens showed formation of layered double hydroxide phases without any impurities. The basal spacing of formed LDH was not affected when concentration of molybdate used in the synthesis process was low. However, at higher concentration of molybdate an increase of cell parameter c was observed. The determined Mg/Al ratio and the amount of Mo in LDH were found to be dependent on the preparation conditions. Molybdate-containing LDH was tested as a catalyst in solvent free synthesis of 2-adamantylidene(phenyl)amine. It was demonstrated, that the addition of molybdenum in LDH improved the yield of Schiff base.

Silica supported boric tri-sulfuric anhydride as a novel and efficient catalyst for solvent-free synthesis of coumarins via Pechmann condensation

It is found that silica supported boric trisulfuric anhydride (BTSA.SiO 2) is a novel, suitable and versatile catalyst for efficient and clean synthesis of coumarins via Pechmann cyclocondensation under mild and solvent-free conditions. Different kinds of phenols and �-ketoesters were subjected to the cyclization reaction. Particularly, this catalyst makes the condensation of less activated phenols feasible. Besides the described benefits, the reported catalyst was applied successfully for the synthesis of novel coumarins from 3-acetyldihydrofuran-2(3 H)-one as well as estradiol (sex hormone).

Host (nanocavity of zeolite-Y)–guest (molybdophosphoric acid) nanocomposite materials: An efficient catalyst for solvent-free synthesis and deprotection of 1,l-diacetates

Abstract In the present work, a mild and efficient method has been developed for the synthesis of acylals from aldehydes with acetic anhydride in the presence of molybdophosphoric acid encapsulated into dealuminated zeolite Y (MPA-DAZY) as a catalyst under solvent-free conditions at 45–55 °C in good to excellent yield. The deprotection of acylals has also been attained using this catalyst in acetonitrile. The catalyst was reused several times without efficient loss of its catalytic activity.

Cellulose sulfuric acid: reusable catalyst for solvent-free synthesis of bis(indolyl)methanes at room temperature

Bis(indolyl)methanes were synthesized from indole and aldehydes under solvent-free conditions using cellulose sulfuric acid (CSA) as a catalyst at room temperature. CSA is easily prepared and it was also found that this catalyst could be recovered quantitatively and reused without much loss of catalytic activity.

Environmentally Benign Chemical Conversion of CO2 into Organic Carbonates Catalyzed by Phosphonium Salts

Quaternary phosphonium salts were proved efficient homogeneous catalysts for solvent-free synthesis of cyclic carbonates from carbon dioxide and epoxides. Propylene carbonate was produced in quantitative yield and excellent selectivity. Furthermore, a PEG-supported phosphonium salt was solidified by adding ether and cooling after reaction and recovered by a simple filtration. Hence immobilization of a phosphonium salt on PEG provides an alternative pathway for realizing homogeneous catalyst recycling.

Sulfated Ce xZr 1− xO 2 solid acid catalyst for solvent free synthesis of coumarins

A novel SO 4 2−/Ce x Zr 1− x O 2 catalyst has been employed for Pechmann condensation of phenols under solvent-free conditions. Catalyst loads as low as 10 wt.% could be used leading to high yields with activated phenols at an oil bath temperature of 393 K. To make the catalyst, Ce–Zr–hydroxide gel was prepared by a coprecipitation method and SO 4 2− ions were deposited by treating the gel with sulfuric acid and calcined at 923 K. Surface and bulk properties of the catalyst was investigated by means of X-ray powder diffraction, ammonia-temperature programmed desorption, Raman spectroscopy, and BET surface area methods. Characterization results reveal the super acidic nature of the catalyst. The methodology presented offers significant improvements for the synthesis of coumarins with regard to yield of products, simplicity in operation, and green aspects by avoiding toxic conventional catalysts and solvents.