Solid Liquid Phase Transfer Catalyst Research Articles

Kinetic model, recycling, regeneration, and reusing of tri-phase catalytic nucleophilic substitution esterification

This research aims to develop a liquid–solid–liquid phase-transfer catalyst (PTC) catalytic kinetic model of carboxylate esterification unpublished previously. The bimolecular nucleophilic substitution reaction of sodium benzoate with benzyl bromide has been experimented with the immobilized solid PTC to propose the kinetic model and calculate the apparent reaction rate constant and activation energy. We proposed the proper kinetic model of the esterification successfully. In addition, the experimental results comprehensively matched the pseudo-first-order reaction formula. Under the multiple steps of recovery, reuse, and regeneration, the structure of tri-phase PTC support remains well, nor will it destroy the activated site immobilized on the support. Comparing the reactivity of the fresh PTC with PTCs recovered four times, the reactivity does not decrease with the continued recovery, indicating excellent catalytic reactivity. Besides, the esterification, etherification, and benzylation reactions catalyzed by regenerated PTCs and their yields are not much different from those of the original fresh PTCs. It shows that the catalytic activity of regenerated PTC is quite excellent. In our opinion, exploring the regeneration and reduction of PTC can reduce cost, save resources, possesses the potential to apply to other reaction systems, and improve conventional production.

Synthesis and Characterization of γ-Fe2O3@HAp@β-CD Core-Shell Nanoparticles as a Novel Magnetic Nanoreactor and Its Application in the One-Pot Preparation of β-azido Alcohols, β-nitro Alcohols, and β-cyanohydrins

In this study, β-cyclodextrin(β-CD) supported, hydroxyapatite encapsulated γ-Fe2O3 (γ-Fe2O3@HAp@β-CD) was successfully prepared and evaluated as a solid-liquid phase transfer catalyst and also a molecular host system and nanoreactor for the nucleophilic ring-opening of epoxides in water for the preparation of β-azido alcohols, β-nitro alcohols, and β-cyanohydrins. The catalyst was characterized by FT-IR, XRD, TGA, and SEM. This procedure offers several advantages including excellent regioselectivity, high yields, short reaction times, recyclable catalyst, easy separation of the catalyst through external magnet, and easy work-up.

The Role of PEG on Pd- and Cu-Catalyzed Cross-Coupling Reactions

Carbon–carbon and carbon–heteroatom coupling reactions are among the most important transformations in organic synthesis as they enable complex structures to be formed from readily available compounds under different routes and conditions. Several metal-catalyzed cross-coupling reactions have been developed creating many efficient methods accessible for the direct formation of new bonds between differently hybridized carbon atoms.During the last decade, much effort has been devoted towards improvement of the sustainability of these reactions, such as catalyst recovery and atom efficiency. Polyethylene glycol (PEG) can be used as a medium, as solid-liquid phase transfer catalyst, or even as a polymer support. PEG has been investigated in a wide variety of cross-coupling reactions either as an alternative solvent to the common organic solvents or as a support for catalyst, substrate, and ligand. In this review we will summarize the different roles of PEG in palladium- and copper-catalyzed cross-coupling reactions, with the focus on Heck, Suzuki–Miyaura, Sonogashira, Buchwald–Hartwig, Stille, Fukuyama, and homocoupling reactions. We will highlight the role of PEG, the preparation of PEGylated catalysts and substrates, and the importance for the reaction outcome and applicability.1 Introduction2 PEG in Heck Reactions3 PEG in Homocoupling Reactions4 PEG in Suzuki–Miyaura Reactions5 PEG in Sonogashira Reactions6 PEG in Buchwald–Hartwig Reactions7 PEG in Stille Reactions8 PEG in Fukuyama Reactions9 PEG in Miscellaneous Cross-Coupling Routes10 Conclusions

A combination of directing groups and chiral anion phase-transfer catalysis for enantioselective fluorination of alkenes.

We report a catalytic enantioselective electrophilic fluorination of alkenes to form tertiary and quaternary C(sp3)-F bonds and generate β-amino- and β-aryl-allylic fluorides. The reaction takes advantage of the ability of chiral phosphate anions to serve as solid-liquid phase transfer catalysts and hydrogen bond with directing groups on the substrate. A variety of heterocyclic, carbocyclic, and acyclic alkenes react with good to excellent yields and high enantioselectivities. Further, we demonstrate a one-pot, tandem dihalogenation-cyclization reaction, using the same catalytic system twice in series, with an analogous electrophilic brominating reagent in the second step.

Synthesis, characterization and application of β-cyclodextrin-silica nanocomposite as potential microvessel in nucleophilic substitution reaction of phenacyl halides

In the present study, β-cyclodextrin-silica hybrid is synthesized as a novel, efficient and eco-friendly microvessel and solid–liquid phase-transfer catalyst. This molecular host system was applied for nucleophilic substitution reaction of phenacyl halides in water. No evidence was observed for the formation of by-product for example isothiocyanate or alcohol. Also the products were obtained in pure form without further purification. The structure and morphology of the obtained system were investigated by infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis and differential thermal analysis techniques. The surface porosity of the synthesized catalyst was evaluated from the nitrogen adsorption isotherm. All the results provided evidence for incorporation of β-cyclodextrin inside silica pores.

Magnetic nanoparticles grafted with β-cyclodextrin–polyurethane polymer as a novel nanomagnetic polymer brush catalyst for nucleophilic substitution reactions of benzyl halides in water

The polymer coated magnetic nanoparticles has gained significant attention for potential applications in biomedicine, separations, and magnetic storage. In this study, β-cyclodextrin–polyurethane polymer coated Fe3O4 magnetic nanoparticle as a novel class of hybrid organic/inorganic molecular catalyst was successfully prepared and evaluated as solid–liquid phase-transfer catalyst and molecular host system for nucleophilic substitution reactions. The nanocomposite has demonstrated the ability to catalytic the nucleophilic substitution reaction of benzyl halides with thiocyanate, azide, cyanide and acetate anions in water. No evidence for the formation of by-products for example isothiocyanate or alcohol was observed and the products obtained in pure form without further purification. The nanomagnetic polymer brush catalyst was easily removed from solution via application of a magnetic field, allowing straightforward recovery and reuse. Results obtained from scanning electron microscopy (SEM) and vibrating sample magnetometery (VSM) show that the synthesized magnetic nanocomposite are superparamagnetic with a mean diameter of 59nm. The grafting of β-cyclodextrin–polyurethane polymer to Fe3O4 magnetic nanoparticle is confirmed by Fourier transform infrared spectroscopy (FT-IR).

β‐Cyclodextrin Immobilized onto Dowex Resin: A Unique Microvessel and Heterogeneous Catalyst in Nucleophilic Substitution Reactions

AbstractThe catalytic activity of β‐cyclodextrin immobilized on Dowex resin as an efficient solid‐liquid phase transfer catalyst was developed for the synthesis of alkyl thiocyanates and phenacyl derivatives in water. The nucleophilic substitution reactions were performed under mild reaction condition and gave the products in excellent yields. Furthermore, the catalyst could be recycled by facile separation without any loss of activity.

Application of β-cyclodextrin-polyurethane as a stationary microvessel and solid–liquid phase-transfer catalyst: Preparation of benzyl cyanides and azides in water

Application of water tolerant heterogeneous catalyst, β-cyclodextrin-polyurethane (β-CDPU) polymer, as an efficient microvessel and polymeric host system for nucleophilic substitution reaction of benzyl halides with cyanide and azide anions in water has been described. The reactions gave only pure products, which did not require any further purification. The most important features of this method are high yields, clean reactions and that the catalyst can be recovered and recycled.

New technique for the synthesis of polyphosphoesters

Polycondensation of arylphosphonic(phosphoric)dichlorides with various bisphenols was carried out using a new technique, namely, solid-liquid phase transfer catalysis. Potassium phosphate was used as the base. The synthesis of polyphosphonate by solid-liquid phase-transfer catalyst (PTC) polycondensation of phenylphosphonic dichloride with 4,4'-cyclohexylidenebisphenol is presented in detail. The structures of the polyphosphonates and flu- orine-polyphosphate were studied using this technique. The polymers were characterized by gel permeation chro- matography, Fourier transform infrared spectroscopy (FTIR), 1 H and 31 P nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry, and thermal analysis. Yields in the range of 80.2-86.5, and inherent viscosities in the range of 1.48-2.5 dL/g were obtained. High molecular weight polymers (Mn of ~11,800-21,600) were successfully prepared. The polymers were self-extinguishing and started losing weight at around 280-380 o C. The glass-transition temperatures of the polymers were detected in the range of 85-180 o C. The flammability was

Simple, Practical and Eco-friendly Reduction of Nitroarenes with Zinc in the Presence of Polyethylene Glycol Immobilized on Silica Gel as a New Solid-liquid Phase Transfer Catalyst in Water

Polyethylene glycol was easily grafted to silica gel and used as a solid-liquid phase transfer catalyst in the reduction of aromatic nitro compounds. This silica-grafted polyethylene glycol is proved to be an efficient heterogeneous catalyst in the reduction of nitroarenes to the corresponding aromatic amines with zinc powder in water. The reduction reactions proceeded efficiently with excellent chemoselectivity without affecting other sensitive functional groups.

Substituted-nicotinyl thiourea derivatives bearing pyrimidine moiety: synthesis and biological evaluation

A series of substituted-nicotinyl thiourea derivatives containing pyrimidine ring were synthesized in good to excellent yield using PEG-400 as solid–liquid phase transfer catalyst under ultrasonic irradiation. The structures of all newly synthesized compounds were elucidated and confirmed by IR, 1H NMR and elemental analysis. The preliminary biological tests show that some of the target compounds present good inhibitory activities against the root and stalk of dicotyledon plants and are safe for monocotyledon plants.

Immobilization of β-cyclodextrin onto Dowex resin as a stationary microvessel and phase transfer catalyst

Abstract In this study, immobilization of β-cyclodextrin onto commercial Dowex resin by covalent bond was reported. The efficiency of this biocatalyst system as a stationary microvessel and new solid–liquid phase transfer catalyst in reduction of epoxides by NaBH 4 was studied.

Poly(ethylene glycol) Grafted onto Dowex Resin: An Efficient, Recyclable, and Mild Polymer-Supported Phase Transfer Catalyst for the Regioselective Azidolysis of Epoxides in Water

In this study, an efficient method was designed to graft poly(ethylene glycol) effectively onto commercial Dowex resin. The catalytic efficiency of the copolymer obtained as a new solid-liquid phase transfer catalyst was studied. It was proved that this organocatalyst is an efficient heterogeneous catalyst for regioselective azidolysis of epoxide in water and gave azidohydrin in excellent yield under mild reaction conditions. The polymeric catalyst was easily recovered by simple filtration and showed no appreciable loss of activity when recycled several times.

Polyethylene glycol immobilized on silica gel as a new solid–liquid phase-transfer catalyst for regioselective azidolysis of epoxides in water: An efficient route to 1,2-azido alcohols

Abstract Polyethylene glycol, a polymer widely used for biomedical applications and in supported synthesis, was easily immobilized on silica gel and used as a new solid–liquid phase-transfer catalyst. It is proved to be an efficient heterogeneous catalyst for regioselective ring opening of epoxide by azide ion in water to give azidohydrine in excellent yield under mild reaction conditions. The polymeric catalyst easily recovered by simple filtration, shows no appreciable loss of activity when recycled several times.

New type of repeated Si–C-podand catalysts for solid–liquid phase transfer reactions

Abstract For the first time Si–C-podands 1 – 3 (with Si–C bonds) have been studied as efficient and powerful catalysts in typical anion promoted reactions under solid–liquid conditions, even in low polarity solvent. Their complexation extent of Na + and K + and catalytic activities are comparable with those of the classical solid–liquid phase transfer catalysts, Si-podands ( 4 , 5 ) reported in our earlier works.

Cross-linked poly(diallyldimethylammonium chloride) as an efficient solid–liquid phase transfer catalyst in reduction of carbonyl compounds with sodium borohydride

Cross-linked poly(diallyldimethylammonium chloride) resin was synthesized as an efficient polymeric phase transfer catalyst. This quaternized polymer catalyzed the chemoselective reduction of aldehydes and ketones by NaBH 4 to give the corresponding alcohols in high yields under mild conditions.

Synthesis of β‐Dihydroxysulfides by Cleavage of Epoxides Using Quaternized Amino‐Functionalized Cross‐Linked Polyacrylamide as a New Polymeric Phase Transfer Catalyst.

Poly[N-(2-aminoethyl)acrylamido]trimethyl ammonium halide resin was developed as a new solid-liquid phase transfer catalyst. This quaternized polyacrylamide catalyzed regioselective ring opening of epoxide by Na 2 S to obtain bis[β -hydroxy-alkyl]sulfide in high yield under mild conditions.

A green procedure for the synthesis of cinnamate esters using Aliquat®336

As an effective solid-liquid phase-transfer catalyst as well as an ionic liquid medium Aliquat® 336 has been applied in the synthesis of cinnamate esters under mild green chemistry procedures involving microwave irradiation.

Synthesis of β -Dihydroxysulfides by Cleavage of Epoxides Using Quaternized Amino-Functionalized Cross-Linked Polyacrylamide as a New Polymeric Phase Transfer Catalyst

Poly[N-(2-aminoethyl)acrylamido]trimethyl ammonium halide resin was developed as a new solid-liquid phase transfer catalyst. This quaternized polyacrylamide catalyzed regioselective ring opening of epoxide by Na 2 S to obtain bis[β -hydroxy-alkyl]sulfide in high yield under mild conditions.

Synthesis of 2-nitroalcohols from epoxides using quaternized amino functionalized cross-linked polyacrylamide as a new polymeric phase transfer catalyst

Poly[ N-(2-aminoethyl)acrylamido]trimethyl ammonium halide resin was developed as new solid–liquid phase transfer catalyst. This quaternized polyacrylamide catalyzed regioselective ring opening of epoxide by nitrite anion ( NO 2 - ) , to give 2-nitroalcohols in high yield under mild conditions.