Derivatives In Aqueous Media Research Articles

Self-Assembly of Amphiphilic Amylose Derivatives in Aqueous Media.

Six amylose derivative (C12CMA) samples with hydrophobic dodecyl ether groups and hydrophilic sodium carboxymethyl groups were synthesized from an enzymatically synthesized amylose for which the weight-average molar mass is 50 kg mol-1 to realize amylose-based amphiphilic polymer micelles. The degree of substitution of hydrophobic (DSC12) and hydrophilic (DSCM) groups ranges between 0.076 and 0.39 and between 0.35 and 1.83, respectively. Static and dynamic light scattering, small-angle X-ray scattering (SAXS), and fluorescence measurements with pyrene as a probe were carried out for the samples in 150 mM aqueous NaCl to characterize the higher-order structure in solution. The fluorescence from pyrene showed that all six samples have hydrophobic environment, while the hydrophobicity tends to increase with rising DSC12. All six samples have high scattering intensity owing to the relatively large concentrated droplets ranging in the hydrodynamic radius from 50 to 110 nm, whereas the weight fraction of such large particles is substantially small except for the highest DSC12 sample. Most polymer chains for relatively low DSC12 of 0.076 were molecularly dispersed with a very small amount of large droplets. The dispersed chain has a slightly smaller helix pitch per residue and a more rigid main chain than those for amylose in dimethyl sulfoxide, suggesting that the amylosic main chain of C12CMA has a helical structure with dodecyl groups at least locally. On the other hand, an anisotropic shaped micelle-like structure is only found for relatively high DSC12 (0.23 and 0.39) samples, which was detected by the SAXS profile at a high scattering vector range. The micelle structure for high DSC12 samples is consistent with the high chain stiffness.

Molecular modelling of fullerene C60 and its amino acid derivatives in aqueous medium

The hydration free energy ΔGs of fullerene C60 has been determined using the quantum mechanical methods and continuum solvent models, microscopic free energy molecular dynamics techniques, and compilation of known experimental data. Theoretical calculations using standard parameterization schemes of solvent models have predicted negative values of ΔGs(C60) whereas application of the revised parameters, that take into account special features of carbon structures, shifts the computed ΔGs(C60) to positive values. Reasonably accurate estimates of the hydration free energies of the neutral and anionic states of functionalized fullerenes were obtained from the generalized Born method. The described data have shown that the calculations of hydration thermodynamics of fullerenes apparently require separate parameterization for the carbon atoms met in these nanomolecules.

Copper-Catalyzed Oxidative Cross-Coupling Reactions for the Synthesis of β-Acyl-α-amino Acid Derivatives in Aqueous Medium

Copper-Catalyzed Oxidative Cross-Coupling Reactions for the Synthesis of <i>β</i>-Acyl-<i>α-</i>amino Acid Derivatives in Aqueous Medium

Tuning the aggregation performance by varying the substituent position: comparative study of neutral bis-urea derivatives in aqueous medium

A set of three neutral bis-urea derivatives has been purposefully chosen to investigate the consequences of positional isomers on the aggregation performance.

Polystyrene-supported 1-methylimidazolium tetrachloro ferrate: Synthesis, characterization, and application as an efficient and reusable heterogeneous catalyst for one-pot synthesis of 4h-chromene derivatives in aqueous media

Polystyrene-supported 1-methylimidazolium tetrachloroferrate (PS[mim][FeCl 4 ]) was prepared and characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The catalytic activity of the heterogeneous catalyst was evaluated through one-pot synthesis of 2-amino-4 H -chromene-3-carbonitriles via the three-component condensation reaction of aromatic aldehydes, malononitrile and dimedone or 2-naphthol in water. The heterogeneous catalyst could be recovered easily and reused five times without significant loss of its catalytic activity. KEY WORDS : Green chemistry, Heterogeneous catalyst, 4 H -chromene derivatives, Multi-component reactions, One-pot synthesis Bull. Chem. Soc. Ethiop. 2018 , 32(3), 531-540. DOI: https://dx.doi.org/10.4314/bcse.v32i3.12

Fe3O4 magnetic nanoparticles in the layers of montmorillonite as a valuable heterogeneous nanocatalyst for the one-pot synthesis of indeno[1,2-b]indolone derivatives in aqueous media

In the present work, iron oxide nanoparticles (Fe3O4-NPs) were prepared using a chemical coprecipitation method. At room temperature, Fe3O4-NPs are put in interlamellar space and external surfaces of montmorillonite (MMT) as a supported solid. The MMT@Fe3O4 was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA) and Fourier transform infrared spectrophotometry (FT-IR). Then, indeno[1,2-b]indolone derivatives were catalyzed by magnetic MMT@Fe3O4-NPs. MMT@Fe3O4-NPs were found to be a recoverable organocatalyst for the effective synthesis of the indeno[1,2-b]indolone derivatives via one-pot multicomponent cyclocondensation of ninhydrin, 1,3-diketo compound and amine derivatives in water. The significant advantages of this method are excellent yield, mild conditions, eco-friendly catalyst, low expense, and not using an environmentally harmful catalyst or solvent.

4‐(4‐Propylpiperazine‐1‐yl)butane‐1‐sulfonic acid‐modified silica‐coated magnetic nanoparticles: A novel and recyclable catalyst for the synthesis of 5‐arylidinebarbituric acids and pyrano[2,3‐d]pyrimidinedione derivatives in aqueous media

A mild, simple and efficient procedure for the preparation of barbituric acid and pyrano[2,3‐d]pyrimidine derivatives in aqueous media is described using 4‐(4‐propylpiperazine‐1‐yl)butane‐1‐sulfonic acid‐modified silica‐coated magnetic nanoparticles as a novel and reusable catalyst. The catalyst was easily isolated from the reaction mixture by magnetic decantation using an external magnet and reused at least eight times without significant degradation in activity.

Simple Schiff‐Base Cu(II) Complexes as Efficient Catalysts for Benzyl Alcohol Oxidation

AbstractHerein, we present synthesis and characterization of new ligand with N2O‐donor moiety based on benzothiazole unit and its two complexes with Cu(II) cations. X‐ray diffraction measurements revealed solid state structures of presented compounds as mono‐ and dinuclear entities. Both complexes appeared to be highly effective catalysts in oxidation process of benzyl alcohol and its derivatives in aqueous media. Copper(II)‐(2,2,6,6‐tetramethylpiperidine‐1‐oxyl) system provides selective conversion in the presence of 0.25 mol% and 1 mol% for complex 1 and 2, respectively. Obtained results revealed that both copper complexes are highly selective towards benzyl alcohols oxidation to its carbonyl analogues. It was tested in the presence of several electron donating and accepting substituents. Consequently, presented systems can provide effective catalytic oxidation of aforementioned groups in the presence of aliphatic alcohols.

Piperazine: An excellent catalyst for the synthesis of 2-amino-3-cyano-4H-pyrans derivatives in aqueous medium

An improved, forthright, and highly efficient one-pot synthesis of a wide range of pharmaceutically exciting diverse kind of functionalized 2-amino-3-cyano-4H-pyrans and especially bis-pyrans compounds is developed using piperazine as a low-cost and environmentally benign commercially available basic catalyst in aqueous media. The attractive features of this process are simple procedure, short reaction times, high yields, no column chromatographic separation and commercial availability and recyclability of the catalyst. Also, piperazine can catalyze the synthesis of the target compounds on a larger scale. Furthermore, rational mechanism was suggested via GC-Mass analysis of the trapped intermediates.

Preparation of Pyrido[2,3‐b]indole Derivatives Using Silicates of Group 1 and 2 Metals

An efficient synthesis of 2,4‐diaryl‐9H‐pyrido[2,3‐b] indole derivatives in aqueous medium via the three‐component reaction of indolin‐2‐one, a chalcone and ammonium acetate was developed using Na2SiO3, K2SiO3, Li2SiO3, CaSiO3, MgSiO3, BaSiO3, SrSiO3, and ZnSiO3 as catalysts. Results of activity evaluations indicated that among of the metal silicate used alkali metal silicates exhibits much higher activity than other samples due to the stronger basicity power and higher solubility in water. Under the optimum reaction conditions, all of the reactions with diverse aromatic aldehydes provided high yields in low reaction times.

Butane‐1‐sulfonic acid immobilized on magnetic Fe3O4@SiO2 nanoparticles: A novel and heterogeneous catalyst for the one‐pot synthesis of barbituric acid and pyrano[2,3‐d] pyrimidine derivatives in aqueous media

Butane‐1‐sulfonic acid immobilized on magnetic Fe3O4@SiO2 nanoparticles (Fe3O4@SiO2‐Sultone) was easily prepared via direct ring opening of 1,4‐butanesultone with nanomagnetic Fe3O4@SiO2. The prepared reagent was characterized and used for the efficient promotion of the synthesis of barbituric acid and pyrano[2,3‐d] pyrimidine derivatives. All reactions were performed under mild and completely heterogeneous reaction conditions affording products in good to high yields. The catalyst is easily isolated from the reaction mixture by magnetic decantation and can be reused at least eight times without significant loss in activity.

One-Pot and Three-Component Condensation of Kojic Acid with Aromatic Aldehydes and Methyl Carbamate: Synthesis of Pyrano-1,3-Oxazine Derivatives in Aqueous Media

A novel method for oxazine ring formation has been established using the reaction of kojic acid and aromatic aldehydes with methyl carbamate in the presence of p-toluenesulfonic acid in aqueous media to afford 4-aryl-6-hydroxymethyl-1,4-dihydropyrano[3,2-e][1,3] oxazine-2,8-diones in excellent yields. The present method does not involve any hazardous organic solvent. Therefore, this procedure could be classified as green chemistry.

Organocatalyst Mediated One Pot Synthesis of 4H-furo[3,4-b]pyran, 4Hbenzo[ g]chromene and 1H-benzo[b]xanthene Derivatives in Aqueous Medium: A Green Approach

Introduction: 4H-furo[3,4-b]pyran, 4H-benzo[g]chromene and1H-benzo[b]xanthene derivatives have been efficiently synthesized in water using glycine as organocatalyst. Methods and Results: The key aspects of the present method are (1) The use glycine as organcatalyst which is metal free and in expensive (2) The synthesis was performed in water which is an ecofriendly solvent. Conclusion: Our reported protocol has several advantages like environmentally benign reaction conditions, operational simplicity, high atom economy, cost effectiveness and excellent yield. Keywords: 1H- benzo[b]xanthenes, 4H-benzo[g]chromene, 4H-furo[3, 4-b]pyrans, glycine, organocatalyst.

A Green Synthesis of Xanthenone Derivatives in Aqueous Media Using TiO2-CNTs Nanocomposite as an Eco-Friendly and Re-Usable Catalyst.

The xanthene (dibenzopyran) framework constitutes the core structure of many biologically active compounds, that they have been of interest because of their pharmacological activities like antiviral, antibacterial, anti-inflammatory, and CCR1 antagonist. As heterogeneous catalysts offer several advantages over homogeneous catalysts, the performance of reactions on the surface of nanosized heterogeneous salts has received a great deal of interest in recent years. In the area of nanosized heterogeneous catalysts there is a noticeable range of reactions that are catalyzed efficiently by TiO2 NPs. Moreover, carbon nanotubes (CNTs) as a support can be used to obtain nanoparticles with modified morphology, structural, chemical, electrical, and optical properties. The catalytic activity of titanium dioxide supported on carbon nanotubes has been greatly improved. The present methodology focus on the synthesis of 7,7-dimethyl-10-aryl- 6,7,8,10-tetrahydro-9H-[1,3]dioxolo[4,5-b]xanthen-9-ones, through a condensation reaction of dimedone, aromatic aldehydes and 3,4-methylenedioxyphenol, using a catalytic amount of TiO2- CNTs nanocomposite (15 mol%) at 80 ˚C in aqueous media, within 60-90 min. The TiO2-CNTs nanocomposite was also prepared by a known simple sonochemical method. A series of 7,7-dimethyl-10-aryl-6,7,8,10-tetrahydro-9H-[1,3]dioxolo[4,5-b]xanthen-9-ones were successfully synthesized in high yields (92-98%). All synthesized compounds were well characterized by their satisfactory elemental analyses, IR, 1H and 13C NMR spectroscopy. The synthesized catalyst was fully characterized by SEM, TEM, XRD, and EDX techniques. In summary, this investigation constitutes a novel and efficient route for the synthesis of 7,7-dimethyl-10-aryl-6,7,8,10-tetrahydro-9H-[1,3]dioxolo[4,5-b]xanthen-9-ones in high yields, by a three-component reaction of dimedone, aromatic aldehydes and 3,4-methylenedioxyphenol in water and in the presence of the TiO2-CNTs nanocomposite as a green, effective and recyclable catalyst. This novel method has the advantages of high yields, mild reaction conditions, short reaction time, easy work-up, inexpensive reagents and environmentally friendly procedure.

Synthesis of novel pyrazolo[3,4-b]pyridine derivatives in aqueous medium

Synthesis of novel pyrazolo[3,4-b]pyridine derivatives in aqueous medium

A novel colorimetric and “turn-on” fluorimetric chemosensor for selective recognition of CN− ions based on asymmetric azine derivatives in aqueous media

A novel chemosensor 2-((Z)-(((E)-quinolin-2-ylmethylene)hydrazono)methyl)phenol PX has been successfully designed and synthesized, which showed both colorimetric and “turn-on” fluorescence responses for CN− in DMSO/H2O (3:2, v/v; pH=7.20) solution. The sensor could respond effectively to the stimulation of CN− ions via deprotonation and sensing mechanism of intramolecular charge transfer (ICT). Moreover, the sensor PX was successfully utilized to detect CN− in bitter almond, and the detection limit on fluorescence response of PX towards CN− was down to 4.5×10−7M. Test strips containing PX were also prepared, which could act as a practical colorimetric tool to detect CN− in aqueous media.

Green and Facile Reaction of Gabapentin with Sulfonyl Chlorides to Synthesize Lactams and Sulfonamides Derivatives in Aqueous Medium

In the current research, a facile and green one pot synthesis of new gabapentin-lactams (G2-G8) has been achieved by reacting gabapentin (G1) with a variety of sulfonyl chlorides. The new lactamization protocol is furnished under the green solvent i.e., water and reaction was completed in a short period of time by just stirring at room temperature. Whereas in some cases, annulation could not happen and furnished un-cyclized sulfonamide products (G9-G12). The structures of the targeted compounds were established by elemental analysis, FT-IR, 1H-NMR and mass spectrometry. The crystals of some new lactams (G2, G3, G4, and G8) were also evaluated by single crystal X-ray diffraction. Keywords: Crystal structure, facile reaction, gabapentin, green synthesis, lactams, sulfonamides.

Impregnated palladium on magnetite as a water compatible catalyst for the cycloisomerization of alkynoic acid derivatives

This work describes the catalytic activity of palladium(ii) species in the cycloisomerization of alkynoic acids and their derivatives in aqueous media as well as in Deep Eutectic Solvents (DESs), with one of the lowest metal catalyst loadings reported so far in the literature.

A novel colorimetric and ratiometric fluorescent CN− sensor based on rhodamine B hydrazone derivatives in aqueous media and its application in sprouting potatoes

A novel cyanide specifically selective and highly sensitive chemosensor Z based on rhodamine B hydrazone derivatives had been designed and synthesized.

Highly Diastereoselective Syntheses of Spiro‐Oxindole Dihydrofuran Derivatives in Aqueous Media and Their Antibacterial Activity

AbstractA series of substituted spiro‐oxindole dihydrofuran ring derivatives were synthesized in good yields up to 94% and excellent diastereoselectivity ≥99% by simple tandem Michael ‐ cyclization in aqueous media using DABCO (1,4‐diazabicyclo[2.2.2]octane) as a catalyst and SDS (sodium dodecyl sulfate) as a promoter at ambient temperature. These molecules displayed promising antibacterial activity in vitro against pathogenic strains viz Vibrio cholerae, Escherichia coli, Bacillus subtilis, Bacillus licheniformis, Pseudomonas fluorescens, Salmonella enterica, Shigella flexneri and Shigella boydii with MIC (minimum inhibitory concentration), MBC (minimum bactericidal concentration) and IC50 (inhibitory concentration) values better than the standard antibiotic ampicillin.