Organic Chemistry Research
Volume:6 Issue: 2, Summer 2020

1-substituted 1H-tetrazoles were efficiently synthesized under solvent-free conditions from the reaction of primary amines, triethylorthoformate, and sodium azide in the presence of Cu/C as a heterogeneous catalyst. Various amines including aromatic and heteroaromatic amines were used to afford the corresponding products in good to excellent yields. The characterization of corresponding products were also performed applying several analysis techniques such as infrared spectroscopy, 1H-NMR, 13C-NMR and elemental analyses. The catalyst can be recycled and reused for five times without noticeable loss of its activity. This procedure has various benefits include high yields, low cost, fast reaction and reusability of the catalyst.

Magnetic nanoparticle-supported sulfanilic acid (MNPs-PhSO3H) has been used as an efficient catalyst for the preparation of 1,4-diazepines containing tetrazole ring. The catalyst has been characterized by FT-IR (Fourier-transform infrared spectroscopy), SEM (scanning electron microscope), XRD (X-ray diffraction) and VSM (vibrating-sample magnetometer). The present synthetic protocol provides several advantages such as easy work-up, excellent yields, short reaction times, reusability of the catalyst and low catalyst loading. The present catalytic procedure is extensible to a wide diversity of substrates for the synthesis of a variety-oriented library of 1,4-diazepines containing tetrazole ring.

An efficient method for the synthesis of novel dihydropyrimidothiazinoquinoline derivatives through the reaction of 2-chloro-3-(chloromethyl)quinolines and 2-thioxo-2,3-dihydropyrimidin-4(1H)-one in the presence of K2CO3 is demonstrated.

Chlorophyll is a natural pigment used for the synthesis of organic substances for instance sugars. At mild conditions, chlorophyll was employed as a green catalyst for the synthesis of tetrahydrobenzo[b]pyran and 3,4-dihydropyrano[c]chromene from the condensation between aromatic aldehydes, malononitrile, and 4-hydroxy-2H-chromen-2-one is an active enolic compound. This methodology has a considerable number of advantages such as mild conditions, natural, affordable catalyst, excellent yields, eco-friendly and, short reaction time. Another point worth mentioning is that purification of the products does not require sophisticated methods like column chromatography.

A new Schiff base ligand, pyridine 3-carbaldehye thiosemicarbazone (1), was synthesized and structurally characterized. Its synthesis involves a Schiffbase condensation of thiosemicarbazide and pyridine 3-carbaldehyde. The new compound was determined through elemental analyses, FT-IR spectroscopy, and single-crystal X-ray crystallography. Compound 1 has a monoclinic crystallographic system with a P21/n space group. It can be introduced as a tridentate NNS donor ligand for the synthesis of several complexes with new structures. With several H-bonding, the structure showed the three-dimensional structures.Inaddition, the electronic properties of pyridine 3-carbaldehyde thiosemicarbazone are studied, in atomic-scale,using density functional theory (DFT) at and quantum theory of atoms in molecules (QTAIM). Also, the external electric field (EF) effects on electronic/vibrationalpropertiescharacteristics of this molecular system (as molecular wire) are studied, using QTAIM, at theatomic scale (EF-QTAIM).Moreover, analysis of the current-voltage (I-V) curve results showed that this molecule can be used as a stable molecular wire.

Nano-sawdust/Sn(IV) was used as a readily available, inexpensive, biodegradable and environmentally benign heterogeneous solid acid biocatalyst for the one pot cascade synthesis of highly functionalized dihydro-2-oxypyrroles. Four-component reactions (4CRs) of the dialkylacetylenedicarboxylates, amines and aldehydes were used for the synthesis of highly functionalized dihydro-2-oxypyrroles under thermal conditions.

A new and efficient approach has been developed for the synthesis of N-amino pyridine-2,6-dione derivatives by a one-pot, three-component reaction of 2-cyanoacetohydrazide, Meldrum's acid, and aryl aldehyde in the presence of piperidine in DMF. All the products were obtained in excellent yields and their structures were established from their spectroscopic data.

A streamlined and efficient method for the synthesis of 2-amino-4H-chromenes is achieved by one-pot three-component reaction of aldehydes, 2-naphthol and malononitrile in the presence of ZnO nanoparticles loaded on zeolite-Y (ZnO@zeolite-Y) as a highly active catalyst under solvent-free conditions. ZnO@zeolite-Y has been successfully prepared via hydrothermal technique and its structure was confirmed using nanoscale-like identification techniques included FT-IR, XRD, FE-SEM, EDX analyses and BET surface area measurements. The higher environmental compatibility and sustainability factors such as reusability of the catalyst as an important principle in green chemistry, use of solvent-less technique as a green synthetic approach and easy isolation of the product along with good yields, make the present protocol a true green process for the synthesis of chromenes compared to conventional methods.

Abstract This work involves the extractive oxidation of mixed thiophenic compounds model oil over an oxidative polyoxometalate-based catalytic system. Phosphotungstic acid-pyridine compound combining of Keggin-structured polyoxometalate anion with sulfonate functionalized cation was applied as catalyst in sulfur removal. Model oil was simulated using a mixture of the sulfur compounds dibenzothiophene, benzothiophene and thiophene in n-heptane. At optimization strategy, different extractive solvents including isopropanol, ethanol, dimethylformamid and acetonitrile in desulfurization performance were used. Some important reaction parameters including catalyst loading, dose of the oxidizing agent, existence of nitrogen compounds and aromatic hydrocarbons (toluene, xylene and mesitylene) were considered on the oxidative desulfurization (ODS) via a one-step process under optimized conditions.

In this research, the effect of different solvents on the stability order, binding energy and hydrogen bond (H-bond) strength of Fluorouracil-Nitrosamine (FU–NA) complex is investigated by using the density functional theory (DFT). The calculations are conducted on M06-2X/6-311++G(d,p) level of theory for optimization of complex geometries and their monomers. Based on the average of the calculated H-bond energies, the H-bond strength in the gas phase is higher than the solution phase and in the polar solvents are close to each other and lower than the non-polar ones. Our findings also show that when the solvent effect is applied the binding energy of complex is significantly changed. The binding energy in the solution phase is also lower than the gas phase. Therefore, the stability in the polar solvents with respect to the water as natural solvent is higher than the non-polar ones. The natural bond orbital (NBO) analysis and the Bader’s quantum theory of “Atoms in Molecules” (QTAIM) are also applied to evaluate the H-bond interactions in the selected solvents.

In this paper, bi-pyridinium chloride supported on the core-shell mesoporous substrate, Fe2O3@MCM was prepared as an organic-inorganic magnet nanocomposite. Characterization of prepared hybrid nanocomposite, Fe2O3@MCM-BP, has taken using FT-IR spectroscopy, X-ray diffraction (XRD),Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Thermal gravimetric analysis (TGA), and Vibrational sample magnetometry (VSM) techniques. The efficacy of the nanocomposite as an alkaline heterogeneous magnetic catalyst in the one-pot multicomponent condensation reaction for preparation of various derivatives of pyrano [C-2,3] pyrazole under solvent-free conditions was investigated. High efficiency, ease of manufacture and reusability are some the features of this catalyst.

In this study, magnetite nanoparticles (Fe3O4) were synthesized as a magnetic core by chemical co-precipitation process and coated with a silica layer. The (Fe3O4@SiO2) core-shell magnetic nanoparticles were functionalized by organic-base tags to produce the MNPs-TBAN nanoparticles as a novel hybrid nanostructure. The morphology, stability, and magnetism of this hybrid nanostructure were characterized and studied by Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), vibrating sample magnetometry (VSM), X-ray powder diffraction analysis (XRD), scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The prepared hybrid nanomaterial was successfully used as a basic heterogeneous catalyst for the synthesis of pyrano[2,3-d]pyrimidine derivatives, via the condensation of an aldehyde, malononitrile and barbituric acid or thiobarbituric acid. The reaction was afforded the desired products in high purity and has advantages of excellent yields, simple workup procedure, and short reaction time. The catalyst was easily separated from the reaction mixture with the assistance of an external magnet and reused for several runs without noticeable deterioration in catalytic activity.