Silica Sulphuric Acid as an Efficient Catalyst for the Catalytic and Metal-free Oxidation of Aromatic Amines to their Corresponding Nitro Compounds with Sodium Perborate under Micellar Media

Electron-donating substituted anilines were converted to their corresponding nitro compounds with sodium perborate in the presence of a catalytic amount of silica sulphuric acid under micellar media in moderate to good yields.Keywords: Sodium perborate, nitro compounds, silica sulphuric acid, oxidation of aniline

Preconcentration of Co, Ni, Cd and Zn on naphthalene–2,4,6-trimorpholino-1,3,5-triazin adsorbent and flame atomic absorption determination

A preconcentration method was developed for the determination of trace amounts of Co, Ni, Cd and Zn by atomic absorption spectrometry. The method is based on the retention of the metal cations by naphthalene–2,4,6-trimorpholino-1,3,5-triazin adsorbent in a column. The adsorbed metals were then eluted from the column with hydrochloric acid and the Co, Ni, Cd and Zn were determined by flame atomic absorption spectrometry. The optimal extraction and elution conditions were studied. The effects of diverse ions on the preconcentration were also investigated. A preconcentration factor of 250 for Co(II), Ni(II) and Zn(II), and 400 for Cd(II) can easily be achieved. Calibration graphs were obtained and the detection limits of the method for Co(II), Ni(II), Cd(II) and Zn(II) were 0.51, 0.49, 0.17 and 0.10 ng mL-1, respectively. The relative standard deviations (RSD) of 0.37–2.31 % for Co, 0.37–3.73 % for Ni, 2.20–2.40 % for Cd and 1.50–2.56 % for Zn were obtained. The method was also used for the simultaneous preconcentration of these elements and the method was successfully applied to their preconcentration and determination. The method was applied to the determination of Co, Ni, Cd and Zn in several real samples

Nitration of Substituted Phenols by Different Efficient Heterogeneous Systems

Nitration of substituted phenols were carried out by the mixture of sodium nitrite and wet SiO2 (50% w/w) in the presence of four different efficient heterogeneous systems: 1) oxalic acid dihydrate (I), 2) sodium hydrogen sulphate (II), 3) aluminum hydrogen sulphate (III) and 4) silica sulphuric acid (IV) in CH2Cl2 at room  temperature and high yields. Optimum conditions for theses systems and the regioselectivities of the reactions are reported.KEYWORDS: Nitration, nitrophenols, sodium nitrate, oxalic acid dihydrate, sodium hydrogen sulphate, aluminum hydrogen sulphate, silica sulphuric acid, wet SiO2

Tribromoisocyanuric Acid/NaNO2: a New Reagent for Mononitration of Phenols under Mild and Heterogeneous Conditions

Nitrophenols can be obtained via direct nitration of phenols with tribromoisocyanuric acid,NaNO2 and wet SiO2 at room temperature in good to high yields.KEYWORDS: Tribromoisocyanuric acid, nitrophenols, heterogeneous conditions, sodium nitrite, nitration of phenols

Molybdatophosphoric acid as an efficient catalyst for the catalytic and chemoselective oxidation of sulfides to sulfoxides using urea hydrogen peroxide as a commercially available oxidant

An efficient procedure for the chemoselective oxidation of alkyl (aryl) sulfides to the corresponding sulfoxides using urea hydrogen peroxide (UHP) in the presence of a catalytic amount of molybdatophosphoric acid at room temperature is described. The advantages of described method are: generality, high yield and chemoselectivity, short reaction time, low cost and compliment with green chemistry protocols

[H2-Cryptand 222]2+(Br3 –)2 as a Tribromide-Type Catalyst for the Trimethylsilylation/Tetrahydropyranylation of Alcohols

A stable organic tribromide, [H2-cryptand 222]2+(Br3–)2 was utilized as an active catalyst for the trimethylsilylation/tetrahydropyranylation of alcohols. The method is general for the preparation of OH-protected aliphatic (acyclic and cyclic), aromatic, primary, secondary and tertiary alcohols.Keywords: [H2-cryptand 222]2+(Br3–)2, trimethylsilylation, tetrahydropyranylation, alcohols, tribromide, TMS-ether, THP-ethe

Synthesis of Nano Magnetite Fe3O4 Based Vanadic Acid: A Highly Efficient and Recyclable Novel Nano-catalyst for the Synthesis of 4,4’-(arylmethylene)-bis(3-methyl-1-phenyl-1H-pyrazol-5-ols)

Nano magnetic Fe3O4 based vanadic acid [MNPs@VO(OH)2] (average diameter 20–26 nm) has been synthesized by grafting VOCl3 on the Fe3O4 surface nanoparticles as a retrievable supporter to produce novel heterogeneous reusable solid acid with dual ability (Bronsted and Lewis acid) followed by stirring in the air. The resultant material was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) analysis and energy-dispersive X-ray spectroscopy (EDX). Significantly, the as-prepared [MNPs@VO(OH)2] exhibits a high catalytic activity in the synthesis of 4,4’-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ols). Additionally, the newly synthesized heterogeneous solid acid catalyst can be reused for several times without apparent loss of its catalytic activity. This work is licensed under a Creative Commons Attribution 4.0 International License

Reaction of 4-n-propyl-1,2,4-triazoline-3,5-dione with some selected dienes

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Nano-Fe3O4/O2: Green, Magnetic and Reusable Catalytic System for the Synthesis of Benzimidazoles

Magnetic nano-Fe3O4 was applied in the presence of atmospheric air as a green, efficient, heterogeneous and reusable catalytic system for the synthesis of benzimidazoles via the reactions of o-phenylenediamine (1 eq) with aryl aldehydes (1 eq) in excellentyields (85–97 %) and short reaction times (30–100 min) with a proposed mechanism.Keywords: Benzimidazole, benzene-1,2-diamine, aldehyde, nano-Fe3O4, heterogeneous catalyst, magnetite, O

Sulfonic acid functionalized imidazolium salts/ FeCl3 as novel and highly efficient catalytic systems for the synthesis of benzimidazoles at room temperature

AbstractIonic liquid 3-methyl-1-sulfonic acid imidazolium chloride/ FeCl3, as well as ionic liquid 1, 3-disulfonic acid imidazolium chloride/ FeCl3 catalytic systems, efficiently catalyzes the condensation of benzene-1, 2-diamine with aromatic aldehydes in the presence of atmospheric air as a green oxidant in ethyl acetate at room temperature to afford benzimidazole derivatives in high yields and in short reaction times. The reaction is also efficiently performed when carboxylic acids are used instead of aldehydes