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A three-dimensional reduced graphene oxide aerogel modified by sulfamic acid and ethylenediamine was prepared via one-step reduction self-assembly under atmospheric pressure within 90 °C heating constantly. The adsorption efficiency of palladium (II) was ~ 97.0% at pH 11 within 50 min by the prepared composite. While the composite exhibited adsorption for platinum (IV) at acid condition, giving a rising to an adsorption efficiency was 61.7% at pH 5. Only 25.8% adsorption efficiency of platinum (IV) was found at pH 11, and 17.0% adsorption efficiency of palladium (II) was obtained at pH 5. The adsorption capacity of the composite for palladium (II) was 80 μg mg−1 above, and the adsorption capacity of the composite for platinum (IV) was ~ 160 μg mg−1. The obtained palladium (II) and platinum (IV) can be eluted by urea and surfactant from the surface of the composite, respectively. Understanding the mechanism of the adsorption/desorption between palladium (II)/platinum (IV) and the composite, explored a promising way for recycling and enrichment of noble metal at a low concentration. [ABSTRACT FROM AUTHOR]

Heterogeneous acid-catalyzed organic transformations can be classified as one of the most important aspects of catalysis mostly due to its ability in recycling. This review deals with general discussion on the preparation of sulfonic acid derivatives immobilized on inorganic supports such as silica, periodic mesoporous silica, magnetic nanoparticles, metal organic frameworks, KIT-6, ZSM-5, MCM-41, bentonite, boehmite, clay, and other inorganic supports via organic linker. In addition, application of these inorganic supports in the acceleration of organic transformation is discussed one by one. This review aims to provide an overview of the recent developments in the field of heterogenizing homogeneous catalysts with a particular emphasis on the reaction scope and advantages of heterogeneous solid acid catalysts. [ABSTRACT FROM AUTHOR]

Good to excellent yields of α-aminonitriles are achieved through three-component Strecker reaction of aldehydes or ketones with amines and trimethylsilyl cyanides over homopiperazine sulfamic acid functionalized mesoporous silica nanoparticles (MSNs-HPZ-SO3H). The advantages of this protocol include: simplicity, short reaction time, high yields, ease of product isolation and reusability of the catalyst. MSNs-HPZ-SO3H is prepared as an acid catalyst and successfully used for three-component Strecker reaction of aldehydes or ketones with amines and trimethylsilyl cyanides (TMSCN) under solvent-free conditions, a straightforward strategy for the synthesis of α-aminonitriles. [ABSTRACT FROM AUTHOR]

Sulfonylbis(1,4-phenylene) bis(sulfamic acid) (SPSA) is easily prepared and recognized as a new heterogeneous catalyst by the reaction of 4,4′-sulfonyldianiline with chlorosulfonic acid. This reagent was used for the synthesis of the mono- and bis-chromene derivatives. All reactions were performed under mild reaction conditions in high to excellent yields. The advantages of using the SPSA as a heterogeneous catalyst in these reactions are: being environmentally friendly, low cost, commercially availability and easy to separate from the mixture of the reaction and high reusable catalyst. Using this catalyst, results in acceptable reaction time and high yields with high purity of the obtained products without utilizing any organic solvents. The catalyst was characterized by FT-IR, H NMR, C NMR, mass and TGA studies. All the products were characterized by FT-IR, H, C NMR, HRMS, melting point and elemental analyses. [ABSTRACT FROM AUTHOR]

In this work, for the first time, a highly stable and efficient super-paramagnetic catalyst, H-FeO@DA-SOH, involving hollow morphology of FeO as core and dopamine as shell was prepared through hydrothermal template-free method. It has been used as a new and recoverable catalyst for various one-pot multi-component organic reactions such as synthesis of 1,4-dihydropyridine (1,4-DHP) and 1,8-dioxodecahyroacridine derivatives. The new magnetic catalyst was characterized with different analyses including X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), vibrating sample magnetometer (VSM) and thermogravimetric analysis (TGA). Moreover, the ρ of the prepared hollow-FeO microparticles was calculated, being found just slightly lighter than that of solid sphere-like FeO. The catalyst was conventionally recovered, using an external magnet and reused at least in six successive runs, without appreciable loss of its activity. Graphical Abstract: [ABSTRACT FROM AUTHOR]

(Triazinediyl)bis sulfamic acid-functionalized silica-coated magnetite nanoparticles have been prepared and applicated as an efficient catalyst for synthesis of mono-, bis-, tris- and spiro-perimidines. The desired products have been synthesized in high purity and good yields. The workup procedure of reaction is simple. The catalyst was easily separated from the reaction mixture with the assistance of an external magnetic field and reused for several runs without deterioration in catalytic activity. The core/shell nanoparticles were characterized by transmission electron microscopy, scanning electron microscope, powder X-ray diffraction, energy dispersive spectrometer, Fourier transform infrared spectroscopy and vibrating sample magnetometer. [ABSTRACT FROM AUTHOR]

Sulfamic acid has been used as an active, low-cost and reusable solid catalyst for conversion of ketones and aldehydes to corresponding gem-dihydroperoxides using 30 % aqueous hydrogen peroxide at room temperature. The reactions proceed with high rates and excellent yields. [ABSTRACT FROM AUTHOR]

2-Arylbenzothiazoles have been synthesized in water in good to excellent yield from direct condensation of various aromatic aldehydes with 2-aminothiophenol promoted by catalytic amount of sulfamic acid at room temperature. This method provides a simple, rapid and efficient protocol in terms of mild reaction conditions, clean reaction profiles, small quantity of catalyst and simple work-up procedure. [ABSTRACT FROM AUTHOR]

α-β-Unsaturated carbonyl compounds on condensation with o-phenylenediamine in the presence of catalyst sulfamic acid under solvent free conditions, resulted in the formation of corresponding benzo-[b]-1,4-diazepines in excellent yields. [ABSTRACT FROM AUTHOR]