Silica Sulfuric Acid/ NaNO2 as a Novel Heterogeneous System for the Nitration of Phenols under Mild Conditions

An easy-to-use platform for colorimetric determination of dextran: A potential application for the sugar industry

A user-friendly platform based on foam sheets and silica solid support was developed for colorimetric sensing of dextran via phenol-sulfuric acid assay. The chemical reagents, sulfuric acid and phenol were separately preserved by silica gel. The brown color product of the phenol-sulfuric acid reaction occurred on the silica solid support when sample solutions were added. The color intensity of brown products was easily obtained by a smartphone and color processing software. Subsequently, a broad concentration range of dextran could be determined up to 10,000 mg/L dextran, with a detection limit of 360 mg/L. Furthermore, a precision study, including inter-day and intra-day studies, presented a satisfactory performance for dextran detection. The developed platform was successfully applied for the sugar industry's dextran determination of syrup samples.

Waste-to-wealth transition: application of natural waste materials as sustainable catalysts in multicomponent reactions

Application of natural waste materials as sustainable catalysts in multicomponent reactions.

An Expedient Catalytic Process to Obtain Solketal from Biobased Glycerol

Developing simple and effective chemistry able to convert industrial waste streams into valuable chemicals is a primary contributor to sustainable development. Working in the context of biodiesel production, we found that plain bisulfate on silica (SSANa, 3.0 mmol/g) proved to be an optimal catalyst to convert glycerol into solketal. With the assistance of a proper anhydrification technique, isolated yields of 96% were achieved working in mild conditions, on 100 g scale.

Silica–sulfuric acid and alumina–sulfuric acid: versatile supported Brønsted acid catalysts

–SO3H functionalized silica and alumina have emerged as efficient and eco-compatible heterogeneous solid acid catalysts for the construction of various important molecular skeletons.

Abiotic Formation of Humic-Like Substances through Freezing-Accelerated Reaction of Phenolic Compounds and Nitrite

A previously unknown abiotic humification pathway which is highly accelerated in frozen solution containing phenolic compounds and nitrite was investigated and proposed. The production of humic-like acids (HLA) and fulvic-like acids (FLA) was observed in the frozen solution (-20 °C) whereas it was negligible in aqueous solution (20 °C). Inorganic nitrogen was transformed into organic nitrogen during the humification process. Mass spectrometry (MS) and elemental analyses, including pyrolysis-GC/MS and FT-ion cyclotron resonance/MS, showed that humification products (HLA and FLA) have chemical structures and compositions similar to nature humic substances. The enhanced humification reaction could be attributed to the freeze-concentration effect, whereby nitrite ions in the unfrozen grain boundary region are transformed into nitrosonium ions which oxidize phenols to phenolic radicals. Confocal Raman microscopy confirmed that catechol and nitrite ions are preferentially concentrated at the ice grain boundary and electron paramagnetic resonance spectroscopic analysis of catechol/nitrite solution detected the phenolic radicals only in frozen solution, not in aqueous solution. The freezing-induced generation of phenolic radicals should lead to the formation of humic-like substances through polymerization. This study identifies and proposes a new humic formation pathway that might work as a model abiotic "bottom-up" mechanism in frozen environmental conditions.

Silica Sulfuric Acid/Kclo3/Wet SiO2 as an Efficient Heterogeneous Method for the Oxidation of Alcohols Under Mild Conditions

A combination of silica sulfuric acid and potassium chlorate in the presence of wet SiO2 was used as an effective oxidising agent for the oxidation of alcohols to their corresponding aldehyde or ketone derivatives in acetonitrile or toluene with good yields.

Ultrasonic-assisted environmentally-friendly synergetic synthesis of nitroaromatic compounds in core/shell nanoreactor: A green protocol

An efficient sonochemical protocol for the nitration of aromatic compounds was described in the presence of a catalytic amount of sulfuric acid-functionalized silica-based core/shell magnetic nanocomposite at room temperature in an eco-friendly and recyclable media, deep eutectic solvent (DES), based on choline chloride and urea. The particle size, morphology and elemental analysis of the core/shell nanocatalyst were carried out by TEM, SEM, EDX and XRD analyses. The nanocatalyst and DES were easily recovered from the reaction mixture quantitatively and reused several times.

Nitration of arenes by 1-sulfopyridinium nitrate as an ionic liquid and reagent by in situ generation of NO2

1-Sulfopyridinium nitrate was synthesized as a potent nitrating agent for the nitration of arenes without the need for any co-catalysts.

Operative conversions of 3-carboxy-4-quinolones into 3-nitro-4-quinolones via ipso-nitration: potential antifilarial agents as inhibitors of Brugia malayi thymidylate kinase

An efficient, cost effective and green methodology for ipso nitration in the synthesis of the 3-nitro derivative of 3-carboxy 4-quinolones has been developed by the quantitative use of copper acetate and silver nitrate in water.

Acyl transfer reactions of carbohydrates, alcohols, phenols, thiols and thiophenols under green reaction conditions

Acyl transfer reactions of various carbohydrates, alcohols, phenols, thiols and thiophenols were achieved at room temperature in high yields and catalytic efficiency in the presence of methane sulfonic acid, a green organic acid, under solvent-free conditions over short time periods.

Highly Efficient Nitration of Phenolic Compounds using Some Nitrates and Oxalic Acid under Solvent-Free Conditions

Nitrophenols can be obtained by direct nitration of phenols with some nitrates and oxalic acid at room temperature in moderate to high yields under solvent-free conditions. A small amount of water proved to be important in the initial period of the reaction.

Environmentally compatible next generation green energetic materials (GEMs)

This paper briefly reviews the literature work reported on the environmentally compatible green energetic materials (GEMs) for defence and space applications. Currently, great emphasis is laid in the field of high-energy materials (HEMs) to increase the environmental stewardship along with the deliverance of improved performance. This emphasis is especially strong in the areas of energetic materials, weapon development, processing, and disposal operations. Therefore, efforts are on to develop energetic materials systems under the broad concept of green energetic materials (GEMs) in different schools all over the globe. The GEMs program initiated globally by different schools addresses these challenges and establishes the framework for advances in energetic materials processing and production that promote compliance with environmental regulations. This review also briefs the principles of green chemistry pertaining to HEMs, followed by the work carried out globally on environmentally compatible green energetic materials and allied ingredients.

AI2O3/MeSO3H (AMA) as a Novel Heterogeneous System for the Nitration of Aromatic Compounds by Magnesium Nitrate Hexahydrate

Mg(NO3)2.6H2O was an efficient nitrating agent in the presence of a mixture of AI2O3/MeSO3H (AMA) as a novel heterogeneous system for the nitration of aromatic compounds without use of any organic solvents and with high selectivity. The reaction proceeds at room temperature for the nitration of highly reactive aromatic compounds such as phenols and anilines.

Advances in science and technology of modern energetic materials: an overview

Energetic materials such as explosives, propellants and pyrotechnics are widely used for both civilian and military explosives applications. The present review focuses briefly on the synthesis aspects and some of the physico-chemical properties of energetic materials of the class: (a) aminopyridine-N-oxides, (b) energetic azides, (c) high nitrogen content energetic materials, (d) imidazoles, (e) insensitive energetic materials, (f) oxidizers, (g) nitramines, (h) nitrate esters and (i) thermally stable explosives. A brief comment is also made on the emerging nitration concepts. This paper also reviews work done on primary explosives of current and futuristic interest based on energetic co-ordination compounds. Lead-free co-ordination compounds are the candidates of tomorrow's choice in view of their additional advantage of being eco-friendly. Another desirable attribute of lead free class of energetic compounds is the presence of almost equivalent quantity of fuel and oxidizer moieties. These compounds may find wide spectrum of futuristic applications in the area of energetic materials. The over all aim of the high energy materials research community is to develop the more powerful energetic materials/explosive formulations/propellant formulations in comparison to currently known benchmark materials/compositions. Therefore, an attempt is also made to highlight the important contributions made by the various researchers in the frontier areas energetic ballistic modifiers, energetic binders and energetic plasticizers.

Highly Efficient Nitration of Phenolic Compounds in Solid Phase or Solution Using Bi(NO3)3·5H2O as Nitrating Reagent

[reaction: see text] Bi(NO(3))(3).5H(2)O was used as an efficient nitrating reagent in the nitration of phenolic compounds to give nitrated phenols in good to high yields. The nitration reaction proceeded smoothly by grinding 1 equiv of phenol, 2-methylphenol, 4-methylphenol, or 4-chlorophenol and Bi(NO(3))(3).5H(2)O, and the nitration of other phenolic compounds could be performed in acetone at ambient temperature (22-30 degrees C).