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Copper nanoparticles as an efficient, inexpensive catalyst were prepared via ball milling for synthesis of β-carbonyl 1, 2, 3-triazoles from azido alcohol by click reaction in water. An extensive range of raw materials such as sodium azide, phenacyl bromide, epichlorohydrin, and terminal alkynes were used. Complete reduction of CuO in presence of NaBH4 was done via ball milling with a ball-to-powder weight ratio of 50:1 under air atmosphere at room temperature. The final copper nanoparticles (Cu NPs) were characterized by SEM, EDX, XRD and FT-IR. The Cu NPs catalyzed one-pot three component synthesis of β-carbonyl 1, 2, 3-triazoles at room temperature with short reaction time and high product yields. The catalyst could be easily recovered and reused in several successive runs.

A powerful, magnetic, supported, acid catalyst, NiFe2O4@SiO2–H3PW12O40, was prepared by chemical support of Keggin (H3PW12O40) heteropolyacid (HPA) on silica-coated NiFe2O4 magnetic nanoparticles. XRD, TEM, SEM, VSM, and FTIR confirmed that the keggin HPA is well dispersed on the surface of silica-coated NiFe2O4 magnetic nanoparticles. The magnetically recoverable catalyst could be easily recycled at least six times without significant loss of catalytic activity. After full characterization, its catalytic activity was investigated in the synthesis of tetrahydrobenzo[b]pyran and pyrano[2,3-c]pyrazole derivatives. (1) Novel silica-coated magnetic NiFe2O4 nanoparticles-supported H3PW12O40 was fabricated and characterized. (2) Recyclability of the catalyst. (3) Avoiding use of corrosive acid catalysts. (4) Green chemistry.

Polyphosphoric acid functionalized silica-coated magnetic nanoparticles with core–shell structure (NiFe2O4@SiO2–PPA) has been used as a magnetically recyclable green catalyst for the one-pot three-component synthesis of 2-thioxoquinazolinones by the reaction of isatoic anhydride, primary amines and thiourea under neat conditions. The catalyst is readily recovered by simple magnetic decantation and can be recycled five times with no significant loss of catalytic activity.

2,3-Dihydro-5,8-dihydroxynaphthalene-1,4-dione (naphthazarin) (2) is used for the first time as a biologically important reagent in the synthesis of gold nanoparticles in water–methanol medium through the chemical reduction of HAuCl4 at room temperature without using any capping agents other than naphthazarin. The ratio of HAuCl4 and naphthazarin played a vital role in controlling the shape and size of gold nanoparticles. Three samples with significant differences in sizes (range of 10–200 nm) have been prepared through increasing the initial naphthazarin/HAuCl4 molar ratio from 50 to 200. The size, distribution, and formation of gold nanoparticles were confirmed by transmission electron microscopy, Fourier transform infrared spectroscopy, and UV–Visible absorption spectroscopic measurements. 2,3-Dihydro-5,8-dihydroxynaphthalene-1,4-dione (naphthazarin) as a green reagent is introduced for the first time in the synthesis of gold nanoparticles in water–methanol medium through chemical reduction of AuCl4 − by a suitable molar ratio of this reagent to HAuCl4 at room temperature without using any capping agents other than naphthazarin. The ratio of HAuCl4 and naphthazarin played a vital role in controlling the shape and size of gold nanoparticles. The size, distribution, and formation of gold nanoparticles were confirmed by transmission electron microscopy and Fourier transform infrared spectroscopy.

A series of fluorescein aralkyl esters were synthesized through esterification of fluorescein with carboxylic acids or acyl chlorides and applied to the fluorometric assay of lipase. The rate of spontaneous hydrolysis and enzymatic hydrolysis was measured by monitoring of fluorescence intensities of the solution and correlated with the enzyme activity. In addition, the chain length effect of aralkyl fluorescein esters was studied. Fluorescein di(5-phenylpentanoate) was found to be a better substrate than their homologs for the fluorometric assay of lipase with the higher rate of hydrolysis and better K m value. As little as 15 ng mL−1 of lipase can be detected with fluorescein di(5-phenylpentanoate). Substitute’s effects on the enzymatic hydrolysis of phenyl acetic acid and replacement of phenyl with other polycyclic aromatics such as biphenyl or naphthyl showed a decrease in enzymatic hydrolysis rate.

β-Amino carbonyl compounds are attractive targets for chemical synthesis, because they are widely used as biologically active compounds and are important synthons for a variety of pharmaceuticals. Nano-manganese hydrogen sulfate was prepared and used as a novel nano-catalyst for the named organic transformation, i.e. Mannich-type reaction of benzaldehyde, aniline, and cyclohexanone in water. Mannich products were obtained in high yields, with excellent diastereoselectivity, and short reaction time in the presence of a catalytic system comprising nano-Mn(HSO4)2 and a surfactant, for example sodium dodecyl sulfate. Use of mild, environmentally benign reaction conditions, low loading, and ready accessibility are the main features of this new catalyst.

A novel acidic ionic liquid based on imidazoliumcation is designed, synthesized, and successfully used as a catalyst for the one-pot synthesis of 2-aryl-1H-phenanthro[9,10-d]imidazole derivatives. The remarkable feature of this new catalyst is its ethyleneoxy bridge which participates in dissolving organic compounds in ionic liquids. The application of this acidic ionic liquid is studied in a new one-pot method for the synthesis of imidazole derivatives under solvent-free conditions. The advantages of this method are the reusability of the catalyst, high conversion, short reaction time, and simple experimental procedure.

A new ionic liquid, 1-methyl-3-(2-[2-(1-methyl-1H-imidazol-3-ium-3-yl)ethyloxy] ethyl)-1H-imidazol-3-ium dinitrite, was synthesized. This ionic liquid was used as a convenient nitrosonium source in diazotization of aryl amines into their corresponding diazonium salts, which were converted into aryl iodides and aryl azides using potassium iodide or sodium azide, respectively. Various aryl amines possessing electron-withdrawing groups or electron-donating groups were converted into the corresponding aryl iodides and aryl azides in excellent yields. Advantages of this methodology are the use of mild reaction conditions, short reaction times, and avoiding the use of toxic solvents.

PPh3 was used as an efficient catalyst for the one-pot three-component Mannich reactions of acetophenone with different aromatic amines and aromatic aldehydes under solvent-free conditions at room temperature. This method provides a novel and improved method for preparing β-amino carbonyl compounds in the absence of acidic catalyst in excellent yield. Little catalyst loading, easy accessibility of the catalyst, mild conditions, and simple work-up procedure are the main features of this protocol.

Efficient synthesis of 2,4,5-trisubstituted imidazoles has been achieved by three-component cyclocondensation of benzil or benzoin, an aldehyde, and ammonium acetate by use of an acidic catalyst. The catalyst is a deep eutectic mixture of choline chloride and oxalic acid that is non-toxic and biodegradable. Crucial advantages of this process are high yields, shorter reaction times, easy work-up, purification of products by non-chromatographic methods, and reusability of the catalyst.

Dimethyl and diethyl acetylenedicarboxylate react smoothly with naphthols, such as methyl 1-hydroxynaphthalene-2-carboxylate and methyl 2-hydroxynaphthalene-1-carboxylate, in the presence of triphenylphosphine to produce highly functionalized benzochromenes (coumarins) in high yields via intramolecular Wittig reaction on the ylide intermediate. The 1H and 13C NMR data of these compounds are compared with results obtained from theoretical calculations.

Bis(2-N-methylimidazoliumethyl)ether dichloroiodate/dibromochlorate is found to be an effective reagent system for the α-chlorination/bromination of carbonyl compounds. These novel solid halogenating reagents are readily prepared from an ionic liquid and molecular halogen in high yields. α-halogenation reaction occurs under mild conditions yielding the products in good to excellent yields.