Silica-supported Perchloric Acid Research Articles

SiO2-supported HClO4 catalyzed synthesis of (Z)-thiazolylhydrazonoindolin-2-ones and their electrochemical properties

In this paper, an environmentally benign silica-supported perchloric acid (HClO4–SiO2) catalyzed green FCDR strategy has been developed for the synthesis of (Z)-THIs (6) with high stereospecificity via an intramolecular hydrogen bond (IHB) directed approach, involving the reaction of methyl ketones (1), N-bromosuccinimide (NBS) (2), isatins (4) and thiosemicarbazide (5) in ethanol at reflux temperature for 45–60 min in one-pot. The reaction proceeds through the construction of C–Br (α-bromination), C–S & C–N (heterocyclization), and CN (condensation) bonds in one pot. The absolute structure of the compound (Z)-3-(2-(4-(4-bromophenyl)thiazol-2-yl)hydrazono)indolin-2-one (6e) has been confirmed by single-crystal XRD analysis. Further, the role of IHB on Z-configuration of the synthesized (Z)-THIs is proved by single-crystal XRD and 1H NMR studies. Wide substrate scope, good functional group tolerance, scalability, improved safety since the method circumvents the use of highly lachrymatric α-bromoketones as starting materials, high product yields (up to 98%), short reaction times, reusable solid Brønsted acid catalyst (HClO4–SiO2), and products that do not require column chromatography purification are all attractive features of this FCDR strategy. Electrochemical properties of THIs (6) are examined by cyclic voltammetry. The HOMO and LUMO energy level of THIs, 6a, 6c, 6d, 6j, 6o-6v, 6y, and 6aa are comparable with the reported ambipolar materials, and the HOMO levels of other THIs, 6b, 6e-6i, 6n, 6w, 6x, 6z and 6 ab-6ae are similar with the most commonly used hole transporting materials (HTMs).

Preparation of alkyl levulinates from biomass-derived 5-(halomethyl)furfural (X = Cl, Br), furfuryl alcohol, and angelica lactone using silica-supported perchloric acid as a heterogeneous acid catalyst

This work reports the synthesis of a series of alkyl levulinates from biomass-derived 5-(halomethyl)furfural (X = Cl, Br), furfuryl alcohol, and angelica lactone using silica-supported perchloric acid (HClO4-SiO2) as a heterogeneous acid catalyst. The solvent-free, one-pot preparation afforded levulinate esters in excellent isolated yields (> 84%). The reactions were performed at 120 °C for 6 h in a batch-type glass pressure reactor using XMF and furfuryl alcohol in presence of excess of the alcohol reagent and 4 wt.% of the HClO4-SiO2 catalyst (0.028 mmol HClO4). Furthermore, the reaction protocol was extended for the synthesis of ALs starting with angelica lactone at 90 °C for 2 h in a round-bottomed flask by using excess alcohol and 4 wt.% of the HClO4-SiO2 catalyst.

SILICA SUPPORTED PERCHLORIC ACID: AN EFFICIENT AND RECYCLABLE CATALYST FOR SYNTHESIS OF BENZIMIDAZOLO[2,3-b]QUINAZOLINONES

Synthesis of benzimidazolo[2,3- b ]quinazolinone derivatives has been reported in excellent yields by using silica-supported perchloric acid (HClO 4 -SiO 2 ) as a mild and reusable heterogeneous catalyst. The procedure is simple, environmentally benign and has the advantage of high atom economy. Furthermore, the catalyst can be recovered and reused several times efficiently without substantial loss of catalytic activity.

Silica-supported perchloric acid and potassium bisulfate as reusable green catalysts for nitration of aromatics under solvent-free microwave conditions

ABSTRACTSilica-supported perchloric acid and bisulfate (SiO2/HClO4 and SiO2/KHSO4) have been developed as reusable green catalysts for nitration of aromatic compounds using NaNO2 in acetonitrile medium under conventional and solvent-free microwave conditions. The reaction times under microwave irradiation are significantly shorter than conventional method even though the yields obtained in microwave-assisted reactions are comparable with those obtained under reflux conditions.

Silica-supported perchloric acid (HClO4/SiO2) as efficient catalyst for the synthesis of tetraazamacrocyclic complexes of transition metals

Silica-supported perchloric acid (HClO4/SiO2) was used to catalyze the synthesis of tetraazamacrocyclic complexes of Co(II), Ni(II), Cu(II), and Zn(II) from the corresponding metal chlorides, nitrates, or acetates, isatin, and benzene-1,2-diamine in ethanol. The use of HClO4/SiO2 as catalyst allowed the reaction to be performed under stirring at room temperature instead of traditional reflux and completed in two hours. The synthesized complexes were characterized by molar conductance and magnetic susceptibility measurements, IR, electronic, 1H NMR, and mass spectra, and thermogravimetric and X-ray powder analyses. On the basis of these data, six-coordinate octahedral geometry was proposed for all complexes. The synthesized complexes were also tested for antimicrobial activity.

Complete doping in solid-state by silica-supported perchloric acid as dopant solid acid: Synthesis and characterization of the novel chiral composite of poly [(±)-2-(sec-butyl) aniline

Poly [(±)-2-(sec-butyl) aniline]/silica-supported perchloric acid composites were synthesized by combination of poly[(±)-2-sec-butylaniline] base (PSBA) and the silica-supported perchloric acid (SSPA) as dopant solid acid in solid-state. The X-ray photoelectron spectroscopy (XPS) and CHNS results confirm nigraniline oxidation state and complete doping for composites (about 75%) and non-complete for the PSBA·HCl salt (about 49%). The conductivity of samples was (≈0.07S/cm) in agreement with the percent of doping obtained of the XPS analysis. Also, contact resistance was determined by circular-TLM measurement. The morphology of samples by the scanning electron microscopy (SEM) and their coating were investigated by XPS, SEM-map and energy-dispersive X-ray spectroscopy (EDX). The key benefits of this work are the preparation of conductive chiral composite with the delocalized polaron structure under green chemistry and solid-state condition, the improvement of the processability by inclusion of the 2-sec-butyl group and the use of dopant solid acid (SSPA) as dopant.

Efficient and Convenient Protocol for the Synthesis of 3,5-Disubstituted 1,2,4-Oxadiazoles Using HClO4-SiO2 as a Heterogeneous Recyclable Catalyst

Silica-supported perchloric acid (HClO4-SiO2) was found to be a new, highly efficient, inexpensive, and reusable catalyst for a rapid and efficient synthesis of various 1,2,4-oxadiazoles with good to excellent yields under solvent-free conditions. The present methodology has been effectively utilized for the synthesis of oxolamine, an anti-inflammatory drug.

HClO<sub>4</sub>-SiO<sub>2</sub> as an Efficient and Reusable Heterogeneous Catalyst for the Synthesis of 1-substituted Tetrazoles

An efficient and direct protocol is described for the preparation of 1-substituted 1H-1,2,3,4-tetrazoles by the reaction of primary amines, triethyl orthoformate and sodium azide in the presence of catalytic amount of silica-supported perchloric acid under solvent-free and heterogeneous conditions. The thermal solvent-free green procedure offers advantages such as simple methodology, easy work-up, high yield, recovery and reusability of catalyst. Keywords: Primary amines, triethyl orthoformate, 1-substituted 1H-1, 2, 3, 4-tetrazole, HClO4-SiO2, heterogeneous catalyst.

ChemInform Abstract: Synthesis of Silica Supported Perchloric Acid Nanoparticles (HClO4—SiO2 NPs): Efficient Synthesis of Biscoumarin Derivatives in Water.

AbstractBiscoumarin derivatives (III) and (V) are obtained in a simple and efficient reaction between aromatic aldehydes (II) or phenylglyoxals (IV) and 4‐hydroxycoumarin (I).

SYNTHESIS AND CHARACTERIZATION OF FORMAMIDINE DERIVATIVES FROM IMIDATE VIA DIFFERENT CATALYSTS

Normal 0 In this research, synthesis of (1E)-N'-((Z)-2-amino-1,2-dicyanovinyl)-N-(4-ethoxyphenyl)formamidine from imidate was investigated in the presence of different catalysts such as sulfonic acid (-SO 3 H), P-Toluene sulfonic acid (PTSA), aluminium chloride (AlCl 3 ), ceric ammonium nitrate (CAN), anilinium chloride (C 6 H 5 NH 3 + Cl - ), Montmorillonite (K10), silica sulfuric acid (SiO 2 -OSO 3 H), silica-supported perchloric acid (HClO 4 -SiO 2 ). Silica sulfuric acid exhibited high catalytic activity for this reaction and afforded excellent yields within a lesser time. Other formamidine derivatives were prepared from the reaction of imidate with amines in the presence of silica sulfuric acid under argon at room temperature.

Synthesis of Silica Supported Perchloric Acid Nanoparticles (HClO4–SiO2 NPs): Efficient Synthesis of Biscoumarin Derivatives in Water

Reaction between aromatic aldehydes or phenylglyoxals and 4-hydroxycoumarin catalysed by silica supported perchloric acid nanoparticles (HClO4–SiO2 NPs) in water at reflux provided a simple and efficient route for the synthesis of biscoumarin derivatives in high yields.

An eco-friendly catalytic route for one-pot synthesis of 2-amino-6-(2-oxo-2Hchromen-3-yl)-4-arylnicotinonitrile derivatives by silica-supported perchloric acid (HClO4–SiO2) under solvent-free conditions

A facile and environmentally benign synthesis of some 2-amino-6-(2-oxo-2H-chromen-3-yl)-4-arylnicotinonitrile derivatives from the reaction of 3-acetylcoumarin, aromatic aldehydes, and malononitrile under solvent-free condition in the presence of silica-supported perchloric acid (HClO4–SiO2) is described. The ability to reuse the catalyst, the high yields, and ease of purification are the important features of this process.

An Efficient Synthesis of SymmetricalN,N’-Alkylidene Bisamides Catalyzed by Silica Supported Perchloric Acid

An Efficient Synthesis of Symmetrical<i>N</i>,<i>N’</i>-Alkylidene Bisamides Catalyzed by Silica Supported Perchloric Acid

Silica-supported perchloric acid (HClO4–SiO2): a mild, reusable and highly efficient heterogeneous catalyst for multicomponent synthesis of 1,4-dihydropyridines via unsymmetrical Hantzsch reaction

Facile synthesis of some 1,4-dihydropyridine derivatives via Hantzsch reaction of 5,5-dimethyl-1,3-cyclohexanedione (dimedone), 1,3-diphenyl-2-propen-1-one derivatives and ammonium acetate under solvent-free condition in the presence of silica-supported perchloric acid (HClO4–SiO2) is described. The catalyst is easily prepared, stable, reusable and efficient under the reaction conditions.

ChemInform Abstract: Silica Supported Perchloric Acid Catalyzed Rapid N‐Formylation under Solvent‐Free Conditions.

AbstractVarious primary and secondary amines can be successfully formylated under conditions A).

ChemInform Abstract: Eco‐Friendly HClO4—SiO2 Catalyzed Synthesis of Mono‐ and Bis‐diaryl‐2H‐1,4‐benzothiazines.

Mono- and bis-diaryl-2H-1,4-benzothiazines were obtained in quantitative yields through silica-supported perchloric acid catalyzed reaction cascade of double condensation and 1,4 addition of diaroylacetylenes with 2-aminothiophenol at room temperature. The structures were confirmed by spectroscopic analyses and X-ray crystallographic studies. J. Heterocyclic Chem., (2011)

Efficient Synthesis of 3-Aminoimidazo[1,2-a] Pyridines Using Silica-Supported Perchloric Acid (HClO4-SiO2) as a Novel Heterogenous Catalyst

One pot three-component reaction of 2-amino pyridines, aldehydes and isocyanides in the presence of silicasupported perchloric acid (HClO4-SiO2), produces 3-aminoimidazo[1,2-a] pyridines in excellent yields. The reaction time is short and work up of reaction is very easy. New compounds were identified by IR, 1H NMR, 13C NMR and Mass spectrum. Keywords: 3-Aminoimidazo[1,2-a] pyridine, isocyanide, multi-component reaction, silica-supported perchloric acid (HClO4-SiO2), annulanes, calcium, heterocycles, medicinal chemistry, pyrazine, aldehydes

ChemInform Abstract: Synthesis of 1,6‐Anhydro Sugars Catalyzed by Silica Supported Perchloric Acid.

AbstractThe reaction requires only a few minutes under mild conditions.

ChemInform Abstract: Silica Supported Perchloric Acid: A Convenient and Environmentally Friendly Catalyst for the One‐Pot Multicomponent Synthesis of β‐Acetamido Ketones.

AbstractA modified Dakin‐West condensation is promoted by silica‐supported perchloric acid as an inexpensive and recyclable catalyst.

ChemInform Abstract: Silica Supported Perchloric Acid (HClO4—SiO2): Highly Efficient Heterogeneous Catalyst for the Synthesis of α‐Amino Phosphonates.

ChemInform Abstract: Silica Supported Perchloric Acid (HClO₄—SiO₂): Highly Efficient Heterogeneous Catalyst for the Synthesis of α‐Amino Phosphonates.