Zirconyl triflate as an efficient and reusable catalyst for one-pot synthesis of 1-amidoalkyl-2-naphthols under solvent-free conditions

In the present work, the preparation of 1-amidoalkyl-2-naphthols via one-pot three-component condensation of amides, aldehydes, and β-naphthol in the presence of catalytic amounts of zirconyl triflate, as a highly efficient, low toxic, stable and non-hygroscopic catalyst under solvent-free conditions is reported. This low-cost procedure offers several other advantages such as short reaction times and good to excellent yields.     

Facile one-pot synthesis of polysubstituted quinolines under solvent-free conditions using sulfamic acid as a reusable catalyst

Abstract  

A facile one-pot synthesis of polysubstituted quinoline derivatives has been demonstrated by using sulfamic acid as a reusable catalyst under solvent-free conditions. The synthetic method provides the basis and advantages of a simple experimental procedure and easy recovery and reuse of catalyst, which makes it a highly practical and environmentally benign pathway for the synthesis of polysubstituted quinolines. Interestingly, this one-pot synthesis could produce the products regioselectively in the presence of dis-symmetrical arylamines.     

Brønsted acidic ionic liquid as an efficient and reusable catalyst for one-pot synthesis of 1-amidoalkyl 2-naphthols under solvent-free conditions

A mild and efficient method has been developed for the preparation of amidoalkyl naphthols from condensation of aldehydes with amides or urea and 2-naphthol in the presence of a catalytic amount of Brønsted acidic ionic liquid ([TEBSA][HSO₄]) under thermal solvent-free conditions. High yields, short reaction time, easy work-up and reusability of the catalyst are advantages of this procedure.     

Formation of β- and β″-Al2O3 by the solid state reaction between NaAlO2 and γ-Al2O3

The solid state reaction of NaAlO₂ with γ-Al₂O₃ was investigated kinetically. Powdered compacts with various compositions (Al₂O₃/NaAlO₂ = 1–5) were fired at 700–1200°C for 1–768 hr. The amounts of the reaction product were determined by peak heights of X-ray diffraction patterns. β″-Al₂O₃ was formed predominantly from the sample with Al₂O₃/NaAlO₂ = 2. The firing time for the β″-Al₂O₃ formation was shortened as the firing temperature was raised, and the activation energy, E_a, for formation was about 130–135 kcal/mole. The sample of Al₂O₃/NaAlO₂ = 5 formed m-Al₂O₃ with the mullite structure and was observed to transform gradually to β-Al₂O₃. E_a for the m-Al₂O₃ formation and for the transition were about 55–60 and 40 kcal/mole, respectively, which resulted in E_a of about 95–100 kcal/mole for the β-Al₂O₃ formation. The mechanism of the m-Al₂O₃ formation is discussed briefly.     

P2O5/Al2O3 as an efficient heterogeneous catalyst for chemoselective synthesis of 1,1-diacetates under solvent-free conditions

An efficient and chemoselective method for the preparation of acylals from different aldehydes using P₂O₅/Al₂O₃ and acetic anhydride under solvent-free conditions.     

Mild and convenient one pot synthesis of Schiff bases in the presence of P2O5/Al2O3 as new catalyst under solvent-free conditions

In this study P₂O₅/Al₂O₃ is found to catalyze the preparation of Schiff bases from the reaction of carbonyl compounds with primary amines efficiently under solvent-free conditions. The advantages of this friendly, environmentally and mild method are such as simplicity of the reaction procedure, the elimination of solvents, simple work-up, high product yields and short reaction times.     

A one-pot synthesis of 5,5-disubstituted hydantoin derivatives using magnetic Fe3O4 nanoparticles as a reusable heterogeneous catalyst

A facile and rapid method for the one-pot synthesis of 5,5-disubstituted hydantoins in the presence of magnetic Fe₃O₄ nanoparticles has been developed. The multicomponent reactions of carbonyl compounds (aldehydes and ketones), potassium cyanide and ammonium carbonate were carried out under solvent-free conditions to obtain various hydantoin derivatives. The magnetic catalyst could be readily separated by an external magnet from the reaction mixture. This procedure has many advantages, such as the use of a reusable magnetic catalyst, high yields, short reaction times, simplicity and very easiness with implementing the methodology.     

Ru/g-al2o3 as reusable catalyst for dehydrogenation of alcohols without hydrogen acceptor

Summary Ru/g-Al₂O₃ catalyzed the dehydrogenation of alcohols to carbonyl compounds without employing hydrogen acceptor. The catalyst was readily recovered from the reaction mixture and could be reused.     

Zirconium(IV) 4-sulphophenylethyliminobismethylphosphonate as an efficient and reusable catalyst for one-pot synthesis of 3,4-dihydropyrimidones under solvent-free conditions

Zirconium(IV) 4-sulphophenylethyliminobismethylphosphonate (ZSBEDP) was prepared and characterised by elemental analysis, IR, TG-DSC, and XRD. ZSBEDP was found to be an efficient catalyst for the Biginelli reaction of aromatic aldehyde, ethyl acetoacetate, and urea or thiourea under solvent-free conditions so as to give 3,4-dihydropyrimidones in good to excellent yields. The catalyst can be separated by simple filtration and reused without significant loss of its catalytic activity.     

NaY zeolite functionalized by sulfamic acid/Cu(OAc)2 as a new and reusable heterogeneous hybrid catalyst for efficient solvent-free formylation of amines

NaY zeolite functionalized by sulfamic acid/Cu(OAc)_2[NaY/SA/Cu(Ⅱ)] was synthesized and used as a new,efficient and recyclable catalyst for preparation of formamides. This novel organic-inorganic hybrid catalyst was characterized by several techniques such as FT-IR, XRD, SEM, EDX and TG analysis.Chemoselectivity, easy procedure, excellent yields, very short reaction times, solvent-free and mild reaction conditions are some benefits of this new protocol.     

Sulfamic acid as a green,reusable catalyst for stepwise,tandem & one-pot solvent-free synthesis of pyrazole derivatives

Sulfamic acid (SA) is a bi-functional, cost-effective and reusable green catalyst for the synthesis of 4- (pyrazol-4-yl)methylenepyrazol-5(4H)-one derivatives by one-pot, three-component condensation of pyrazol-4-carbaxaldehydes, β-ketoesters and phenyl hydrazine (Route-I). In addition to this method, another simple condensation of pyrazol-4-carbaxaldehydes with pyrazolone in the presence of SA under the solvent-free condition in good yield is reported. The merits of these protocols are mild conditions, non-aqueous workup, high yields, easy availability of the catalyst, no chromatographic separation and inexpensive solid acid catalyst. Furthermore, SA could be recycled and reused for five times without losing its catalytic activity.     

AlCl3 as a powerful catalyst for the one-pot preparation of 1,1,3-triheteroaryl compounds

A general and efficient procedure for the synthesis of 1,1,3-triheteroaryl compounds in good to excellent yield at room temperature is developed. The reaction proceeds via mixed Michael and Friedel-Crafts reactions of α,β-enals or α,β-enones and indoles, 2-methylfuran or 2-methylthiophene in the presence of a catalytic amount of AlCl₃.     

Nanocrystalline TiO2-HClO4:A novel,efficient and recyclable catalyst for the chemoselective N-Boc protection of amines under solvent-free conditions

Nanocrystalline TiO₂-HClO₄,as newly reported catalyst,has been used as an efficient and reusable catalyst for the chemoselective N-Boc protection of amines.The clean,mild acidity condition, quantitative yields of products,short reaction time and low reaction temperature are attractive features of this reaction.In practice,this method is a combination of a satisfactory synthesis and more significantly easy product isolation and purification.     

Differences in the Low-Energy Collision-Activated Dissociation of Car☐ylate Anions from Structurally Similar Prostaglandins: E2, F2α, D2 and DHKF2α

Some intriguing discoveries were made concerning the collision-activated dissociation behavior of the derivatized car☐ylate anions of PGE₂ and PGF_2α. The car☐ylate anion [M-PFB]⁻ formed from electron-capture negative chemical ionization of the pentafluorobenzyl ester-trimethylsilyl derivative of PGF_2α showed little fragmentation under typical collision gas pressures and energies (<2.0 mtorr N₂ and <20 eV). In contrast, the daughter spectra of the car☐ylate anion of the methoxime-pentafluorobenzyl ester-trimethylsilyl derivative of PGE₂ produced many intense fragments under the same conditions.     

An efficient ‘on-water’ synthesis of 1,4-dihydropyridines using Fe3O4@SiO2 nanoparticles as a reusable catalyst

An ‘on-water’, efficient, high yielding, expeditious method has been developed for the synthesis of 1,4-dihydropyridine (1,4-DHP) derivatives via an one-pot multi-component condensation of dimedone or 4-hydroxycoumarine, aldehydes, and ammonium acetate using Fe₃O₄@SiO₂ nanoparticles as a recyclable heterogeneous catalyst. This method takes advantage of the fact that water, a green solvent is used in combination with Fe₃O₄@SiO₂ nanoparticles as catalyst which can be easily recovered magnetically and reused for further runs.     

Dy2O3 as a catalyst for a Meerwein-Ponndorf-Verley reaction

Dy₂O₃ activated at high temperature is reported as a catalyst for the liquid phase reduction of cyclohexanone. The catalytic activity of Dy₂O₃ activated at 300, 500 and 800°C and its mixed oxides with alumina for the reduction of cyclohexanone with 2-propanol has been reported. The data have been correlated with the electron donating properties of the catalysts which were reported from the adsorption of electron acceptors [EA] of various electron affinity on the surface of these oxides.     

A simple and efficient one-pot synthesis of Hantzsch 1,4-dihydropyridines using silica sulphuric acid as a heterogeneous and reusable catalyst under solvent-free conditions

A simple, inexpensive and efficient one-pot synthesis of 1,4-dihydropyridine derivatives under solvent-free conditions using silica sulphuric acid (SSA) as a heterogeneous and recyclable catalyst is reported.     

TiO_2-Al_2O_3复合载体的制备及Co-Mo/TiO_2-Al_2O_3催化剂加氢脱硫性能的研究

通过改进的溶胶-凝胶法(SG)、共沉淀法(CP)、表面沉淀法(PR)及混捏法(ME)制备TiO_2-Al_2O_3复合载体,考察了不同制备方法对复合载体物理性质的影响。采用浸渍法制备Co-Mo/TiO_2-Al_2O_3-X加氢脱硫催化剂,研究了Co-Mo/TiO_2-Al_2O_3-X加氢脱硫催化剂的脱硫性能。利用XRD、BET、SEM等表征手段对复合载体及催化剂进行表征分析。结果表明,SG法制备的复合载体粒径均一,具有较大的比表面积、孔径和孔体积;CP法制备复合载体时TiO_2以单层或亚单层的分散状态高度分散于γ-Al_2O_3中。在氢气压力3.0 MPa、反应温度280℃、反应时间4 h、液时空速1.4 h-1和氢油比600的条件下,SG法制备的Co-Mo/TiO_2-Al_2O_3催化剂具有较高加氢脱硫活性,噻吩转化率达到96.6%。     

A mild and efficient chemoselective tetrahydropyranylation of primary alcohols using La(NO3)3·6H2O as a catalyst under solvent-free conditions

Primary alcohols undergo selective and efficient tetrahydropyranylation in the presence of a catalytic amount of La(NO₃)₃·6H₂O under solvent-free conditions.