Characterization and catalytic performance of basaltic dust as an efficient catalyst in the liquid‐phase esterification of acetic acid with n‐butanol

Three natural basaltic samples were collected and used as efficient catalysts for the liquid‐phase synthesis of n‐butyl acetate. The samples were characterized by X‐ray fluorescence analysis (XRF), X‐ray diffraction (XRD), thermogravimetry (TG), differential thermal analysis (DTA), Fourier transform infrared (FT‐IR), scanning electron microscopy (SEM), and N₂ sorption. The acidity of the samples was determined using isopropanol dehydration, and the strength of the acid sites was measured using chemisorption of basic probes. The catalytic activity of the samples towards the esterification of acetic acid with n‐butanol was extensively examined. The influence of different parameters, such as the reaction refluxing time, molar ratio, catalyst loading, reusability, and calcination temperature, on the esterification reaction was studied in detail. The results revealed that all samples had high catalytic activity with a selectivity of 100% to n‐butyl acetate formation. In addition, the sample obtained from the top hill of Volcano had the highest activity with a 80% yield of n‐butyl acetate. Moreover, the significant catalytic performances were well correlated with the acidity of the samples and to the reaction rate constants.     

Synthesis of Some New Thiazolo[3,2‐a]pyrimidine Derivatives and Their Applications as Disperse Dyes

A series of novel thiazolo[3,2‐a]pyrimidine derivatives were synthesized by using β‐ketoanilides 1a–c as starting materials and as key intermediates for preparation of new pyrimidinecompounds 3a–e and fused heterocyclic pyrimidine derivatives 5a–c . The new compounds were transformed to disperse dyes 6a,b and 7 . The chemical structures were elucidated by spectroscopic and elemental analyses and found to be in good agreement with the proposed structures. The versatility of compounds 6a,b and 7 for textile dyeing as disperse dyes was reported. The synthesized dyes were applied to polyester fabrics by using high temperature dyeing method at 120°C. The dye uptake expressed as color strength (k/s) of the dyed samples has been measured. Moreover, the color strength was examined in detail. In addition, the position of color in CIELAB coordinates (L*, a*, b*, h, and C*) was assessed. The color fastness of the dyed samples gave excellent results for washing and rubbing; however, the light fastness was moderate. Raman spectra of dyed samples unequivocally excluded ring dyeing and found to match with the proposed structures.     

Direct Synthesis of Multi‐functional Pyrimidine,Pyrazine, and Pyridine Scaffolds via Inter‐ and Intramolecular Annulations of 3‐Amino‐thieno[2,3‐b]pyridine‐2‐carboxylate

The synthesis of a new series of annulated thieno[2,3‐b]pyridines was performed. Ester compound 1 underwent heterocyclization upon reaction with phenylisothiocyanate and formamide to afford pyrimidines 2 and 3 , respectively. Thienopyrimidine 5 was resulted via reaction of amino derivative 1 with triethyl orthoformate to afford the non‐isolable intermediate 4 , which allowed hydrazinolysis with hydrazine hydrate to afford the target compound. Pyrimidine type 5 was condensed with p‐nitrobenzaldehyde to afford Schiff base 6 . Refluxing of ester 1 with ethyl cyanoacetate and diethyl malonate followed by base‐mediated heterocyclization afforded condensed pyridines 8 and 9 , respectively. The tetracyclic pyrazine derivative 14 was obtained from the reaction of amino compound 1 with 2,5‐dimethoxytetrahydrofuran followed by hydrazinolysis to give carbohydrazide 11 , which undergo diazotization followed by Curtius rearrangement. The antibacterial results illustrated no significant results for the investigated compounds except compound 5 , which has moderate activity against Gram‐positive bacteria.     

Ring Opening and Recyclization Reactions with Chromone‐3‐carbonitrile

Chemical transformations of chromone‐3‐carbonitrile ( 1 ) with some substituted hydrazines, namely, thiosemicarbazide, S‐methyl/benzyldithiocarbazate, 7‐chloro‐4‐hydrazinoquinoline, and 3‐hydrazino‐5,6‐diphenyl‐1,2,4‐triazine, led to substituted pyrazoles 2 , 5 – 8 . Ring opening of carbonitrile 1 followed by recyclization with 3‐amino‐1,2,4‐triazole and 2‐aminobenzimidazole gave triazolo[1,5‐a]pyrimidine 9 and pyrimido[1,2‐a]benzimidazole 10 , respectively. Treatment of carbonitrile 1 with some heterocyclic amines produced 2‐amino‐3‐substituted‐chromones 11 and 12 . The novel 3‐hydroxychromeno[4,3‐b]pyrazolo[4,3‐e]pyridin‐5(1H)‐one ( 13 ) was efficiently synthesized from the ring conversion of carbonitrile 1 with cyanoacetohydrazide. A mixture of chromeno[2,3‐b]naphthyridine 14 and chromeno[4,3‐b]pyridine 15 was obtained from base catalyzed transformation of carbonitrile 1 with malononitrile dimer. A diversity of novel annulated chromeno[2,3‐b]pyridines 16 – 22 was also synthesized. Chromeno[2,3‐b]pyrrole‐2‐carboxylate 23 was obtained from the reaction of carbonitrile 1 with ethyl chloroacetate. Structures of the new synthesized products were deduced on the basis of their analytical and spectral data.     

Cycloaddition of Aroyl Isothiocyanate: A Novel Synthesis of Triazine,Oxazine, Pyrimidine,and Pyridine Derivatives

A simple and direct synthetic methodology for a novel series of azines and their annulated systems was performed. Heterocyclization of acyl isothiocyanate 2 with urea or malononitrile gave s‐triazine 4 and 1,3‐oxazine 7 derivatives, respectively. The reaction of heteroallene 1 with acetylacetone tolerated 2‐thioxopyridine derivative 9 . The latter compound underwent heterocyclization with urea, hydrazine hydrate, or phenyl hydrazine to give the annulated pyridines 10 – 12 . Pyrimidinethione 14 was resulted from reaction of acylisothiocyanate with enamine 13 . Condensation of compound 14 with hydrazine hydrate, phenyl hydrazine, urea, and 3‐nitrobenzaldehyde in the presence of ethyl cyanoacetate or sodium hydroxide afforded 15 – 20 , respectively.     

Catalytic C1 Alkylation with Methanol and Isotope‐Labeled Methanol

A metal‐catalyzed methylation process has been developed. By employing an air‐ and moisture‐stable manganese catalyst together with isotopically labeled methanol, a series of D‐, CD₃‐, and ¹³C‐labeled products were obtained in good yields under mild reaction conditions with water as the only byproduct.     

Efficient synthesis of (-)-gamma-lycorane alkaloid by two Bu3SnH-mediated radical cyclisations

An asymmetric induction using (S)-1-arylethylamine-based chiral auxiliary and two Bu(3)SnH-mediated radical cyclisations have been developed for a total synthesis of (-)-gamma-lycorane (1). The first cyclisation proceeded in 5-endo-trig manner with moderate diastereoselectivtiy to give (3aR,7aR)-octahydroindol-2-one 6b as the major product using alpha-iodo-N-(6-oxocyclohexen-1-yl)-N-[(S)-1-phenylethyl] acetamide (5b). In the second cyclisation, the radical precursor 8 was used as substrate to construct the optically active lycorane skeleton 15 which was reduced using LiAlH4 into (-)-gamma-lycorane (1).     

Synthesis of two new linear trinuclear Cu(II) complexes: mechanism of magnetic coupling through hybrid B3LYP functional and CShM studies

Two new Cu(II) linear trinuclear Schiff base complexes, [Cu3(L)2(CH3COO)2] (1) and [Cu3(L)2(CF3COO)2] (2), have been prepared using a symmetrical Schiff base ligand H2L [where H2L = N,N'-bis(2-hydroxyacetophenone)propylenediimine]. Both of the complexes have been characterized by elemental analyses, Fourier transform IR, UV/vis, and electron paramagnetic resonance spectroscopy. Single-crystal X-ray structures show that the adjacent Cu(II) ions are linked by double phenoxo bridges and a mu(2)-eta(1):eta(1) carboxylato bridge. In each complex, the central copper atom is located in an inversion center with distorted octahedral coordination geometry, while the terminal copper atoms have square-pyramidal geometry. Cryomagnetic susceptibility measurements over a wide range of temperature exhibit a distinct antiferromagnetic interaction of J = -36.5 and -72.3 cm(-1) for 1 and 2, respectively. Density functional theory calculations (B3LYP functional) and continuous-shape measurement (CShM) studies have been performed on the trinuclear unit to provide a qualitative theoretical interpretation of the antiferromagnetic behavior shown by the complexes.     

"Nanocasting": using SBA-15 silicas as hard templates to obtain ultrasmall monodispersed gamma-Fe2O3 nanoparticles

This work describes the use of mesoporous SBA-15 silicas as hard templates for the size-controlled synthesis of oxide nanoparticles, with the pores acting as nanoscale reactors. This fundamental work is mainly aimed at understanding unresolved issues concerning the occurrence and size dependence of phase transitions in oxide nanocrystals. Aqueous solutions of Fe(NO3)3*9H2O are deposited inside the pores of SBA-15 silicas with mesopore diameters of 4.3, 6.6, and 9.5 nm. By calcination, the nitrate salt transforms into FeOx oxides. The XRD peaks of nanocrystals are broad and overlapping, resulting in ambiguities attributed to a given allotropic variety of Fe2O3 (alpha, epsilon, or gamma) or Fe3O4. The association of XRD, SAED, and Raman information is necessary to solve these ambiguities. The metastable gamma-Fe2O3 variety is selectively formed at low Fe/Si atomic ratio (ca. 0.20) and when a low calcination temperature is used (773 or 873 K followed by quenching to room temperature once the targeted temperature is reached). The small size dispersion of the patterned nanoparticles, suggested on a local scale by TEM, is confirmed statistically by magnetic measurements. The nanoparticles have a superparamagnetic behavior around room temperature. Their magnetic moments (from 220 to 370 mB), their sizes (from 4.0 to 4.8 nm), and their blocking temperatures (from 36 to 58 K) increase with the silica template mesopore diameter. Their magnetic properties are compared to those of standard gamma-Fe2O3 nanoparticles of similar size, obtained by coprecipitation in water and stabilized by a citrate coating.