Band 5, Heft 3

1-Substituted 1,2,4-triazole derivatives present in a large number of compounds and display a variety of bioactivities such as antibiotic, anti-inflammatory, anti-diabetic, antipsychotic, and anticancer. A regioselective protocol has been developed for the alkylation of 1,2,4- triazole using mild conditions. The 1-alkyl-1,2,4-triazole derivatives were synthesized under microwave conditions using potassium carbonate as a base and ionic liquid (hexylpyridinium bromide) as a solvent. The products were obtained in excellent yield, and the base-ionic liquid combination was recycled for a number of times.

N -alkyl imidazoles are the basic components of the widely used and studied imidazolium ionic liquids. The need for these materials multiplied since the field of ionic liquids has been gaining more and more importance. Our aim was to develop a continuous flow method for the N -alkylation of imidazole that provides the alkylated derivatives with high productivity and selectivity, using only cheap, preferably green starting materials. Herein, we report a novel method for the preparation of N -alkyl imidazoles over a zeolite catalyst using high temperature and pressure in a heterogeneous catalytic flow reactor. The yield and selectivity exceeded 95% for n -chain alcohols while the residence time was kept at 13 min, thus, the productivities were between 9 g/h and 14 g/h. The only side product in the reaction is water, thus, the process expresses high atom economy.

A simple, environmentally friendly, one-pot method for the synthesis of 4-aminoquinazolines using microwave irradiation has been developed. Structures of derivatives 3 , 4 , and 5 were confirmed by single-crystal X-ray diffraction. The in vitro cytotoxicity of each compound was investigated using an MTT assay with A549 and HepG2 cell lines to calculate half-maximal inhibitory concentrations.

Development of economical and rapid high yielding industrial processes for isolation of commercially important plant molecules have been in current industrial vogue. Adhatoda vasica , a functional dietary supplemental plant, is found to harbor vasicine, a commercially important and physiologically active alkaloid. Attempts were made to increase the yields of vasicine by a viable “green” process – microwave assisted adsorption based elution (MAABE) with silica gel. Microwave (300 W) assisted extraction was done with 6% HCl/water (solid loading – 10%), which in 4 h yielded vasicine (8.8 mg/g of leaves, 0.88%). A Box-Behnken designed response surface methodology (RSM) optimized the extraction parameters to 9.31% solid loading, 6.64% HCl/water and 4.1 h, respectively. Further, adsorption based elution using silica gel and desorption with 70% ethanol/water yielded pure vasicine (1.12%) (recovery=93%, purity=95%). The adsorption isotherms studied to understand the adsorption mechanism suggested that the process followed the Langmuir theory. MAABE required less time and labor, in addition to its relative safety and as a “green” alternative process, to give high yields of commercially important vasicine.

In this paper, the removal of arsenic from arsenic-bearing gold ore through air oxidation and sodium hydroxide leaching with microwave irradiation was studied. Firstly, single-factor experiments were carried out. The results indicated that the removal rate of arsenic was influenced by the sodium hydroxide concentration, ratio of liquid to solid, microwave power, and reaction time. Then, orthogonal experiments were done to determine the main influencing factors. The results obtained from the experiments of orthogonal arrays showed that reaction time and microwave power were the important influencing factors, and the optimum conditions of sodium hydroxide concentration, reaction time, microwave power, and ratio of liquid to solid were 18 wt.%, 60 min, 700 W, and 5, respectively. Under the optimal conditions, the removal of arsenic could reach approximately 81.46 wt.% and, at the same conditions, the sulfur removal rate was about 55.56 wt.%. The results of X-ray diffraction analysis revealed that AsS and FeAsS were decomposed during the leaching process, while FeS 2 was not.

Chicken eggshell (ES) is an aviculture by-product that has been listed worldwide as one of the worst environmental problems. The effective utilisation of ES biowaste is strongly encouraged in our society due to environmental and economic reasons. The aluminium alloy (AA) 2014/5 wt% carbonised ES metal matrix composite used in this study was fabricated by electromagnetic stir casting technique at parameters of 12 A (current), 180 s (time) and 700°C (matrix pouring temperature), respectively, and immediately extruded on universal testing machine at 60 MPa using cylindrical H13 tool steel die coated with graphite to avoid upper flow of ES particles and to improve wettability of carbonised ES with AA2014 alloy. Microstructures of composites show uniform distribution of carbonised ES particles. Density and overall cost of the metal matrix composite decreases 3.57% and 5%, respectively, when carbonised ES particulate is added 5% by weight. Tensile strength, hardness, toughness and fatigue strength of AA2014/5 wt% carbonized eggshell composite were also measured. Results show an improvement in these mechanical properties with addition of ES in the matrix alloy.

A solvent-free, efficient, and green approach for the synthesis of monomethine cyanine dyes was carried out via grinding at room temperature in the presence of a minimum amount of catalyst. This green methodology aims to overcome the limitations and drawbacks of previously reported methods such as heating at high temperatures, use of large amounts of catalysts, use of solvents, modest yields, and long reaction times. Moreover, the advantages of the process include mild conditions with excellent conversion, and inexpensive procedure. The new synthetic method was demonstrated for eight reported dyes, as representatives, and showed high applicability for their analogues in the same way. The green context of the new methodology was noticeable, compared with the non-green components of the conventional one. The structure and purity of the resulting compounds were compared with the previously reported data and confirmed using thin layer chromatography, absorption spectra, elemental analysis, mass spectrometry, 1 H-nuclear magnetic resonance (NMR) and 13 C-NMR spectroscopy.

A grit like nanostructure of MgO was prepared in a medium of mulberry leaves extract and characterized on the basis of field emission scanning electronic microscopy (FE-SEM), X-ray diffraction (XRD), and energy dispersive X-ray (EDX) analysis. It was found to be an efficient catalyst for one-pot synthesis of 4 H -pyrans from the reaction of malononitrile and α,α′-bis(substituted-benzylidene) cycloalkanones in good to high yields.

This paper reports the improved procedure for aldol condensation between citral and 2-octanone with Amberlyst A-26 OH to give 11,15-dimethyl-hexadeca-8,10,14-trien-7-one. The improved synthesis utilizing Amberlyst A-26 OH as the solid catalyst produces better yield (93.0%) and enables simple work-up procedure. The experimental conditions are evaluated and optimized at 2-octanone/citral molar ratio of 10, catalyst amount of 5% (mole of citral), and temperature of 60°C in 3.5 h reaction time. 11,15-Dimethyl-hexadeca-8,10,14-trien-7-one is isolated using preparative thin layer chromatography with hexane:ethyl acetate (9.5:0.5) and confirmed by gas chromatography-mass spectrometry (GC-MS), ultraviolet-visible (UV-Vis), Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR).

As an environmentally friendly method, spray pyrolysis has been widely used to produce a variety of metal oxides and composite metal oxides. Spray pyrolysis is used to synthesize amorphous Al 2 O 3 and γ-Al 2 O 3 . A pyrolysis temperature ranging from 1073 to 1273 K and a collector temperature ranging from 273 to 283 K result in amorphous Al 2 O 3 . To strengthen the stability of the amorphous Al 2 O 3 , La 3+ was added to modify amorphous Al 2 O 3 with different La 3+ concentrations. With a particle residence time of 2.6–3.0 s in the calciner, the pyrolysis temperature of γ-Al 2 O 3 was obtained at 1373 and 1273 K, respectively. Microstructural and morphological analyses conducted by using X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and infrared absorption spectrum showed that the obtained alumina are amorphous or γ crystalline forms flake.

Diamond films were synthesized in a CH 4 -H 2 system with good surface quality by adjusting the additive amount of argon and oxygen gas. The diamond phase content and surface roughness of samples are 86.1% and 81.5 nm, respectively. The results indicate that only Ar addition will decrease the purity of diamond films, whereas Ar-O 2 mixed gas can further increase the diamond phase content. It is worth noting that the content of diamond phase has no significant increase when O 2 flow exceed 1 sccm. The surface roughness reduced from 199.8 to 81.5 nm by the addition of 14 sccm Ar and 1 sccm O 2 , and the surface quality will be deteriorated in case of further increasing O 2 or decreasing Ar concentration. Meanwhile, the growth rate under different conditions and the synergetic surface modification effect of Ar-O 2 mixed gas for diamond films growth process were discussed.

Response surface methodology was successfully applied to optimize esterification of butanol with butyric acids over amino acid-functionalized heteropolyacids, namely, [GlyH] x H 3 -x PW 12 O 40 ( x =1.0–3.0). A series of catalysts were prepared by incorporating tungstophosphoric acid (TPA) with varied amounts of glycine (Gly). The [GlyH] 1.0 H 2.0 PW 12 O 40 catalyst was found to exhibit the best activity with an optimal butyl butyrate yield of 97.9%, which was in excellent agreement with the predicted value by the Box-Behnken design (BBD) model. These superior esterification activities observed for the organic TPA salt catalysts might be due to their highly acidic nature, weak molecular transport resistance, and “pseudoliquid” catalysis modes. Furthermore, the catalytic activity of [GlyH] 1.0 H 2.0 PW 12 O 40 catalyst was observed to have no appreciable change in the conversion after five consecutive runs. A kinetic study for the esterification was also performed under optimal reaction conditions. The results revealed that the reaction followed second-order kinetics, and the activation energy was found to be 81.90 kJ/mol.

A classical Merrifield resin was modified with pendant terpyridine heterocycles in order to develop a new material for heterogeneous catalysis. The protocol relies on the reaction of a pyrrolyl anion with chloromethyl groups present on the resin. The modified polymer was then reacted with a Pd salt to afford a catalyst that was tested in the Suzuki cross-coupling reaction in environmentally friendly solvents.