Jan Šimbera

Ag-Cu colloid synthesis: bimetallic nanoparticle characterisation and thermal treatment

The Ag-Cu bimetallic colloidal nanoparticles (NPs) were prepared by solvothermal synthesis from metalloorganic precursors in a mixture of organic solvents. The nanoparticles were characterized by dynamic light scattering (DLS) and small angle X-ray scattering (SAXS). The properties of metallic core and organic shell of the nanoparticles were studied by direct inlet probe mass spectrometry (DIP/MS), Knudsen effusion mass spectrometry (KEMS), double-pulse laser-induced breakdown spectroscopy (DPLIBS), and differential scanning calorimetry (DSC). The transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used for particle characterization before and after thermal analysis. The experiment yielded results that were for AgCu nanoparticles for the first time. The detected liquidus temperature has been compared with the prediction obtained from calculation of the phase diagram of Ag-Cu nanoalloy. The experimental results show that of near-eutectic composition AgCu nanoparticles possess the fcc crystal lattice. Surprisingly, spinodal decomposition was not observed inside the AgCu nanoparticles at temperatures up to 230°C. The depression of the eutectic AgCu melting point was calculated but not observed. The eutectic AgCu microparticles are formed before melting.

Convenient Synthesis of Substituted Aryl Cyanides and 1,1-Dicyanobenzyl Benzoate

This paper demonstrates that a sophistic approach can be very effective and simple method for Green Chemistry. Sophistic approach is shown on examples of preparation of two different pure products from the very same kit of reagents, i. e. for reaction of cyanide anion with 2,4-dichlorobenzyl chloride and benzoyl chloride, respectively. An application of suitable reaction conditions provide for reactions of 2,4-dichlorobenzyl chloride both 2,4-dichlorobenzyl cyanide and 2,3-bis(2,4-dichlorophenyl)propanenitrile, for benzoyl chloride reaction produce benzoyl cyanide and benzoyloxy-phenylmalonodinitrile, respectively.

Facile Carbethoxylation and Carbamoylation of Ketones

Facile methods for direct ethoxycarbonylation and carbamoylation reactions of ketones are described and discussed. Our approach is based on application of ultrasonic solid-liquid phase-transfer-catalysis (S-L PTC) for enolate generation under environment friendly conditions and also a support for cleaner industrial production.

A Simplified Method for the Efficient Preparation of Pivaloylacetonitrile

Pivaloylacetonitrile is a crucial intermediate for the synthesis of the isoxazole skeleton of the selective herbicide isouron and for the construction of inhibitors of p38 MAP kinase based on pyrazolyl ureas. The current method of synthesis is based on the nucleophilic substitution of halogen of 1-chloro- or 1-bromopinacolone by alkali metal cyanide in protic solvents. In the course of substitution reaction occurs but the 2-tert-butyloxirane-2-carbonitrile as a side-product in an amount of 20-35% and by-products of the condensation reaction of the corresponding 1-halopinacolone and emerging pivaloylacetonitrile, all due to non-selective action of cyanide. Our sophisticated solution of this problem is based on the addition of a catalytic amount of alkali iodide, leading to the suppression of undesirable side reactions and to obtain pivaloylacetonitrile in 95% yield with a purity of 99%. Explanation of the effect of added alkali iodide to increase the selectivity of the process being carried out.