Tomáš Weidlich

Long-range spin–spin interactions in the 13C-n.m.r. spectra of the nickel(II) complex of the Schiff base of (S)-N-benzylproline (2-benzoylphenyl)amide and glycine. Quantum-chemical calculations and possible donation of electron density from the π-system of the benzyl group to nickel

Long-range [nJ(13C, 13C), nJ(15N, 15N) and nJ(15N, 13C)] interactions in the 13C-n.m.r. spectra of CDCl3 solutions of selectively labeled nickel(II) complexes of the Schiff base derived from (S)-N-benzylproline (2-benzoylphenyl)amide and glycine provide experimental evidence for the necessity of the donation of electron density from the π-system of the benzyl ring to the nickel orbitals. No such interactions were observed in (2H)DMSO solutions, where the complex exists in a different conformation.

Debromination of 2,4,6-tribromophenol coupled with biodegradation

AbstractThe application effect of aluminium and their alloys and mixtures with nickel was studied for the complete hydrodebromination of 2,4,6-tribromophenol (TBP) to phenol in aqueous NaOH solution at room temperature. It was found that the Raney Al-Ni alloy can rapidly transform TBP to phenol. Removal efficiency of 25 mM TBP solution in aqueous NaOH (15 g L−1) solution at the end of 1h reaction was 100% using 4 g L−1 Al-Ni. The hydrodebromination is accompanied by the dissolution of aluminium and formation of soluble Al(OH)4−1 anions under these reaction conditions. After completion of the hydrodebromination reaction removal of the dissolved metals was achieved by precipitation of appropriate hydroxides by adjustment of the pH value and filtration, the filtrate was treated with Pseudomonas or Rhodococcus bacterial strains to degrade dissolved phenol. The combined application of both (chemical-biological) treatments produced degradations of 100% of aromatic compounds.

Aryl ethyl ethers prepared by ethylation using diethyl carbonate

Abstract An environmentally more convenient reaction for the production of industrially important aryl ethyl ethers (ArOEts) is described. ArOEts were selectively obtained in essentially quantitative yields by the reaction of corresponding (hetero)aromatic alcohols (ArOHs) with diethyl carbonate as the environmentally friendly alkylating reagent in the presence of N,N-dimethylacetamide used as polar aprotic cosolvent, and sodium ethoxide as the base. The reactions were carried out in the air under atmospheric pressure at 137°C. Reaction equilibrium was shifted by distilling the ethanol from the reaction mixture. All ArOEts were isolated by evaporation of the reaction mixture, and subsequent extraction with water and diethoxymethane. The ethylation agent and used solvents were non-toxic, recyclable and biologically degradable. Wastewater from the extraction was successfully treated by Fenton oxidation and returned to the next work-up process.

Facile dehalogenation of halogenated anilines and their derivatives using Al-Ni alloy in alkaline aqueous solution

AbstractThis article describes the simple hydrodehalogenation of halogenated anilines and their derivatives by the action of Raney aluminium-nickel alloy in aqueous alkaline solution at room temperature. The reaction course was monitored by means of 1H nuclear magnetic resonance (NMR) spectroscopy and GC-MS spectra. The effect of Al and Ni and the nature and quantity of the base for effective hydrodehalogenation were studied.The possibility of lowering Al content more than 500 times and Ni content more than 10 times in the filtered mother liquor by a dehalogenation procedure was tested using precipitation.The reduction method described was satisfactorily proved for dehalogenation of polyhalogenated anilines in the multiphase dimethoxymethane/aqueous NaOH/Al-Ni reaction mixture. Dehalogenation under multi-phase conditions was demonstrated for the preparation of ortho-alkylated anilines from simply available 2-substituted-4-chloroanilines.

Application of Tetraphenyl- and Ethyltriphenylphosphonium Salts for Separation of Reactive Dyes from Aqueous Solution

The decolorization efficiency of four anionic dyes dissolved in aqueous solution using two quaternary phosphonium salts, ethyltriphenylphosphonium bromide, and tetraphenylphosphonium bromide, has been investigated by spectroscopic measurements in neutral, acidic and basic media. The NMR studies suggest possible formation of ion pairs of tetrasubstituted phosphonium salts with the reactive dyes. According to the results, the tetraphenylphosphonium bromide, which contains a more hydrophobic and bulky cation, exhibited a stronger tendency to associate with the dyes.

Possibilities for removal of chlorinated dye Mordant Blue 9 from model waste water

This comparative study focused on the different methods used for the treatment of model waste water polluted with the chlorinated acid dye Mordant Blue 9. Low-cost and commercially available ionic liquids — benzalkonium chloride and Aliquat 336 — were applied as liquid ion-exchangers to precipitate the Mordant Blue 9 by way of ion pair formation between the bulky ammonium cations of ionic liquids and anions of the above dye. The decolorisation efficiency of the ionic liquid application and the effect on reduction of the absorbance, adsorbable organic halogens, chemical oxygen demand and biological oxygen demand were compared with the conventional coagulation, sorption and Fenton oxidation techniques.

Hydrodebromination of 2,4,6-tribromophenol in aqueous solution using Devarda’s alloy

The effectiveness of application of aluminium and its alloys and mixtures with copper was studied for complete hydrodebromination of 2,4,6-tribromophenol to phenol in aqueous NaOH solution at room temperature. Dissolved metals were removed using precipitation and subsequent filtration.Graphical Abstract

Application of diffusion dialysis in hydrometallurgical separation of nickel from spent Raney Ni catalyst

ABSTRACT The hydrometallurgical separation of nickel from spent Raney Ni catalyst is based on the dissolution of separated nickel slurry in hot diluted sulphuric acid (H2SO4) with the addition of an appropriate oxidation agent. Consecutive diffusion dialysis, which was performed in a two-compartment countercurrent dialyzer with an anion-exchange membrane Neosepta-AFN at steady state, enables the removal of excess of H2SO4 from a solution of aluminium and nickel sulphate in H2SO4 and simple recycling of the isolated H2SO4. Next, the obtained dialysate was alkalized using excess of NaOH solution. Using this procedure, the Ni(OH)2 contaminated with only 8.9 wt.% Al was obtained.