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Cuernavaca Morelos, Mexico

Castaneda I.,Av. University 1001 | Romero M.,Metropolitan Autonomous University | Malo J.M.,Electric Research Institute of Mexico | Uruchurtu J.,Av. University 1001 | Uruchurtu J.,Metropolitan Autonomous University
Revista de Metalurgia (Madrid) | Year: 2010

This work presents the electrochemical noise results obtained of the surface degradation on copper, due to erosion corrosion phenomena, which were a function of the hydrodynamic parameters of the system (fluid movement). A modified rotating cylinder (RC) comprising three ring electrodes under two rotating speeds (880 and 1750 rpm with a Reynolds numbers 1486 Re and 2972 Re, respectively) were used. Characteristic electrochemical noise spectra as a function of the hydrodynamic parameters were found, as well as surface attack intensities the noise signal. An increase and a more uniform attack due to particle impact was related to larger particle size and lesser erosion corrosion intensity, in the form of more localized attack over the surface, was obtained for smaller ones. Erosion corrosion attack presents characteristic electrochemical current and potential noise signals, according to the laminar or transitional turbulent regime and particle size added. Source

Tiempos-Flores N.,Av. University 1001 | Metta-Magana A.-J.,Av. University 1001 | Montiel-Palma V.,Av. University 1001 | Cortes-Llamas S.-A.,Av. University 1001 | Munoz-Hernandez M.-A.,Av. University 1001
Dalton Transactions | Year: 2010

Organoaluminium(iii) thioetherbis(phenolate) complexes derived from 2,2′-thiobis(4,6-diterbuthylphenolate) (Stdiol) and 2,2′-thiobis(4, 6-dimethylphenolate) (Smdiol) were prepared by reaction of AlMe3 with the diol proligands LH2 (SmdiolH2, StdiolH2). Monomeric complexes of general formulae [LAlR(L′)] (L = Stdiol, R = Me, L′ = THF (1); L = Stdiol, R = Me, L′ = Et2O (2); L = Stdiol, R = iBu, L′ = THF) (3); L = Smdiol, R = Me, L′ = THF (4); L = Smdiol, R = iBu, L′ = THF (5)) and [LAlCl(THF)] (L = Stdiol (6); L = Smdiol (7)) were obtained when the reactions were performed in THF or Et2O in hexane or toluene, species of formulae [(L 2Al)AlR2] (L = Stdiol, R = Me (8); L = Stdiol, R = iBu (9); L = Smdiol, R = Me (10)) were formed as evidenced by spectroscopic methods. Crystals suitable for X-ray diffraction studies were obtained for 2, 3, 4, 6, 8, 9 and 10. In these cases the sulfur atom coordinates to the aluminium center with Al-S bond lengths between 2.43-2.75 Å adopting boat-boat conformations. Compounds 1, 3, 4, and 8 were tested in the catalytic Diels-Alder cycloaddition reaction between methacrolein and cyclopentadiene showing excellent regioselectivities with good conversion yields. © 2010 The Royal Society of Chemistry. Source

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