Resumo

PARIHAR, M.S.  e  KHAN, F.. Study of 'Transition State' with Applied Potential [Mn - Sulfonamides - Cephalothin] System. Port. Electrochim. Acta [online]. 2008, vol.26, n.5, pp.377-384. ISSN 0872-1904.

Kinetic parameters and stability constants of [Mn - sulfonamides - cephalothin] system were reported at pH = 7.30 ± 0.01 in 1.0 M NaCO₄ at 25 ºC. The sulfonamides were sulfadiazine, sulfisoxazoe, sulfamethaxyzoe, sulfamethazine, sulfathiazoe, sulfacetamide and sulfaniamide as primary ligands, and cephalothin as secondary ligand. Values of transfer coefficient (α) varied from (0.41 to 0.59), showing that transition state behaves between oxidant and reductant response to applied potential and it adjusts itself in such a way that the transition state is located midway between dropping mercury electrode and solution interface. The rate constants (k) varied from 3.61 x 10^-3 cm.sec.^-1 to 9.93 x 10^-3 cm.sec.^-1, confirming that the electrode processes were quasi reversible. Small changes in potential not only affect the rate of the electrochemical reaction, but also strongly affect the rate constant. Values of stability constants (log β) varied from 1.75 to 9.13, showing that these drugs or their complexes could be used against Mn toxicity.

Palavras-chave : electrode kinetics in [Mn - sulfonamides - cephalothin] system.

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