Implicações termodinamicas e cineticas na titulação termometrica catalitica de acido salicilico em acetona

AUTOR(ES)
DATA DE PUBLICAÇÃO

1991

RESUMO

The infIuence of concentration of reactants in the titrations of salicylic acid in acetone with the titrants potassium and tetramethyIammonium hydroxides by the technique of cataIytic thermometric titrimetry is investigated. It is observed that in the case of potassiurn hydroxide titrant the stoichiometry of the reaction increases from one to two with the increase of the concentration of reagents. On contrary, in the case of tetramethyIammonium hydroxide only one acid group is determined independently of concentrations of titrant and titrand. It is also observed that in the potentiometric titration af salicylic acid with tetramethylammonium and diIuted solutions of potassium hydroxide (<0,1 M) only one inflection corresponding to the titration of carboxylic group is observed. However, for more concentrated solutions of potassium hydroxide a second inflection corresponding to the titration of the phenolic group is aIso observed. It is observed the formation of a white precipitate of potassium salicylate in the case of the more concentrated solution of potassium hydroxide. Otherwise, the formation of precipitate is not observed in the case of titrant tetramethylammonium and more diluted solutions of potassium hydroxides. These data and others of Iiterature on the titration of poIyfunctional acide capable of forming intramolecular hydrogen bond are expIained by considering the thermodynamic and kinetic impIications involved in these titrations.

ASSUNTO(S)

termodinamica acido salicilico acetona

ACESSO AO ARTIGO

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