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Master's Dissertation
DOI
https://doi.org/10.11606/D.46.2016.tde-15022016-165753
Document
Author
Full name
Ivanise Gaubeur
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1997
Supervisor
Committee
Iha, Maria Encarnacion Vazquez Suarez (President)
Angnes, Lucio
Mazo, Luiz Henrique
Title in Portuguese
Determinação das constantes de dissociação/ionização da di-2-piridil cetona benzoilhidrazona (DPKBH) em diferentes porcentagens de etanol
Keywords in Portuguese
Constantes de dissociaçãoionização
DPKBH
Método eletroquímico
Mistura etanol-água
Química analítica
Reagentes
Abstract in Portuguese
A di-2-piridil cetona benzoilhidrazona (DPKBH) é um reagente solúvel em uma série de solventes orgânicos mas pouco solúvel em água. Vem sendo utilizado para a determinação de metais, (principalmente do grupo de transição) como Fe(II), Fe(III), Ni(II), Cu(II), entre outros e como ligante de referência para estudar o comportamento dos íons Fe(II) e Fe(III) em presença de espécies orgânicos encontrados em águas naturais. Com o objetivo de entender melhor as propriedades do DPKBH em meio de etanol, foi necessário determinar as constantes de dissociaçãolionização em diferentes porcentagens desse solvente orgânico (10, 19, 29 e 48 %). Nestas porcentagens de etanol, através de medidas absolutas de pH determinaram-se os pKs do DPKBH utilizando-se a técnica potenciométrica e em 10 e 48 % de etanol através de medidas absolutas de pH associadas às absorbâncias das espécies presentes nos equilíbrios, utilizando-se a técnica espectrofotométrica. Nas devidas porcentagens de etanol, o comportamento do eletrodo foi previamente determinado. Os valores de pK1 3,210; 3,342; 3,398 e 3,360 e de pK2 10,834; 11,013; 11,793 e 11,382 foram obtidos respectivamente para 10, 19, 29 e 48 % de etanol, utilizando-se a técnica potenciométrica. Através da técnica espectrofotométrica os valores de pK1 foram 3,257 e 3,322 e pK2 10,880 e 11,820, em 10 e 48 % de etanol, respectivamente.
Title in English
Determination of dissociation constants/ionization di-2-pyridyl ketone benzoylhydrazone (DPKBH) at different percentages of ethanol
Keywords in English
Analytical chemistry
Dissociation constants ionization
DPK BH
Electrochemical method
Ethanol-water mixture
Reagents
Abstract in English
The di-2-pyridyl ketone benzoylhydrazone (DPKBH) is a soluble reagent in different organic solvents but slightly soluble in water. It has been used for metal determinations, (mainly transition metals) such as for Fe (II), Fe(III), Ni(II), Cu(II) and also like a reference ligand to study the behavior of Fe(II) and Fe(III) ions in the presence of organic species found in natural waters. So as to better understand the DPKBH properties In ethanol, it was necessary to determine the dissociation/ionization constant in different percentages of ethanol (l0, 19, 29 and 48%). In these ethanol percentages, through absolute pH measurements, pKs of DPKBH could be the found by using the potentiometric technique, and in 10 and 48% of ethanol the pKs of DPKBH were determined with pH measurements associated to absorbance of the species present in the equilibria by using the spectrophotometric technique. In appropiate percentage of ethanol the behavior of the glass electrode was previously determined. The pK1 values 3.210; 3.342; 3.398 and 3.362, and pK2 10.834; 11.013; 11.793 and 11.382 were found for 10,19,29,48 % of ethanol, by using the potentiometric technique. The spectrophotometric technique led to pK1 values 3.257 and 3.322, and the pK2 ones 10.880 and 11. 820 in 10 and 48 % of ethanol respectively.
 
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Publishing Date
2016-02-15
 
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