Determination of pKa's for thymol blue in aqueous medium:: evidence of dimer formation.

被引：28

作者：

Balderas-Hernandez, P

Ramirez, MT

Rojas-Hernandez, A

Gutierrez, A

机构：

[1] Univ Autonoma Metropolitana Iztapalapa, Dept Quim, Mexico City 09340, DF, Mexico

[2] Univ Nacl Autonoma Mexico, Secc Quim Analit, Dac Estudios Super Cuautitlan, Estado De Mexico 54740, Mexico

来源：

TALANTA | 1998年 / 46卷 / 06期

关键词：

aqueous medium; formation constants; recrystallized thymol blue;

D O I：

10.1016/S0039-9140(98)00015-0

中图分类号：

O65 [分析化学];

学科分类号：

070302 ; 081704 ;

摘要：

Formation constants for recrystallized thymol blue were determined in water, using the SQUAD and SUPERQUAD programs. The best model correlating spectrophotometric, potentiometric and conductimetric data was fitted with the dissociation of HL- = L2- + H+ - log K = 8.918 +/- 0.070 and H3L2- = 2L(2-) + 3H(+) - log K = 29.806 +/- 0.133 with the SUPERQUAD program at variable low ionic strength (1.5 x 10(-4)-3.0 x 10(-4) M); and HL = L2- + H+ - log K = 8.9 +/- 0.000, H3L2- = 2L(2-) + 3H(+) - log K = 30.730 +/- 0.032, H4L2 = 2L(2-) + 4H(+) - log K = 32.106 +/- 0.033 with SQUAD at 1.1 M ionic strength. (C) 1998 Elsevier Science B.V. All rights reserved.

引用

页码：1439 / 1452

页数：14

共 14 条

[1] CHARACTERIZATION OF THE IONIZATION AND SPECTRAL PROPERTIES OF SULFONEPHTHALEIN INDICATORS - CORRELATION WITH SUBSTITUENT EFFECTS AND STRUCTURAL FEATURES [J].