Contribution to the thermodynamics of 1-(2-thiazolylazo)-2-naphthol in the water-nitrobenzene extraction system

• Main Authors: PETR VANURA, EMANUEL MAKRLIK
• Format: Article
• Language: English
• Published: Serbian Chemical Society 2000-08-01
• Series: Journal of the Serbian Chemical Society
• Subjects: 1-(2-thiazolylazo)-2-naphthol; water -nitrobenzene system; distribution constant; dissociation constants
• Online Access: http://www.shd.org.yu/HtDocs/SHD/Vol65/No8-Pdf/jscs8-07.pdf

General relations among thermodynamic parameters characterizing chemical equilibria including species H2A+, HA, H+ and A- in both phases of a two-phase water-nitrobenzene extraction system have been derived. From the extraction measurements, the equilibrium distribution constant of electroneutral 1-(2-thiazolylazo)-2-naphthol (TAN, HA) between the nitrobenzene and aqueous phases has been determined: log KD(HA) = 3.90±0.02. By using this value and further known constants and applying the mentioned relations, the following values of dissociation constants of TAN in nitrobenzene saturated with water have been calculated for a temperature of 25°C: pKdnb(H2A+) = -log Kdnb(H2A+) = 4.9 and pKdnb(HA) = -log Kdnb(HA) = 16.5.