Distribution of picric acid into various diluents

Abstract

Extraction constants, defined as Kex=HPico/[H+][Pic -], for picric acid (HPic) into ten diluents were spectrophotometrically determined at 298 K, where the subscript "o" refers to an organic (o) phase which is composed of the diluent. Their values for the HPic extraction into benzene and chloroform were fairly consistent with those reported before. From the Kex values, distribution constants (KD,HPic) of HPic into the o phases were estimated using the thermodynamic relation Kex=KD,HPicKHPic, where KHPic corresponds to a protonation constant of Pic - in water. Thereby, contributions of functional groups, such as -Cl and -CH3, involved in the diluents molecules to KD,HPic were discussed. The same discussion was also applied for the distribution of the ion pair, composed of CdPic2 and 18-crown-6 ether, into the diluents. © 2013 Yoshihiro Kudo et al.