EXTRACTION OF 4-(2-PYRIDYLAZO)RESORCINOL AND 4-(2-THIAZOLYLAZO)RESORCINOL WITH CHLOROFORM AND TETRAPHENYLARSONIUM AND PHOSPHONIUM CHLORIDES

The extraction of 4-(2-pyridylazo)resorcinol (PAR) and 4-(2-thiazolyla zo)resorcinol (TAR) with chloroform alone and in the presence of tetra phenylarsonium or tetraphenylphosphonium chloride (Ph(4)XCl) was studi ed. In the optimum pH range 3.5-5 for PAR and 1.5-5 for TAR, 94-95% of the reagents was extracted into chloroform. In the presence of Ph(4)X Cl in 10-100-fold excess 95-98% of PAR and TAR were extracted within t he pH range 3.5-10 and 1.5-10, respectively. The species extracted wit h chloroform alone were estimated to be H(2)R molecules. A quantitativ e interpretation of PAR and TAR distribution between aqueous solution (mu=0.33) and chloroform was made. Distribution constants for H(2)R we re determined as 14.9 for PAR and 19.2 for TAR. In the presence of Ph( 4)XCl as extractant H(2)R molecules were predominantly extracted up to pH 4; between pH 4 and pH 8 two species H(2)R and Ph(4)X(+)HR(-) were transferred to the chloroform phase. Above pH 8 the Ph(4)X(+)HR(-) io n pairs were the only extracted species. They were studied in solution and by characterization of solid compounds isolated from the organic phase and aqueous solution.