Solvent extraction of tungsten(6) with arylazopyrocatechins in the presence of diphenyl- and triphenylquanidine

Spectrophotometric investigation has been conducted of extraction of ionic associates of diphenylguanidine (DPG) and triphenylguanidine (TPG) with anionic complexes formed by tungsten (6) with pyrocatechol (PC), p-nitrobenzeneazopyrocatechol, thiazolylazopyroeatechol and 2-(3'+4'-dihydroxyphenylazo)-4-carbomethoxyphenyl-5-carboethoxythiazol. It has been established that extraction of complexes of W with PC and its azo-derivatives takes place only in the presence of DPG of TPG, the best extracting agent in this case being a mixture of isoamyl alcohol and chloroform (1:1). Extraction equilibrium is attained after 1-3 minutes. In the system W-PC-DPG several associates are formed with a ratio between the components 1:1:1, 1:1:2, and 1:1:3 at pH 2.7-4.0 and 1:2:1, 1:2:2, and 1:2:3 at ph 5.4-6.8. In all the rest associates the ratio between the components is 1:2:2. It has been shown that, during extraction of W, it is preferable to use azo-derivatives of PC than PC itself