SPECTROPHOTOMETRIC STUDY OF XANTHATE AND DIXANTHOGEN SOLUTIONS

Abstract

Xanthate solutions of pH 6–10, prepared from "aged" potassium ethyl xanthate crystals, KEtX, were investigated spectrophotometrically in the region 190–400 mμ and showed coexistence of xanthate ions, EtX − , dixanthogen, (EtX) 2 , and carbon disulphide, CS 2 . Optical density measurements on the spectra of dixanthogen solutions led to the evaluation of: molar absorptivities of dixanthogen at wavelengths corresponding to the two main bands in the xanthate ion spectrum, i.e. at 301 mμ—6130 liter/mole cm, and at 226 mμ—18,400 liter/mole cm; the solubility of dixanthogen, ca. 1.3 × 10 −5 mole/liter; and the equilibrium constant, k = 3 × 10 10 , of the reaction 2(EtX) 2 + 4OH − → 4EtX − + 2H 2 O + O 2 , for solutions saturated with air at atmospheric pressure. Simultaneous reactions leading to decomposition of xanthate and/or dixanthogen species to alcohol and carbon disulphide have been detected by a strong band at 206.5 mμ due to CS 2 (with an estimated molar absorptivity of the order of 60,000–70,000 liter/mole cm).