Abstract
β-Mercaptoacrylic acid and β-mercaptocrotonic acid were synthesized through thiuronium salt obtained by addition of thiourea to propiolic acid or tetrolic acid. Although both compounds exhibit sensitive color with various metal ions, they are not suitable as practical reagents on account of their instability in air and pungent odor. Instead of using these mercapto acids, the applicabilities of their thiuronium salts as the analytical reagents were investigated. The thiuronium salts were found to be readily hydrolyzed by alkali to produce quantitatively the mercapto acids. Simultaneous determination of nickel and cobalt ions using the thiuronium salts were possible by the measurement of the absorbances at the wavelength of absorption maximum of each complex, namely, 505 mμ for nickel and 640 mμ for cobalt. The compositions of nickel and cobalt complexes were 1 : 2 and 1 : 3 in molar ratio of metal to reagent, respectively. Thiuronium salt is very stable, prepared easily, and can be used conveniently as the analytical reagent.
