Formation of Phenylthiocyanate in the Reaction of Benzenediazonium Sulfate, Thiocyanate Ion and Some Kinds of Metal Ions

Abstract

Catalytic effect of some kinds of metal ions on the reaction of benzenediazonium sulfate and thiocyanate ion was examined by determination of phenyl thiocyanate produced using gas-liquid chromatography. Catalytic activities of metal ions were as follows : Cu²⁺>Cu⁺, Fe²⁺> Hg⁺ > Th⁴⁺> Fe³⁺, Bi³⁺, Al³⁺, Cr³⁺, Pb²⁺, Cd²⁺, UO₂²⁺, Ce³⁺, Zn³⁺, Co²⁺> K⁺, Na⁺, NH₄⁺, Mg²⁺, Mn²⁺, Hg²⁺, Ni²⁺, Ag⁺ > Sn²⁺. As a catalyst, Cu²⁺, Cu⁺, and Fe²⁺were found to be more effective than Co²⁺ and Fe³⁺, which were proposed by Korozynski, et al. The yield of phenyl thiocyanate was better, the larger the amount of thiocyanate ion added. When Cu²⁺ was used as a catalyst, the yield of phenyl thiocyanate was increased rapidly until the molar ratio of thiocyanate ion to metal ion became 4, and then slowed down according to the amount of thiocyanate ion. This new method of mixing one mole of benzene-diazonium sulfate, 4 or more mole of potassium thiocyanate, and 1 mole of cupric sulfate in neutral solution and allowing them to react is recommended for synthesis of phenyl thiocyanate, which is obtained in ca. 30% yield by this procedure.