Titrimetric determination of Δ2-pyrazol-5-ones and Δ3-pyrazol-5-ones via bromination

Abstract

A novel titrimetric method for the determination of 0.1–10 mg of Δ²-pyrazol- or Δ³-pyrazol-5-ones is described. It is based on their reaction with an excess of bromine water to form the corresponding N-bromo derivatives, which liberate equivalent amounts of iodine when treated with iodide. The liberated iodine is determined titrimetrically with thiosulphate. The method is simple, rapid and accurate; the complete procedure requires about 5 min.