Soman hydrolysis catalysed by hypochlorite ions

Institute of Chemical Defense (Army), Beijing, 102205, China

^* Corresponding author’s e-mail: wangly09@sina.com; fhzch@163.com

Abstract

Sarin (GB) and soman (GD) are severely toxic nerve agents that react slowly in water, resulting in long-term poisoning of the water and a serious threat to personnel. Some ions can catalyse GB and GD hydrolysis in water; the relevant research for GB is detailed, whereas that for GD is relatively less so. In this paper, GD hydrolysis catalysed by hypochlorite (ClO⁻) ions was studied via kinetic experiments. A fluorite-ion-specific electrode was used to monitor F⁻ ions produced, allowing the rate constant and half-life of the GD hydrolysis to be calculated. The results showed that ClO⁻ ions promote GD hydrolysis well; the higher the concentration of ClO⁻, the faster the GD was hydrolysed. In NaClO solution at pH 8.0 with 3.22×10^–3 M ClO⁻ ions, the half-life of GD hydrolysis was 82.5 s, about 875 times shorter than that in water at pH 8.0. The rate constant for catalysis of GD hydrolysis by ClO^- ions ++(kc1o⁻)++ was 2.6 M⁻¹ s⁻¹, about one quarter the value of ++koh⁻ ++but over 1500 times greater than k_B and ++k_PO4,++ with B representing N-2-hydroxyethylpiperazine-N’-2-ethanesulfonic acid present as a free base; this result indicated that ClO⁻ ions catalyse GD hydrolysis well.