Chemical Properties
Mustard gas is very slowly decomposed by water, owing to its very slight solubility. The products are dihydroxyethylsulfide and hydrochloric acid:
(ClCH₂CH₂)₂S + 2H₂O = (HOCH₂CH₂)₂S + 2HCl
Certain sulfonated oils accelerate the rate of hydrolysis, both by increasing the rate of solution and the solubility of the mustard gas. Alkalies also increase the rate of hydrolysis. Oxidizing agents destroy mustard gas. This reaction was made use of practically in that solid bleaching powder was early introduced as a means of destroying mustard gas in the field. ([Fig. 9].)
Chlorinating agents (chlorine, sulfur dichloride, etc.) rapidly transform mustard gas into an inactive (non-blistering) substance. Sulfur dichloride was a valuable reagent in both laboratory and works in “cleaning up” mustard gas. This reaction also explains why the early attempts to prepare mustard gas by the interaction of ethylene and sulfur dichloride were unsuccessful. Mustard gas is probably formed, but is almost immediately chlorinated by the excess of sulfur dichloride. Sulfur chloride on the other hand has no effect on mustard gas. Chloramine-T and Dichloramine-T (the valuable therapeutic agents introduced by Dakin and Carrel for treatment of wounds) also react with mustard gas. For this reason they were advocated as treatment for mustard gas burns. But as we will see later, they were not altogether successful.