A study of the behavior of 2-chlorvinyldichloroarisine in soils

The conversion of 2-chlorvinyldichloroarisine ClCH=CHAsCl 2 (lewisite, I ) in various soil samples is studied by IR spectroscopy. At the initial stage of the process, the rate and character of lewisite conversion are primarily determined by the presence of free surface hydroxyl groups in the sample (which manifest themselves as narrow intense absorption bands at 3700 and 3620 cm −1 ), being nearly independent of the content of physically adsorbed water (a wide band at 3430 cm −1 ). In sandy soils, which contain only a small concentration of hydroxyls, if any, lewisite experiences no noticeable decomposition, at least over a period of five days. By contrast, in clayey soils, possessing a high sorbability, the concentration of hydroxyls, highly reactive species, is large enough to completely hydrolyze lewisite into 2-chlorovinylarsonous acid ClCH=CHAs(OH) 2 and then 2-chlorovinylarsineoxide ClCH=CHAsO within several hours.