Chlorovinyl arsonous acid

Lewisite 1 per se is never found in the environment. Figure 18 shows that this compound hydrolyzes rapidly on contact with moisture to 2-chlorovinyl arsonous acid, which in turn slowly dehydrates to lewisite oxide (syn. 2-chlorovinyl arsenous oxide) (16). Both 2-chlorovinyl arsonous acid and lewisite oxide are nonvolatile. The most frequently used method for the identification of CWC-related chemicals is based on gas chromatography (GC) in combination with mass spectrometry (GC/MS). Indirect GC/MS analysis of lewisite 1 requires sample preparation, which involves conversion of lewisite oxide to 2-chlorovinyl arsonous acid in an acidic environment, followed by derivatization (12). The obtained species is both volatile and thermally stable, and thus amenable to GC analysis. Often, a mercaptan reagent is used as a derivatization agent. The reaction with 3,4-dimercaptotoluene is shown in Figure 19. 

Figure 19. Formation of cyclic disulfide derivative of 2-chlorovinyl arsonous acid using 3,4-dimercaptotoluene (16)...

E.M. Jakubowski Haas, J.R. Smith, T.P. Logan, N.D. Wiltshire, C.L. Woodard, R.A. Evans and T.W. Dolzine, Verification of Lewisite exposure quantification of chlorovinyl arsonous acid in biological samples, Proceedings of the 1993 Medical Defense Bioscience Review, 10-13 May,... 

Logan TP, Smith JR, Jakubowski EM, Nielson RE. Verification of lewisite exposure by the analysis of 2-chlorovinyl arsonous acid in urine. Toxicol Methods, 1999 9 275-284. 

Lewisite is practically insoluble in water, but the small amount that dissolves is rapidly hydrolyzed (Rosenblatt et al., 1975), resulting in the formation of the water-soluble dihydroxy arsine or 2-chlorovinyl arsonous acid. Lewisite in solution becomes essentially 100% 2-chlorovinyl arsonous acid (Major, 1998) ... 

With the removal of water, 2-chlorovinyl arsonous acid forms lewisite oxide (2-chlorovinyl... 

Lewisite has vesicant properties as well as systemic toxicity. Because lewisite rapidly hydrolyzes to 2-chlorovinyl arsonous acid upon contact with moist surfaces, the toxic properties of lewisite may actually be those of 2-chlorovinyl arsonous acid (Fowler etal., 1991). Percutaneous LD50 values in small mammals range from 5 to 24 mg/kg (Marrs et al., 1996). Lewisite oxide most likely also has vesicant properties (US Army, 1974). The vesicant potency of lewisite degradation products compared to lewisite is... 

Chlorovinyl arsonous acid (CVA) 2-Chlorovinyl arsenous acid 2-Chloroethenyl arsonous acid Dihydroxy(2-Chlorovinyl)arsine 2-Chloroethenyl dihydroxyarsine C2H4AsC102 85090-33-1 Hydrolysis of Lewisite... 

Chlorovinyl arsenous oxide 2-Chlorovinyl arsenic oxide 2-Chlorovinyl arsine oxide 2-Chloroethenyl arsinic oxide Lewisite oxide C2H2AsC10 3088-37-7 Hydrolysis or dehydration of 2-chlorovinyl arsonous acid... 

Chlorovinyl arsonic acid 2-Chloroethenyl arsonic acid C2H4AsC103 64038-44-4 Oxidation of lewisite oxide... 

RTECS (2005). 2-Chlorovinyl arsonic acid. Registry of Toxic Effects of Chemical Substances, MEDLARS Online Information Retrieval System, National Library of Medicine, retrieved... 

Although Lewisite is only slightly soluble in water (0.5 g L j [123], hydrolysis is rapid and results in the formation of the water-soluble dihydroxy arsine (2-chlorovinyl arsonous acid). In basic solution, the traws-Lewisite isomer is cleaved by the hydroxyl ion to give acetylene and sodium arsenite this occurs even at low temperatures [79, 123]. ds-Lewisite must be heated to over 40°C to react with NaOH to yield vinyl chloride, sodium arsenite and acetylene. In aqueous solution, the ds-isomer undergoes a photoconversion into the tr zws-isomer. In water and in the presence of oxidizers naturally present in the environment, the toxic trivalent arsenic of Lewisite oxide is oxidized to the less toxic pentavalent arsenic [124]. Regardless of the degradation pathway, arsenical compounds will ultimately be formed. 

The effects of acute exposure to Lewisite degradation products are given in Table 2.10 [5]. When Lewisite 1 reacts with water, an arsenic based compound will form chlorovinyl arsonous acid (CVAA) and hydrochloric acid (HCl), see Equation 2.1 ... 

Clark II diphenylcyanoarsine, DC CMPA cyclohexyl methylphosphonic acid CTAB cetyltrimethylammoniumbromide CVAA chlorovinyl arsonous acid CVAO chlorovinyl arsonous oxide CWA Chemical Warfare Agent CWC Chemical Weapons Convention CWS Chemical Warfare Service CX phosgene oxime DA Diphenylcyanoarsine (Clark I)... 

---