Dew of Death: The Story of Lewisite, America's World War I Weapon of Mass Destruction

Appendix 2. Lewisite Production

Appendix 2 Lewisite Production The chemical process that was used to produce lewisite during World War II is detailed in a Department of Justice document pertaining to the waste product remediation done at Rocky Mountain Arsenal. Production was based on a process using mercury chloride as a catalyst, whereas earlier production (e.g., World War I) had used aluminum chloride. At all the arsenals, the production processes included synthesizing the two primary compounds involved in the production of lewisite: arsenic trichloride and acetylene. ARSENIC TRICHLORIDE 1. Reactions to Make Disulfur Dichloride Chlorine (Cl2) was produced in two ways: some made by re-vaporizing liquid chlorine that was purchased as a raw material; most, however, was made by electrolyzing aqueous brine (NaCl; salt) solutions: 2 NaCl + 2 H2O → H2 + Cl2 + 2 NaOH Disulfur dichloride (S2Cl2) was then made by reacting sulfur and chlorine. S8 + 4 C12 → 4 S2Cl2 2. Reaction to Make Arsenic Trichloride The disulfur dichloride (S2Cl2) produced in #1 was reacted with purchased arsenic trioxide (As2O3) to give arsenic trichloride (AsCl3). 16 As2O3 + 48 S2Cl2 → 32 AsCl3 + 9 S8 + 24 SO2 Not detailed here is the manufacture of an intermediate product, thionyl chloride (SOCl2), which improved the ef¤ciency of the production of disulfur dichloride. ACETYLENE 3. Reaction to Make Acetylene Calcium carbide (CaC2) was reactedwithwatertoproduceacetylene (C2H2). CaC2 + 2 H2O → C2H2 + Ca(OH)2 LEWISITE 4. Reaction to Make Lewisite The arsenic trichloride (AsCl3) made in #2 was reacted with the acetylene (C2H2) made in #3 with a catalyst (aqueous hydrochloric acid solution of mercury chloride) to produce lewisite (C2H2AsCl3; can also be represented as ClCH=CHAsCl2). AsC13 + C2H2 catalyst → C2H2AsCl3 Source: USDOJ, “Assessment of CERCLA.” 164 Appendix 2 ...