Lewisite Gas- C2H2AsCl3

Chemical weapons simply have no place in the 21st century. Progress in this vital area will help generate momentum to meet our goal of eliminating all weapons of mass destruction.

1)What is Lewisite Gas?

Lewisite (L) is an organoarsenic compound. It was once manufactured in the U.S., Japan, Germany and the Soviet Union For use as a chemical weapon, acting as a vesicant (blister agent) and lung irritant. Although colourless and odourless, impure samples of lewisite are a yellow, brown, violet-black, green, or amber oily liquid with a distinctive odour that has been described as similar to geraniums. Some important summarise points are given below about lewisite:

  • Lewisite is a type of chemical warfare agent. This kind of agent is called a vesicant or blistering agent because it causes blistering of the skin and mucous membranes on contact.
  • Lewisite is an oily, colourless liquid in its pure form and can appear amber to black in its impure form.
  • Lewisite has an odour like geraniums.
  • Lewisite contains arsenic, a poisonous element.
  • Lewisite is also known for its military designation, “L.”

2)Preparation of Lewisite

The preparation of Lewisite (L-1) by the original procedure is complicated and dangerous. It involves the reaction of acetylene with arsenic trichloride, by using aluminium chloride as a catalyst. The reaction yields three principal products 

The optimum yield of Lewisite is about 20 per cent, obtained along with L-2, L-3, tar, and explosive material. Acetylene reacts with AsCl3 in hydrochloric acid solution, with mercuric chloride as a catalyst, to give Lewisite an 80 to 85 per cent yield (based on AsCl 3). Cuprous chloride and ethanolamine hydrochloride used together, however, constitute the best catalyst for the reaction.

The hydrolysis of Lewisite by water involves the following equilibria

The only substance isolated is polymeric 2-chloro vinylarsinoxide, a white insoluble powder.

The cold aqueous media of pH = 0.5 Lewisite decomposes as follows 

The vesicant character of arsenicals such as Lewisite is not a property of the AsCl2 group exclusively since carefully prepared solutions of the corresponding oxide or di-hydroxide are equally vesicant. Lewisite reacts with sodium alkoxides to give derivatives that are volatile, vesicant liquids that hydrolyze irreversibly on contact with water:

Reaction with sodium mercaptides gives the analogous thioethers, which are only slightly soluble in water and in general are hydrolyzed reversibly, giving toxic and sometimes vesicant solutions, although the equilibrium generally favours thioether formation 

Aqueous and alcoholic solutions of sodium dialkyl dithiocarbamates react readily with Lewisite to give crystalline, sharp-melting solids that are useful for its characterization. These dithiocarbamates are much more stable than the simple thioethers. However, hydrolysis of cyclic thioethers, such as the reaction product of Lewisite and BAL (British Anti-Lewisite) is negligible.

Alkali hydrolysis all of these compounds with the evolution of acetylene. Hydrogen peroxide causes decomposition of the ethers and thioethers in neutral or acid solution, giving free arsenic acids.

Little information is available in the literature concerning the reactions of Lewisite with biologically important molecules, although it is reasonable to assume that, as with sulfur mustard, DNA is a major target.

3) In World War II

The development of Lewisite as a war gas was made by W. Lee Lewis in 1918 while working at the Chemical Laboratory of the Catholic University of America in Washington, D.C. (Lewis and Perkins, 1923). The thrust of the work in this laboratory during WWI was the evaluation of substituted arsines (arsenic-containing chemicals) as potential chemical warfare agents. Lewis had noticed a paragraph in a 1904 student dissertation by J.A. Nieuwland that documented the formation of an "extremely poisonous" substance after a reaction of arsenic chloride with dry acetylene in the presence of aluminium chloride (cited in Lewis and Perkins, 1923). The toxicity that had caused Nieuwland to stop further work on the reaction spurred Lewis to investigate the substance more fully. In addition, Lewis and his group worked out safer and more efficient production methods and elaborated plans for large-scale production (Lewis and Perkins, 1923; Lewis and Steigler, 1925). A production plant was eventually constructed in Willoughby, Ohio, and approximately 150 tons of Lewisite were in transit to Europe when the Armistice was signed in November 1918. The vessel was sunk at sea (Spiers, 1986; Tarbell and Tarbell, 1981; Trammell, 1992), and all experimental work with Lewisite in the U.S. Chemical Warfare Service abruptly ceased until WWII (Gates et al., 1946).

In mid-2006, China and Japan were negotiating the disposal of stocks of lewisite in northeastern China, left by the Japanese military during World War II. Residents of China have died over the past twenty years from accidental exposure to these stockpiles.

What are the signs and symptoms of exposure to lewisite?

Eyes: irritation, pain, swelling, and tearing may occur on contact. Respiratory tract: runny nose, sneezing, hoarseness, bloody nose, sinus pain, shortness of breath, and cough. Digestive tract: diarrhoea, nausea, and vomiting. Cardiovascular: “Lewisite shock” or low blood pressure may occur.

What does lewisite gas do to your skin?

Lewisite gas is a chemical agent that causes severe burning of the skin, eyes and respiratory tract. It can be absorbed into the body through inhalation, ingestion or by coming into contact with the skin or eyes.

How do blister agents work?

Blister agents (whether as a gas, aerosol, or liquid) enter the body primarily through inhalation and dermal contact. They may act on the eyes, mucous membranes, lungs, and skin. Mustard agent symptoms are delayed - with little or no pain at the time of exposure.