10-chloro-5,10-dihydrophenarsazine

Adamsite (DM) was first synthesized in 1915 by a German chemist Heinrich Wieland, and again in 1918 by a US chemist Robert Adams who named it adamsite. DM is a yellow-green, odorless crystalline solid at room temperature with low volatility. It is insoluble in water and relatively insoluble in organic solvents.

Adamsite, or Agent DM, is a light green to yellow, crystalline, organometallic solid at room temperature; it can be dark green depending on purity and age; canary yellow when concentrated; colorless when diluted with air. Odorless but irritating; similar to pepper

DM has been used as a vomiting agent and as a riot-control agent. It is considered insufficiently toxic for use in war, but too potent for control of civilian disturbances. Thus, it was banned in 1930 for use against civilians. Adverse health effects due to exposure are generally self-limiting, resolving within 30 min, and do not require specific therapy. Prolonged exposure or exposure to high concentrations may result in more severe adverse health effects, serious illness, or death. DM has found extensive use as a pesticide for treatment of wood against insects.

As war gas, dispersed in air in the form of minute particles. For riots in combination with tear gas (chloroacetophenone). In the formulation of wood-treating solutions, against marine borers and similar pests.

10-chloro-5,10-dihydrophenarsazine is in the form of yellow crystals. The vapors are very irritating to the eyes and mucous membranes and are also nauseating.

Organometallics, such as 10-chloro-5,10-dihydrophenarsazine , are reactive with many other groups. Incompatible with acids and bases. Organometallics are good reducing agents and therefore incompatible with oxidizing agents. Often reactive with water to generate toxic or flammable gases.

TOXIC; inhalation, ingestion or skin contact with material may cause severe injury or death. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.

Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated.

Human poison by inhalation. Poison experimentally by intravenous route. Human systemic effects by inhalation: changes in function or structure of salivary glands, nausea or vomiting, cough. May be irritating to skin, eyes, and mucous membranes. A vomiting type of poison gas (non-persistent). When heated to decomposition it emits very toxic fumes of As and Cl-. See also ARSENIC COMPOUNDS

Adamsite (military designation DM), a chloroarsenical, was first produced during World War I. Adamsite (DM) is used as a riot control or harassing agent, tear gas, and (vomiting agent) gas. It was designed as a battlefield agent and can be dissolved in acetone and dispersed as an aerosol. Adverse health effects due to exposure to adamsite (DM) are generally self-limited and do not require specific therapy. Most adverse health effects resolve within 30 minutes. Exposure to large concentrations of adamsite (DM), or exposure to adamsite (DM) within an enclosed space or under adverse weather conditions, may result in more severe adverse health effects, serious illness, or death. Adamsite (DM) is more disagreeable than tear gas, but less dangerous than sarin. It is considered to be too extreme for use against civilian populations, and was banned for this use in the 1930s by western nations. Produced worldwide, DM was superseded by the CN series of tear agents. It produces irritation to the upper respiratory tract and the eyes. Although DM has been replaced by CS, it might be mixed with a nerve agent. This may cause a vomiting victim to remove respiratory

DM’s primary action is on the upper respiratory tract, causing irritation of the nasal mucosa and nasal sinuses, burning in the throat, tightness and pain in the chest, and uncontrollable coughing and sneezing. It also causes eye irritation and burning, with tearing, blepharospasm, and injected conjunctiva.
DM is more toxic than other riot-control agents; the LCt50 for humans has been estimated to be 11 000 mg min m^-3. The amount that is intolerable for humans has been estimated by some to be 22 mg min m^-3 and by others to be 150 mg min m^-3. The threshold for irritation in humans is about 1 mg m^-3, but some people have tolerated exposures of 100–150 mg min m^-3.

UN1698 DPA chloroarsine, Hazard class: 6.1; Label: 6.1-Poisonous materials. Military driver shall be given full and complete information regarding shipment and conditions in case of emergency. AR 50-6 deals specifically with the shipment of chemical agents. Shipments of agent will be escorted in accordance with AR 740-32.

DM has an estimated Koc value of 5750 which indicates a lack of mobility once it is released into sediment. Also, its volatility from moist soil and water is not expected to be significant. Its environmental fate is based upon its estimated Henry’s law constant of 3.3×10^-8 atm-m3 mol^-1. DM was reported to hydrolyze slowly under alkaline conditions to bis(diphenylaminoarsine) oxide in moist alkaline soils. DM is not expected to volatilize from dry soil surfaces based upon its vapor pressure of 2×10^-13 mmHg at 20°C. With such low vapor pressure, once released into air it will exist as particulates at ambient pressure and could be removed from air through wet and dry deposition. DM release into water will be expected to adsorb to suspended solids and sediment based upon its estimated Koc. DM’s effect on aquatic life could be extrapolated from its estimated bioconcentration factor (BCF) value of 263, which indicates high potential for accumulation in aquatic organisms. There are no available data for arsenical vomiting agents on their biodegradation. The hydrolysis of solid DM is generally considered negligible due to the formation of an oxide coating. However, in the aerosol state it hydrolyzes more rapidly. DM lacks chromospheres capable of light absorption beyond 290 nm, which makes it less susceptible to undergo photolysis when exposed to sunlight.

A reducing agent and an organometallic, reacts, possibly violently, with oxidizers, acids and bases. Slowly hydrolyzes in water. Stability: stable in pure form; after 3 months, caused extensive corrosion of aluminum, anodized aluminum, and stainless steel; will corrode iron, bronze, and brass when moist. Corrosive properties: titanium—71 C, 6 months, appeared good. Stainless steel— 43 C, 30 days, slight discoloration. Common steel—43 C, 30 days, covered with rust. Aluminum anodized—43 C, 30 days, minor corrosion and pitting. Aluminum—43 C, 30 days, severe corrosion. Contact with metals may evolve flammable hydrogen gas.

Approximately 9 t of Adamsite were discovered on the territory of Poland after World War II. This agent was stored in steel barrels and special preventive measures were undertaken in order to protect it against spreading. The Polish government decided to destroy the abandoned Adamsite and different suitable technologies were considered. The first laboratory experiments have started in 1996 and elimination of the Adamsite on semitechnical scale will begin by June 1998. In this paper, methods of neutralization of Adamsite, based on its hydrolysis with hydrochloric acid, reduction with phosphorous acid and fusion with sulfur are discussed. These methods were found to be useful at the laboratory scale. Advantages and disadvantages of considered methods of destruction of organic arsenical agents have been discussed. The most promising method seems to be the reduction of Adamsite with phosphorous acid. The products of this reaction are: metallic arsenic, DPA and hydrogen chloride. These products can be separated and reused or neutralized