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Halogenated compounds

Lewisite

Also known as Chlorovinyl dichloroarsine, beta-Chlorovinylbichloroarsine, beta-Chlorovinyldichloroarsine

CAS 541-25-3Formula C2H2AsCl3Molar mass 207.32 g/mol
Prohibited, not for trade
Why it is not for trade
Lewisite chemical structure, C2H2AsCl3, CAS 541-25-3
2D chemical structure

Key facts

What buyers check first

All properties
Appearance
Colorless liquid when pure, impurities lead to colors ranging from violet to brown
Melting point
0.1 °C
Boiling point
190 °C
Density
1.888 at 20 °C/4 °C
Flash point
None (EPA, 1998)
HS code
293190
Category
Halogenated compounds

What is Lewisite?

Plain description, key identifiers and synonyms

Lewisite appears as a chemical warfare blister agent. Very toxic. When pure, a colorless oily liquid solidifying at -13 °C. Impurities cause colors ranging from brown to violet. Faint odor of geranium. Irritating to the eyes and mucous membranes at concentrations below the threshold of odor. Produces severe vesication (blistering) even through rubber (Merck), absorbed through the skin to produce seven systemic effects. Antidote: dimercaprol (British Anti-Lewisite). Prolonged exposure of container to fire or intense heat may result in violent rupturing and rocketing of container.

Identifiers

Registry numbers, names and line notations, tap to copy

IUPAC name
dichloro(2-chloroethenyl)arsane
CAS number
541-25-3 CAS number cross-checked
Molecular formula
C2H2AsCl3
InChIKey
GIKLTQKNOXNBNY-UHFFFAOYSA-N
InChI
InChI=1S/C2H2AsCl3/c4-2-1-3(5)6/h1-2H
SMILES (canonical and isomeric)
C(=C[As](Cl)Cl)Cl

Synonyms

  • Chlorovinyl dichloroarsine
  • beta-Chlorovinylbichloroarsine
  • beta-Chlorovinyldichloroarsine
  • 1-Chloro-2-di-chloroarsinoethane
  • (2-Chloroethenyl)arsonous dichloride
  • 2-Chlorovinyldichloroarsine
  • Arsine, dichloro(2-chlorovinyl)-
  • Arsonous dichloride, (2-chloroethenyl)-
  • Chlorovinylarsine dichloride
  • Dichloro(2-chlorovinyl)arsine
  • Lewisite (arsenic compound)
  • Chlorvinyldichlorarsin

Physical and chemical properties

Measured values and descriptors computed from the structure

Physical and chemical properties

Measured values, check the supplier specification for your grade

Appearance
Colorless liquid when pure, impurities lead to colors ranging from violet to brownexp.
Odour
Faint odor of geraniumexp.
Melting point
0.1 °Cexp.
Boiling point
190 °Cexp.
Density
1.888 at 20 °C/4 °Cexp.
Flash point
None (EPA, 1998)exp.
Solubility
Greater than 10% in ethyl ether, greater than 10% in ethanolexp.
Vapour pressure
0.4 mm Hg at 25 °C /trans-isomer/exp.

Values vary by grade. Ask suppliers for the COA or TDS of the batch you buy.

Computed descriptors

Calculated from the structure, useful for screening and formulation

Molecular weight
207.32 g/molcalc.
Exact mass
205.8438 Dacalc.
LogP (octanol/water)
2.24calc.
Topological polar surface area
0 Ųcalc.
Hydrogen bond donors
0calc.
Hydrogen bond acceptors
0calc.
Rotatable bonds
1calc.
Heavy atoms
6calc.
Rings
0calc.
Aromatic rings
0calc.
Fraction sp3 carbons
0calc.
Formal charge
0calc.
Stereocentres
0calc.
Lipinski rule of five
Passes (0 violations)calc.

Calculated for screening. Confirm critical figures with the supplier.

Safety and hazards

GHS classification summary, not a safety data sheet

No GHS hazard classification is recorded for this substance yet. That does not mean it is harmless.

GHS classification summary, not a safety data sheet (SDS). Classifications can differ by supplier, grade and concentration. Always check the supplier's SDS.

Lewisite suppliers

Trading restrictions apply to this substance

Chemical Weapons Convention Schedule 1

Lewisite is prohibited on CompoundList. Listings, quotes and messages are disabled. This page is kept for information only.

Listing and enquiries are not allowed for this substance.

Reference: OPCW Chemical Weapons Convention Schedule 1

Our policy on controlled substances

Lewisite price

Indicative price range per kg from live supplier offers

Prices are not shown for prohibited substances.

Uses and applications

What the substance is used for, by industry and function

Poison gas, skin-blistering agent.

War gas. Respiratory and systemic poison.

Lewisite is an extremely toxic, arsenic-containing blister agent (vesicant) that affects the lungs and causes whole-body (systemic) effects. It has an odor of geraniums. It was developed as a potential chemical warfare agent (military designation, L), but has not been used on the battlefield. Exposure to large amounts can be fatal. Pain and irritation from exposure to either liquid or vapor lewisite are immediate, and early tissue destruction is more obvious than after exposure to mustard. Lewisite causes burning pain in the respiratory tract at a concentration that cannot be detected by odor.

Use classes: Warfare and Terrorism Agents.

Pharmacological actions

  • Chemical Warfare Agents

How it is made

Obtained together with bis(2-chlorovinyl)chloroarsine and tris(2-chlorovinyl)arsine upon passing acetylene into a mixture of arsenic trichloride and aluminum chloride and fractionating the product in a current of hydrogen chloride gas.

Condensation of arsenic trichloride with acetylene in the presence of aluminum or copper or mercury chloride. The mixed arsines are separated by fractionating.

Regulatory status

Inventories, regulations and trade controls that list this substance

Chemical Weapons Convention Schedule 1

Lewisite is prohibited on CompoundList. Listings, quotes and messages are disabled. This page is kept for information only.

Listing and enquiries are not allowed for this substance.

Reference: OPCW Chemical Weapons Convention Schedule 1

Our policy on controlled substances

Controls

  • Chemical Weapons Convention Schedule 1

United States

  • TSCA inventory (USA)
    Status: Active in US commerce

HS code and trade data

Customs classification and reported world trade statistics

Global trade

World import and export statistics for the HS code Lewisite is traded under.

HS 2931.90Indicative HS code

Organo-inorganic compounds, other than tetramethyl lead, tetraethyl lead, tributyltin compounds…

World exports in 2024
$3.97B
+5.3% vs 2023, imports $3.93B
2019 to 2024
Top exporters
  1. China28.3%
  2. United States15.6%
  3. Germany15.1%
Top importers
  1. United States14.6%
  2. China13.0%
  3. South Korea8.5%
Reported customs values in USD, not prices.Full trade data

The HS code shown for Lewisite is indicative (it was assigned by structure rules). Confirm the classification with your customs broker before shipping.

Frequently asked questions

Quick answers about Lewisite, based on the data on this page

What is Lewisite?

Lewisite appears as a chemical warfare blister agent. Very toxic. When pure, a colorless oily liquid solidifying at -13 °C. Impurities cause colors ranging from brown to violet. Faint odor of geranium. Irritating to the eyes and mucous membranes at concentrations below the threshold of odor.

What is the CAS number of Lewisite?

The CAS registry number of Lewisite is 541-25-3.

What is the molecular formula and weight of Lewisite?

The molecular formula of Lewisite is C2H2AsCl3 and its molar mass is 207.32 g/mol.

What is Lewisite used for?

Poison gas, skin-blistering agent. War gas. Respiratory and systemic poison. Lewisite is an extremely toxic, arsenic-containing blister agent (vesicant) that affects the lungs and causes whole-body (systemic) effects. It has an odor of geraniums.

Is Lewisite hazardous?

No GHS hazard classification for Lewisite is recorded on CompoundList yet. That does not prove it is safe. Always read the supplier safety data sheet.

What is the HS code of Lewisite?

Lewisite is usually classified under HS code 293190 (X. ORGANO-INORGANIC COMPOUNDS, HETEROCYCLIC COMPOUNDS, NUCLEIC ACIDS AND THEIR SALTS…). This is indicative, confirm it with your customs broker before shipping.

Can I buy Lewisite on CompoundList?

No. Lewisite is on our prohibited list, so listings, quotes and messages for it are disabled. This page is kept for information only.

Guides for buyers

Practical guides that help when you source, ship or handle Lewisite

Data last updated 7 Oct 2026. Details may have changed, please confirm them with the supplier. Report an error on this page

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