o-Chlorobenzylidene malononitrile Chemical Properties

Melting point:

68-70 °C(lit.)

Boiling point:

126 °C0.1 mm Hg(lit.)

Density 

1.2906 (rough estimate)

vapor pressure 

3 x 10^-5 mmHg at 20 °C (NIOSH, 1997)

refractive index 

1.5500 (estimate)

storage temp. 

2-8°C

solubility 

Soluble in acetone, benzene, 1,4-dioxane, ethyl acetate, and methylene chloride (Windholz et al., 1983)

form 

White, crystalline solid

color 

White crystalline solid with a pepper-like odor

Water Solubility 

0.1-0.5 g/100 mL at 16 ºC

Exposure limits

NIOSH REL: ceiling 0.05 ppm (0.4 mg/m³), IDLH 2 mg/m³; OSHA PEL: TWA 0.05 ppm; ACGIH TLV: ceiling 0.05 ppm (adopted).

Stability:

Stable. Incompatible with strong oxidizing agents. Combustible.

CAS DataBase Reference

2698-41-1(CAS DataBase Reference)

NIST Chemistry Reference

2-Chlorobenzalmalononitrile(2698-41-1)

EPA Substance Registry System

o-Chlorobenzylidene malononitrile (2698-41-1)

Safety Information

Hazard Codes 

Xi,T

Risk Statements 

36/37/38-42/43-25

Safety Statements 

26-27-37/39-45-36/37/39

RIDADR 

UN 3448 6.1/PG 2

OEL

Ceiling: 0.05 ppm (0.4 mg/m3) [skin]

WGK Germany 

3

RTECS 

OO3675000

HazardClass 

6.1(a)

PackingGroup 

I

Hazardous Substances Data

2698-41-1(Hazardous Substances Data)

Toxicity

LD50 in rats (mg/kg): 28 i.v., 48 i.p.; LC50 in rats: 88,480 mg/min/m3 (Ballantyne, Swanston)

IDLA

2 mg/m3

MSDS

• Language:English Provider:[(2-Chlorophenyl)methylene]malononitrile
• Language:English Provider:SigmaAldrich

o-Chlorobenzylidene malononitrile Usage And Synthesis

Description

CS, also known as o-chlorobenzylidene malononitrile, is a riot control agent (RCA) currently used by U.S. military forces. It was synthesized in 1928 and named 'CS' after its creators, Corson and Stoughton. CS replaced chloroacetophenone (CN) in 1959 as the primary RCA due to its higher safety ratio. It is more potent and safer than CN. CS can be disseminated pyrotechnically or in powder formulations like CS1 and CS2.

Chemical Properties

o-Chlorobenzylidene malonitrile is a combustible, white crystalline solid with a pepper-like odor. It is the defining component of tear gas (CS gas).

Uses

2-Chlorobenzylidenemalononitrile has found extensive application in exploring the effects of irritants on the human body. It is used as a tear gas and riot control agent.

Definition

ChEBI: 2-Chlorobenzylidenemalononitrile is an organochlorine compound.

General Description

White crystalline solid or light beige powder. Odor of pepper.

Air & Water Reactions

The finely powdered nitrile is a significant dust explosion hazard. Slightly soluble in water.

Reactivity Profile

[(2-Chlorophenyl)methylene]malononitrile may react with strong oxidizers.

Hazard

Toxic by inhalation and skin contact. Strong irritant to eyes and mucous membranes.

Health Hazard

o-Chlorobenzylidene malononitrile (CS) aerosol is a potent lacrimator and upper respiratory irritant.
Characteristic effects of CS exposure are instantaneous conjunctivitis, blepharospasm, burning, and pain.1 Prolonged exposure to high concentrations in enclosed spaces may cause pulmonary edema and severe bronchospasm.

Fire Hazard

Flash point data for [(2-Chlorophenyl)methylene]malononitrile are not available, but [(2-Chlorophenyl)methylene]malononitrile is probably combustible.

Safety Profile

Poison by ingestion, intraperitoneal, and intravenous routes. Moderately toxic by inhalation. Human systemic effects by inhalation: conjunctiva irritation, cough, and unspecified respiratory system effects. A human skin and eye irritant. Human exposure data suggest relatively low systemic toxicity, but intense irritation of eyes, skin, and mucous membranes. Mutation data reported. A tear gas used for riot control. When heated to decomposition it emits very toxic fumes of Cl-, NOx, and CN-. See also NITRILES.

Potential Exposure

CS tear gas is used as a riot control agent and is also used as an agent in CS1, CS2, and CSX riot control, and tear gases.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 minutes, occasionally lifting upper and lower lids. Seekmedical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit.

Carcinogenicity

o-Chlorobenzylidene malononitrile did not cause a mutagenic response when tested in a variety of assays that examined point mutations, germinal gene mutations, chromosomal breaks, and mitotic chromosome misdistribution. 5 Although limited, a study of the repeated inhalation toxicity of CS in mice, rats, and guinea pigs did not find a relationship between tumors in a particular site and total dose of CS.6 F344N rats exposed at 0.075, 0.25, or 0.75mg/ m3 and B6C3F1 mice exposed at 0.75 or 1.5mg/m3 6 hours/day, 5 days/week for 2 years had no compound-related incidences of neoplasm. 7 Nonneoplastic lesions occurred primarily in the nasal passages and included hyperplasia and squamous metaplasia of the respiratory epithelium.

Environmental Fate

Chemical/Physical. Hydrolyzes in water forming 2-chlorobenzaldehyde and malononitrile (quoted, Verschueren, 1983).

storage

Color Code—Blue: Health Hazard/Poison: Storein a secure poison location. Prior to working with thischemical you should be trained on its proper handling andstorage. Store in tightly closed containers in a refrigeratoror cool, well-ventilated area. Use only nonsparking toolsand equipment, especially when opening and closing containers of this chemical. Sources of ignition, such as smoking and open flames, are prohibited where this chemical isused, handled, or stored in a manner that could create apotential fire or explosion hazard.

Shipping

UN2810 Toxic liquids, organic, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous materials, Technical Name Required. 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.

Toxicity evaluation

Tests conducted at Eglin Air Force Base near Ft. Walton Beach, Florida, concluded that CS in soil has a ‘conservative’ half-life of 3.9 days. Degradation of CS increases with soil and air moisture, and with light exposure as it undergoes a slow hydrolysis process. Olajos (2004) concluded that CS degrades to o-chlorobenzaldehyde and malononitrile, the former of which is ultimately converted to catechol under aerobic conditions. Nitriles such as the malononitrile degradation product of CS have a short half-life in soil and can be converted readily to organic acids. Anaerobically, microalgae have been reported to transform CS breakdown products into benzoate. The U.S. Army Edgewood Research Development and Engineering Center (USAERDEC) reports a solubility of 200 mg l^-1.
CS concentrations attenuate in the atmosphere through three processes: reaction with hydroxyl radicals, hydrolysis reactions with atmospheric humidity, and deposition of particulate CS. It should be noted that vapor pressure increases with temperature, as should be expected. At 20°C, CS vapor pressure is 3.5×10^-5 mmHg, and at 60°C, it is 5–7 mmHg.

Incompatibilities

Contact with strong oxidizers may cause fire and explosion. May be explosive if dust mixes with air.

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