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| | [(2-Chlorophenyl)methylene]malononitrile Basic information |
| | [(2-Chlorophenyl)methylene]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) |
| | [(2-Chlorophenyl)methylene]malononitrile Usage And Synthesis |
| Description | CS, or o-chlorobenzylidene malononitrile, is the current major
riot control agent (RCA) used by U.S. military forces. It was
originally synthesized in 1928 by Corson and Stoughton, and
the U.S. Army designated the compound ‘CS’ for the authors’
initials. CS replaced CN, chloroacetophenone, in 1959 as the
U.S. Army’s premier RCA due to its higher safety ratio over CN.
CS is more effective as an RCA, that is to say, more potent and
safer than its predecessor CN. CS can be disseminated pyrotechnically,
or in the cases of CS1 and CS2, in powder
formulations. | | Chemical Properties | white crystalline solid with a peppery smell | | Chemical Properties | o-Chlorobenzylidene malonitrile is a combustible, white crystalline solid. Pepper-like odor. | | Uses | The defining component of tear gas (CS gas). | | Uses | Riot control agent. | | Uses | Active ingredient in tear gas | | 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. | | 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). | | 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. |
| | [(2-Chlorophenyl)methylene]malononitrile Preparation Products And Raw materials |
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![[(2-Chlorophenyl)methylene]malononitrile Structure](CAS/GIF/2698-41-1.gif)
