Names & Synonyms
Name of Substance
- Benzene, hexahydro-
- Cyclohexane [UN1145] [Flammable liquid]
- RCRA waste no. U056
- Benzene, hexahydro-
- CCRIS 3928
- CTFA 06225
- Caswell No. 269
- Cicloesano [Italian]
- Cyclohexaan [Dutch]
- Cyclohexan [German]
- Cyclohexane (ACGIH:OSHA)
- Cykloheksan [Polish]
- EINECS 203-806-2
- EPA Pesticide Chemical Code 025901
- HSDB 60
- NSC 406835
- RCRA waste number U056
- Cyclohexane(DOT) (8CI)(9CI)
- Mutation data
- Skin / Eye Irritant
- TSCA Flag: T [Subject to a Section 4 test rule]
Superlist Classification Code
- Reportable Quantity (RQ) = 1000 lb
- TWA (300 ppm)
- TWA 300 mg/m3 (1050 ppm);
- EPA Envirofacts
- NIOSH ICSC
- NIOSH Pocket Guide
- NIST WebBook
Appearance and odor
Cyclohexane is a colorless liquid with a mild, sweet odor resembling that of
chloroform or benzene. Air odor thresholds ranging from 25 to 300 parts per
million (ppm) parts of air have been reported.
CHEMICAL AND PHYSICAL PROPERTIES
* Physical data
1. Molecular weight: 84.18
2. Boiling point (at 760 mm Hg): 80.7 degrees C (177.26 degrees F)
3. Specific gravity: 0.78 at 20 degrees C (68 degrees F)
4. Vapor density: 2.90
5. Melting point: 6.47 degrees C (43.65 degrees F)
6. Vapor pressure at 20 degrees C (68 degrees F): 95 mm Hg
7. Solubility: Insoluble in water; soluble in alcohol, ether, acetone,
benzene, and ligroin.
HEALTH HAZARD INFORMATION
* Routes of Exposure
Exposure to cyclohexane can occur through inhalation, ingestion, and eye or skin
contact [Sittig 1991].
* Summary of toxicology
1. Effects on Animals: Cyclohexane is an eye and mucous membrane irritant; at
high concentrations, it causes narcosis in experimental animals [Hathaway et al.
1991]. Exposure to high vapor concentrations causes convulsions, and ingestion
of toxic doses causes diarrhea, circulatory collapse, and death [Gosselin 1984].
Rabbits exposed for 8 hours to 18,500 ppm survived; exposure to 26,000 ppm
proved fatal after 1 hour. Exposure to 12,600 ppm resulted in lethargy,
narcosis, increased respiratory rates, and convulsions. Rabbits exposed to 786
ppm for 50 6-hour exposures showed microscopic changes in liver and kidney
tissue [ACGIH 1991]. Mice exposed to 18,000 ppm developed tremors in 5 minutes,
disturbed equilibrium in 15 minutes, and recumbency in 25 minutes [Hathaway et
al. 1991]. A monkey exposed to 1,243 ppm for 50 6-hour exposures showed no
adverse effects during or after exposure, and postmortem examination showed no
histological changes [NLM 1995].
2. Effects on Humans: Cyclohexane is an irritant of the eyes and mucous
membranes in humans. By analogy with the effects in animals, exposure to high
concentrations is expected to cause narcosis. Exposure to 300 ppm caused
irritation to the eyes and mucous membranes in workers [Hathaway et al. 1991].
Exposure to higher concentrations is likely to cause dizziness, nausea, and
other narcotic effects. On repeated contact, cyclohexane is a defatting agent.
Cyclohexane has not been shown to cause the hematologic changes associated with
exposure to benzene [Hathaway et al. 1991].
* Signs and symptoms of exposure
1. Acute exposure: Exposure to the vapors of cyclohexane causes
irritation of the eyes and mucous membranes. If exposure is severe, nausea,
vomiting, incoordination, and coma may occur [Hathaway et al. 1991].
2. Chronic exposure: Chronic dermal contact may cause a dry, scaly,
fissured dermatitis [Sittig 1991; Hathaway et al. 1991].