Title: Methyl Iodide
CAS Registry Number: 74-88-4
Additional Names: Iodomethane
Molecular Formula: CH3I
Molecular Weight: 141.94
Percent Composition: C 8.46%, H 2.13%, I 89.41%
Literature References: Prepd from methyl alcohol, iodine and red phosphorus: King, Org. Synth. coll. vol. II, 399 (1943); from potassium iodide and methyl sulfate: Hartman, ibid. 404. Review of toxicity and carcinogenic risk: IARC Monographs 41, 213-227 (1986); ibid. Suppl. 7, p 47, 52 (1987); Evaluation of the Potential Carcinogenicity of Methyl Iodide (PB93-196343, 1988) 17 pp.
Properties: Colorless, transparent liquid; turns brown on exposure to light. Poisonous! d420 2.28. mp -66.5°. bp 42.5°; dec at 270°. nD21 1.5293. Sol in about 50 parts water; miscible with alcohol, ether. Protect from light. LD50 orally in rats: 76 mg/kg; LD50 s.c. in mice: 0.78 mmoles/kg (IARC, 1986).
Melting point: mp -66.5°
Boiling point: bp 42.5°
Index of refraction: nD21 1.5293
Density: d420 2.28
Toxicity data: LD50 orally in rats: 76 mg/kg; LD50 s.c. in mice: 0.78 mmoles/kg (IARC, 1986)
CAUTION: Potential symptoms of overexposure are nausea, vomiting; vertigo, ataxia; slurred speech, drowsiness; dermatitis; direct contact may cause irritation of eyes, skin and respiratory system. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 210. See also Patty's Industrial Hygiene and Toxicology vol. 2E, G. D. Clayton, F. E. Clayton, Eds. (John Wiley & Sons, Inc., New York, 4th ed., 1994) pp 4030-4034; Clinical Toxicology of Commercial Products, R. E. Gosselin et al., Eds. (Williams & Wilkins, Baltimore, 5th ed., 1984) Section II, pp 158-159. This substance has been listed as reasonably anticipated to be a carcinogen: Fourth Annual Report on Carcinogens (NTP 85-002, 1985) p 132; delisted due to IARC reevaluation as unclassifiable as to its human carcinogenicity: Fifth Annual Report on Carcinogens (NTP 89-239, 1989) p 340.
Use: Methylating agent; in microscopy because of its high refractive index; as imbedding material for examining diatoms; in testing for pyridine. Light sensitive etching agent for electronic circuits; component in fire extinguishers.