General Description
A colorless liquid that turns brown on exposure to light. Denser than water. Contact may irritate skin, eyes and mucous membranes. Very toxic by ingestion, inhalation and skin absorption.
Reactivity Profile
Halogenated aliphatic compounds, such as METHYL IODIDE(74-88-4), are moderately or very reactive. Reactivity generally decreases with increased degree of substitution of halogen for hydrogen atoms. Low molecular weight haloalkanes are highly flammable and can react with some metals to form dangerous products. Materials in this group are incompatible with strong oxidizing and reducing agents. Also, they are incompatible with many amines, alkylphosphines, nitrides, azo/diazo compounds, alkali metals (sodium), and epoxides.
Air & Water Reactions
Soluble in water. Sinks and slowly decomposes in water forming poisonous vapor cloud of HI.
Hazard
Toxic by ingestion, inhalation, and skinabsorption; narcotic, irritant to skin. Eye damageand central nervous system impairment. Question-able carcinogen.
Health Hazard
Inhalation of vapor causes lung congestion and pulmonary edema. Higher concentrations causes rapid narcosis and death. Contact with liquid irritates eyes and burns skin.
Potential Exposure
Methyl iodide is used in fire
extinguishers; as an intermediate in the manufacture of
pharmaceuticals and some pesticides.
First aid
If this chemical gets into the eyes, remove any
contact lenses at once and irrigate immediately for at least
15 minutes, occasionally lifting upper and lower lids. Seek
medical attention immediately. If this chemical contacts the
skin, remove contaminated clothing and wash immediately
with soap and water. Seek medical attention immediately.
If this chemical has been inhaled, remove from exposure,
begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if
heart action has stopped. Transfer promptly to a medical
facility. When this chemical has been swallowed, get medical attention. Give large quantities of water and induce
vomiting. Do not make an unconscious person vomit.
Medical observation is recommended for 24 to 48 hours
after breathing overexposure, as pulmonary edema may be
delayed. As first aid for pulmonary edema, a doctor or authorized paramedic may consider administering a drug or
other inhalation therapy.
Shipping
UN2644 Methyl iodide, Hazard Class: 6.1;
Labels: 6.1-Poison Inhalation Hazard, Inhalation Hazard
Zone B
Incompatibilities
May form explosive mixture with air.
Slowly reacts with water forming poisonous hydrogen
iodide. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep
away from alkaline materials, strong bases, strong acids,
oxoacids, epoxides. Violent reaction with strong oxidizers,
strong reducing agents, strong bases; trialkylphosphines,
silver chlorite; calcium, oxygen, sodium. Decomposes @
270C. Halogenated aliphatic compounds are moderately or
very reactive. Halogenated organics generally become less
reactive as more of their hydrogen atoms are replaced with
halogen atoms. Low molecular weight haloalkanes are
highly flammable and can react with some metals to form
dangerous products. Materials in this group are incompatible with strong oxidizing and reducing agents. Also, they
are incompatible with many amines, alkylphosphines,
nitrides, azo/diazo compounds, alkali metals (sodium), and
epoxides
Description
Methyl iodide is a colorless liquid with a pungent, ether-like odor. Turns yellow, red, or brown on exposureto light and moisture. Molecular weight = 141.94; Specificgravity (H2O:1) 5 2.28; Boiling point = 42.8℃; Vaporpressure 5 400 mmHg; Freezing/Melting point 5 2 66.7℃.It is noncombustible. Hazard Identification (based on NFPA704 M Rating System): Health 2, Flammability 1, Reactivity0. Slightly soluble in water; solubility 5 1%.
Chemical Properties
light yellow to light pink liquid
Chemical Properties
Methyl iodide is a colorless liquid. Pungent,
ethereal odor. Turns yellow, red, or brown on exposure to
light and moisture.
Waste Disposal
Consult with environmental
regulatory agencies for guidance on acceptable disposal
practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform to EPA regulations governing storage, transportation, treatment, and
waste disposal
Physical properties
Clear, colorless liquid which may become yellow, red, or brown on exposure to light and moisture
Uses
.Iodomethane is an approved pesticide used to control insects, plant parasitic nematodes, soil borne pathogens and weed seeds.
Uses
Methyl iodide is used in the analysis of pyridine; microscopy; as an embedding materialfor examining diatoms (Merck 1996); and asa methylating agent.
Uses
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.
Definition
(methyl
iodide; CH3I) A liquid alkyl halide made
by reaction of methanol with iodine in the
presence of red phosphorus.
Definition
ChEBI: A member of the class of iodomethanes that is methane in which one of the hydrogens is replaced by iodine.
Production Methods
Methyl iodide has had very limited use as a chemical
intermediate (methylations), and in microscopy because of
its high refractive index, as imbedding materials for examining
diatoms, and in tests for pyridine. It has been proposed
as a fire extinguisher and insecticidal fumigant. It is a product
of natural biological processes. Methyl iodide is a currently
registered pesticide.
Fire Hazard
Noncombustible. High vapor pressure may cause containers to burst at elevated
temperatures.
Flammability and Explosibility
Noncombustible. High vapor pressure may cause containers to burst at elevated
temperatures.
Mechanism of action
Fumigant action thought to be via the nucleophilic displacement (SN2) reaction in various amino acids and peptides within target organisms
Carcinogenicity
Druckrey et al. reported
local sarcomas following weekly subcutaneous injection in
BD strain rats. Strain A mice (a susceptible strain) that were
injected with methyl iodide were reported to have a slight but
significant increase in the number of lung tumors per mouse.
Poirer et al. administered iodomethane dissolved in
tricaprylin to male and female strain A mice (10/sex/dose)
three times weekly by intraperitoneal injection. There was a
marginally statistically significant trend for increased lung
tumors in treated mice but the outcome was considered
equivocal: no clear dose–response relationship and occurrence
of spontaneous tumors in untreated mice.
Under the 2005 Guidelines for Carcinogen Risk Assessment
(121), the lack of available evidence suggests that there
is “inadequate information to assess the carcinogenic potential
for iodomethane.”
An early evaluation by the IARC classified
iodomethane as carcinogenic in rats. Two subsequent evaluations
(123, 124) determined that there is limited evidence
for carcinogenicity in experimental animals and the compound
is not classifiable regarding carcinogenicity to
humans. ACGIH has also reviewed iodomethane
carcinogenicity and classified it as category A2, suspected
human carcinogen; however, the A2 classification was withdrawn
in 1996. Iodomethane was delisted as a carcinogen
in the NTP 5th Annual Report on Carcinogens on the
basis of the 1986 IARC reevaluation. NTP
has not tested iodomethane for carcinogenicity. The State of
California determined under Proposition 65 that methyl
iodide is a carcinogen, based on the 1977 IARC evaluation. Neither a Toxicological Profile nor an
Environmental Health Criteria Monograph has been
published.
Environmental Fate
Chemical/Physical. Anticipated products from the reaction of methyl iodide with ozone or OH
radicals in the atmosphere are formaldehyde, iodoformaldehyde, carbon monoxide, and iodine
radicals (Cupitt, 1980). With OH radicals, CH2, methyl radical, HOI and water are possible
reaction products (Brown et al., 1990). The estimated half-life of methyl iodide in the atmosphere,
based on a measured rate constant for the vapor phase reaction with OH radicals, ranges from 535
h to 32 wk (Garraway and Donovan, 1979).
Hydrolyzes in water forming methyl alcohol and hydriodic acid. The estimated half-life in water
at 25 °C and pH 7 is 110 d (Mabey and Mill, 1978). At 70 °C, the hydrolysis rate was determined
to be 3.2 x 10-5/sec which is equivalent to a half-life of 6 h. (Glows and Wren, 2003). May react
with chlorides in seawater to form methyl chloride (Zafiriou, 1975).
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 cool, wellventilated area away from oxidizers. Where possible, automatically pump liquid from drums or other storage containers to process containers. A regulated, marked area shouldbe established where this chemical is handled, used, orstored in compliance with OSHA Standard 1910.1045.
Purification Methods
Methyl iodide deteriorates rapidly with liberation of iodine if exposed to light. It is usually purified by shaking with dilute aqueous Na2S2O3 or NaHSO3 until colourless, then washing with water, dilute aqueous Na2CO3, and more water, drying with CaCl2 and distilling. It is stored in a brown bottle away from sunlight in contact with a small amount of mercury, powdered silver or copper. (Prolonged exposure of mercury to methyl iodide forms methylmercuric iodide.) Methyl iodide can be dried further using CaSO4 or P2O5. An alternative purification is by percolation through a column of silica gel or activated alumina, then distillation. The solution can be degassed by using a repeated freeze-pump-thaw cycle. [Beilstein 1 IV 87.]
Toxics Screening Level
The initial threshold screening level (ITSL) for methyl iodide (a.k.a., iodomethane) is 120 μg/m3 with an 8 hour averaging time (AT).
Pesticide Type
Soil sterilant; Insecticide; Nematicide
