Bromomethane: Difference between revisions

{{chembox

| verifiedrevid = 431576413

| ImageFileL1_Ref = {{chemboximage|correct|??}}

| ImageFileL1 = Methyl bromide.svg

| ImageSizeL1 =

| ImageFileR1 = Bromomethane-3D-vdW.png

| ImageSizeR1 = 120px

| IUPACName = Bromomethane

| OtherNames = Methyl bromide, Monobromomethane, Methyl fume, Halon 1001, Curafume, Embafume, R-40 B1, UN 1062, Embafume, Terabol

| Section1 = {{Chembox Identifiers

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChemSpiderID = 6083

| ChEMBL_Ref = {{ebicite|correct|EBI}}

| ChEMBL = 48339

| InChIKey = GZUXJHMPEANEGY-UHFFFAOYAV

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChI = 1S/CH3Br/c1-2/h1H3

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = GZUXJHMPEANEGY-UHFFFAOYSA-N

| CASNo = 74-83-9

| CASNo_Ref = {{cascite|correct|CAS}}

| EINECS = 200-813-2

| PubChem = 6323

| ChEBI = 39275

| SMILES = BrC

| InChI = 1/CH3Br/c1-2/h1H3| RTECS = PA4900000

| KEGG_Ref = {{keggcite|correct|kegg}}

| KEGG = C18447

}}

| Section2 = {{Chembox Properties

|C=1|H=3|Br=1

| Appearance = Colorless gas with chloroform-like odor (at high conc.)

| Density = 1.730 g/cm³ (0°C, liquid) <ref>''Merck Index'', 11th Edition, '''5951'''.</ref>

3.974 g/l (20 °C, gas)

| MeltingPt = −93.66 °C

| BoilingPt = 3.56 °C

| Solubility = 15.22 g/L

| LogP = 1.19

| VaporPressure = 1900 hPa (20 °C)

}}

| Section3 = {{Chembox Hazards

| MainHazards = Toxic ('''T'''), Dangerous for the environment ('''N'''), [[Carcinogen|Carc. Cat. 3]]

| FlashPt = < -30 °C (liquid)

| Autoignition = 535 °C

| NFPA-H = 3

| NFPA-F = 1

| NFPA-R = 0

| NFPA-O =

| RPhrases = {{R23/24/25}}, {{R34}}, {{R36/37/38}}, {{R45}}, {{R48/20}}, {{R50}}, {{R59}}, {{R68}}

| SPhrases = {{S1/2}}, {{S15}}, {{S27}}, {{S36/39}}, {{S38}}, {{S45}}, {{S59}}, {{S61}}

| ExploLimits = 8.6 - 20 %

}}

'''Bromomethane''', commonly known as '''methyl bromide''', is an [[organobromine compound]] with [[chemical formula|formula]] [[Carbon|C]][[Hydrogen|H]]₃[[Bromine|Br]]. This colorless, odorless, nonflammable gas is produced both industrially and particularly biologically. It has a tetrahedral shape and it is a recognized [[ozone depletion|ozone-depleting]] chemical. It was used extensively as a [[pesticide]] until being phased out by most countries in the early 2000s.

Bromomethane originates from both natural and human sources. In the [[ocean]], marine organisms are estimated to produce 1-2 billion kilograms annually.<ref>Gordon W. Gribble “The diversity of naturally occurring organobromine compounds” Chemical Society Reviews, 1999, volume 28, pages 335 – 346.{{DOI|10.1039/a900201d}}</ref> It is also produced in small quantities by certain terrestrial plants, such as members of the [[Brassicaceae]] family. It is manufactured for agricultural and industrial use by reacting [[methanol]] with [[hydrogen bromide]]:

:CH₃OH + HBr → CH₃Br + H₂O

In 1999, an estimated 71,500 tonnes of synthetic methyl bromide were used annually worldwide.<ref name=uneptie>http://www.uneptie.org/ozonaction/information/mmc/lib_detail.asp?r=4202</ref> 97% of this estimate is used for fumigation purposes, whilst 3% is used for the manufacture of other products. Moreover 75% of the consumption takes place in developed nations, led by the U.S (43%)and Europe (24%). Asia and the Middle East combine to use 24% whereas Latin America and Africa have the lowest consumption rates at 9%.<ref name=uneptie />

Until its production and use were curtailed by the [[Montreal Protocol]], bromomethane was widely applied as a [[soil]] [[Sterilization (microbiology)|sterilant]], mainly for production of [[seed]] but also for some crops such as [[Strawberry|strawberries]] and [[almond]]s. In [[Green Revolution|commercial large-scale monoculture]] [[seed production]], unlike [[crop production]], it is of vital importance to avoid contaminating the crop with off-type seed of the same species. Therefore, selective [[herbicides]] cannot be used. Whereas bromomethane is dangerous, it is considerably safer and more effective than some other soil sterilants. Its loss to the seed industry has resulted in changes to cultural practices, with increased reliance on [[soil steam sterilization]], mechanical [[rogueing]], and [[fallow]] seasons. Bromomethane was also used as a general-purpose [[fumigant]] to kill a variety of pests including [[rat]]s and [[insect]]s. Bromomethane has poor fungicidal properties. Bromomethane is the only fumigant allowed (heat treatment is only other option) under [[ISPM 15]] regulations when exporting solid wood packaging (forklift pallets, crates, bracing) to ISPM 15 compliant countries. Bromomethane is used to prepare golf courses, particularly to control [[Bermuda grass]]. The Montreal Protocol stipulates that bromomethane use be phased out.

Bromomethane is also a precursor in the manufacture of other chemicals as a [[methylation|methylating]] agent, and has been used as a [[solvent]] to [[solvent extraction|extract]] [[oil]] from [[seed]]s and [[wool]].

Bromomethane was once used in specialty fire extinguishers, prior to the advent of less toxic halons, as it is electrically non-conductive and leaves no residue. It was used primarily for electrical substations, military aircraft, and other industrial hazards. It was never as popular as other agents due to its high cost and toxicity. Bromomethane was used from the 1920s to the 60s, and continued to be used in aircraft engine fire suppression systems into the late 60s.

[[Image:National Methyl Bromide 6.jpg|thumb|left|170px|A selection of stored-pressure bromomethane fire extinguishers, circa 1930s-40s, UK]]

Bromomethane is readily [[Photodissociation|photolyzed]] in the atmosphere to release elemental bromine, which is far more destructive to stratospheric ozone than chlorine. As such, it is subject to phase-out requirements of the 1987 [[Montreal Protocol on Ozone Depleting Substances]].

The London Amendment in 1990 added methyl bromide to the list of ODS to be phased out. In 2003 the Global Environment Facility approved funds for a UNEP-UNDP joint project for methyl bromide total sector phase out in seven countries in Central Europe and Central Asia, due for completion in 2007.<ref>http://www.uneptie.org/ozonaction/information/mmc/lib_detail.asp?r=5315</ref>

In [[Australia]], bromomethane (methyl bromide) is the preferred fumigant required by the Australian Quarantine and Inspection Service (AQIS) for most organic goods imported into Australia.<ref>{{Cite web|url=http://www.daff.gov.au/aqis/import/general-info/qtfp/treatments-fumigants|title=Quarantine Treatments and Fumigants|publisher=Australian Quarantine and Inspection Service|accessdate=2011-02-21}}</ref> AQIS conducts methyl bromide fumigation certification for both domestic and foreign fumigators who can then fumigate containers destined for Australia. A list of alternative fumigants is available for goods imported from Europe (known as the ICON database), where methyl bromide fumigation has been banned.<ref>{{Cite web|url=http://www.daff.gov.au/aqis/import/general-info/ian/10/08-2010|title=European Union (EU) Phase out of Methyl Bromide Use|publisher=Australian Quarantine and Inspection Service|accessdate=2011-02-21}}</ref> Alternatively, AQIS allows containers from Europe to be fumigated with methyl bromide on arrival to Australia.

In [[New Zealand]], bromomethane is used as a fumigant for whole logs destined for export. Environmental groups and the [[Green Party of Aotearoa New Zealand|Green Party]] oppose its use.<ref>{{Cite web|url=http://www.guardiansofthesounds.co.nz/wordpress/index.php/category/methyl-bromide/|title=Methyl Bromide Threat Again in Picton|publisher=Guardians of the Sounds|accessdate=2009-02-02}}</ref><ref>{{Cite web|url=http://www.greens.org.nz/node/20520|title=Picton residents need protection from poison fumes: Greens|last=Kedgley|first=Sue|date=2008-02-02|publisher=Green Party|accessdate=2009-02-02}}</ref> In May 2011 the [[Environmental Risk Management Authority]] (ERMA) introduced new rules for its use which restrict the level of public exposure to the fumigant, set minimum buffer zones around fumigation sites, provide for notification to nearby residents and require users to monitor air quality during fumigations and report back to ERMA each year. All methyl bromide fumigations must use recapture technology by 2021.<ref>{{cite web|url=http://www.ermanz.govt.nz/publications-resources/topics/Methyl-bromide-fumigations/Pages/Methyl%20bromide%20fumigations.aspx|title=New rules for methyl bromide fumigations|publisher=Environmental Risk Management Authority|accessdate=7 June 2011}}</ref>

In the [[United States]] bromomethane is regulated as a pesticide under the [[Federal Insecticide, Fungicide, and Rodenticide Act]] (FIFRA; 7 U.S.C. 136 et seq.) and as a hazardous substance under the [[Resource Conservation and Recovery Act]] (RCRA; 42 U.S.C. 6901 et seq.), and is subject to reporting requirements under the [[Emergency Planning and Community Right-to-Know Act]] (EPCRA; 42 U.S.C. 11001 et seq.). The U.S. [[Clean Air Act]] (CAA; 42 U.S.C. 7401 et seq.). A 1998 amendment (P.L. 105-178, Title VI) conformed the Clean Air Act phase out date with that of the Montreal Protocol.<ref>{{Cite web|url=http://www.epa.gov/spdpublc/mbr/|title=The Phaseout of Methyl Bromide|publisher=U.S. Environmental Protection Agency|accessdate=2009-10-28}}</ref><ref>[http://ncseonline.org/nle/crsreports/05jun/97-905.pdf CRS Report for Congress: Agriculture: A Glossary of Terms, Programs, and Laws, 2005 Edition - Order Code 97-905]</ref> Whereas the Montreal Protocol has severely restricted the use of bromomethane internationally, the United States has successfully lobbied for critical-use exemptions. In 2004, over 7 million pounds of bromomethane were applied to California. Applications include tomato, strawberry, and ornamental shrub growers, and fumigation of ham/pork products. Also exempt is the treatment of solid wood packaging (forklift pallets, crates, bracing), and the packaged goods, being exported to ISPM 15 countries(to include Canada in 2012).

Has to phase out the use in agriculture by 2015.{{Citation needed|date=October 2009}}

==Health effects==

Brief exposure to high concentrations and prolonged inhalation of lower concentrations are problematic.<ref name="HitCL">Muir, GD (ed.) 1971, ''Hazards in the Chemical Laboratory'', The Royal Institute of Chemistry, London.</ref> Exposure levels leading to death vary from 1,600 to 60,000 ppm, depending on the duration of exposure (as a comparison exposure levels of 70 to 400 ppm of [[carbon monoxide]] cover the same spectrum of illness/death).

"A TLV–TWA of 1 ppm (3.89 mg/m3) is recommended for occupational exposure to methyl bromide"-ACGIH 8 hour time weighted average. Immediately Dangerous To Life or Health Concentration by NIOSH: "The revised IDLH for methyl bromide is 250 ppm based on acute inhalation toxicity data in humans [Clarke et al. 1945]. This may be a conservative value due to the lack of relevant acute toxicity data for workers exposed to concentrations above 220 ppm. [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for methyl bromide at any detectable concentration.]" Detectable concentration by Drager Tube is 0.5 ppm.

Respiratory, kidney, and neurological effects are of the greatest concern. Scientists have investigated whether bromomethane exposure was linked to the death of four New Zealand port workers who died of neuro-degenerative motor neurone disease between 2002 and 2004 and found no connection.<ref>http://www.neilsonpromotions.com/news-releases/865-methyl-bromide-scare</ref>

"Cases of severe methyl bromide poisoning in humans, some of them fatal, were frequently reported. For example, von Oettingen recorded 47 fatal and 174 nonfatal cases of methyl bromide intoxication between 1899 and 1952...Severe poisoning with some fatalities resulted from soil disinfection by injection of methyl bromide into greenhouse soil."-ACGIH

Treatment of wood packaging requires a concentration of up to 16,000 ppm. An Australian Customs officer died of methyl bromide poisioning while inspecting a shipping container that was fumigated in the United States. Canada Border Services Officers avoided the same fate because a Mexican container of granite was fumigated with 98% methyl bromide and 2% [[chloropicrin]] fumigant, the chloropicrin has a tear-gas effect.

NIOSH considers methyl bromide to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990]. "methyl bromide showed asignificant dose-response relationship with prostate cancer risk"-www.aghealth.org

* [[List of highly toxic gases]]

<!--See [[Wikipedia:Footnotes]] for an explanation of how to generate footnotes using the <ref(erences/)> tags-->

{{Reflist|2}}

*[http://npic.orst.edu/factsheets/MBtech.pdf Methyl Bromide Technical Fact Sheet - National Pesticide Information Center]

*{{ecb}}

<!-- *[[IARC]] Monograph "[http://www-cie.iarc.fr/htdocs/monographs/vol71/025-methylbromide.html Methyl bromide.]" -->

*[http://www.the-scientist.com/article/display/18858/ The banned pesticide in our soil]

*[http://ptcl.chem.ox.ac.uk/MSDS/ME/methyl_bromide.html MSDS at Oxford University]

*[http://www.inchem.org/documents/sids/sids/methbrom.pdf OECD SIDS document]

[[Category:Organobromides]]

[[cs:Methylbromid]]

[[de:Brommethan]]

[[el:Βρωμομεθάνιο]]

[[es:Bromuro de metilo]]

[[fr:Bromométhane]]

[[it:Bromometano]]

[[he:מתיל ברומיד]]

[[hu:Metil-bromid]]

[[nl:Broommethaan]]

[[ja:ブロモメタン]]

[[pt:Bromometano]]

[[ru:Бромистый метил]]

[[fi:Metyylibromidi]]

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[[th:เมทธิลโบรไมด์]]

[[uk:Бромометан]]

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