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性質
1. 物理的性質
臭化メチルは無色無臭の気体で、分子量は94.94、CAS番号は 74-83-9で登録されています。融点−93.66℃、沸点、初留点及び沸騰範囲4℃、自然発火温度537℃、爆発範囲 10～16vol%の極めて可燃性、引火性が高いガスです。
蒸気密度は3.3 (空気 = 1) と空気より重く、比重は1.730 (液体) です。
2. 化学的性質
水への溶解度は1.75g/100g (20℃) (748mmHg) 、また アルコール、クロロホルム、エーテル、二硫化炭素、四塩化炭素、ベンゼンと混和します。加熱、燃焼により分解し、臭化水素、臭素、オキシ臭化炭素を含む有毒で腐食性のヒュームを生じます。
また、水の存在下で多くの金属を侵す性質を持ち、アルミニウム、亜鉛、マグネシウムを侵して発火化合物を生成し、火災および爆発の危険があるため、注意が必要です。強酸化剤と反応する性質があり、強酸化剤、加熱、燃焼、水との接触を避けて使用、保管を行います。
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解説
ブロモメタン，臭化メチルともいう．硫酸の存在下，メタノールを臭化水素酸または臭化ナトリウムで臭素化すると得られる．クロロホルム様の臭気をもち，無色で揮発性の液体または気体．融点－94 ℃，沸点4.5 ℃．d00 1.732．有機溶媒に易溶，水に不溶．空気中では非引火性であり，安定で腐食性がない．有機合成におけるメチル化試薬である．玄米，小麦そのほかの燻蒸剤，害虫の防除剤，除草剤として広く用いられている．眼を刺激し，皮膚に水泡を生じるなど，毒性の強い有機ハロゲン化物の一つである．許容濃度は長期で5 ppm，短期で15 ppm．
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用途
防虫、防菌及び防鼠のための土壌等のくん蒸剤、穀物等の農産物のくん蒸、その他多くの医薬品及び化学製品の合成上のメチル化剤として使用。
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説明
Methyl bromide is a colorless liquid or gas with
practically no odor. It is a poisonous gas at
room temperature and atmospheric pressure. At
high concentrations, it has a chloroform-like
odor. Detection of lower concentrations is often
facilitated by a warning odorant, chloropicrin,
which is added by the manufacturer.
Methyl bromide is flammable only in the
range of 10 percent to 16 percent by volume in
air. Its physical properties do not meet the definition
of a flammable gas as defined by DOT
and TC. The onset of thermal decomposition
occurs at approximately 752°F (400°C).
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化学的特性
Methyl bromide is a colorless gas with a
chloroform-like odor at high concentrations. A liquid below 3.3C. Shipped as a liquefied compressed gas.
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物理的性質
Colorless liquid or gas with an odor similar to chloroform at high concentrations. Ruth (1986)
reported odor threshold concentrations ranging from 80 to 4,000 mg/m3.
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天然物の起源
An organic compound, present in the atmosphere as the result of both natural (oceanic production) and anthropogenic (use as a soil fumigant) sources; this compound is the largest single source of bromine to the stratosphere, with a tropospheric mixing ratio of about 10 parts per trillion (by volume).
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使用
Methyl bromide is used as a fumigant forpest control, for degreasing wool, and as a methylating agent. Its use as a refrigerant andin fire extinguishers is restrained because ofits health hazards.
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定義
ChEBI: A one-carbon compound in which the carbon is attached by single bonds to three bromine atoms and one hydrogen atom. It is produced naturally by marine algae.
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調製方法
The commercial manufacture of methyl bromide is based on the reaction of hydrogen bromide with methanol. The hydrogen bromide used could be generated in situ from bromine and a reducing agent. The uses of sulfur or hydrogen sulfide as reducing agents are described, the latter process having the advantage. A new continuous process for the production of methyl bromide from methanol and aqueous HBr in the presence of a silica supported heteropolyacid catalyst has recently been described. Methyl bromide can also be coproduced with other organic bromine compounds by the reaction of the methanol solvent with hydrogen bromide formed as a by-product. The processes include coproduction of methyl bromide with bromostyrenes, tribromophenol, potassium and sodium bromide, and especially tetrabromo bisphenol A.
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反応性
Methyl bromide is present in the atmosphere as the result of both natural (oceanic production) and anthropogenic (use as a soil fumigant) sources; this compound is the largest single source of bromine to the stratosphere, with a tropospheric mixing ratio of about 10 parts per trillion (by volume). Methyl bromide reacts with several nucleophiles and is a useful methylation agent for the preparation of ethers, sulfides, amines, etc. Tertiary amines are methylated by methyl bromide to form quaternary ammonium bromides. The reactivity of methyl bromide is summarized in Figure 1.
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製造法
メタノール（メチルアルコール）に臭化水素酸と少量の硫酸を加えて蒸留すれば得られる。
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安全性
吸引、飲み込むと有害であり、皮膚および眼への刺激のおそれがあります。また、遺伝子疾患や生殖能または胎児への悪影響の危険性に加え、神経系、呼吸器、肝臓、腎臓、消化器系の障害を引き起こす可能性があり、人体に有害です。
長期や反復ばく露により神経系、心臓、血液障害を引き起こす可能性があることから、取扱い時は適切な保護具、設備が必要です。また、水生生物に対し非常に強い毒性を持つことから、環境への流出を避けるとともに、廃棄時は都道府県知事の許可を受けた専門の廃棄物処理業者に業務委託することが定められています。
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一般的な説明
Colorless highly toxic volatile liquid or a gas. Boiling point 3.56°C (38.41°F). Usually odorless, but has a sweetish chloroform-like odor at high concentrations. Used as an insecticide, a rodenticide, a fumigant, a nematocide, a chemical intermediate and as a fire extinguishing agent.
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空気と水の反応
Nonflammable over a wide range of concentrations in air. Slightly soluble in water (about 1.75 g/100 mL of solution at 20° C). Reacts slowly with water to give methyl alcohol and hydrobromic acid. [K-O Vol. 4].
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反応プロフィール
Methyl bromide is incompatible with metals, dimethyl sulfoxide, ethylene oxide. [Lewis]. Can give flammable products if mixed with potassium hydroxide, sodium hydroxide and other strong bases. Methyl bromide in a steel tank reacted with an aluminum tube (part of the level gauge) producing methyl aluminum bromide. When the latter was subsequently exposed to air, enough heat was produced to ignite the Methyl bromide -compressed air mixture above the liquid layer. The ensuing explosion shattered the tank (also incompatible with zinc, magnesium, and alloys)[Chem. Eng. Pro. 58(8). 1962]. A reaction between Methyl bromide and dimethyl sulfoxide resulted in an explosion that shattered the apparatus [NFPA 491M. 1991].
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危険性
Toxic by ingestion, inhalation, and skin
absorption; strong irritant to skin and upper respiratory tract. Questionable carcinogen.
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健康ハザード
Methyl bromide is a dangerous cumulative poison with delayed symptoms of central nervous system intoxication that may appear as long as several months after exposure. High concentrations can produce fatal pulmonary edema. Chronic exposure can cause central nervous system depression and kidney injury. It may cause severe and permanent brain damage. Severe neurological signs may appear when there is a sudden exposure to high concentrations following continuous slight exposure. Methyl bromide has practically no odor or irritating effects and therefore no warning, even at hazardous concentrations.
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火災危険
When heated to decomposition, Methyl bromide emits toxic fumes of bromides. Hazardous polymerization may not occur.
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取扱い方法
適切な呼吸器系保護具、保護手袋、眼の保護具、保護衣を着用し、取扱時は飲食、喫煙を避け、取扱後はよく手を洗い、人体への接触を避けます。作業場は、洗眼器と安全シャワーを設置し、ばく露を防止するため、装置の密閉化、または防爆タイプの局所排気装置を設置が必要です。
火災発生時、ガス漏洩が停止出来ない場合は、非常に危険なため消火活動を行いません。安全に対処できる場合に限り、着火源を除去し、火災区域から容器を移動させます。
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応急処置
万が一吸引した場合は、空気が新鮮な場所へ移動し、呼吸しやすい姿勢で休息させ、直ちに医師に連絡します。皮膚、または眼に付着した場合は、大量の水で数分間洗い流し、刺激が継続する場合は医師の診断、手当が必要が必要です。
臭化メチルは、人体の許容濃度を超えても臭気を十分に感じません。高濃度の場合、死に至る可能性があることから、使用時は、換気が行われているか必ず確認を行います。
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保管
保管容器は密閉し、冷乾所にて、日光を遮断し、換気のよい場所で施錠して保管します。熱、火花、裸火、高温などの着火源から離し、強酸化剤との接触を避けることで、安全に保管が可能です。
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使用用途
臭化メチルは、液化ガスとして販売されており、1980年代では土壌病害防除や雑草防除、検疫処理を行う際に、有用なくん蒸剤として利用されていました。
しかし、1992年に開催された、オゾン層を破壊する物質に関するモントリオール議定書第 4回締約国会合において、臭化メチルがオゾン層破壊物質として指定されたことから、先進国では 2005年に、開発途上国では2015年に全廃されています。
検疫処理用、および必要不可欠な用途での臭化メチルの使用については、現在のところ規制対象外です。
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农业用途
Fumigant, Herbicide, Insecticide, Nematicide: The primary use of methyl bromide is as an insect
fumigant to control insects, nematodes, weeds and pathogens
in more than 100 crops and for soil, grain storage,
warehouses, mills, ships, etc. Use of methyl bromide in
the U.S. will be phased out under the requirements of the
Montreal Protocol, with some exemptions. Methyl bromide
is also used as a chemical intermediate and a methylating
agent, a refrigerant, a herbicide, a fire-extinguishing
agent, a low-boiling solvent in aniline dye manufacture,
for degreasing wool, for extracting oils from nuts, seeds,
and flowers, and in ionization chambers. It is used as an
intermediate in the manufacture of many drugs. A U.S.
EPA restricted Use Pesticide (RUP), NO INERT. Still
actively
registered for use in the U.S. (2013). As of March
18, 2005, the use of methyl bromide in the EU was banned
for most purposes, including quarantine and pre-shipment
fumigations.Registered for use in the U.S.
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製品名
BROM-O-GAS®; BROM-OSOL
®; DAWSON® 100; DOWFUME®; EDCO®;
EMBAFUME®; HALON 1001®; ISCOBROME®;
KAYAFUME®; MATABROM®; METHO-GAS®; M-B-C
FUMIGANT®; R 40B1®; ROTOX®; TERABOL®;
TERR-O-GAS®; ZYTOX®
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材料の用途
Dry methyl bromide is inert and noncorrosive in
the presence of most structural metals. However,
in the presence of impurities such as alcohols
and water, reactions will take place on zinc,
tin, and iron surfaces. Aluminum and its
alloys should not be used for methyl bromide
service because of the formation of trimethyl
aluminum, which is pyrophoric.
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職業ばく露
Methyl bromide is used in fire extinguishers; as a fumigant in pest control and as a methylation
agent in industry as an insect fumigant for soil, grain, warehouses, mills, ships, etc. It is also used as a chemical intermediate and a methylating agent; a refrigerant; a herbicide;
a low-boiling solvent in aniline dye manufacture; for
degreasing wool; for extracting oils from nuts, seeds, and
flowers; and in ionization chambers. It is used as an intermediate in the manufacture of many drugs.
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発がん性
Data on the carcinogenicity of
bromomethane for oral exposure are lacking, but oral exposure
is unlikely due to the volatility of bromomethane.
A 1-year study in dogs consuming bromomethane-exposed
food found no evidence of carcinogenicity. Data on
carcinogenicity in humans following inhalation exposure in
humans are not available. Animal inhalation studies exist
but do not demonstrate evidence of bromomethane-induced
carcinogenic changes. They include studies in F344
and Wistar rats, and in B6C3F1 and Crj:BDF1. The EPA
descriptor for cancer is “inadequate information to assess
the carcinogenic potential of bromomethane in humans.”
Specifically, IRIS states: “Inadequate human and animal data: a single mortality study from which direct exposure
associations could not be deduced and studies in several
animal species with too few animals, too brief exposure or
observation time for adequate power.” Bromomethane has
shown genotoxicity. NAS reported that although methyl
bromide is genotoxic without metabolic activation and has
been shown to alkylate DNA in different organs in in vivo
studies, there is no clear evidence of oncogenicity under
experimental conditions used in the chronic inhalation studies
with rat and mice.
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製造方法
メタノールと臭化水素酸との相互作用により製造されるのが一般的です。一部の工程では、テトラブロモビスフェニールAとの、同時製造物として製造されます。
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環境運命予測
Photolytic. When methyl bromide and bromine gas (concentration = 3%) was irradiated
at 1850 ?, methane was produced (Kobrinsky and Martin, 1968).
Chemical/Physical. Methyl bromide hydrolyzes in water forming methanol and hydrobromic
acid. The estimated hydrolysis half-life in water at 25°C and pH 7 is 20 days
(Mabey and Mill, 1978). Forms a voluminous crystalline hydrate at 0–5°C (Keith and
Walters, 1992).
When methyl bromide was heated to 550°C in the absence of oxygen, methane,
hydrogen, bromine, ethyl bromide, anthracene, pyrene and free radicals were produced
(Chaigneau et al., 1966).
Emits toxic bromide fumes when heated to decomposition (Lewis, 1990).
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代謝経路
Methyl bromide degrades in aqueous and soil environments mainly via
dehalogenation to yield bromide ions with the incorporation of the
methyl carbon moiety into polar natural components.
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貯蔵
Methyl bromide (Bromomethane) should be kept stored in sealed containers to keep it from evaporating.
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輸送方法
UN1062 Methyl bromide, Hazard Class: 2.3;
Labels: 2.3-Poisonous gas, Inhalation Hazard Zone C.
Cylinders must be transported in a secure upright position,
in a well-ventilated truck. Protect cylinder and labels from
physical damage. The owner of the compressed gas cylinder is the only entity allowed by federal law (49CFR) to
transport and refill them. It is a violation of transportation
regulations to refill compressed gas cylinders without the
express written permission of the owner
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純化方法
Purify it by bubbling through conc H2SO4, followed by passage through a tube containing glass beads coated with P2O5. Also purify it by distillation from AlBr3 at -80o, by passage through a tower of KOH pellets and by partial condensation. [Beilstein 1 IV 68.]
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不和合性
Attacks aluminum to form spontaneously
flammable aluminum trimethyl. Incompatible with strong
oxidizers, aluminum, dimethylsulfoxide, ethylene oxide;
water. Attacks zinc, magnesium, alkali metals and their
alloys. Attacks some rubbers and coatings. Methyl bromide
reacts with water to generate hydrobromic acid and methanol but the reaction is so slow that it can be disregarded for
most practical purposes.
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廃棄物の処理
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. A
poisonous gas. Must be handled by experts: the recommended disposal procedure is to spray the gas into the fire
box of an incinerator equipped with an afterburner and
scrubber (alkali).
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予防処置
Occupational workers should use appropriate ventilation during production and formulation of bromomethane at the workplace. The ventilation must be suffi cient to maintain the
levels of bromomethane below the prescribed OEL. Local exhaust ventilation at source or
vapor extraction may also be used. Gloves or rubber boots should not be used as the liquid
or concentrated vapor may be trapped inside them
