MeOH

• メタノール

関

methanol

WordNet

1. a light volatile flammable poisonous liquid alcohol; used as an antifreeze and solvent and fuel and as a denaturant for ethyl alcohol (同)methyl_alcohol, wood_alcohol, wood_spirit

PrepTutorEJDIC

1. =methyl alcohol

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/04/17 18:27:09」(JST)

wiki ja

[Wiki ja表示]

メタノール
IUPAC名 methanol
別称 木精 メチルアルコール カルビノール ヒドロキシメタン
識別情報
CAS登録番号	67-56-1
PubChem	887
ChemSpider	864
日化辞番号	J2.364G
RTECS番号	PC1400000
SMILES CO
特性
化学式	CH4O
モル質量	32.04 g mol−1
外観	無色液体
密度	0.7918 g cm-3
融点	-97 °C, 176 K, -143 °F
沸点	64.7 °C, 338 K, 148 °F
水への溶解度	任意に混和
蒸気圧	133 hPa
酸解離定数 pKa	~ 15.5
屈折率 (nD)	1.3292 (20 ℃)
粘度	0.59 mPa·s (20 °C)
双極子モーメント	1.69 D（気体）
危険性
EU分類	F T
Rフレーズ	R11, R23/24/25, R39/23/24/25
Sフレーズ	（S1/2） S7 S16 S36/37 S45
引火点	79 °C
関連する物質
関連するアルコール	エタノール プロパノール ブタノール
関連物質	クロロメタン メトキシメタン
出典
ICSC番号:0057
特記なき場合、データは常温（25 °C）・常圧（100 kPa）におけるものである。

メタノール (methanol) は有機溶媒などとして用いられるアルコールの一種である。別名として、メチルアルコール (methyl alcohol)、木精 (wood spirit)、カルビノール (carbinol) メチールとも呼ばれる。示性式は CH₃OH で、一連のアルコールの中で最も単純な分子構造を持つ。ホルマリンの原料、アルコールランプなどの燃料として広く使われる。燃料電池の水素の供給源としても注目されている。

製法

1. 木材由来による木酢液の蒸留（"木精"という名の由来）。
2. 石炭ないし天然ガスの部分酸化で製造した一酸化炭素 (CO) に、酸化銅-酸化亜鉛/アルミナ複合酸化物を触媒として、50-100気圧、240-260℃で水素 (H₂) を反応させる。
   
3. メタノール産生菌による発酵。

現代の工業製法はコスト面の事情により2.の製法で天然ガスから製造する製法が主流である

主要な用途

• 化学用途　フェノール樹脂や接着剤、酢酸およびホルマリンの合成原料。さまざまな化学反応の溶媒。
• 燃料用途　石油代替自動車燃料としてはエタノールより安価でCNGと並ぶ価格競争力がある（詳細：アルコール燃料）。また、ノートパソコンなどのモバイル機器を長時間稼動させるため、直接メタノール燃料電池 (DMFC) が期待されている。

主な化学反応

• 燃焼時の反応で二酸化炭素と水が生成する。
• 熱した銅 (Cu) を触媒として空気中で酸化するとホルムアルデヒド (HCHO) が生成する。
• ナトリウム (Na) と反応して、ナトリウムメトキシド (CH₃ONa) と水素 (H₂) が生成する。

危険性

日本においてメタノールは危険物第四類アルコール類に指定されているなど、引火の危険性の高い液体である。揮発性が高く、メタノールの入った容器を直接火にかけると爆発する恐れがあるため、保管場所・使用場所における火気や電気火花について念入りに注意しなければならない。特に使用する場所では十分な換気と、容器を倒さないこと、液をこぼさないことに留意されたい。換気は防火上有効であるとともに、後述する中毒の防止にも有効である。

引火して炎上した際は、粉末の消火器、二酸化炭素、砂を用いる。注水消火は、薄められたメタノールが溢れ火災が広がる可能性があり、極少量の火災以外には用いるべきではない。噴霧注水は差し支えない。 泡消火は泡がメタノールに吸収されてしまうので、泡消火薬剤を用いる場合は特に耐アルコール性の泡消火薬剤を用いる必要がある。

メタノールの炎は薄青色であるが、特に昼間は視認しにくい。キャンプ用品として販売されている木炭用の着火剤はゲル状物質にメタノールが含まれている。 特に復元性を持つ樹脂容器に充填された製品は着火後に継ぎ足すと、容器内の空洞に生じた可燃性混合気に引火・破裂拡散し火のついたゲル状燃料を撒き散らす危険があるので決して着火後に継ぎ足してはならない。この種の事故が相次いだ為に使いかけの製品でも容器内に空洞を生じない製品も多い。金属製チューブ・使い切りのパック入りの製品ではこの危険は無い。 また、適正な使用であっても、炎が見難いために火傷を負う事故がある。

飲用毒性（中毒）

メタノール中毒は、取り扱い時の吸入、故意の摂取、誤飲などで起こる。メタノールの致死量に関しては様々な報告があり、個人差が大きいと考えられるが、ヒト、経口での最小致死量は0.3-1.0g/kg程度であると考えられている。ヒトを含む霊長類の場合、メタノールはアルコールデヒドロゲナーゼによってホルムアルデヒドに代謝され、さらにホルムアルデヒドデヒドロゲナーゼによってギ酸に代謝される。ホルムアルデヒドの体内半減期はおよそ一分であり、ホルムアルデヒドからギ酸への代謝は迅速に行われるため、ホルムアルデヒドによる毒性はほとんど問題にならない。メタノールの毒性はギ酸による代謝性アシドーシスとニューロンへの毒性によるものである。ギ酸の代謝能力は種によって異なっており、げっ歯類に比べてギ酸の代謝能力に劣る霊長類はメタノールの毒性が強く出ることが知られている。

メタノール中毒による症状としては、目の網膜を損傷することによる失明がよく知られている。これは次の網膜でのメカニズムによる。βカロテンが鎖の真ん中で切断されると二つのトランス型のレチノールというアルコール型のビタミンAを生成する。このレチノールは酸化されてレチナールというアルデヒドになるが、このトランス型のレチナールはシス型のレチナールに変化してオプシンというタンパク質に収納される。この状態がロドプシンである｡このロドプシンに光が当たるとシス型だったレチナールが安定なトランス型に戻った結果、分子はオプシンに収まらず外れてしまう｡この変化が細胞内を伝わり化学的に増幅され「光が当たった」という信号となって視神経に伝播する｡トランス型レチナールは再びイソメラーゼの働きでシス型に折り曲げられてオプシンに収納されるが、やがてレチナールは消耗し不足してゆく。そしてこの不足した分はレチノールから酸化して補われる｡このため網膜にはレチノールをレチナールに酸化するためのアルコール脱水素酵素が豊富に存在する｡そのためメタノールを飲んだ場合には網膜でホルムアルデヒドが大量に作られ、そのホルムアルデヒドの毒性が視細胞に悪影響を及ぼし、その結果として失明することになる｡またギ酸がミトコンドリアの電子伝達系に関わるシトクロムオキシダーゼを阻害するために視神経毒性が現れるとする意見もある。

日本ではエタノールを混合していないメタノールは医薬用外劇物であり、購入時の毒劇物譲受書への署名捺印を義務付けられている。

日本

戦前の1933年にメタノールで嵩増しした粕取り焼酎の飲用から30名以上の死者が出たほか、第二次世界大戦後の混乱期には安価な変性アルコールを用いた密造酒によるメタノール中毒もしばしば起きた。エタノールは（醸造用に供されることから）酒税の課税対象となるが、メタノールなどを加えて変性アルコールにしてしまうと非課税となったことから、（メタノールがエタノールより沸点が低いことを利用して）変性アルコールを加熱してメタノールを分離したものを密造酒として供することが横行したのである。しかし加熱中の吸入事故や処理の不手際・目減りを惜しんでの不十分な加熱からメタノールが分離し切れず、これが中毒の原因となった。そればかりか、メタノールを水で希釈しただけのカストリ酒も広く出回り、中毒事故が多発した。

失明者が多く出たことから、メタノールの別称である「メチルアルコール」を当てて「目散るアルコール」や、その危険性を象徴してバクダン等と呼ばれた。サザエさんの中でカツオが、書初めで「メチール」と書いて、波平がメチルアルコールを呑んでいる事を揶揄したエピソードもある。

イタリア

1986年、メタノール入りのワインを飲んで22人が死亡した。

ケニア

ケニアで一般的に飲まれているトウモロコシの発酵酒は、製造時にメタノールを添加し、アルコール度数を高める手法が密かに行われている。その添加量は中毒患者が出るギリギリで調節されているというが、しばしば中毒事件が発生する。2000年には、「チャンガー」と呼ばれる密造酒により134人が死亡、1000人以上が病院に収容される大事件が発生したほか、2005年にも30人程度の死亡者が発生するなど事件は後を絶たない。

中国

1998年の旧正月直前に、山西省でメタノールが入った密造酒による中毒死事件が起きた。約400人が入院し、約30人が死亡した。

韓国

1988年のソウルオリンピックの際にソ連のオリンピック協会職員が、薬局でエタノールを購入しようとしたところ（当時のソ連の財政難とルーブルの暴落のために、通常の酒類が購入できなかった）誤ってメタノールを購入してこれを飲んでしまい、死亡する事故が起こった。

ロシア

2006年冬、ロシアでは、ウォッカの代用として工業用アルコール等を飲んだ者が中毒を起こすという事故が相次ぎ、300人以上の死者を出した。また2008年1月にはモンゴルで、メタノールが混入したアルコールをウォッカと称して売る「偽造ウォッカ」によって11人が死亡した。

ベトナム

零細な酒造メーカーに於いては、蒸留酒のアルコール度数を増やすために、安価な燃料用メタノールを混入することが常習的に行われていることがある。2008年にもホーチミン市において20人程度の死亡者が出た。

インドネシア

2009年5月、バリ島でメタノールが混じった酒を飲んで中毒を起こす人が続出。外国人を含む20人以上が死亡、多数が入院する事態となった。地元の酒造業者がアラック（米やヤシの実が原料の蒸留酒）にメタノールを混ぜて製造した酒が原因とみられる。

ウガンダ

2010年4月、ウガンダの南西のカバレ県、カムウェンゲ県において、メタノールが混入したワラギ（東アフリカの蒸留酒）による多臓器不全が原因となり、3週間で89人が死亡、100人以上が入院するという事件が起きた（英語版ワラギの項目も参照）。

インド

2011年12月、インド西ベンガル州で違法に醸造されたメタノール入りの酒を飲んだ労働者がメタノール中毒を起こし、140人以上の死者、100人以上の入院患者を出した。

リビア

2013年3月、首都のトリポリにてメタノール入りの密造酒による中毒が原因で50人以上が死亡、400人近くが病院で手当を受けた。

脚注

関連項目

• エタノール
• アルコール（化学）
• アルコール燃料
• 直接メタノール燃料電池
• 化学性食中毒

wiki en

[Wiki en表示]

Not to be confused with menthol.

For methane-water "ice", see Methane clathrate. For resolution of hydrate / clathrate confusion, see hydrate.

Methanol
Systematic name Methanol
Other names Hydroxymethane Methyl alcohol Methyl hydrate Methyl hydroxide Methylic alcohol Methylol Wood alcohol
Identifiers
CAS number	67-56-1 Y
PubChem	887
ChemSpider	864 Y
UNII	Y4S76JWI15 Y
EC number	200-659-6
UN number	1230
KEGG	D02309 Y
MeSH	Methanol
ChEBI	CHEBI:17790 Y
ChEMBL	CHEMBL14688 Y
RTECS number	PC1400000
Beilstein Reference	1098229
Gmelin Reference	449
3DMet	B01170
Jmol-3D images	Image 1
SMILES CO
InChI InChI=1S/CH4O/c1-2/h2H,1H3 Y Key: OKKJLVBELUTLKV-UHFFFAOYSA-N Y InChI=1/CH4O/c1-2/h2H,1H3 Key: OKKJLVBELUTLKV-UHFFFAOYAX
Properties
Molecular formula	CH4O
Molar mass	32.04 g mol−1
Appearance	Colorless liquid
Density	0.7918 g/cm3
Melting point	-97.6 °C, 176 K, -144 °F
Boiling point	64.7 °C, 338 K, 148 °F
log P	-0.69
Vapor pressure	13.02 kPa (at 20 °C)
Acidity (pKa)	15.5
Viscosity	5.9×10−4 Pa s (at 20 °C)
Dipole moment	1.69 D
Hazards
MSDS	External MSDS
EU Index	603-001-00-X
EU classification	F T
R-phrases	R11, R23/24/25, R39/23/24/25
S-phrases	(S1/2), S7, S16, S36/37, S45
NFPA 704	3 1 0
Flash point	11–12 °C
Autoignition temperature	385 °C
Explosive limits	36%
Related compounds
Related compounds	Methanethiol Silanol
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH₃OH (often abbreviated MeOH). Methanol acquired the name "wood alcohol" because it was once produced chiefly as a byproduct of the destructive distillation of wood. Modern methanol is produced in a catalytic industrial process directly from carbon monoxide, carbon dioxide, and hydrogen.

Methanol is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than ethanol (drinking alcohol). At room temperature, it is a polar liquid, and is used as an antifreeze, solvent, fuel, and as a denaturant for ethanol. It is also used for producing biodiesel via transesterification reaction.

Methanol is produced naturally in the anaerobic metabolism of many varieties of bacteria, and is ubiquitous in small amounts in the environment. As a result, there is a small fraction of methanol vapor in the atmosphere. Over the course of several days, atmospheric methanol is oxidized with the help of sunlight to carbon dioxide and water.

Methanol burns in oxygen (including open air), forming carbon dioxide and water:

2 CH₃OH + 3 O₂ → 2 CO₂ + 4 H₂O

Methanol ingested in large quantities is metabolized to formic acid or formate salts, which is poisonous to the central nervous system, and may cause blindness, coma, and death. Because of these toxic properties, methanol is frequently used as a denaturant additive for ethanol manufactured for industrial uses. This addition of methanol exempts industrial ethanol (commonly known as "denatured alcohol" or "methylated spirit") from liquor excise taxation in the USA and some other nations.

History

In their embalming process, the ancient Egyptians used a mixture of substances, including methanol, which they obtained from the pyrolysis of wood. Pure methanol, however, was first isolated in 1661 by Robert Boyle, when he produced it via the distillation of buxus (boxwood). It later became known as "pyroxylic spirit". In 1834, the French chemists Jean-Baptiste Dumas and Eugene Peligot determined its elemental composition.

They also introduced the word "methylene" to organic chemistry, forming it from Greek methy = "wine" + hȳlē = wood (patch of trees), with Greek language errors: "wood (substance)" (Greek xylon) was intended, and the components are in the wrong order for Greek. The term "methyl" was derived in about 1840 by back-formation from "methylene", and was then applied to describe "methyl alcohol". This was shortened to "methanol" in 1892 by the International Conference on Chemical Nomenclature. The suffix -yl used in organic chemistry to form names of carbon groups, was extracted from the word "methyl".

In 1923, the German chemists Alwin Mittasch and Mathias Pier, working for BASF, developed a means to convert synthesis gas (a mixture of carbon monoxide, carbon dioxide, and hydrogen) into methanol. A patent was filed Jan 12 1926 (reference no. 1,569,775). This process used a chromium and manganese oxide catalyst, and required extremely vigorous conditions—pressures ranging from 50 to 220 atm, and temperatures up to 450 °C. Modern methanol production has been made more efficient through use of catalysts (commonly copper) capable of operating at lower pressures, the modern low pressure methanol (LPM) was developed by ICI in the late 1960s with the technology now owned^{[citation needed]} by Johnson Matthey, which is a leading licensor of methanol technology.

Methanol is one of the most heavily traded chemical commodities in the world, with an estimated global demand of around 27 to 29 million metric tons. In recent years, production capacity has expanded considerably, with new plants coming on-stream in South America, China and the Middle East, the latter based on access to abundant supplies of methane gas. Even though nameplate production capacity (coal-based) in China has grown significantly, operating rates are estimated to be as low as 50 to 60%. No new production capacity is scheduled to come on-stream until 2015.

The main applications for methanol are the production of formaldehyde (used in construction and wooden boarding), acetic acid (basis for a.o. PET-bottles), MTBE (fuel component and replacement for the very volatile diethyl ether) and more recently for the formation of methyl esters in the production of bio-diesel. In China, demand is expected to grow exponentially, not only caused by a growing internal market of the traditional applications, but accelerated by new applications, such as direct blending (with gasoline), Methanol-To-Olefins (e.g. propylene) and DME. Methanol can also be used to produce gasoline.

The use of methanol as a motor fuel received attention during the oil crises of the 1970s due to its availability, low cost, and environmental benefits. By the mid-1990s, over 20,000 methanol "flexible fuel vehicles" capable of operating on methanol or gasoline were introduced in the U.S. In addition, low levels of methanol were blended in gasoline fuels sold in Europe during much of the 1980s and early-1990s. Automakers stopped building methanol FFVs by the late-1990s, switching their attention to ethanol-fueled vehicles. While the methanol FFV program was a technical success, rising methanol pricing in the mid- to late-1990s during a period of slumping gasoline pump prices diminished the interest in methanol fuels.

In 2006, astronomers using the MERLIN array of radio telescopes at Jodrell Bank Observatory discovered a large cloud of methanol in space, 288 billion miles across.

Production

From synthesis gas

Carbon monoxide and hydrogen react over a catalyst to produce methanol. Today, the most widely used catalyst is a mixture of copper, zinc oxide, and alumina first used by ICI in 1966. At 5–10 MPa (50–100 atm) and 250 °C, it can catalyze the production of methanol from carbon monoxide and hydrogen with high selectivity (>99.8%):

CO + 2 H₂ → CH₃OH

It is worth noting that the production of synthesis gas from methane produces three moles of hydrogen gas for every mole of carbon monoxide, while the methanol synthesis consumes only two moles of hydrogen gas per mole of carbon monoxide. One way of dealing with the excess hydrogen is to inject carbon dioxide into the methanol synthesis reactor, where it, too, reacts to form methanol according to the equation:

CO₂ + 3 H₂ → CH₃OH + H₂O

Some chemists believe that the certain catalysts synthesize methanol using CO₂ as an intermediary, and consuming CO only indirectly.

CO₂ + 3 H₂ → CH₃OH + H₂O

where the H₂O byproduct is recycled via the water-gas shift reaction

CO + H₂O → CO₂ + H₂,

This gives an overall reaction, which is the same as listed above.

CO + 2 H₂ → CH₃OH

From methane

The direct catalytic conversion of methane to methanol using Cu-zeolites or other catalysts is an alternative process for the efficient production of methanol.

From carbon dioxide

Methanol has been generated directly from carbon dioxide in solution using CuO nanorods coated by CuO₂ and energy from (simulated) sunlight. The process operated with 95% electrochemical efficiency and is claimed to be scalable to industrial size.

Feedstocks

Production of synthesis gas

Originally, synthesis gas for the production of methanol came from coal. Today, synthesis gas is most commonly produced from the methane component in natural gas, because natural gas contains hydrogen. Three processes are commercially practiced. At moderate pressures of 4 MPa (40 atm) and high temperatures (around 850 °C), methane reacts with steam on a nickel catalyst to produce syngas according to the chemical equation:

CH₄ + H₂O → CO + 3 H₂

This reaction, commonly called steam-methane reforming or SMR, is endothermic, and the heat transfer limitations place limits on the size of and pressure in the catalytic reactors used. Methane can also undergo partial oxidation with molecular oxygen (at atmospheric pressure) to produce syngas, as the following equation shows:

2 CH₄ + O₂ → 2 CO + 4 H₂

This reaction is exothermic, and the heat given off can be used in-situ to drive the steam-methane reforming reaction. When the two processes are combined, it is referred to as autothermal reforming. The high pressures and high temperatures needed for steam-reforming require a greater capital investment in equipment than is needed for a simple partial-oxidation process; however, the energy-efficiency of steam-reforming is higher than for partial-oxidation, unless the waste-heat from partial-oxidation is used.

Stoichiometry adjustment

Stoichiometry for methanol production requires the ratio of H₂ / CO to equal 2. The partial oxidation process yields a ratio of 2, and the steam reforming process yields a ratio of 3. The H₂ / CO ratio can be adjusted to some extent by the water-gas shift reaction,

CO + H₂O → CO₂ + H₂,

to provide the appropriate stoichiometry for methanol synthesis.

Alternate feedstock materials

Although natural gas is the most economical and widely used feedstock for methanol production, many other feedstocks can be used to produce syngas via steam reforming. Steam-reformed coal is sometimes used as a feedstock for methanol production, particularly in China. In addition, mature technologies available for biomass gasification are being used for methanol production. For instance, woody biomass can be gasified to water gas (a hydrogen-rich syngas), by introducing a blast of steam in a blast furnace. The water-gas / syngas can then be synthesized to methanol using standard methods. The net process is carbon neutral, since the CO₂ byproduct is required to produce biomass via photosynthesis.

2 C₁₆H₂₃O₁₁ + 19 H₂O + O₂ → 42 H₂ + 21 CO + 11 CO₂ → 21 CH₃OH + 11 CO₂

Applications

Methanol, a common laboratory solvent, is especially useful for HPLC, UV/VIS spectroscopy, and LCMS due to its low UV cutoff.

Feedstock

The largest use of methanol by far is in making other chemicals. About 40% of methanol is converted to formaldehyde, and from there into products as diverse as plastics, plywood, paints, explosives, and permanent press textiles.

Also in the early 1970s, a methanol to gasoline process was developed by Mobil for producing gasoline ready for use in vehicles. One such industrial facility was built at Motunui in New Zealand in the 1980s. In the 1990s, large amounts of methanol were used in the United States to produce the gasoline additive methyl tert-butyl ether (MTBE). While MTBE is no longer marketed in the U.S., it is still widely used in other parts of the world. In addition to direct use as a fuel, methanol (or less commonly, ethanol) is used as a component in the transesterification of triglycerides to yield a form of biodiesel.

Other chemical derivatives of methanol include dimethyl ether, which has replaced chlorofluorocarbons as an aerosol spray propellant, and acetic acid. Dimethyl ether (DME) also can be blended with liquified petroleum gas (LPG) for home heating and cooking, and can be used as a diesel replacement for transportation fuel.

Methanol-to-Olefins/Methanol-to-Propylene (MTO/MTP), among others processes such as: Metathesis, Propane Dehydrogenation (PDH), High Severity FCC, and Olefins Cracking, is a new and novel lower-cost chemical process for on-purpose propylene production technology of high interest to the petrochemical marketplace, to supply the tight propylene market.

The market became tight because of the ethane prices falling in the USA, due to the exploration of shale gas reserves. The low price ethylene produced from this raw material has given chemical producers in North America a feedstock advantage. Such change has put naphtha-fed steam crackers at a disadvantageous position, with many of them shutting down or revamping to use ethane as feedstock. Nevertheless, the propylene output rates from ethane-fed crackers are negligible.

Fuel for vehicles

Main articles: Methanol fuel and methanol economy

Methanol is used on a limited basis to fuel internal combustion engines. Pure methanol is required by rule to be used in Champcars, Monster Trucks, USAC sprint cars (as well as midgets, modifieds, etc.), and other dirt track series, such as World of Outlaws, and Motorcycle Speedway. Methanol is also used, as the primary fuel ingredient since the late 1940s, in the powerplants for radio control, control line and free flight airplanes (as methanol is required in the engines that primarily power them), cars and trucks, from such an engine's use of a platinum filament glow plug being able to ignite the methanol vapor through a catalytic reaction. Drag racers and mud racers, as well as heavily modified tractor pullers, also use methanol as their primary fuel source. Methanol is required with a supercharged engine in a Top Alcohol dragster and, until the end of the 2006 season, all vehicles in the Indianapolis 500 had to run methanol. Mud racers have mixed methanol with gasoline with nitrous oxide to produce more power than mixing gasoline and nitrous oxide alone.

One of the potential drawbacks of using high concentrations of methanol (and other alcohols, such as ethanol) in fuel is the corrosivity to some metals of methanol, particularly to aluminium. Methanol, although a weak acid, attacks the oxide coating that normally protects the aluminum from corrosion:

6 CH₃OH + Al₂O₃ → 2 Al(OCH₃)₃ + 3 H₂O

The resulting methoxide salts are soluble in methanol, resulting in a clean aluminium surface, which is readily oxidized by dissolved oxygen. Also, the methanol can act as an oxidizer:

6 CH₃OH + 2 Al → 2 Al(OCH₃)₃ + 3 H₂

This reciprocal process effectively fuels corrosion until either the metal is eaten away or the concentration of CH₃OH is negligible. Concerns with methanol's corrosivity have been addressed by using methanol-compatible materials, and fuel additives that serve as corrosion inhibitors.

When produced from wood or other organic materials, the resulting organic methanol (bioalcohol) has been suggested as renewable alternative to petroleum-based hydrocarbons. Low levels of methanol can be used in existing vehicles, with the use of proper cosolvents and corrosion inhibitors. The European Fuel Quality Directive allows up to 3% methanol with an equal amount of cosolvent to be blending in gasoline sold in Europe. Today, China uses more than one billion gallons of methanol per year as a transportation fuel in both low level blends used in existing vehicles, and as high level blends in vehicles designed to accommodate the use of methanol fuels.

Because of climate change, alternatives to fossil fuels have been sought to run ground vehicles. Various alternatives have been proposed. Biofuels are carbon-neutral, but they require a great deal of fresh water to produce and are not practical in most climates. If a source of renewable or sustainable energy becomes widely available (such as wind, solar or nuclear power), various chemical alternatives have been proposed to power ground vehicles in places of batteries. An example is a hydrogen economy. However, various alcohol-based economies, including a methanol based economy has been proposed in which artificially produced methanol stores all power which cannot be directly used from sustainable sources, and also is used for ground transportation. The chief advantage of a methanol economy is that it could be adapted to present internal combustion engines with a minimum of modification in both engines and infrastructure to store and deliver liquid fuel.

In 2011, the Open Fuel Standard Act of 2011 was introduced into Congress to encourage car manufacturers to warrant their cars to burn methanol as a fuel in addition to gasoline and ethanol. The bill is being championed by the Open Fuel Standard Coalition.^{[citation needed]}

Other applications

Methanol is a traditional denaturant for ethanol, the product being known as "denatured alcohol" or "methylated spirit". This was commonly used during the Prohibition to discourage consumption of bootlegged liquor, and ended up causing several deaths

Methanol is also used as a solvent, and as an antifreeze in pipelines and windshield washer fluid.

In some wastewater treatment plants, a small amount of methanol is added to wastewater to provide a carbon food source for the denitrifying bacteria, which convert nitrates to nitrogen to reduce the nitrification of sensitive aquifers.

During World War II, methanol was used as a fuel in several German military rocket designs, under the name M-Stoff, and in a roughly 50/50 mixture with hydrazine, known as C-Stoff.

Methanol was used as an automobile coolant antifreeze in the early 1900s.

Methanol is used as a denaturing agent in polyacrylamide gel electrophoresis.

Direct-methanol fuel cells are unique in their low temperature, atmospheric pressure operation, allowing them to be miniaturized to an unprecedented degree. This, combined with the relatively easy and safe storage and handling of methanol, may open the possibility of fuel cell-powered consumer electronics, such as for laptop computers and mobile phones.

Methanol is also a widely used fuel in camping and boating stoves. Methanol burns well in an unpressurized burner, so alcohol stoves are often very simple, sometimes little more than a cup to hold fuel. This lack of complexity makes them a favorite of hikers who spend extended time in the wilderness. Similarly, the alcohol can also be gelled to reduce risk of leaking or spilling, as with the brand "Sterno".

Methanol is mixed with water and injected into high performance diesel and gasoline engines for an increase of power and a decrease in intake air temperature in a process known as water methanol injection.

Energy carrier

Methanol is also useful as an energy carrier. It is easier to store than hydrogen, burns cleaner than fossil fuels, and is biodegradable.^{[citation needed]}

Health and safety

Toxicity

Methanol has a high toxicity in humans. If as little as 10 mL of pure methanol is ingested, for example, it can break down into formic acid, which can cause permanent blindness by destruction of the optic nerve, and 30 mL is potentially fatal, although the median lethal dose is typically 100 mL (4 fl oz) (i.e. 1–2 mL/kg body weight of pure methanol). Reference dose for methanol is 0,5 mg/kg/day. Toxic effects take hours to start, and effective antidotes can often prevent permanent damage. Because of its similarities in both appearance and odor to ethanol (the alcohol in beverages), it is difficult to differentiate between the two (such is also the case with denatured alcohol). However, there are cases of methanol resistance, such as that of Mike Malloy, who was the victim of a failed murder attempt by methanol in the early 1930s.

Methanol is toxic by two mechanisms. First, methanol (whether it enters the body by ingestion, inhalation, or absorption through the skin) can be fatal due to its CNS depressant properties in the same manner as ethanol poisoning. Second, in a process of toxication, it is metabolized to formic acid (which is present as the formate ion) via formaldehyde in a process initiated by the enzyme alcohol dehydrogenase in the liver. Methanol is converted to formaldehyde via alcohol dehydrogenase (ADH) and formaldehyde is converted to formic acid (formate) via aldehyde dehydrogenase (ALDH). The conversion to formate via ALDH proceeds completely, with no detectable formaldehyde remaining. Formate is toxic because it inhibits mitochondrial cytochrome c oxidase, causing the symptoms of hypoxia at the cellular level, and also causing metabolic acidosis, among a variety of other metabolic disturbances.

Methanol poisoning can be treated with the antidotes ethanol or fomepizole. Both drugs act to reduce the action of alcohol dehydrogenase on methanol by means of competitive inhibition, so it is excreted by the kidneys rather than being transformed into toxic metabolites. Further treatment may include giving sodium bicarbonate for metabolic acidosis, and hemodialysis or hemodiafiltration can be used to remove methanol and formate from the blood. Folinic acid or folic acid is also administered to enhance the metabolism of formate.

The initial symptoms of methanol intoxication include central nervous system depression, headache, dizziness, nausea, lack of coordination, and confusion. Sufficiently large doses can cause unconsciousness and death. The initial symptoms of methanol exposure are usually less severe than the symptoms resulting from the ingestion of a similar quantity of ethanol. Once the initial symptoms have passed, a second set of symptoms arises, 10 to as many as 30 hours after the initial exposure to methanol, including blurring or complete loss of vision and acidosis. These symptoms result from the accumulation of toxic levels of formate in the blood, and may progress to death by respiratory failure. Physical examination may show tachypnea, and opthalmologic examination may show dilated pupils with hyperemia of the optic disc and retinal edema. Small amounts of methanol are produced by the metabolism of food and are generally harmless, being metabolized quickly and completely.

Ethanol is sometimes denatured (adulterated), and made poisonous, by the addition of methanol. The result is known as methylated spirit, "meths" (British use) or "metho" (Australian slang). These are not to be confused with "meth", a common U.S. abbreviation for methamphetamine, and British abbreviation for methadone.

The formic acid and formaldehyde produced as metabolites of methanol are responsible for the optic nerve damage, causing blindness seen in methanol poisoning.

Safety in automotive fuels

Pure methanol has been used in open wheel auto racing since the mid-1960s. Unlike petroleum fires, methanol fires can be extinguished with plain water. A methanol-based fire burns invisibly, unlike gasoline, which burns with a visible flame. If a fire occurs on the track, there is no flame or smoke to obstruct the view of fast approaching drivers, but this can also delay visual detection of the fire and the initiation of fire suppression. The decision to permanently switch to methanol in American IndyCar racing was a result of the devastating crash and explosion at the 1964 Indianapolis 500, which killed drivers Eddie Sachs and Dave MacDonald. In 2007 IndyCars switched to ethanol.

Methanol is readily biodegradable in both aerobic (oxygen present) and anaerobic (oxygen absent) environments. Methanol will not persist in the environment. The half-life for methanol in groundwater is just one to seven days, while many common gasoline components have half-lives in the hundreds of days (such as benzene at 10–730 days). Since methanol is miscible with water and biodegradable, it is unlikely to accumulate in groundwater, surface water, air or soil.

Occurrence in freeze distillation

Freeze distillation can concentrate methanol and fusel alcohols (by-products of fermentation which true distillation separates out) in applejack to unhealthy levels. As a result, many countries prohibit such applejack as a health measure.

See also

• Methanol (data page)
• Methanol epidemic poisonings
• Deuterated methanol

References

Further reading

• Robert Boyle, The Sceptical Chymist (1661) – contains account of distillation of wood alcohol.

External links

• International Chemical Safety Card 0057
• The Methanol Institute Industry trade group, lots of information on methanol's use in fuel cells and as an alternative fuel.
• Methyl Alcohol (Methanol) CDC/NIOSH, links to safety information
• CDC - NIOSH Pocket Guide to Chemical Hazards - Methyl Alcohol
• China Takes Gold in Methanol Fuel
• The methanol story: a sustainable fuel for the future article by Ford Motor's Roberta Nichols, the mother of the flexible fuel vehicle, discussing Gasoline-Ethanol-Methanol flexibility in the Journal of Scientific & Industrial Research
• Methanol Fact Sheet – National Pollutant Inventory
• Methanol Discovered in Space
• Calculation of vapor pressure, liquid density, dynamic liquid viscosity, surface tension of methanol

English Journal

• Development and validation of an analytical method for determination of pharmaceuticals in fish muscle based on QuEChERS extraction and SWATH acquisition using LC-QTOF-MS/MS system.

• Peña-Herrera JM, Montemurro N, Barceló D, Pérez S.
• Talanta. 2019 Jul;199()370-379.
• This study aimed at developing an analytical method for the extraction and quantification of 21 pharmaceutical actives compounds (PhACs) present in fish muscle. Using Norwegian Atlantic salmon as matrix, two extraction methods for PhACs were tested: ultrasound extraction (USE) using methanol (MeOH),
• PMID 30952272

• Comprehensive analysis of pig feces metabolome by chromatographic techniques coupled to mass spectrometry in high resolution mode: Influence of sample preparation on the identification coverage.

• López-Bascón MA, Calderón-Santiago M, Argüello H, Morera L, Garrido JJ, Priego-Capote F.
• Talanta. 2019 Jul;199()303-309.
• Pig feces is an interesting biological sample to be implemented in metabolomics experiments by virtue of the information that can be deduced from the interaction between host and microbiome. However, pig fecal samples have received scant attention, especially in untargeted metabolomic studies. In th
• PMID 30952262

• Analysis of the retention of tetracyclines on reversed-phase columns: Chemometrics, design of experiments and quantitative structure-property relationship (QSPR) study for interpretation and optimization.

• Lafossas C, Benoit-Marquié F, Garrigues JC.
• Talanta. 2019 Jun;198()550-559.
• In this study, design of experiments was applied for the analysis of 6 reversed phase U-HPLC columns used for the separation of four tetracyclines (TCs): tetracycline, doxycycline, chlortetracycline and oxytetracycline in different elution conditions. In a first part, a fractional factorial design (
• PMID 30876599

Japanese Journal

• Chemical Constituents of Bhale Chiraito(Swertia angustifolia)

• Joshi Khem Raj,Devkota Hari Prasad,Yahara Shoji
• 生薬學雜誌 68(2), 95-96, 2014-08-20
• … Swertiamarin (1), isoorientin (2), isovitexin 6"-O-α-L-arabinopyranoside (3) and isovitexin (4) were isolated from the 30% MeOH extract of whole plants of Swertia angustifolia, a Nepalese crude drug commonly known as "Bhale Chiraito." Structures of the isolated compounds were elucidated on the basis of spectroscopic methods. …
• NAID 110009838892

• 横波型弾性表面波センサを用いた直接メタノール燃料電池のメタノール濃度計測 (超音波)

• 野澤 卓也,近藤 淳
• 電子情報通信学会技術研究報告 = IEICE technical report : 信学技報 114(16), 25-30, 2014-04-22
• NAID 40020059196

• CO₂からMeOHへの省エネルギー変換法の開拓 : 分子触媒を用いるウレタン類の脱水的合成と水素化

• 斎藤 進
• 旭硝子財団助成研究成果報告, 1-7, 2014
• NAID 40020192547

Related Links

• メタノール - Wikipedia

メタノール (methanol) は有機溶媒などとして用いられるアルコールの一種である。別名 として、メチルアルコール (methyl alcohol)、木精 (wood spirit)、カルビノール (carbinol ) メチールとも呼ばれる。示性式は CH3OH で、一連のアルコールの中で最も単純な ...

Related Pictures

---

★リンクテーブル★

関連記事

「Me」

「Me」

　　[★] メチオニン methionine