Methanol
19712
225685919
2008-07-14T22:07:48Z
71.34.224.33
/* Production */
{{Chembox new
| Name = Methanol
| ImageFileL1 = Methanol-2D.png
| ImageSizeL1 = 120px
| ImageNameL1 = Methanol
| ImageFileR1 = Methanol-3D-balls.png
| ImageSizeR1 = 120px
| ImageNameR1 = Methanol
| ImageFile2 = Methanol-3D-vdW.png
| ImageSize2 = 150px
| ImageName2 = Methanol
| IUPACName = methanol
| OtherNames = hydroxymethane<br/>methyl alcohol<br/>methyl hydrate</br>wood alcohol<br/>carbinol
| Section1 = {{Chembox Identifiers
| SMILES = CO
| CASNo = 67-56-1
| RTECS = PC1400000
}}
| Section2 = {{Chembox Properties
| Formula = CH<sub>3</sub>OH
| MolarMass = 32.04 g/mol
| Appearance = colorless liquid
| Density = 0.7918 g/cm³, liquid
| Solubility = Fully [[miscible]]
| MeltingPt = –97 °C (176 K)
| BoilingPt = 64.7 °C (337.8 K)
| pKa = ~ 15.5
| Viscosity = 0.59 [[Pascal-second|mPa·s]] at 20 °C
| Dipole = 1.69 [[Debye|D]] (gas)
}}
| Section7 = {{Chembox Hazards
| FlashPt = 11 °C
| EUClass = Flammable ('''F''')<br/>Toxic ('''T''')
| NFPA-H = 3
| NFPA-F = 3
| NFPA-R = 1
| RPhrases = {{R11}}, {{R23/24/25}}, {{R39/23/24/25}}
| SPhrases = {{S1/2}}, {{S7}}, {{S16}}, {{S36/37}}, {{S45}}
}}
| Section8 = {{Chembox Related
| Function = [[alkanol]]s
| OtherFunctn = [[ethanol]]<br/>[[butanol]]
| OtherCpds = [[chloromethane]]<br/>[[methoxymethane]]}}
}}
'''Methanol''', also known as '''methyl alcohol''', '''carbinol''', '''wood alcohol''', '''wood naphtha''' or '''wood spirits''', is a [[chemical compound]] with [[chemical formula]] [[carbon|C]][[hydrogen|H]]<sub>3</sub>[[Hydroxide|OH]] (often abbreviated MeOH). It is the simplest [[alcohol]], and is a light, [[Volatility (chemistry)|volatile]], [[colour]]less, [[flammable]], [[poison]]ous liquid with a distinctive odor that is somewhat milder and sweeter than [[ethanol]] ([[ethyl alcohol]]). At room temperature it is a [[Solvent#Polarity.2C_solubility.2C_and_miscibility|polar liquid]] and is used as an [[antifreeze (coolant)|antifreeze]], [[solvent]], [[fuel]], and as a [[denatured alcohol|denaturant]] for [[ethyl alcohol]]. It is also used for producing [[biodiesel]] via [[transesterification]] reaction.
Methanol is produced naturally in the [[anaerobic organism|anaerobic]] [[metabolism]] of many varieties of bacteria. As a result, there is a small fraction of methanol vapor in the atmosphere. Over the course of several days, atmospheric methanol is [[oxidized]] by oxygen with the help of sunlight to carbon dioxide and water.
Methanol burns in air forming [[carbon dioxide]] and [[water]]:
:2 CH<sub>3</sub>OH + 3 O<sub>2</sub> → 2 CO<sub>2</sub> + 4 H<sub>2</sub>O
A methanol flame is almost colorless, causing an additional safety hazard around open methanol flames.
Because of its poisonous properties, methanol is frequently used as a denaturant additive for ethanol manufactured for industrial uses— this addition of a [[poison]] economically exempts industrial ethanol from the rather significant 'liquor' taxes that would otherwise be levied as it is the essence of all potable alcoholic beverages. Methanol is often called wood alcohol because it was once produced chiefly as a byproduct of the destructive distillation of wood. It is now produced synthetically by a multi-step process: [[natural gas]] and steam are reformed in a furnace to produce hydrogen and carbon monoxide; then, hydrogen and carbon monoxide gases react under pressure in the presence of a catalyst.
An entire [[methanol economy]], based on methanol as a primary energy-storage medium and fuel, has been seriously proposed.
==History==<!-- This section is linked from [[Methyl group]] -->
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]], who called it ''spirit of box'', because he produced it via the distillation of [[boxwood]]. It later became known as ''pyroxylic spirit''. In 1834, the [[France|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 language|Greek]] ''methy'' = "[[wine]]" + ''hȳlē'' = [[wood]] (patch of trees). Its intended origin was "[[alcohol]] made from [[wood]] (substance)," but it has Greek language errors. 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 (linguistics)|suffix]] [[-yl]] used in [[organic chemistry]] to form names of [[Radical (chemistry)|radical]]s, was extracted from the word "methyl."
In 1923, the [[Germany|German]] chemists Matthias and Pier, working for [[BASF]] developed a means to convert [[syngas|''synthesis gas'']] (a mixture of [[carbon oxide]]s 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 [[atmosphere (unit)|atm]]), and temperatures up to 450 °[[Celsius|C]]. Modern methanol production has been made more efficient through use of catalysts (commonly [[copper]]) capable of operating at lower pressures.
The use of methanol as a motor fuel received attention during the oil crises of the 1970s due to its availability and low cost. Problems occurred early in the development of gasoline-methanol blends. As a result of its low price, some gasoline marketers over-blended. Others used improper blending and handling techniques.
In 2006 astronomers using the [[MERLIN]] array of radio telescopes at [[Jodrell Bank|Jodrell Bank Observatory]] discovered a large cloud of methanol in space, 300 billion miles across.
==Production==
Today, synthesis gas is most commonly produced from the [[methane]] component in [[natural gas]] rather than from coal. Three processes are commercially practiced. At moderate pressures of 1 to 2 [[MPa]] (10–20 atm) and high temperatures (around 850 °C), methane [[chemical reaction|reacts]] with [[steam]] on a nickel catalyst to produce [[syngas]] according to the [[chemical equation]]:
:[[methane|CH<sub>4</sub>]] + [[water|H<sub>2</sub>O]] → [[carbon monoxide|CO]] + 3 [[hydrogen|H<sub>2</sub>]]
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 to produce syngas, as the following equation shows:
:2 [[methane|CH<sub>4</sub>]] + [[oxygen|O<sub>2</sub>]] → 2 [[carbon monoxide|CO]] + 4 [[hydrogen|H<sub>2</sub>]]
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 ratio of CO and H<sub>2</sub> can be adjusted to some extent by the [[water gas shift reaction|water-gas shift reaction]],
:[[carbon monoxide|CO]] + [[water|H<sub>2</sub>O]] → [[carbon dioxide|CO<sub>2</sub>]] + [[hydrogen|H<sub>2</sub>]],
to provide the appropriate stoichiometry for methanol synthesis.
The carbon monoxide and hydrogen then react on a second catalyst to produce methanol. Today, the most widely used catalyst is a mixture of [[copper]], [[zinc oxide]], and [[alumina]] first used by [[Imperial Chemical Industries|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
:[[carbon monoxide|CO]] + 2 [[hydrogen|H<sub>2</sub>]] → CH<sub>3</sub>OH
It is worth noting that the production of synthesis gas from methane produces 3 [[Mole (unit)|mole]]s of hydrogen for every mole of carbon monoxide, while the methanol synthesis consumes only 2 moles of hydrogen for every 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 [[chemical equation]]
:[[carbon dioxide|CO<sub>2</sub>]] + 3 [[hydrogen|H<sub>2</sub>]] → CH<sub>3</sub>OH + [[water|H<sub>2</sub>O]]
Although natural gas is the most economical and widely used feedstock for methanol production, other feedstocks can be used. Where natural gas is unavailable, light [[petroleum]] products can be used in its place.
==Applications==
Methanol is a common laboratory solvent. It is especially useful for [[HPLC]] and [[UV/VIS spectroscopy]] 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 [[plastic]]s, [[plywood]], [[paint]]s, [[explosive]]s, and [[permanent press]] [[textile]]s.
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 in [[New Zealand]] in the 1980s.{{Fact|date=May 2008}} In the 1990s, large amounts of methanol were used in the [[United States]] to produce the gasoline additive [[methyl tert-butyl ether]] (MTBE), though leakage has led to many states banning it. 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 [[chlorofluorocarbon]]s as an [[aerosol spray#Propellant|aerosol spray propellant]], and [[acetic acid]].
===Automotive fuel===
{{main|Methanol fuel}}
Methanol is used on a limited basis to fuel [[internal combustion engine]]s, mainly by virtue of the fact that it is not nearly as [[flammable]] as [[gasoline]]. Pure methanol is required by rule to be used in [[Champcars]], [[United States Automobile Club|USAC]] sprint cars (as well as midgets, modifieds, etc.), and other dirt track series such as [[World of Outlaws]]. Methanol is also used in [[radio controlled model|radio control]], [[control line]] and [[free flight (model aircraft)|free flight]] [[Model aircraft|airplanes]] (required in the "[[Glow plug (model engine)|glow-plug]]" engines that primarily power them), cars and trucks. [[Drag racing|Drag racers]] and mud racers 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 racer]]s have mixed methanol with gasoline and nitrous oxide to produce more power than gasoline and nitrous oxide alone.
One of the drawbacks of methanol as a fuel is its [[corrosion|corrosivity]] to some metals, including [[aluminium]]. Methanol, although a weak acid, attacks the oxide coating that normally protects the aluminium from corrosion:
:6 CH<sub>3</sub>OH + Al<sub>2</sub>O<sub>3</sub> → 2 Al(OCH<sub>3</sub>)<sub>3</sub> + 3 H<sub>2</sub>O
The resulting [[methoxide]] salts are soluble in methanol, resulting in clean aluminum surface, which is readily oxidised by some dissolved [[oxygen]]. Also the methanol can act as an oxidizer:
:6 CH<sub>3</sub>OH + 2 Al → 2 Al(OCH<sub>3</sub>)<sub>3</sub> + 3 H<sub>2</sub>
This reciprocal process effectively fuels corrosion until either the metal is eaten away or the concentration of CH<sub>3</sub>OH is negligible.
When produced from wood or other organic materials, the resulting organic methanol ([[bioalcohol]]) has been suggested as renewable alternative to petroleum-based [[hydrocarbon]]s. However, one cannot use pure methanol in modern petroleum cars without modification, due to potential damage to metal piping and rubber seals.
===Other applications===
Methanol is a traditional denaturant for ethanol, thus giving the term ''[[methylated spirit]]''.
Methanol is also used as a [[solvent]], and as an [[antifreeze (coolant)|antifreeze]] in [[Pipeline transport|pipelines]] and [[windshield washer fluid]].
In some [[wastewater treatment plant]]s, a small amount of methanol is added to [[wastewater]] to provide a food source of carbon for the [[denitrifying bacteria]], which convert [[nitrate]]s to [[nitrogen]].
During [[World War II]], methanol was used as a fuel in several German military rocket designs, under name '''M-Stoff''', and in a mixture as [[C-Stoff]].
Methanol is used as a denaturing agent in [[polyacrylamide gel electrophoresis]].
[[Direct-methanol fuel cell]]s 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.<ref>{{cite web|url=http://www.compukiss.com/populartopics/tech_gadgetshtm/article887.htm|title=Methanol Laptop Fuel|author=Sandy Berger|publisher=Compu·Kiss|date=September 30, 2006|accessdate=2007-05-22}}</ref>
Methanol is also a widely used fuel in camping and boating stoves. The Swedish made Trangia stoves are the probably the best known alcohol burning 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. In Roland Mueser's book Long-Distance Hiking: Lessons from the Appalachian Trail, Mueser did a survey of stoves used by thru-hikers and found that alcohol was the only stove type with a zero percent failure rate.
==Health and safety==
Methanol is [[toxic]] by two mechanisms. Firstly, methanol (whether it enters the body by [[ingestion]], [[inhalation]], or [[absorption (chemistry)|absorption]] through the [[skin]]) can be fatal due to its [[CNS depressant]] properties in the same manner as [[ethanol]] poisoning. Secondly, it is [[toxic]] by its metabolism ([[toxication]]) via the [[enzyme]] [[alcohol dehydrogenase]] in the [[liver]] by forming [[formic acid]] and [[formaldehyde]] which cause permanent [[blindness]] by destruction of the [[optic nerve]].<ref>{{cite web|url=http://www.newton.dep.anl.gov/askasci/chem03/chem03561.htm|title=Methanol and Blindness|publisher=Ask A Scientist, Chemistry Archive|accessdaymonth=22 May|accessyear=2007}}</ref> Fetal tissue will not tolerate methanol. Dangerous doses will build up if a person is regularly exposed to vapors or handles liquid without skin protection. If methanol has been ingested, a doctor should be contacted immediately. The usual fatal dose is 100–125 mL (4 fl oz). Toxic effects take hours to start, and effective antidotes can often prevent permanent damage. This is treated using [[ethanol]] or [[fomepizole]].<ref>{{cite online journal|url=http://pediatrics.aappublications.org/cgi/content/full/107/1/170|title=Fomepizole in the Treatment of Poisoning|journal=Pediatrics|date=January 2001|issue=No. 1|volume=107|accessdaymonth=22 May|accessyear=2007}}</ref> Either of these drugs acts to slow down the action of [[alcohol dehydrogenase]] on methanol by means of [[competitive inhibition]], so that it is excreted by the [[kidney]]s rather than being transformed into toxic metabolites.
The initial symptoms of methanol intoxication are those of [[central nervous system]] [[depressant|depression]]: headache, dizziness, nausea, lack of coordination, confusion, drowsiness, and with sufficiently large doses, 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 [[ethyl alcohol]].
Once the initial symptoms have passed, a second set of symptoms arises 10–30 hours after the initial exposure to methanol: blurring or complete loss of vision, together with [[acidosis]]. These symptoms result from the accumulation of toxic levels of [[formate]] in the bloodstream, and may progress to death by [[respiratory failure]]. The [[ester]] derivatives of methanol do not share this toxicity.
Ethanol is sometimes denatured (adulterated), and thus made undrinkable, by the addition of methanol. The result is known as [[methylated spirit]] or "meths" (UK use). (The latter should not be confused with ''meth'', a common abbreviation for [[methamphetamine]].)
Pure methanol has been used in [[open wheel car|open wheel auto racing]] since the mid-1960s. Unlike petroleum fires, methanol fires can be [[active fire protection|extinguished]] with plain water. A methanol-based fire burns invisibly, unlike gasoline, which burns with visible smoke. If a fire occurs on the track, there is no 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 actions. The decision to permanently switch to methanol in American [[American Championship Car Racing|IndyCar]] racing was a result of the devastating crash and explosion at the [[1964 Indianapolis 500]] which killed drivers [[Eddie Sachs]] and [[Dave MacDonald]].<ref>{{Citation
| last = McDonald
| first = Norris
| title = Green no longer bad luck at Indy
| newspaper = Toronto Star
| url = http://www.thestar.com/comment/columnists/article/205088 }}</ref>
One concern with the addition of methanol to automotive fuels is highlighted by recent groundwater impacts from the fuel additive [[methyl tert-butyl ether]] (MTBE). Leaking underground gasoline storage tanks created MTBE plumes in groundwater that eventually contaminated well water. Methanol's high solubility in water raises concerns that similar well water contamination could arise from the widespread use of methanol as an automotive fuel{{Fact|date=February 2008}}.
==See also==
* [[Liquid fuel]]s
* [[Methanol fuel]]
* [[List of Stoffs]]
* [[Methanol (data page)]]
* [[Methanol economy]]
* [[Aspartame]]
* [[Methanol to gasoline]]
==References==
<references/>
*[[Robert Boyle]], ''[[The Sceptical Chymist]]'' (1661) – contains account of distillation of wood alcohol.
* Gallucci, F., Basile, A., Drioli, E., Methanol as an energy source and/or energy carrier in membrane processes Separation and Purification Reviews 36 (2), pp. 175-202
==External links==
*{{ICSC|0057|00}}
*[http://www.racecarbook.com Race Car Book] RaceCarBook.com, includes technical articles and methanol racing book information.
*[http://methanol.org The Methanol Institute] Industry trade group, lots of information on methanol's use in fuel cells and as an alternative fuel.
*[http://www.setamericafree.org/Rnichols.pdf 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
* [http://www.npi.gov.au/database/substance-info/profiles/54.html National Pollutant Inventory - Methanol Fact Sheet]
*[http://www.bluerhinos.co.uk/molview/indv.php?id=1 Molview from bluerhinos.co.uk] See Methanol in 3D
*[http://www.labnews.co.uk/new_labnews/article.php?artid=1017&categoryid=2&scheme=2 Methanol Discovered in Space]
{{Alcohols}}
[[Category:Alcohols]]
[[Category:Biofuels]]
[[Category:Hazardous air pollutants]]
[[Category:Alcohol solvents]]
[[Category:anatomical preservation]]
[[Category:Oxygenates]]
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