Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic
chemical
A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., wit ...
and the simplest
aliphatic
In organic chemistry, hydrocarbons ( compounds composed solely of carbon and hydrogen) are divided into two classes: aromatic compounds and aliphatic compounds (; G. ''aleiphar'', fat, oil). Aliphatic compounds can be saturated, like hexane, o ...
alcohol
Alcohol most commonly refers to:
* Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom
* Alcohol (drug), an intoxicant found in alcoholic drinks
Alcohol may also refer to:
Chemicals
* Ethanol, one of se ...
, with the
formula
In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a '' chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betw ...
C H3 O H (a
methyl group
In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula . In formulas, the group is often abbreviated as Me. This hydrocarbon group occurs in ma ...
linked to a
hydroxyl group
In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...
, often abbreviated as MeOH). It is a light,
volatile, colourless,
flammable
A combustible material is something that can burn (i.e., ''combust'') in air. A combustible material is flammable if it ignites easily at ambient temperatures. In other words, a combustible material ignites with some effort and a flammable mat ...
liquid with a distinctive alcoholic odour similar to that of
ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
(potable alcohol).
[
]
A polar solvent, methanol acquired the name wood alcohol because it was once produced chiefly by the
destructive distillation
Destruction may refer to:
Concepts
* Destruktion, a term from the philosophy of Martin Heidegger
* Destructive narcissism, a pathological form of narcissism
* Self-destructive behaviour, a widely used phrase that ''conceptualises'' certain k ...
of
wood
Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin ...
. Today, methanol is mainly produced industrially by
hydrogenation
Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organic c ...
of
carbon monoxide
Carbon monoxide ( chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simp ...
.
[
Methanol consists of a methyl group linked to a polar hydroxyl group. With more than 20 million tons produced annually, it is used as a precursor to other ]commodity chemicals
Commodity chemicals (or bulk commodities or bulk chemicals) are a group of chemicals that are made on a very large scale to satisfy global markets. The average prices of commodity chemicals are regularly published in the chemical trade magazines an ...
, including formaldehyde
Formaldehyde ( , ) ( systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...
, acetic acid
Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main compon ...
, methyl tert-butyl ether
Methyl ''tertiary''-butyl ether (MTBE), also known as methyl tert-butyl ether and ''tert''-butyl methyl ether, is an organic compound with a structural formula (CH3)3COCH3. MTBE is a volatile, flammable, and colorless liquid that is sparingly sol ...
, methyl benzoate, anisole
Anisole, or methoxybenzene, is an organic compound with the formula CH3OC6H5. It is a colorless liquid with a smell reminiscent of anise seed, and in fact many of its derivatives are found in natural and artificial fragrances. The compound is m ...
, peroxyacid
A peroxy acid (often spelled as one word, peroxyacid, and sometimes called peracid) is an acid which contains an acidic –OOH group. The two main classes are those derived from conventional mineral acids, especially sulfuric acid, and the peroxy ...
s, as well as a host of more specialised chemicals.[
]
Occurrence
Small amounts of methanol are present in normal, healthy human individuals. One study found a mean of 4.5 ppm in the exhaled breath of test subjects. The mean endogenous methanol in humans of 0.45 g/d may be metabolized from pectin
Pectin ( grc, πηκτικός ': "congealed" and "curdled") is a heteropolysaccharide, a structural acid contained in the primary lamella, in the middle lamella, and in the cell walls of terrestrial plants. The principal, chemical component ...
found in fruit; one kilogram of apple produces up to 1.4 g of pectin (0.6 g of methanol.)
Methanol is produced by anaerobic bacteria
An anaerobic organism or anaerobe is any organism that does not require molecular oxygen for growth. It may react negatively or even die if free oxygen is present. In contrast, an aerobic organism (aerobe) is an organism that requires an oxygenat ...
and phytoplankton.
Interstellar medium
Methanol is also found in abundant quantities in star-forming regions of space and is used in astronomy as a marker for such regions. It is detected through its spectral emission lines.
In 2006, astronomers using the MERLIN
Merlin ( cy, Myrddin, kw, Marzhin, br, Merzhin) is a mythical figure prominently featured in the legend of King Arthur and best known as a mage, with several other main roles. His usual depiction, based on an amalgamation of historic and leg ...
array of radio telescopes at Jodrell Bank Observatory
Jodrell Bank Observatory () in Cheshire, England, hosts a number of radio telescopes as part of the Jodrell Bank Centre for Astrophysics at the University of Manchester. The observatory was established in 1945 by Bernard Lovell, a radio astr ...
discovered a large cloud of methanol in space across. In 2016, astronomers detected methanol in a planet-forming disc around the young star TW Hydrae
TW Hydrae is a T Tauri star approximately 196 light-years away in the constellation of Hydra (the Sea Serpent). TW Hydrae is about 80% of the mass of the Sun, but is only about 5-10 million years old. The star appears to be accreting from ...
using the Atacama Large Millimeter Array
The Atacama Large Millimeter/submillimeter Array (ALMA) is an astronomical interferometer of 66 radio telescopes in the Atacama Desert of northern Chile, which observe electromagnetic radiation at millimeter and submillimeter wavelengths. T ...
radio telescope.
Safety
Methanol is highly flammable. Its vapours are slightly heavier than air, can travel and ignite. Methanol fires should be extinguished with dry chemical, carbon dioxide
Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is tr ...
, water spray or alcohol-resistant foam.[
]
Toxicity
Ingesting as little as of pure methanol can cause permanent blindness by destruction of the optic nerve
In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual information from the retina to the brain. In humans, the optic nerve is derived from ...
. is potentially fatal. The median lethal dose is , ''i.e.'', 1–2 mL/kg body weight of pure methanol. The reference dose A reference dose is the United States Environmental Protection Agency's maximum acceptable oral dose of a toxic substance.Reference doses are most commonly determined for pesticides. The EPA defines an oral reference dose (abbreviated RfD) as:
es ...
for methanol is 0.5 mg/kg in a day. Toxic effects begin hours after ingestion, and antidotes can often prevent permanent damage. Because of its similarities in both appearance and odor to ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
(the alcohol in beverages), it is difficult to differentiate between the two; such is also the case with denatured alcohol
Denatured alcohol (also called methylated spirits in Australia, Canada, Ireland, New Zealand, South Africa, and the United Kingdom; wood spirit; and denatured rectified spirit) is ethanol that has additives to make it poisonous, bad-tasting, foul ...
, adulterated liquors or very low quality alcoholic beverages.
Methanol is toxic
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subs ...
by two mechanisms. First, methanol can be fatal due to effects on the central nervous system, acting as a central nervous system depressant
A depressant, or central depressant, is a drug that lowers neurotransmission levels, which is to depress or reduce arousal or stimulation, in various areas of the brain. Depressants are also colloquially referred to as downers as they lower the l ...
in the same manner as ethanol poisoning. Second, in a process of toxication
Toxication, toxification or toxicity exaltation is the conversion of a chemical compound into a more toxic form in living organisms or in substrates such as soil or water. The conversion can be caused by enzymatic metabolism in the organisms, ...
, it is metabolised
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
to formic acid
Formic acid (), systematically named methanoic acid, is the simplest carboxylic acid, and has the chemical formula HCOOH and structure . It is an important intermediate in chemical synthesis and occurs naturally, most notably in some ants. Es ...
(which is present as the formate ion) via formaldehyde
Formaldehyde ( , ) ( systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...
in a process initiated by the enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. ...
alcohol dehydrogenase
Alcohol dehydrogenases (ADH) () are a group of dehydrogenase enzymes that occur in many organisms and facilitate the interconversion between alcohols and aldehydes or ketones with the reduction of nicotinamide adenine dinucleotide (NAD+) to NADH ...
in the liver
The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it ...
. Methanol is converted to formaldehyde via alcohol dehydrogenase (ADH) and formaldehyde is converted to formic acid (formate) via aldehyde dehydrogenase
Aldehyde dehydrogenases () are a group of enzymes that catalyse the oxidation of aldehydes. They convert aldehydes (R–C(=O)) to carboxylic acids (R–C(=O)). The oxygen comes from a water molecule. To date, nineteen ALDH genes have ...
(ALDH). The conversion to formate via ALDH proceeds completely, with no detectable formaldehyde remaining. Formate is toxic because it inhibits mitochondrial cytochrome c oxidase
The enzyme cytochrome c oxidase or Complex IV, (was , now reclassified as a translocasEC 7.1.1.9 is a large transmembrane protein complex found in bacteria, archaea, and mitochondria of eukaryotes.
It is the last enzyme in the respiratory elec ...
, causing hypoxia at the cellular level, and metabolic acidosis
Metabolic acidosis is a serious electrolyte disorder characterized by an imbalance in the body's acid-base balance. Metabolic acidosis has three main root causes: increased acid production, loss of bicarbonate, and a reduced ability of the kidneys ...
, among a variety of other metabolic disturbances.
Outbreaks of methanol poisoning have occurred primarily due to contamination of drinking alcohol
Alcohol, sometimes referred to by the chemical name ''ethanol'', is a depressant drug that is the active ingredient in drinks such as beer, wine, and distilled spirits (hard liquor). It is one of the oldest and most commonly consumed recreati ...
. This is more common in the developing world
A developing country is a sovereign state with a lesser developed industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is also no clear agreem ...
. In 2013 more than 1700 cases nonetheless occurred in the United States. Those affected are often adult men. Outcomes may be good with early treatment. Toxicity to methanol was described as early as 1856.
Because of its 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
Denatured alcohol (also called methylated spirits in Australia, Canada, Ireland, New Zealand, South Africa, and the United Kingdom; wood spirit; and denatured rectified spirit) is ethanol that has additives to make it poisonous, bad-tasting, foul ...
" or "methylated spirit") from liquor excise taxation in the U.S. and other countries.
During the course of the COVID-19 pandemic
The COVID-19 pandemic, also known as the coronavirus pandemic, is an ongoing global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The novel virus was first identif ...
, the U.S. Food and Drug Administration
The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...
(FDA) found a number of hand sanitizer products being sold that were labeled as containing ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
but tested positive for methanol contamination. Due to the toxic effects of methanol when absorbed through the skin or ingested, in contrast to the relatively safer ethanol, the FDA ordered recalls of such hand sanitizer products containing methanol, and issued an import alert to stop these products from illegally entering the U.S. market.
Applications
Formaldehyde, acetic acid, methyl ''tert''-butylether
Methanol is primarily converted to formaldehyde, which is widely used in many areas, especially polymers. The conversion entails oxidation:
:2 CH3OH + O2 -> 2 CH2O + 2 H2O
Acetic acid
Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main compon ...
can be produced from methanol.
Methanol and isobutene
Isobutylene (or 2-methylpropene) is a hydrocarbon with the chemical formula . It is a four-carbon branched alkene (olefin), one of the four isomers of butylene. It is a colorless flammable gas, and is of considerable industrial value.
Produ ...
are combined to give methyl ''tert''-butyl ether (MTBE). MTBE is a major octane booster in gasoline.
Methanol to hydrocarbons, olefins, gasoline
Condensation of methanol to produce hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak ...
s and even aromatic
In chemistry, aromaticity is a chemical property of cyclic ( ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to satu ...
systems is the basis of several technologies related to gas to liquids
Gas to liquids (GTL) is a refinery process to convert natural gas or other gaseous hydrocarbons into longer-chain hydrocarbons, such as gasoline or diesel fuel. Methane-rich gases are converted into liquid synthetic fuels. Two general strategies e ...
. These include methanol-to-hydrocarbons (MtH), methanol to gasoline (MtG), methanol to olefins (MtO), and methanol to propylene (MtP). These conversions are catalyzed by zeolite
Zeolites are microporous, crystalline aluminosilicate materials commonly used as commercial adsorbents and catalysts. They mainly consist of silicon, aluminium, oxygen, and have the general formula ・y where is either a metal ion or H+. These p ...
s as heterogeneous catalyst
In chemistry, heterogeneous catalysis is catalysis where the phase of catalysts differs from that of the reactants or products. The process contrasts with homogeneous catalysis where the reactants, products and catalyst exist in the same phase. ...
s. The MtG process was once commercialized at Motunui
Motunui (''large island'' in Māori, from ''Motu Nui'') is a settlement in northern Taranaki, in the North Island of New Zealand. It is located on State Highway 3 close to the shore of the North Taranaki Bight, six kilometres east of Waitara.
...
in New Zealand.
Gasoline additive
The European Fuel Quality Directive allows fuel producers to blend up to 3% methanol, with an equal amount of cosolvent, with gasoline sold in Europe. China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...
uses more than 4.5 billion liters of methanol per year as a transportation fuel in low level blends for conventional vehicles, and high level blends in vehicles designed for methanol fuels. In recent years, however, most modern gasoline-using vehicles can use a variety of alcohol fuels, resulting in similar or higher horsepower, but for a simple change in the vehicle's software settings and possibly a 50 cent seal or tube part.
Other chemicals
Methanol is the precursor to most simple methylamine
Methylamine is an organic compound with a formula of . This colorless gas is a derivative of ammonia, but with one hydrogen atom being replaced by a methyl group. It is the simplest primary amine.
Methylamine is sold as a solution in methanol, e ...
s, methyl halides, and methyl ethers. Methyl esters are produced from methanol, including the transesterification of fats and production of biodiesel
Biodiesel is a form of diesel fuel derived from plants or animals and consisting of long-chain fatty acid esters. It is typically made by chemically reacting lipids such as animal fat (tallow), soybean oil, or some other vegetable oil wit ...
via transesterification
In organic chemistry, transesterification is the process of exchanging the organic group R″ of an ester with the organic group R' of an alcohol. These reactions are often catalyzed by the addition of an acid or base catalyst. The reaction can ...
.
Niche and potential uses
Energy carrier
Methanol is a promising energy carrier because, as a liquid, it is easier to store than hydrogen and natural gas. Its energy density
In physics, energy density is the amount of energy stored in a given system or region of space per unit volume. It is sometimes confused with energy per unit mass which is properly called specific energy or .
Often only the ''useful'' or extract ...
is, however, lower than methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on ...
, per kg. Its combustion energy density is 15.6 MJ/ L ( LHV), whereas that of ethanol is 24 and gasoline is 33 MJ/L.
Further advantages for methanol is its ready biodegradability and low environmental toxicity. It does not persist in either aerobic (oxygen-present) or anaerobic (oxygen-absent) environments. 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
Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen a ...
at 10–730 days). Since methanol is miscible
Miscibility () is the property of two substances to mix in all proportions (that is, to fully dissolve in each other at any concentration), forming a homogeneous mixture (a solution). The term is most often applied to liquids but also applie ...
with water and biodegradable, it is unlikely to accumulate in groundwater, surface water, air or soil.
Fuel
Methanol is occasionally used to fuel internal combustion engine
An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal com ...
s. It burns forming carbon dioxide and water:
: 2 CH3OH + 3 O2 -> 2 CO2 + 4 H2O
Methanol fuel has been proposed for ground transportation. The chief advantage of a methanol economy is that it could be adapted to gasoline internal combustion engines with minimum modification to the engines and to the infrastructure that delivers and stores liquid fuel. Its energy density, however, is less than gasoline, meaning more frequent fill ups would be required. However, it is equivalent to super high-octane gasoline in horsepower, and most modern computer-controlled fuel injection systems can already use it.
Methanol is an alternative fuel for ships that helps the shipping industry meet increasingly strict emissions regulations. It significantly reduces emissions of sulphur oxides (SOx), nitrogen oxides (NOx) and particulate matter. Methanol can be used with high efficiency in marine diesel engines after minor modifications using a small amount of pilot fuel (Dual fuel).
In China, methanol fuels industrial boilers, which are used extensively to generate heat and steam for various industrial applications and residential heating. Its use is displacing coal, which is under pressure from increasingly stringent environmental regulations.
Direct-methanol fuel cells are unique in their low temperature, atmospheric pressure operation, which lets them be greatly miniaturized. This, combined with the relatively easy and safe storage and handling of methanol, may open the possibility of fuel cell-powered consumer electronics
Consumer electronics or home electronics are electronic ( analog or digital) equipment intended for everyday use, typically in private homes. Consumer electronics include devices used for entertainment, communications and recreation. Usually ...
, such as 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 be gelled to reduce risk of leaking or spilling, as with the brand "Sterno
Sterno is a brand of jellied, denatured alcohol sold in a can and meant to be burned directly in its can. Its primary uses are in food service for buffet heating, in the home for fondue, and as a chafing fuel for heating chafing dishes. Other u ...
".
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.
Other applications
Methanol is used as a denaturant for ethanol, the product being known as "denatured alcohol" or "methylated spirit". This was commonly used during the U.S. prohibition to discourage consumption of bootlegged liquor, and ended up causing several deaths. These types of practices are now illegal in the U.S., being considered homicide.
Methanol is used as a solvent
A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...
and as an antifreeze
An antifreeze is an additive which lowers the freezing point of a water-based liquid. An antifreeze mixture is used to achieve freezing-point depression for cold environments. Common antifreezes also increase the boiling point of the liquid, al ...
in pipelines and windshield washer fluid
Windshield washer fluid (also called windshield wiper fluid, wiper fluid, screen wash (in the UK), or washer fluid) is a fluid for motor vehicles that is used in cleaning the windshield with the windshield wiper while the vehicle is being driven ...
. Methanol was used as an automobile coolant antifreeze in the early 1900s. As of May 2018, methanol was banned in the EU for use in windscreen washing or defrosting due to its risk of human consumption as a result of 2012 Czech Republic methanol poisonings.
In some wastewater treatment plants, a small amount of methanol is added to wastewater
Wastewater is water generated after the use of freshwater, raw water, drinking water or saline water in a variety of deliberate applications or processes. Another definition of wastewater is "Used water from any combination of domestic, industri ...
to provide a carbon food source for the denitrifying bacteria Denitrifying bacteria are a diverse group of bacteria that encompass many different phyla. This group of bacteria, together with denitrifying fungi and archaea, is capable of performing denitrification as part of the nitrogen cycle. Denitrification ...
, which convert nitrate
Nitrate is a polyatomic ion with the chemical formula . Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. An example of an insolubl ...
s to nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at sevent ...
gas and reduce the nitrification of sensitive aquifer
An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials (gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their character ...
s.
Methanol is used as a destaining agent in polyacrylamide gel electrophoresis
Polyacrylamide gel electrophoresis (PAGE) is a technique widely used in biochemistry, forensic chemistry, genetics, molecular biology and biotechnology to separate biological macromolecules, usually proteins or nucleic acids, according to th ...
.
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 and zinc oxide
Zinc oxide is an inorganic compound with the formula . It is a white powder that is insoluble in water. ZnO is used as an additive in numerous materials and products including cosmetics, food supplements, rubbers, plastics, ceramics, glass, cemen ...
s, supported on alumina, as first used by ICI in 1966. At 5–10 MPa (50–100 atm) and , the reaction
:CO + 2 H2 -> CH3OH
is characterized by high selectivity (>99.8%). The production of synthesis gas
Syngas, or synthesis gas, is a mixture of hydrogen and carbon monoxide, in various ratios. The gas often contains some carbon dioxide and methane. It is principly used for producing ammonia or methanol. Syngas is combustible and can be used as ...
from methane produces three moles of hydrogen for every mole of carbon monoxide, whereas the 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
Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is tr ...
into the methanol synthesis reactor, where it, too, reacts to form methanol according to the equation
:CO2 + 3 H2 -> CH3OH + H2O.
In terms of mechanism, the process occurs via initial conversion of CO into CO2, which is then hydrogenated
Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organic co ...
:
: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
:CO + 2 H2 -> CH3OH,
which is the same as listed above. In a process closely related to methanol production from synthesis gas, a feed of hydrogen and CO2 can be used directly. The main advantage of this process is that captured CO2 and hydrogen sourced from electrolysis
In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from na ...
could be used, removing the dependence on fossil fuels.
Biosynthesis
The catalytic conversion of methane to methanol is effected by enzymes including methane monooxygenase
Methane monooxygenase (MMO) is an enzyme capable of oxidizing the C-H bond in methane as well as other alkanes. Methane monooxygenase belongs to the class of oxidoreductase enzymes ().
There are two forms of MMO: the well-studied soluble form (s ...
s. These enzymes are mixed-function oxygenases, i.e. oxygenation is coupled with production of water and NAD+:
:CH4 + O2 + NADPH + H^+ -> CH3OH + H2O + NAD^+ .
Both Fe- and Cu-dependent enzymes have been characterized. Intense but largely fruitless efforts have been undertaken to emulate this reactivity. Methanol is more easily oxidized than is the feedstock methane, so the reactions tend not to be selective. Some strategies exist to circumvent this problem. Examples include Shilov system
The Shilov system is a classic example of catalytic C-H bond activation and oxidation which preferentially activates stronger C-H bonds over weaker C-H bonds for an overall partial oxidation.
C. I. Herrerias, X. Yao, Z. Li, C.-J. Li, Reactions o ...
s and Fe- and Cu containing zeolites. These systems do not necessarily mimic the mechanisms employed by metalloenzymes, but draw some inspiration from them. Active sites can vary substantially from those known in the enzymes. For example, a dinuclear active site is proposed in the sMMO enzyme, whereas a mononuclear iron ( alpha-oxygen) is proposed in the Fe-zeolite.
Global emissions of methanol by plants are estimated at between 180 and 250 million tons per year. This is between two and three times larger than man-made industrial production of methanol.
Quality specifications and analysis
Methanol is available commercially in various purity grades. Commercial methanol is generally classified according to ASTM purity grades A and AA. Both grade A and grade AA purity are 99.85% methanol by weight. Grade "AA" methanol contains trace amounts of ethanol as well.
Methanol for chemical use normally corresponds to Grade AA. In addition to water, typical impurities include acetone and ethanol (which are very difficult to separate by distillation). UV-vis spectroscopy is a convenient method for detecting aromatic impurities. Water content can be determined by the Karl-Fischer titration.
History
In their embalming
Embalming is the art and science of preserving human remains by treating them (in its modern form with chemicals) to forestall decomposition. This is usually done to make the deceased suitable for public or private viewing as part of the funeral ...
process, the ancient Egyptians used a mixture of substances, including methanol, which they obtained from the pyrolysis
The pyrolysis (or devolatilization) process is the thermal decomposition of materials at elevated temperatures, often in an inert atmosphere. It involves a change of chemical composition. The word is coined from the Greek-derived elements ''pyr ...
of wood. Pure methanol, however, was first isolated in 1661 by Robert Boyle
Robert Boyle (; 25 January 1627 – 31 December 1691) was an Anglo-Irish natural philosopher, chemist, physicist, alchemist and inventor. Boyle is largely regarded today as the first modern chemist, and therefore one of the founders of ...
, when he produced it via the distillation of buxus
''Buxus'' is a genus of about seventy species in the family Buxaceae. Common names include box or boxwood.
The boxes are native to western and southern Europe, southwest, southern and eastern Asia, Africa, Madagascar, northernmost Sout ...
(boxwood). It later became known as "pyroxylic spirit". In 1834, the French chemists Jean-Baptiste Dumas
Jean Baptiste André Dumas (14 July 180010 April 1884) was a French chemist, best known for his works on organic analysis and synthesis, as well as the determination of atomic weights (relative atomic masses) and molecular weights by measuring v ...
and Eugene Peligot
Eugene may refer to:
People and fictional characters
* Eugene (given name), including a list of people and fictional characters with the given name
* Eugene (actress) (born 1981), Kim Yoo-jin, South Korean actress and former member of the si ...
determined its elemental composition.[A report on methanol to the French Academy of Sciences by J. Dumas and E. Péligot began during the Academy's meeting of 27 October 1834 and finished during the meeting of 3 November 1834. See: ''Procès-verbaux des séances de l'Académie'', 10 : 600–601. Available on:]
Gallica
The complete report appears in: J. Dumas and E. Péligot (1835) "Mémoire sur l'espirit de bois et sur les divers composés ethérés qui en proviennent"(Memoir on spirit of wood and on the various ethereal compounds that derive therefrom), ''Annales de chimie et de physique'', 58 : 5–74; from page 9 ''Nous donnerons le nom de ''méthylène'' (1) à un radical ... (1) Μεθυ, vin, et υλη, bois; c'est-à-dire vin ou liqueur spiritueuse du bois.'' (We will give the name methylene (1) to a radical ... (1) ''methy'', wine, and ''hulē'', wood; that is, wine or spirit of wood.)
They also introduced the word "methylène" to organic chemistry, forming it from Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
''methy'' = "alcoholic liquid" + '' hȳlē'' = "forest, wood, timber, material". "Methylène" designated a "radical" that was about 14% hydrogen by weight and contained one carbon atom. This would be CH2, but at the time carbon was thought to have an atomic weight
Relative atomic mass (symbol: ''A''; sometimes abbreviated RAM or r.a.m.), also known by the deprecated synonym atomic weight, is a dimensionless physical quantity defined as the ratio of the average mass of atoms of a chemical element in a giv ...
only six times that of hydrogen, so they gave the formula as CH.[ They then called wood alcohol (l'esprit de bois) "bihydrate de méthylène" (bihydrate because they thought the formula was C4H8O4 = (CH)4(H2O)2). The term "methyl" was derived in about 1840 by ]back-formation
In etymology, back-formation is the process or result of creating a new word via inflection, typically by removing or substituting actual or supposed affixes from a lexical item, in a way that expands the number of lexemes associated with the c ...
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
In linguistics, a suffix is an affix which is placed after the stem of a word. Common examples are case endings, which indicate the grammatical case of nouns, adjectives, and verb endings, which form the conjugation of verbs. Suffixes can carry ...
-yl, which, in organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J. ...
, forms names of carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon makes u ...
groups, is from the word ''methyl''.
French chemist Paul Sabatier presented the first process
A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic.
Things called a process include:
Business and management
* Business process, activities that produce a specific s ...
that could be used to produce methanol synthetically in 1905. This process suggested that carbon dioxide and hydrogen could be reacted to produce methanol. German chemists Alwin Mittasch and Mathias Pier, working for Badische-Anilin & Soda-Fabrik (BASF), developed a means to convert synthesis gas
Syngas, or synthesis gas, is a mixture of hydrogen and carbon monoxide, in various ratios. The gas often contains some carbon dioxide and methane. It is principly used for producing ammonia or methanol. Syngas is combustible and can be used as ...
(a mixture of carbon monoxide
Carbon monoxide ( chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simp ...
, carbon dioxide
Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is tr ...
, and hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxi ...
) into methanol and received a patent. According to Bozzano and Manenti, BASF's process was first utilized in Leuna
Leuna is a town in Saxony-Anhalt, eastern Germany, south of Merseburg and Halle, on the river Saale.
The town is known for the '' Leunawerke'', at 13 km2 one of the biggest chemical industrial complexes in Germany, where a very wide range ...
, Germany in 1923. Operating conditions consisted of "high" temperatures (between 300 and 400 °C) and pressures (between 250 and 350 atm) with a zinc
Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic t ...
/chromium oxide Chromium oxide may refer to:
* Chromium(II) oxide, CrO
* Chromium(III) oxide, Cr2O3
* Chromium dioxide (chromium(IV) oxide), CrO2, which includes the hypothetical compound chromium(II) chromate
* Chromium trioxide (chromium(VI) oxide), CrO3
* Chro ...
catalyst.
US patent 1,569,775 () was applied for on 4 Sep 1924 and issued on 12 January 1926 to BASF; the process used a chromium
Chromium is a chemical element with the symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard, and brittle transition metal.
Chromium metal is valued for its high corrosion resistance and ha ...
and manganese oxide Manganese oxide is any of a variety of manganese oxides and hydroxides.Wells A.F. (1984) ''Structural inorganic chemistry'' 5th edition Oxford Science Publications, . These include
* Manganese(II) oxide, MnO
* Manganese(II,III) oxide, Mn3O4
* Mang ...
catalyst
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recy ...
with 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) process was developed by ICI in the late 1960s with the technology patent since long expired.
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
Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazin ...
, known as C-Stoff
C-Stoff (; "substance C") was a reductant used in bipropellant rocket fuels (as a fuel itself) developed by Hellmuth Walter Kommanditgesellschaft in Germany during World War II. It was developed for use with T-Stoff (a high-test peroxide) as a ...
.
The use of methanol as a motor fuel received attention during the oil crises of the 1970s. By the mid-1990s, over 20,000 methanol " flexible fuel vehicles" (FFV) 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 interest in methanol fuel
Methanol fuel is an alternative biofuel for internal combustion and other engines, either in combination with gasoline or independently. Methanol ( C H3 O H) is less expensive to produce sustainably than ethanol fuel, although it produces more t ...
s.
In the early 1970s, a process was developed by Mobil
Mobil is a petroleum brand owned and operated by American oil and gas corporation ExxonMobil. The brand was formerly owned and operated by an oil and gas corporation of the same name, which itself merged with Exxon to form ExxonMobil in 1999.
...
for producing gasoline fuel from methanol.
Between the 1960s and 1980s methanol emerged as a precursor to the feedstock chemicals acetic acid and acetic anhydride
Acetic anhydride, or ethanoic anhydride, is the chemical compound with the formula (CH3CO)2O. Commonly abbreviated Ac2O, it is the simplest isolable anhydride of a carboxylic acid and is widely used as a reagent in organic synthesis. It is a colo ...
. These processes include the Monsanto acetic acid synthesis, Cativa process
The Cativa process is a method for the production of acetic acid by the carbonylation of methanol. The technology, which is similar to the Monsanto process, was developed by BP Chemicals and is under license by BP Plc. The process is based on a ...
, and Tennessee Eastman acetic anhydride process.
See also
* Aminomethanol
* Methanol (data page)
* Trimethyl carbinol
References
Further reading
*Robert Boyle
Robert Boyle (; 25 January 1627 – 31 December 1691) was an Anglo-Irish natural philosopher, chemist, physicist, alchemist and inventor. Boyle is largely regarded today as the first modern chemist, and therefore one of the founders of ...
, '' The Sceptical Chymist'' (1661) – contains account of distillation of wood alcohol.
External links
*
Methyl Alcohol (Methanol)
CDC/NIOSH, links to safety information
* ttp://www.npi.gov.au/resource/methanol Methanol Fact Sheet– National Pollutant Inventory
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