Ethanol is naturally produced by thefermentation process ofsugars byyeasts or viapetrochemical processes such asethylene hydration. Historically it was used as ageneral anesthetic, and has modern medical applications as anantiseptic,disinfectant, solvent for some medications, andantidote formethanol poisoning andethylene glycol poisoning.[14][15] It is used as a chemicalsolvent and in thesynthesis of organic compounds, and as afuel source for lamps, stoves, and internal combustion engines. Ethanol also can be dehydrated to make ethylene, an important chemical feedstock. As of 2023, world production of ethanol fuel was 112.0 gigalitres (2.96×1010 US gallons), coming mostly from the U.S. (51%) and Brazil (26%).[16]
The "eth-" prefix and the qualifier "ethyl" in "ethyl alcohol" originally came from the name "ethyl" assigned in 1834 to the groupC 2H 5− byJustus Liebig. He coined the word from theGerman nameAether of the compoundC 2H 5−O−C 2H 5 (commonly called "ether" inEnglish, more specifically called "diethyl ether").[18] According to theOxford English Dictionary,Ethyl is a contraction of the Ancient Greekαἰθήρ (aithḗr, "upper air") and the Greek wordὕλη (hýlē, "wood, raw material", hence "matter, substance").[19]Ethanol was coined as a result of a resolution on naming alcohols and phenols that was adopted at the International Conference onChemical Nomenclature that was held in April 1892 inGeneva, Switzerland.[20]
The termalcohol now refers to a wider class of substances in chemistry nomenclature, but in common parlance it remains the name of ethanol. It is a medieval loan fromArabical-kuḥl, a powdered ore ofantimony used since antiquity as a cosmetic, and retained that meaning inMiddle Latin.[21] The use of 'alcohol' for ethanol (in full, "alcohol of wine") was first recorded in 1753. Before the late 18th century the termalcohol generally referred to any sublimated substance.[22]
As acentral nervous systemdepressant, ethanol is one of the most commonly consumedpsychoactive drugs.[23] Despite alcohol's psychoactive, addictive, andcarcinogenic properties,[citation needed] it is readily available and legal for sale in many countries. There are laws regulating the sale, exportation/importation, taxation, manufacturing, consumption, and possession of alcoholic beverages. The most common regulation is prohibition for minors.
When present in significant concentrations, this metabolism of ethanol is additionally aided by thecytochrome P450 enzymeCYP2E1 in humans, while trace amounts are also metabolized bycatalase.[26] The resulting intermediate, acetaldehyde, is a known carcinogen, and poses significantly greater toxicity in humans than ethanol itself. Many of the symptoms typically associated with alcohol intoxication—as well as many of the health hazards typically associated with the long-term consumption of ethanol—can be attributed to acetaldehyde toxicity in humans.[27]
The subsequent oxidation of acetaldehyde intoacetate is performed byaldehyde dehydrogenase (ALDH) enzymes. A mutation in the ALDH2 gene that encodes for an inactive or dysfunctional form of this enzyme affects roughly 50% of east Asian populations, contributing to the characteristicalcohol flush reaction that can cause temporary reddening of the skin as well as a number of related, and often unpleasant, symptoms of acetaldehyde toxicity.[28] This mutation is typically accompanied by another mutation in the ADH enzymeADH1B in roughly 80% of east Asians, which improves the catalytic efficiency of converting ethanol into acetaldehyde.[28]
A solution of 70% ethanol is more effective than pure ethanol because ethanol relies on water molecules for optimal antimicrobial activity. Absolute ethanol may inactivate microbes without destroying them because the alcohol is unable to fully permeate the microbe's membrane.[33][34] Ethanol can also be used as a disinfectant and antiseptic by inducing cell dehydration through disruption of the osmotic balance across the cell membrane, causing water to leave the cell, leading to cell death.[35]
The largest single use of ethanol is as an enginefuel andfuel additive.Brazil in particular relies heavily upon the use of ethanol as an engine fuel, due in part to its role as one of the world's leading producers of ethanol.[46][47]Gasoline sold in Brazil contains at least 25%anhydrous ethanol. Hydrous ethanol (about 95% ethanol and 5% water) can be used as fuel in more than 90% of new gasoline-fueled cars sold in the country.
The US and many other countries primarily use E10 (10% ethanol, sometimes known as gasohol) and E85 (85% ethanol) ethanol/gasoline mixtures. Over time, it is believed that a material portion of the ≈150-billion-US-gallon (570,000,000 m3) per year market for gasoline will begin to be replaced with fuel ethanol.[48]
Australian law limits the use of pure ethanol fromsugarcane waste to 10% in automobiles. Older cars (and vintage cars designed to use a slower burning fuel) should have the engine valves upgraded or replaced.[49]
According to an industryadvocacy group, ethanol as a fuel reduces harmfultailpipe emissions of carbon monoxide, particulate matter,oxides of nitrogen, and other ozone-forming pollutants.[50]Argonne National Laboratory analyzed greenhouse gas emissions of many different engine and fuel combinations, and found thatbiodiesel/petrodiesel blend (B20) showed a reduction of 8%, conventionalE85 ethanol blend a reduction of 17% andcellulosic ethanol 64%, compared with pure gasoline.[51] Ethanol has a much greater research octane number (RON) than gasoline, meaning it is less prone to pre-ignition, allowing for better ignition advance which means more torque, and efficiency in addition to the lower carbon emissions.[52]
Ethanolcombustion in aninternal combustion engine yields many of the products of incomplete combustion produced by gasoline and significantly larger amounts offormaldehyde and related species such as acetaldehyde.[53] This leads to a significantly larger photochemical reactivity and moreground level ozone.[54] This data has been assembled into The Clean Fuels Report comparison of fuel emissions[55] and show that ethanol exhaust generates 2.14 times as much ozone as gasoline exhaust.[56] When this is added into the customLocalized Pollution Index of The Clean Fuels Report, the local pollution of ethanol (pollution that contributes to smog) is rated 1.7, where gasoline is 1.0 and higher numbers signify greater pollution.[57] TheCalifornia Air Resources Board formalized this issue in 2008 by recognizing control standards for formaldehydes as an emissions control group, much like the conventionalNOx and reactive organic gases (ROGs).[58]
More than 20% of Brazilian cars are able to use 100% ethanol as fuel, which includes ethanol-only engines andflex-fuel engines.[59] Flex-fuel engines in Brazil are able to work with all ethanol, all gasoline or any mixture of both. In the United States, flex-fuel vehicles can run on 0% to 85% ethanol (15% gasoline) since higher ethanol blends are not yet allowed or efficient. Brazil supports this fleet of ethanol-burning automobiles with large national infrastructure that produces ethanol from domestically grown sugarcane.
Ethanol's highmiscibility with water makes it unsuitable for shipping through modernpipelines like liquid hydrocarbons.[60] Mechanics have seen increased cases of damage to small engines (in particular, thecarburetor) and attribute the damage to the increased water retention by ethanol in fuel.[61]
Ethanol was commonly used as fuel in earlybipropellantrocket (liquid-propelled) vehicles, in conjunction with anoxidizer such as liquid oxygen. The German A-4 ballistic rocket ofWorld War II (better known by its propaganda nameV-2),[62] which is credited as having begun the space age, used ethanol as the main constituent ofB-Stoff. Under such nomenclature, the ethanol was mixed with 25% water to reduce the combustion chamber temperature.[63][64] TheV-2's design team helped develop U.S. rockets following World War II, including the ethanol-fueledRedstone rocket, which launched the first U.S. astronaut onsuborbital spaceflight.[65][66] Alcohols fell into general disuse as more energy-dense rocket fuels were developed,[64] although ethanol was used in recent experimentallightweightrocket-powered racing aircraft.[67]
Commercial fuel cells operate on reformed natural gas,hydrogen or methanol. Ethanol is an attractive alternative due to its wide availability, low cost, high purity and low toxicity. There is a wide range of fuel cell concepts that have entered trials includingdirect-ethanol fuel cells, auto-thermal reforming systems and thermally integrated systems. The majority of work is being conducted at a research level although there are a number of organizations at the beginning of the commercialization of ethanol fuel cells.[68]
Ethanol fireplaces can be used for home heating or for decoration. Ethanol can also be used as stove fuel for cooking.[69][70]
Ethanol is an important industrial ingredient. It has widespread use as a precursor for other organic compounds such as ethylhalides, ethylesters, diethyl ether, acetic acid, and ethylamines. It is considered a universalsolvent, as itsmolecular structure allows for the dissolving of bothpolar,hydrophilic andnonpolar,hydrophobic compounds. As ethanol also has a lowboiling point, it is easy to remove from a solution that has been used to dissolve other compounds, making it a popular extracting agent for botanical oils.Cannabis oil extraction methods often use ethanol as an extraction solvent,[71] and also as a post-processing solvent to remove oils, waxes, andchlorophyll from solution in a process known aswinterization.
Ethanol is found inpaints, tinctures, markers, personal care products such as mouthwashes, perfumes and deodorants, andwet specimen preservatives.Polysaccharidesprecipitate from aqueous solution in the presence of alcohol, and ethanol precipitation is used for this reason in the purification ofDNA andRNA. Because of its lowfreezing point of −114 °C (−173 °F) and low toxicity, ethanol is sometimes used in laboratories (withdry ice or other coolants) as acooling bath to keep vessels at temperatures below the freezing point of water. For the same reason, it is also used as the active fluid inalcohol thermometers.
Ethanol is a 2-carbonalcohol. Itsmolecular formula isCH3CH2OH. The structure of the molecule of ethanol isCH3−CH2−OH (anethyl group linked to ahydroxyl group), which indicates that the carbon of amethyl group (−CH3) is attached to the carbon of amethylene group (−CH2−), which is attached to the oxygen of a hydroxyl group (−OH). It is a constitutionalisomer ofdimethyl ether. Ethanol is sometimes abbreviated asEtOH, using the common organic chemistry notation of representing the ethyl group (−CH2CH3) withEt.
Ethanol is a volatile, colorless liquid that has a slight odor. It burns with a smokeless blue flame that is not always visible in normal light. The physical properties of ethanol stem primarily from the presence of its hydroxyl group and the shortness of its carbon chain. Ethanol's hydroxyl group is able to participate in hydrogen bonding, rendering it more viscous and less volatile than less polar organic compounds of similar molecular weight, such aspropane.[citation needed] Ethanol'sadiabatic flame temperature for combustion in air is 2082 °C or 3779 °F.[72]
Ethanol is slightly more refractive than water, having arefractive index of 1.36242 (at λ=589.3 nm and 18.35 °C or 65.03 °F).[73] Thetriple point for ethanol is150 ± 20K.[74]
Ethanol's miscibility with water contrasts with the immiscibility of longer-chain alcohols (five or more carbon atoms), whose water miscibility decreases sharply as the number of carbons increases.[76] The miscibility of ethanol withalkanes is limited to alkanes up toundecane: mixtures withdodecane and higher alkanes show amiscibility gap below a certain temperature (about 13 °C for dodecane[77]). The miscibility gap tends to get wider with higher alkanes, and the temperature for complete miscibility increases.
Ethanol-water mixtures have less volume than the sum of their individual components at the given fractions. Mixing equal volumes of ethanol and water results in only 1.92 volumes of mixture.[73][78] Mixing ethanol and water isexothermic, with up to 777 J/mol[79] being released at 298 K.
The addition of even a few percent of ethanol to water sharply reduces thesurface tension of water. This property partially explains the "tears of wine" phenomenon. When wine is swirled in a glass, ethanol evaporates quickly from the thin film of wine on the wall of the glass. As the wine's ethanol content decreases, its surface tension increases and the thin film "beads up" and runs down the glass in channels rather than as a smooth sheet.
At atmospheric pressure, mixtures of ethanol and water form anazeotrope at about 89.4 mol% ethanol (95.6% ethanol by mass,[81] 97%alcohol by volume), with a boiling point of 351.3 K (78.1 °C).[82] At lower pressure, the composition of the ethanol-water azeotrope shifts to more ethanol-rich mixtures.[83] The minimum-pressure azeotrope has an ethanol fraction of 100%[83] and a boiling point of 306 K (33 °C),[82] corresponding to a pressure of roughly 70 torr (9.333 kPa).[84] Below this pressure, there is no azeotrope, and it is possible to distill absolute ethanol from an ethanol-water mixture.[84]
An ethanol–water solution will catch fire if heated above a temperature called itsflash point and an ignition source is then applied to it.[85] For 20% alcohol by mass (about 25% by volume), this will occur at about 25 °C (77 °F). The flash point of pure ethanol is 13 °C (55 °F),[86] but may be influenced very slightly by atmospheric composition such as pressure and humidity. Ethanol mixtures can ignite below average room temperature. Ethanol is considered a flammable liquid (Class 3 Hazardous Material) in concentrations above 2.35% by mass (3.0% by volume; 6proof).[87][88][89] Dishes using burning alcohol for culinary effects are calledflambé.
Flash points of ethanol–water mixtures[90][88][91]
Ethanol is a byproduct of the metabolic process of yeast. As such, ethanol will be present in any yeast habitat. Ethanol can commonly be found in overripe fruit.[92] Ethanol produced by symbiotic yeast can be found inbertam palm blossoms. Although some animal species, such as thepentailed treeshrew, exhibit ethanol-seeking behaviors, most show no interest or avoidance of food sources containing ethanol.[93] Ethanol is also produced during the germination of many plants as a result of naturalanaerobiosis.[94]
Ethanol has been detected inouter space, forming an icy coating around dust grains ininterstellar clouds.[95]Minute quantity amounts (average 196ppb) of endogenous ethanol and acetaldehyde were found in the exhaled breath of healthy volunteers.[96]Auto-brewery syndrome, also known as gut fermentation syndrome, is a rare medical condition in which intoxicating quantities of ethanol are produced throughendogenousfermentation within thedigestive system.[97]
94% denatured ethanol sold in a bottle for household use
Ethanol is produced both as apetrochemical, through the hydration ofethylene and, via biological processes, by fermentingsugars withyeast.[98] Which process is more economical depends on prevailing prices ofpetroleum and grain feed stocks.
World production of ethanol in 2006 was 51 gigalitres (1.3×1010 US gal), with 69% of the world supply coming from Brazil and the U.S.[16] Brazilian ethanol is produced from sugarcane, which has relatively high yields (830% more fuel than the fossil fuels used to produce it) compared to some otherenergy crops.[99] Sugarcane not only has a greater concentration of sucrose than corn (by about 30%), but is also much easier to extract. Thebagasse generated by the process is not discarded, but burned by power plants to produce electricity. Bagasse burning accounts for around 9% of the electricity produced in Brazil.[100]
In the 1970s most industrial ethanol in the U.S. was made as a petrochemical, but in the 1980s the U.S. introduced subsidies forcorn-based ethanol.[101] According to the Renewable Fuels Association, as of 30 October 2007, 131 grain ethanol bio-refineries in the U.S. have the capacity to produce 7×10^9 US gal (26,000,000 m3) of ethanol per year. An additional 72 construction projects underway (in the U.S.) can add 6.4 billion US gallons (24,000,000 m3) of new capacity in the next 18 months.[48]
In India ethanol is made from sugarcane.[102]Sweet sorghum is another potential source of ethanol, and is suitable for growing in dryland conditions. TheInternational Crops Research Institute for the Semi-Arid Tropics is investigating the possibility of growing sorghum as a source of fuel, food, and animal feed in arid parts ofAsia andAfrica.[103] Sweet sorghum has one-third the water requirement of sugarcane over the same time period. It also requires about 22% less water than corn. The world's first sweet sorghum ethanol distillery began commercial production in 2007 inAndhra Pradesh,India.[104]
Ethanol can be produced from petrochemical feed stocks, primarily by theacid-catalyzedhydration of ethylene. It is often referred to as synthetic ethanol.
C2H4 + H2O → C2H5OH
The catalyst is most commonlyphosphoric acid,[107][108]adsorbed onto a porous support such assilica gel ordiatomaceous earth. This catalyst was first used for large-scale ethanol production by theShell Oil Company in 1947.[109] The reaction is carried out in the presence of high pressure steam at 300 °C (572 °F) where a 5:3 ethylene to steam ratio is maintained.[110][111] This process was used on an industrial scale byUnion Carbide Corporation and others. It is no longer practiced in the US as fermentation ethanol produced from corn is more economical.[112]
In an older process, first practiced on the industrial scale in 1930 by Union Carbide[113] but now almost entirely obsolete, ethylene was hydrated indirectly by reacting it with concentratedsulfuric acid to produceethyl sulfate, which washydrolyzed to yield ethanol and regenerate the sulfuric acid:[114]
Ethanol inalcoholic beverages and fuel is produced by fermentation. Certain species of yeast (e.g.,Saccharomyces cerevisiae) metabolize sugar (namelypolysaccharides), producing ethanol and carbon dioxide. The chemical equations below summarize the conversion:
Fermentation is the process of culturing yeast under favorable thermal conditions to produce alcohol. This process is carried out at around 35–40 °C (95–104 °F). Toxicity of ethanol to yeast limits the ethanol concentration obtainable by brewing; higher concentrations, therefore, are obtained byfortification ordistillation. The most ethanol-tolerant yeast strains can survive up to approximately 18% ethanol by volume.
To produce ethanol from starchy materials such ascereals, thestarch must first be converted into sugars. In brewingbeer, this has traditionally been accomplished by allowing the grain to germinate, ormalt, which produces theenzymeamylase. When the malted grain ismashed, the amylase converts the remaining starches into sugars.
Sugars forethanol fermentation can be obtained fromcellulose. Deployment of this technology could turn a number of cellulose-containing agricultural by-products, such ascorncobs,straw, andsawdust, into renewable energy resources. Other agricultural residues such as sugarcane bagasse and energy crops such asswitchgrass may also be fermentable sugar sources.[115]
Infrared reflection spectra of liquid ethanol, showing the −OH band centered near 3300 cm−1 and C−H bands near 2950 cm−1Near-infrared spectrum of liquid ethanol
Breweries andbiofuel plants employ two methods for measuring ethanol concentration. Infrared ethanol sensors measure the vibrational frequency of dissolved ethanol using the C−H band at 2900 cm−1. This method uses a relatively inexpensive solid-state sensor that compares the C−H band with a reference band to calculate the ethanol content. The calculation makes use of theBeer–Lambert law. Alternatively, by measuring the density of the starting material and the density of the product, using ahydrometer, the change in specific gravity during fermentation indicates the alcohol content. This inexpensive and indirect method has a long history in the beer brewing industry.
Ethylene hydration or brewing produces an ethanol–water mixture. For most industrial and fuel uses, the ethanol must be purified.Fractional distillation at atmospheric pressure can concentrate ethanol to 95.6% by weight (89.5 mole%). This mixture is an azeotrope with a boiling point of 78.1 °C (172.6 °F), andcannot be further purified by distillation. Addition of an entraining agent, such as benzene,cyclohexane, orheptane, allows a new ternary azeotrope comprising the ethanol, water, and the entraining agent to be formed. This lower-boiling ternary azeotrope is removed preferentially, leading to water-free ethanol.[108]
Apart from distillation, ethanol may be dried by addition of adesiccant, such asmolecular sieves, cellulose, orcornmeal. The desiccants can be dried and reused.[108]Molecular sieves can be used to selectively absorb the water from the 95.6% ethanol solution.[116] Molecular sieves of pore-size 3 Å, a type ofzeolite, effectively sequester water molecules while excluding ethanol molecules. Heating the wet sieves drives out the water, allowing regeneration of their desiccant capability.[117]
Membranes can also be used to separate ethanol and water. Membrane-based separations are not subject to the limitations of the water-ethanol azeotrope because the separations are not based on vapor-liquid equilibria. Membranes are often used in the so-called hybrid membrane distillation process. This process uses a pre-concentration distillation column as the first separating step. The further separation is then accomplished with a membrane operated either in vapor permeation or pervaporation mode. Vapor permeation uses a vapor membrane feed and pervaporation uses a liquid membrane feed.
A variety of other techniques have been discussed, including the following:[108]
Salting usingpotassium carbonate to exploit its insolubility will cause a phase separation with ethanol and water. This offers a very small potassium carbonate impurity to the alcohol that can be removed by distillation. This method is very useful in purification of ethanol by distillation, as ethanol forms anazeotrope with water.
Pure ethanol and alcoholic beverages are heavilytaxed as psychoactive drugs, but ethanol has many uses that do not involve its consumption. To relieve the tax burden on these uses, most jurisdictions waive the tax when an agent has been added to the ethanol to render it unfit to drink. These includebittering agents such asdenatonium benzoate and toxins such as methanol,naphtha, and pyridine. Products of this kind are calleddenatured alcohol.[120][121]
Absolute or anhydrous alcohol refers to ethanol with a low water content. There are various grades with maximum water contents ranging from 1% to a few parts per million (ppm). Ifazeotropic distillation is used to remove water, it will contain trace amounts of the material separation agent (e.g. benzene).[122] Absolute alcohol is not intended for human consumption. Absolute ethanol is used as a solvent for laboratory and industrial applications, where water will react with other chemicals, and as fuel alcohol. Spectroscopic ethanol is an absolute ethanol with a low absorbance inultraviolet and visible light, fit for use as a solvent inultraviolet-visible spectroscopy.[123] Pure ethanol is classed as 200proof in the US, equivalent to 175 degrees proof in the UK system.[124] Rectified spirit, an azeotropic composition of 96% ethanol containing 4% water, is used instead of anhydrous ethanol for various purposes. Spirits of wine are about 94% ethanol (188 proof). The impurities are different from those in 95% (190 proof) laboratory ethanol.[125]
Ethanol is classified as a primary alcohol, meaning that the carbon that its hydroxyl group attaches to has at least two hydrogen atoms attached to it as well. Many ethanol reactions occur at its hydroxyl group.
This reaction, which is conducted on large scale industrially, requires the removal of the water from the reaction mixture as it is formed. Esters react in the presence of an acid or base to give back the alcohol and a salt. This reaction is known assaponification because it is used in the preparation of soap. Ethanol can also form esters with inorganic acids.Diethyl sulfate andtriethyl phosphate are prepared by treating ethanol with sulfur trioxide andphosphorus pentoxide respectively. Diethyl sulfate is a useful ethylating agent inorganic synthesis.Ethyl nitrite, prepared from the reaction of ethanol withsodium nitrite and sulfuric acid, was formerly used as adiuretic.
In the presence of acid catalysts, alcohols can be converted to alkenes such as ethanol to ethylene. Typicallysolid acids such asalumina are used.[126]
CH3CH2OH → H2C=CH2 + H2O
Since water is removed from the same molecule, the reaction is known asintramolecular dehydration. Intramolecular dehydration of an alcohol requires a high temperature and the presence of an acid catalyst such as sulfuric acid.[127] Ethylene produced from sugar-derived ethanol (primarily in Brazil) competes with ethylene produced from petrochemical feedstocks such as naphtha and ethane.[citation needed] At a lower temperature than that of intramolecular dehydration,intermolecular alcohol dehydration may occur producing a symmetrical ether. This is acondensation reaction. In the following example, diethyl ether is produced from ethanol:
Ethanol is a neutral molecule and thepH of a solution of ethanol in water is nearly 7.00. Ethanol can be quantitatively converted to itsconjugate base, theethoxide ion (CH3CH2O−), by reaction with analkali metal such assodium:[76]
The acidities of water and ethanol are nearly the same, as indicated by theirpKa of 15.7 and 16 respectively. Thus, sodium ethoxide and sodium hydroxide exist in an equilibrium that is closely balanced:
Upon treatment with halogens in the presence of base, ethanol gives the correspondinghaloform (CHX3, where X = Cl, Br, I). This conversion is called thehaloform reaction.[131]An intermediate in the reaction with chlorine is thealdehyde calledchloral, which formschloral hydrate upon reaction with water:[132]
Ethanol can be oxidized to acetaldehyde and further oxidized to acetic acid, depending on the reagents and conditions.[114] This oxidation is of no importance industrially, but in the human body, these oxidation reactions are catalyzed by the enzymeliver ADH. The oxidation product of ethanol, acetic acid, is a nutrient for humans, being a precursor toacetyl CoA, where the acetyl group can be spent as energy or used for biosynthesis.
Ethanol is similar tomacronutrients such as proteins, fats, and carbohydrates in that it provides calories. When consumed and metabolized, it contributes 7 kilocalories per gram viaethanol metabolism.[133]
Ethanol is very flammable and should not be used around an open flame.
Pure ethanol will irritate the skin and eyes.[134] Nausea,vomiting, and intoxication are symptoms of ingestion. Long-term use by ingestion can result in serious liver damage.[135] Atmospheric concentrations above one part per thousand are above the European Unionoccupational exposure limits.[135]
The fermentation of sugar into ethanol is one of the earliestbiotechnologies employed by humans. Ethanol has historically been identified variously as spirit of wine or ardent spirits,[136] and asaqua vitae or aqua vita. The intoxicating effects of its consumption have been known since ancient times. Ethanol has been used by humans since prehistory as the intoxicating ingredient of alcoholic beverages. Dried residue on 9,000-year-old pottery found in China suggests thatNeolithic people consumed alcoholic beverages.[137]
The inflammable nature of the exhalations of wine was already known to ancient natural philosophers such asAristotle (384–322 BCE),Theophrastus (c. 371–287 BCE), andPliny the Elder (23/24–79 CE).[138] However, this did not immediately lead to the isolation of ethanol, despite the development of more advanced distillation techniques in second- and third-centuryRoman Egypt.[139] An important recognition, first found in one of the writings attributed toJābir ibn Ḥayyān (ninth century CE), was that byadding salt to boiling wine, which increases the wine'srelative volatility, the flammability of the resulting vapors may be enhanced.[140] The distillation of wine is attested in Arabic works attributed toal-Kindī (c. 801–873 CE) and toal-Fārābī (c. 872–950), and in the 28th book ofal-Zahrāwī's (Latin: Abulcasis, 936–1013)Kitāb al-Taṣrīf (later translated into Latin asLiber servatoris).[141] In the twelfth century, recipes for the production ofaqua ardens ("burning water", i.e., ethanol) by distilling wine with salt started to appear in a number of Latin works, and by the end of the thirteenth century it had become a widely known substance among Western European chemists.[142]
In 1796, German-Russian chemistJohann Tobias Lowitz obtained pure ethanol by mixing partially purified ethanol (the alcohol-water azeotrope) with an excess of anhydrous alkali and then distilling the mixture over low heat.[147] French chemistAntoine Lavoisier described ethanol as a compound of carbon, hydrogen, and oxygen, and in 1807Nicolas-Théodore de Saussure determined ethanol's chemical formula.[148][149] Fifty years later,Archibald Scott Couper published the structural formula of ethanol, one of the first structural formulas determined.[150]
Ethanol was first prepared synthetically in 1825 byMichael Faraday. He found that sulfuric acid could absorb large volumes ofcoal gas.[151] He gave the resulting solution toHenry Hennell, a British chemist, who found in 1826 that it contained "sulphovinic acid" (ethyl hydrogen sulfate).[152] In 1828, Hennell and the French chemistGeorges-Simon Serullas independently discovered that sulphovinic acid could be decomposed into ethanol.[153][154] Thus, in 1825 Faraday had unwittingly discovered that ethanol could be produced from ethylene (a component of coal gas) byacid-catalyzed hydration, a process similar to current industrial ethanol synthesis.[155]
Ethanol was used as lamp fuel in the U.S. as early as 1840, but a tax levied on industrial alcohol during theCivil War made this use uneconomical. The tax was repealed in 1906.[156] Use as an automotive fuel dates back to 1908, with theFord Model T able to run onpetrol (gasoline) or ethanol.[157] It fuels somespirit lamps.
Ethanol intended for industrial use is often produced from ethylene.[158] Ethanol has widespread use as a solvent of substances intended for human contact or consumption, including scents, flavorings, colorings, and medicines. In chemistry, it is both a solvent and a feedstock for the synthesis of other products. It has a long history as a fuel for heat and light, and more recently as a fuel for internal combustion engines.
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^"49 CFR § 172.101 – Purpose and use of hazardous materials table". Legal Information Institute, Cornell University.Hazardous materials descriptions and proper shipping names: Ethanol or Ethyl alcohol or Ethanol solutions or Ethyl alcohol solutions; Hazard class or Division: 3; Identification Numbers: UN1170; PG: II; Label Codes: 3;
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^Turner C, Spanel P, Smith D (2006). "A longitudinal study of ethanol and acetaldehyde in the exhaled breath of healthy volunteers using selected-ion flow-tube mass spectrometry".Rapid Communications in Mass Spectrometry.20 (1):61–68.Bibcode:2006RCMS...20...61T.doi:10.1002/rcm.2275.PMID16312013.
^Swami, V. N. (2020).विद्याभराती जिल्हा मध्यवर्ती सहकारी बँक भारती परीक्षा मार्गदर्शक [Vidyabharti District Co-operative Bank recruitment examination guide (Bank clerk grade examination)] (in Marathi).Latur, Maharashtra, India: Vidyabharti Publication. p. 119.
^abcdKosaric N, Duvnjak Z, Farkas A, Sahm H, Bringer-Meyer S, Goebel O, Mayer D (2011). "Ethanol".Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. pp. 1–72.doi:10.1002/14356007.a09_587.pub2.ISBN978-3-527-30673-2.(subscription required)
^"Ethanol".Encyclopedia of chemical technology. Vol. 9. 1991. p. 82.
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^Jeong JS, Jeon H, Ko Km, Chung B, Choi GW (2012). "Production of anhydrous ethanol using various PSA (Pressure Swing Adsorption) processes in pilot plant".Renewable Energy.42:41–45.Bibcode:2012REne...42...41J.doi:10.1016/j.renene.2011.09.027.
^Rossini FD (1937). "Heats of Formation of Simple Organic Molecules".Ind. Eng. Chem.29 (12):1424–1430.doi:10.1021/ie50336a024.
^Calculated from heats of formation from CRC Handbook of Chemistry and Physics, 49th Edition, 1968–1969.
^Chakrabartty SK (1978). Trahanovsky WS (ed.).Oxidation in Organic Chemistry. New York: Academic Press. pp. 343–370.
^Reinhard J, Kopp E, McKusick BC, Röderer G, Bosch A, Fleischmann G (2007). "Chloroacetaldehydes".Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH.doi:10.1002/14356007.a06_527.pub2.ISBN978-3-527-30673-2.
^al-Hassan, Ahmad Y. (2009). "Alcohol and the Distillation of Wine in Arabic Sources from the 8th Century".Studies in al-Kimya': Critical Issues in Latin and Arabic Alchemy and Chemistry. Hildesheim: Georg Olms Verlag. pp. 283–298. (same content also available onthe author's websiteArchived 29 December 2015 at theWayback Machine).
^abHaw SG (2006)."Wine, women and poison".Marco Polo in China. Routledge. pp. 147–148.ISBN978-1-134-27542-7. Retrieved10 July 2016.The earliest possible period seems to be the Eastern Han dynasty... the most likely period for the beginning of true distillation of spirits for drinking in China is during the Jin and Southern Song dynasties
^Lowitz T (1796)."Anzeige eines, zur volkommen Entwasserung des Weingeistes nothwendig zu beobachtenden, Handgriffs" [Report of a task that must be done for the complete dehydration of wine spirits [i.e., alcohol-water azeotrope])].Chemische Annalen für die Freunde der Naturlehre, Aerznengelartheit, Haushaltungskunde und Manufakturen (in German).1:195–204.See pp. 197–198: Lowitz dehydrated the azeotrope by mixing it with a 2:1 excess of anhydrous alkali and then distilling the mixture over low heat.
^Couper AS (1858)."On a new chemical theory"(online reprint).Philosophical Magazine.16 (104–116). Retrieved3 September 2007.
^Faraday M (1825)."On new compounds of carbon and hydrogen, and on certain other products obtained during the decomposition of oil by heat".Philosophical Transactions of the Royal Society of London.115:440–466.doi:10.1098/rstl.1825.0022. In a footnote on page 448, Faraday notes the action of sulfuric acid on coal gas and coal-gas distillate; specifically, "The [sulfuric] acid combines directly with carbon and hydrogen; and I find when [the resulting compound is] united with bases [it] forms a peculiar class of salts, somewhat resembling the sulphovinates [i.e., ethyl sulfates], but still different from them."
^Sérullas GS (1828). Guyton de Morveau LB, Gay-Lussac JL, Arago F, Michel Eugène Chevreul, Marcellin Berthelot, Éleuthère Élie Nicolas Mascart, Albin Haller (eds.)."De l'action de l'acide sulfurique sur l'alcool, et des produits qui en résultent".Annales de Chimie et de Physique.39:152–186. On page 158, Sérullas mentions the production of alcohol from "sulfate acid d'hydrogène carboné" (hydrocarbon acid sulfate).
