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'''December 8, 2006 version of [[Ethanol]]'''
temporarily archived because this was the date of the last GA review. I will be using it to improve the existing version in anticipation of a new GA review on Sept 8, 2007. [[User:Karlhahn|Karl Hahn]] ([[User talk:Karlhahn|T]]) ([[Special:Contributions/Karlhahn|C]]) 22:20, 3 September 2007 (UTC)

:''This article is about the chemical compound. For drinks containing ethanol, see [[alcoholic beverage]]. For the use of ethanol as a fuel, see [[ethanol fuel]].  For its physiological effects, see [[effects of alcohol on the body]].''

<!-- Here is a table of data; skip past it to edit the text . -->
{| class="infobox"
! {{chembox header}} | Ethanol
|-
| align="center" colspan="2" | [[Image:Ethanol-skeletal.png|150px|Ethanol]]  [[Image:Ethanol-3D-vdW.png|150px|Ethanol]]
|-
! {{chembox header}} | General
|- 
| [[IUPAC nomenclature|Systematic name]]
| Ethanol
|-
| Other names
| Ethyl alcohol,<br/>grain alcohol,<br/>hydroxyethane,<br/>EtOH
|-
| [[Chemical formula|Molecular formula]]
| C<sub>2</sub>H<sub>6</sub>O <!--CH3CH2OH is semi-structural formula - the standard type of formula inserted in these infoboxes in the molecular formula, which is structural, and simply indicates the number of atoms of each element in the compound - so dimethyl ether and ethanol both have molecular formula C2H5OH.  This is standard in chemistry - if in doubt ask a chemist.-->
|-
| [[Simplified molecular input line entry specification|SMILES]]
| CCO
|-
| [[Molar mass]]
| 46.06844(232) g/mol
|-
| Appearance
| colourless clear liquid
|-
| [[CAS registry number|CAS number]]
| [64-17-5]
|-
! {{chembox header}} | Properties
|-
| [[Density]] and [[Phase (matter)|phase]]
| 0.789 g/cm³, liquid
|-
| [[Soluble|Solubility]] in [[Water (molecule)|water]]
| Fully [[miscible]]
|-
<!-- | Other solvents e.g. [[ethanol]], [[acetone]] -->
<!-- | solubility info on other solvents -->
<!-- |- -->
| [[Melting point]]
| &minus;114.3 °C (158.8 K)
|-
| [[Boiling point]]
| 78.4 °C (351.6 K)
|-Vapor Pressure at 298K=59.02mmHg

| [[Acid dissociation constant|Acidity]] (p''K''<sub>a</sub>)
| 15.9 (H<sup>+</sup> from OH group)
|-
| [[Viscosity]]
| 1.200 c[[Poise|P]] at 20 °C
|-
| [[Dipole#Molecular dipoles|Dipole moment]]
| 1.69 [[Debye|D]] (gas)
|-
! {{chembox header}} | Hazards <!--  Summary only- MSDS entry provides more complete information -->
|-
| [[Material safety data sheet|MSDS]]
| [[Ethanol (data page)#Material Safety Data Sheet|External MSDS]]
|-
| [[Directive 67/548/EEC|EU classification]]
| Flammable ('''F''')
|-
| [[NFPA 704]]
| {{NFPA 704|Flammability=3|Health=0|Reactivity=0}}
|-
| [[List of R-phrases|R-phrases]]
| {{R11}}
|-
| [[List of S-phrases|S-phrases]]
| {{S2}}, {{S7}}, {{S16}}
|-
| [[Flash point]]
| 13 °C (55.4 °F)
|-
| [[RTECS]] number
| KQ6300000
|-
! {{chembox header}} | [[Ethanol (data page)|Supplementary data page]]
|-
| [[Ethanol (data page)#Structure and properties|Structure & properties]] 
| [[Refractive index|''n'']], [[Dielectric constant|''ε<sub>r</sub>'']], etc. 
|-
| [[Ethanol (data page)#Thermodynamic properties|Thermodynamic data]] 
| Phase behaviour<br>Solid, liquid, gas
|-
| [[Ethanol (data page)#Spectral data|Spectral data]]
| [[UV/VIS spectroscopy|UV]], [[Infrared spectroscopy|IR]], [[NMR spectroscopy|NMR]], [[Mass spectrometry|MS]]
|-
! {{chembox header}} | Related compounds
|-
| Related [[alcohol]]s
| [[Methanol]], [[1-Propanol]]
|-
| Other heteroatoms 
| [[Ethylamine]], [[Ethyl chloride]],<br/> [[Ethyl bromide]], [[Ethanethiol]]
|-
| Substituted ethanols
| [[Ethylene glycol]], [[Ethanolamine]],<br/> [[2-Chloroethanol]]
|-
| Other compounds
| [[Acetaldehyde]], [[Acetic acid]]
|-
| {{chembox header}} | <small>Except where noted otherwise, data are given for<br> materials in their [[standard state|standard state (at 25°C, 100 kPa)]]<br/>[[wikipedia:Chemical infobox|Infobox disclaimer and references]]</small>
|-
|}
'''Ethanol''', also known as '''ethyl alcohol''' or [[Neutral grain spirit|grain alcohol]], is a flammable, colorless, mildly toxic [[chemical compound]] with a distinctive perfume-like [[odor]], and is the [[alcohol]] found in [[alcoholic beverage]]s. In common usage, it is often referred to simply as ''alcohol''. Its [[chemical formula|molecular formula]] is  variously represented as EtOH, C<sub>2</sub>H<sub>5</sub>OH or as its [[empirical formula]] [[Carbon|C]]<sub>2</sub>[[Hydrogen|H]]<sub>6</sub>[[Oxygen|O]].

== History ==
Ethanol has been used by humans since prehistory as the intoxicating ingredient in [[alcoholic beverage]]s.  Dried residues on 9000-year-old pottery found in northern [[mainland China]] imply the use of alcoholic beverages even among [[Neolithic]] peoples.<ref name="Roach">{{cite journal|author=Roach, J.|date=July 18, 2005|url=http://news.nationalgeographic.com/news/2005/07/0718_050718_ancientbeer.html|title= 9,000-Year-Old Beer Re-Created From Chinese Recipe.|journal=National Geographic News|accessdate= 2007-09-03}}</ref> Its isolation as a relatively pure compound was first achieved by [[Persian people|Persian]] alchemists who developed the art of [[distillation]] during the [[Abbasid caliphate]], the most notable of whom was [[Al-Razi]].  The writings attributed to [[Jabir Ibn Hayyan]] (Geber) (721-815) mention the flammable vapors of boiled wine.  [[Al-Kindī]] (801-873) unambiguously described the distillation of wine.<ref name="al-Hassan">{{cite web|author=[[Ahmad Y Hassan]]|url=http://www.gabarin.com/ayh/Notes/Notes%207.htm|title=Alcohol and the Distillation of Wine in Arabic Sources.|accessdate=2007-09-03|publisher=www.history-science-technology.com}}</ref> Distillation of ethanol from [[water]] yields a product that is at most 95.6% ethanol, because ethanol forms an [[azeotrope]] with water.  Absolute ethanol was first obtained in 1796 by Johann Tobias Lowitz, by filtering distilled ethanol through [[Activated carbon|charcoal]].

[[Antoine Lavoisier]] described ethanol as a compound of carbon, hydrogen, and oxygen, and in 1808, [[Nicolas-Théodore de Saussure]] determined ethanol's chemical formula, {{inote|EB (1911)}} and fifty years later, in 1858, [[Archibald Scott Couper]] published a structural formula for ethanol: this places ethanol among the first chemical compounds to have their chemical structures determined.<ref name="Couper">{{cite journal|author=Couper, A.S.|year=1858|title=On a new chemical theory|journal=Philosophical magazine (online reprint)|volume=16|issue=104&ndash;116|url=http://web.lemoyne.edu/~giunta/couper/couper.html|accessdate=2007-09-03}}</ref>

Ethanol was first prepared synthetically in 1826, through the independent efforts of Henry Hennel in Great Britain and S.G. Sérullas in [[France]]. [[Michael Faraday]] prepared ethanol by the [[Acid catalysis|acid-catalysed]] hydration of [[ethylene]] in 1828, in a process similar to that used for industrial ethanol synthesis today.<ref name="Hennell">{{cite journal|author=Hennell, H. |year=1828|title=On the mutual action of sulfuric acid and alcohol, and on the nature of the process by which ether is formed.|journal=Philosophical Transactions|volume=118|issue=365&ndash;371}}</ref>

Ethanol served as lamp fuel in pre-Civil War United States and helped power early Model T automobiles. But the fuel couldn't compete with the low cost and availability of petroleum, and ethanol faded from the public eye. The recent rise in oil prices has spurred renewed interest.<ref name="Miller">{{cite news|author=Miller, J.|year=2006|title=Petroleum pushed aside grain-based fuel|publisher=Chicago Tribune|date=August 27, 2006|volume=5|issue=8}}</ref>

==Physical properties==
Ethanol's hydroxyl group is able to participate in hydrogen bonding. At the molecular level, liquid ethanol consists of hydrogen-bonded pairs of ethanol molecules; this phenomenon renders ethanol more viscous and less volatile than less polar organic compounds of similar molecular weight. In the vapor phase, there is little hydrogen bonding; ethanol vapor consists of individual ethanol molecules.

Ethanol has a [[refractive index]] of 1.3614.

Ethanol is a versatile solvent. It is miscible with water and with most organic liquids, including nonpolar liquids such as aliphatic hydrocarbons. Organic solids of low molecular weight are usually soluble in ethanol. Among ionic compounds, many monovalent salts are at least somewhat soluble in ethanol, with salts of large, polarizable ions being more soluble than salts of smaller ions. Most salts of polyvalent ions are practically insoluble in ethanol.

Furthermore, ethanol is used as a solvent in dissolving medicines, food flavourings and colourings that do not dissolve easily in water. Once the non-polar material is dissolved in the ethanol, water can be added to prepare a solution that is mostly water. The ethanol molecule has a water-loving ([[hydrophilic]]) -OH group that helps it dissolve polar molecules and ionic substances. The short, water-fearing ([[hydrophobic]]) hydrocarbon chain CH<sub>3</sub>CH<sub>2</sub>- can attract non-polar molecules. Thus ethanol can dissolve both polar and non-polar substances.

Several unusual phenomena are associated with mixtures of ethanol and water. Ethanol-water mixtures have less volume than their individual components: a mixture of equal volumes ethanol and water has only 95.6% of the volume of equal parts ethanol and water, unmixed. The addition of even a few percent of ethanol to water sharply reduces the surface tension of water. This property partially explains the tears of wine phenomenon: when wine is swirled inside a glass, ethanol evaporates quickly from the thin film of wine on the wall of the glass. As its 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.

== Chemistry ==

;This material added 2007-09-04 as draft of replacement for this section
;End of new draft material

[[Image:Ethanol_pc.gif|thumb|200px|Chemical formula of ethanol, (C is [[carbon]], the dash is a [[single bond]], H is [[hydrogen]], O is [[oxygen]])]]
The chemistry of ethanol is largely that of its [[hydroxyl]] group.

; Acid-base chemistry

Ethanol's hydroxyl proton is very weakly acidic; it is an even weaker acid than water. Ethanol can be quantitatively converted to its [[conjugate base]], the [[ethoxide]] ion (CH<sub>3</sub>CH<sub>2</sub>O<sup>−</sup>), by reaction with an [[alkali metal]] such as [[sodium]].  This reaction evolves [[Hydrogen|hydrogen gas]]:

: 2CH<sub>3</sub>CH<sub>2</sub>OH + 2[[sodium|Na]] → 2CH<sub>3</sub>CH<sub>2</sub>ONa + [[hydrogen|H<sub>2</sub>]]

; Nucleophilic substitution

In [[aprotic solvent]]s, ethanol reacts with [[hydrogen halide]]s to produce [[ethyl halide]]s such as [[ethyl chloride]] and [[ethyl bromide]] via [[nucleophilic substitution]]:

: CH<sub>3</sub>CH<sub>2</sub>OH + [[hydrochloric acid|HCl]] → [[ethyl chloride|CH<sub>3</sub>CH<sub>2</sub>Cl]] + [[water|H<sub>2</sub>O]]

: CH<sub>3</sub>CH<sub>2</sub>OH + [[Hydrobromic acid|HBr]] → [[Ethyl bromide|CH<sub>3</sub>CH<sub>2</sub>Br]] + [[water|H<sub>2</sub>O]]

Ethyl halides can also be produced by reacting ethanol by more specialized [[Halogenation|halogenating agent]]s, such as [[thionyl chloride]] for preparing ethyl chloride, or [[phosphorus tribromide]] for preparing ethyl bromide.

; Esterification

Under acid-catalysed conditions, ethanol reacts with [[carboxylic acid]]s to produce ethyl [[ester]]s and water:

: [[carboxylic acid|RCOOH]] + HOCH<sub>2</sub>CH<sub>3</sub> → [[ester|RCOOCH<sub>2</sub>CH<sub>3</sub>]] + [[water|H<sub>2</sub>O]]

The reverse reaction, [[hydrolysis]] of the resulting ester back to ethanol and the carboxylic acid, limits the extent of reaction, and high yields are unusual unless water can be removed from the reaction mixture as it is formed.  Esterification can also be carried out using more a reactive derivative of the carboxylic acid, such as an [[acyl chloride]] or [[acid anhydride]].

Ethanol can also form esters with inorganic acids.  [[Diethyl sulfate]] and [[triethyl phosphate]], prepared by reacting ethanol with [[sulfuric acid|sulfuric]] and [[phosphoric acid]], respectively, are both useful ethylating agents in [[organic synthesis]].  [[Ethyl nitrite]], prepared from the reaction of ethanol with [[sodium nitrite]] and [[sulfuric acid]], was formerly a widely-used [[diuretic]]. 

; Dehydration

Strong acids, such as sulfuric acid, can catalyse ethanol's dehydration to form either [[diethyl ether]] or [[ethylene]]:

: 2 CH<sub>3</sub>CH<sub>2</sub>OH → [[diethyl ether|CH<sub>3</sub>CH<sub>2</sub>OCH<sub>2</sub>CH<sub>3</sub>]] + [[water|H<sub>2</sub>O]]

: CH<sub>3</sub>CH<sub>2</sub>OH → [[ethylene|H<sub>2</sub>C=CH<sub>2</sub>]] + [[water|H<sub>2</sub>O]]

Which product, diethyl ether or ethylene, predominates depends on the precise reaction conditions.

; Oxidation 

Ethanol can be oxidized to [[acetaldehyde]], and further oxidized to [[acetic acid]].  In the human body, these oxidation reactions are catalysed by [[enzyme]]s. In the laboratory, aqueous solutions of strong oxidizing agents, such as [[chromic acid]] or [[potassium permanganate]], oxidize ethanol to acetic acid, and it is difficult to stop the reaction at acetaldehyde at high yield.  Ethanol can be oxidized to acetaldehyde, without overoxidation to acetic acid, by reacting it with [[pyridinium chromic chloride]].

; Combustion

[[image:Chemistry, Combustion of Ethanol 002.jpg|thumb|right|Ethanol combusting in the confines of an evaporating dish]]

[[Combustion]] of ethanol forms [[carbon dioxide]] and [[water]]:

:C<sub>2</sub>H<sub>5</sub>OH + 3 O<sub>2</sub> → 2 CO<sub>2</sub> +3 H<sub>2</sub>O

== Production ==
[[Image:Ethanol Flasche.jpg|thumb|left|94% denatured ethanol sold in a bottle for household use]]

Ethanol is produced both as a [[petrochemical]], through the hydration of [[ethylene]], and biologically, by [[fermentation (biochemistry)|fermenting]] sugars with [[yeast]].

=== Ethylene hydration ===
Ethanol for use as industrial feedstock is most often made from [[petrochemical]] feedstocks, typically by the [[acid]]-[[catalysis|catalyzed]] hydration of ethene, represented by the [[chemical equation]]

: [[ethylene|C<sub>2</sub>H<sub>4</sub>]] + [[water|H<sub>2</sub>O]] → CH<sub>3</sub>CH<sub>2</sub>OH

The catalyst is most commonly [[phosphoric acid]], [[adsorption|adsorbed]] onto a porous support such as [[diatomaceous earth]] or [[charcoal]]; this catalyst was first used for large-scale ethanol production by the [[Shell Oil Company]] in 1947.<ref name="ECT4 820">Lodgsdon, J.E. (1994). "Ethanol." In J.I. Kroschwitz (Ed.) ''Encyclopedia of Chemical Technology, 4th ed.'' vol. 9, p. 820. New York: John Wiley & Sons.</ref>  Solid catalysts, mostly various metal oxides, have also been mentioned in the chemical literature.

In an older process, first practiced on the industrial scale in 1930 by [[Union Carbide]],<ref name="ECT4 817">Lodgsdon, J.E. (1994). p. 817</ref> but now almost entirely obsolete, ethene was hydrated indirectly by reacting it with concentrated [[sulfuric acid]] to product [[ethyl sulfate]], which was then [[hydrolysis|hydrolysed]] to yield ethanol and regenerate the sulfuric acid:<ref name="m_and_b">{{cite book|Morrison, Robert Thornton; Boyd, Robert Neilson|title=Organic Chemistry, 2nd ed.|year=1972|publisher=Allyn and Bacon, inc.}}</ref>

: [[ethylene|C<sub>2</sub>H<sub>4</sub>]] + [[sulfuric acid|H<sub>2</sub>SO<sub>4</sub>]] → [[ethyl sulfate|CH<sub>3</sub>CH<sub>2</sub>SO<sub>4</sub>H]]

: [[ethyl sulfate|CH<sub>3</sub>CH<sub>2</sub>SO<sub>4</sub>H]] + [[water|H<sub>2</sub>O]] → CH<sub>3</sub>CH<sub>2</sub>OH + [[sulfuric acid|H<sub>2</sub>SO<sub>4</sub>]]

=== Fermentation ===
Ethanol for use in [[alcoholic beverage]]s, and the vast majority of ethanol for use as fuel, is produced by fermentation: when certain species of [[yeast]] (most importantly, ''[[Saccharomyces cerevisiae]]'') [[metabolism|metabolize]] [[saccharide|sugar]] in the absence of [[oxygen]], they produce ethanol and [[carbon dioxide]].  The overall chemical reaction conducted by the yeast may be represented by the chemical equation

: [[glucose|C<sub>6</sub>H<sub>12</sub>O<sub>6</sub>]] → 2 CH<sub>3</sub>CH<sub>2</sub>OH + 2 [[carbon dioxide|CO<sub>2</sub>]]

The process of culturing yeast under conditions to produce alcohol is referred to as [[brewing]].  Brewing can only produce relatively dilute concentrations of ethanol in water; concentrated ethanol solutions are [[toxicity|toxic]] to yeast.  The most ethanol-tolerant strains of yeast can survive in up to about 25% ethanol (by volume).

During the fermentation process, it is important to prevent oxygen getting to the ethanol, since otherwise the ethanol would be oxidised to [[acetic acid]] (vinegar). Also, in the presence of oxygen, the yeast would undergo [[aerobic respiration]] to produce just [[carbon dioxide]] and water, without producing ethanol. 

In order to produce ethanol from starchy materials such as [[cereal grain]]s, the starch must first be broken down into sugars.  In brewing [[beer]], this has traditionally been accomplished allowing the grain to germinate, or [[malt]].  In the process of germination, the seed produces [[enzyme]]s that can break its starches into sugars.  For fuel ethanol, this hydrolysis of starch into glucose is accomplished more rapidly by treatment with dilute sulfuric acid, [[fungus|fungal]] [[amylase]] enzymes, or some combination of the two.

At [[petroleum]] prices like those that prevailed through much of the 1990s, ethylene hydration was a decidedly more economical process than fermentation for producing purified ethanol.  Recent increases in petroleum prices, coupled with perennial [[uncertainty]] in agricultural prices, make forecasting the relative production costs of fermented versus petrochemical ethanol difficult at the present time.

=== Purification ===
[[Image:IR_spectrum_of_ethanol.gif|thumb|right|350px|Mid-[[Infrared spectrum]] of a thin film of liquid ethanol.]]
[[Image:Ethanol near IR spectrum.png|thumb|right|350px|[[Near infrared spectrum]] of liquid ethanol.]]
The product of either ethylene hydration or brewing is an ethanol-water mixture.  For most industrial and fuel uses, the ethanol must be purified.  [[Fractional distillation]] can concentrate ethanol to 95.6% volume; the mixture of 95.6% ethanol and 4.4% water (percentage by weight) is an [[azeotrope]] with a boiling point of 78.2 °C, and cannot be further purified by distillation. Therefore, 95% ethanol in water is a fairly common solvent.

After distillation ethanol can be further purified by "drying" it using lime or salt.  Lime, ([[calcium oxide]]), when mixed with the water in ethanol will form [[calcium hydroxide]], which then can be separated.  Dry salt will dissolve some of the water content of the ethanol as it passes through, leaving a purer alcohol.<ref>{{cite book | author = Mathewson, S.W. | title = The Manual for the Home and Farm Production of Alcohol Fuel | url = http://www.journeytoforever.org/biofuel_library/ethanol_manual/manual_ToC.html | accessdate = 2006-07-01 | year = 1980 | publisher = Ten Speed Press | chapter = Drying the Alcohol | chapterurl = http://www.journeytoforever.org/biofuel_library/ethanol_manual/manual12.html}}</ref>

Several approaches are used to produce absolute ethanol.  The ethanol-water azeotrope can be broken by the addition of a small quantity of [[benzene]].  Benzene, ethanol, and water form a ternary azeotrope with a boiling point of 64.9 °C.  Since this azeotrope is more volatile than the ethanol-water azeotrope, it can be fractionally distilled out of the ethanol-water mixture, extracting essentially all of the water in the process.  The bottoms from such a distillation is [[anhydrous]] ethanol, with several [[parts per million]] residual benzene.  Benzene is toxic to humans, and [[cyclohexane]] has largely supplanted benzene in its role as the entrainer in this process.

Alternatively, a [[molecular sieve]] can be used to selectively absorb the water from the 95.6% ethanol solution.  Synthetic [[zeolite]] in pellet form can be used, as well as a variety of plant-derived absorbents, including [[cornmeal]], [[straw]], and [[sawdust]].  The zeolite bed can be regenerated essentially an unlimited number of times by drying it with a blast of hot [[carbon dioxide]].  Cornmeal and other plant-derived absorbents cannot readily be regenerated, but where ethanol is made from grain, they are often available at low cost.  Absolute ethanol produced this way has no residual benzene, and can be used as fuel, or, when diluted, can even be used to fortify port and sherry in traditional winery operations. Pervaporation and Vapor Permeation are membrane processes that breaks the water ethanol azeotrope and does not need regeneration.

At pressures less than atmospheric pressure, the composition of the ethanol-water azeotrope shifts to more ethanol-rich mixtures, and at pressures less than 70 [[torr]] (9.333 kPa) , there is no azeotrope, and it is possible to distill absolute ethanol from an ethanol-water mixture.  While vacuum distillation of ethanol is not presently economical, pressure-swing distillation is a topic of current research.  In this technique, a reduced-pressure distillation first yields an ethanol-water mixture of more than 95.6% ethanol. Then, fractional distillation of this mixture at atmospheric pressure distills off the 95.6% azeotrope, leaving anhydrous ethanol at the bottoms.

=== Prospective technologies ===
{{main|Cellulosic ethanol}}
Glucose for fermentation into ethanol can also be obtained from [[cellulose]]. Until recently, however, the cost of the [[cellulase]] enzymes that could hydrolyse cellulose has been prohibitive. The [[Canada|Canadian]] firm [[Iogen]] brought the first cellulose-based ethanol plant on-stream in 2004.<ref name="Ritter">Ritter, S.K. ([[May 31]] [[2004]]). "Biomass or Bust." ''Chemical & Engineering News'' '''82'''(22), 31–34.</ref> The primary consumer thus far has been the Canadian government, which, along with the United States government (particularly the Department of Energy's National Renewable Energy Laboratory), has invested millions of dollars into assisting the commercialization of cellulosic ethanol.  Realization of this technology would turn a number of cellulose-containing agricultural byproducts, such as [[corncob]]s, [[straw]], and [[sawdust]], into renewable energy resources.

Cellulosic materials typically contain, in addition to [[cellulose]], other [[polysaccharide]]s, including [[hemicellulose]].  When [[hydrolysis|hydrolysed]], hemicellulose breaks down into mostly five-carbon sugars such as [[xylose]].  ''S. cerevisiae'', the yeast most commonly used for ethanol production, cannot metabolize xylose.  Other yeasts and bacteria are under investigation to metabolize xylose and so improve the ethanol yield from cellulosic material.<ref>http://www.lub.lu.se/cgi-bin/show_diss.pl?db=global&fname=tec_748.html</ref><ref>http://www.metabolicengineering.gov/me2001/2001Kompala.pdf</ref> 

The [[anaerobic bacteria|anaerobic bacterium]] ''Clostridium ljungdahlii'', recently discovered in commercial chicken wastes, can produce ethanol from single-carbon sources including [[synthesis gas]], a mixture of [[carbon monoxide]] and [[hydrogen]] that can be generated from the partial [[combustion]] of either [[fossil fuel]]s or [[biomass]].  Use of these bacteria to produce ethanol from synthesis gas has progressed to the pilot plant stage at the [[BRI Energy]] facility in [[Fayetteville, Arkansas]];<ref>http://www.brienergy.com/</ref> in the BRI process, the heat released by gasification can be used to co-produce electricity with ethanol.

Another prospective technology is the closed-loop ethanol plant. Ethanol produced from corn has a number of critics who suggest that it is primarily just recycled fossil fuels because of the energy required to grow the grain and convert it into ethanol. However, the closed-loop ethanol plant attempts to address this criticism. In a closed-loop plant, the energy for the distillation comes from fermented manure, produced from cattle that have been fed the by-products from the distillation. The leftover manure is then used to fertilize the soil used to grow the grain. Such a process is expected to have a much lower fossil fuel requirement.<ref name="Rapier-1">Rapier, R. ([[June 26]] [[2006]]) [http://i-r-squared.blogspot.com/2006/06/e3-biofuels-responsible-ethanol.html "E3 Biofuels: Responsible Ethanol"] R-Squared Energy Blog</ref>

==Ethanol==
=== Denatured alcohol ===
{{Main|Denatured alcohol}}

In most jurisdictions, the sale of ethanol, as a pure substance, or in the form of alcoholic beverages, is heavily taxed.  In order to relieve non-beverage industries of this tax burden, governments specify formulations for denatured alcohol, which consists of ethanol blended with various [[additive]]s to render it unfit for human consumption.  These additives, called [[denaturant]]s, are generally either toxic (such as [[methanol]]) or have unpleasant tastes or odors (such as [[denatonium benzoate]]).

Specialty denatured alcohols are denatured alcohol formulations intended for a particular industrial use, containing denaturants chosen so as not to interfere with that use.  While they are not taxed, purchasers of specialty denatured alcohols must have a government-issued permit for the particular formulation they use and must comply with other regulations.

Completely denatured alcohols are formulations that can be purchased for any legal purpose, without permit, bond, or other regulatory compliance. It is intended that it be difficult to isolate a product fit for human consumption from completely denatured alcohol.  For example, the completely denatured alcohol formulation used in the [[United Kingdom]] contains (by volume) 89.66% ethanol, 9.46% methanol, 0.50% [[pyridine]], 0.38% [[naphtha]], and is dyed purple with [[methyl violet]].<ref>Great Britain (2005). ''[http://www.opsi.gov.uk/si/si2005/20051524.htm The Denatured Alcohol Regulations 2005].'' Statutory Instrument 2005 No. 1524. </ref>

===Hydrous and anhydrous ethanol===
Hydrous and anhydrous ethanol are terms used to describe ethanol by the type of process used to covert biomass into fuel. There are different prices for each anhydrous and hydrous ethanol depending on market demands.

The term hydrous pyrolysis is sometimes used to encompass [[thermolysis]] in the presence of water, such as steam cracking of oil, or more generally hydrous pyrolysis. An example of the latter is thermal depolymerization of organic waste into light [[crude oil]].

Anhydrous (without water) pyrolysis can be used to produce liquid fuel similar to [[diesel]] from solid biomass. The most common technique uses very low residence times (<2 seconds) and high heating rates using a temperature between 350-500 °C. It is called either fast or flash pyrolysis.'

Anhydrous Alcohol can also be produced from hydrous(95-96%) alcohol using [[desiccation|drying agents]] like [[molecular sieve]]s, or by [[azeotropic distillation]], [[extractive distillation]] techniques.

===Absolute ethanol===
Absolute or anhydrous alcohol generally refers to purified ethanol, containing no more than one percent [[water]].

It is not possible to obtain absolute alcohol by simple [[fractional distillation]], because a mixture containing around 95.6% [[alcohol]] and 4.4% water becomes a constant [[boiling]] [[mixture]] (an [[azeotrope|azeotropic]] mixture). In one common industrial method to obtain 100% pure alcohol, a small quantity of [[benzene]] is added to [[rectified spirit]] and the mixture is then distilled. Absolute alcohol is obtained in third fraction that distills over at 78.2 [[degree Celsius|°C]] (351.3 [[kelvin|K]]).

Because a small amount of the benzene used remains in the solution, absolute alcohol produced by this method is not suitable for consumption as benzene is [[carcinogenic]].

There is also an absolute alcohol production process by [[desiccation]] using [[glycerol]]. Alcohol produced by this method is known as spectroscopic alcohol - so called because the absence of benzene makes it suitable as a solvent in [[spectroscopy]].

Currently, the most popular method of purification past 95.6% purity is desiccation using adsorbents such as starch or [[zeolite]]s.  These adsorb water preferentially.

== Feedstocks ==
Currently the main feedstock in the United States for the production of ethanol is corn (see the [[Renewable Fuels Association]]'s list of U.S. ethanol for a complete list and feedstock utilized.  Approximately 2.8 gallons of ethanol are produced from one bushel of corn.  While much of the corn turns into ethanol, some of the corn also yields by-products such as DDGS (distillers dried grains with solubles) that can be used to fullfill a portion of the diet of livestock.  A bushel of corn produces about 18 pounds of DDGS [http://www.ethanolrfa.org/industry/locations/]). 

Trials of a new crop, [[switchgrass]], are showing much greater yields.{{fact}} 

The dominant ethanol feedstock in warmer regions is [[sugarcane]].

In some parts of Europe, particularly France and Italy, wine is used as a feedstock due to [[wine lake|massive oversupply]].

== Use ==
=== As a fuel===
[[Image:Ethanol_Car.jpg|thumb|225px|right|A [[Ford Taurus]] "fueled by clean burning ethanol" owned by [[New York City]].]]
{{main|ethanol fuel}}

The largest single use of ethanol is as a motor [[fuel]] and [[fuel additive]].  The largest national fuel ethanol industries exist in [[Brazil]] (all fuel sold in Brazil contains at least 20% ethanol).<ref name="WaPo-Brazil">Reel, M. ([[August 19]] [[2006]]) [http://www.washingtonpost.com/wp-dyn/content/article/2006/08/19/AR2006081900842.html "Brazil's Road to Energy Independence"] The Washington Post.</ref>  One method of production is through fermentation of [[sugar]]. Ethanol creates very little pollution when being burned. Millions more acres of land are needed if ethanol is to be used to replace gasoline.  Pure ethanol has a lower energy content than [[gasoline]] (about 30% less energy per unit volume).<ref name="Rapier-2">Rapier, R. ([[May 25]] [[2006]]) [http://i-r-squared.blogspot.com/2006/05/e85-spinning-our-wheels.html "E85: Spinning Our Wheels"] R-Squared Energy Blog</ref><ref name=eere.energy.gov>[http://www.eere.energy.gov/afdc/pdfs/fueltable.pdf Fueltable (pdf)]</ref>  At gas stations, ethanol is contained in a mix of ethanol and gasoline, otherwise known as gasohol. In the United States, the color yellow (symbolizing the color of corn) has become associated with the fuel and is commonly used on fuel pumps and labels.

According to the Renewable Fuels Association, as of November 2006; 107 grain ethanol biorefineries in the United States have the capacity to produce 5.1 billion gallons of ethanol.  An additional 56 construction projects underway (in the U.S.) can add 3.8 billion gallons of new capacity in the next 18 months.  Over time, it is believed that a material portion of the ~150 billion gallon per year market for gasoline will begin to be replaced with fuel ethanol.  [http://www.ethanolrfa.org/media/press/rfa/view.php?id=909] Growth in fuel ethanol in the United States is largely being driven by financial incentives that naturally exist when oil prices are over a certain level, as ethanol typically costs under $1.50 per gallon to manufacture (of course this is sensitive to corn prices) and is exempt from the $0.52 per gallon federal gasoline tax.  However, the United States RFS (renewable fuel standard) requires that 4 billion gallons of "renewable fuel" be used in 2006 and this requirement will grow to 7.5 billion gallons per annum by 2012.[http://www.epa.gov/otaq/renewablefuels/].

=== Alcoholic beverages ===
{{main|Alcoholic beverage}}

Alcoholic beverages vary considerably in their ethanol content and in the foodstuffs from which they are produced.  Most alcoholic beverages can be broadly classified as [[fermented beverage]]s, beverages made by the action of yeast on sugary foodstuffs, or as [[distilled beverage]]s, beverages whose preparation involves concentrating the ethanol in fermented beverages by [[distillation]].  The ethanol content of a beverage is usually measured in terms of the volume fraction of ethanol in the beverage, expressed either as a percentage or in [[alcoholic proof]] units.

Fermented beverages can be broadly classified by the foodstuff from which they are fermented.  [[Beer]]s are made from [[cereal grain]]s or other [[starch]]y materials, [[wine]]s and [[cider]]s from [[fruit juice]]s, and [[mead]]s from [[honey]].  Cultures around the world have made fermented beverages from numerous other foodstuffs, and local and national names for various fermented beverages abound.  Fermented beverages may contain up to 15&ndash;20% ethanol by volume, the upper limit being set by the yeast's tolerance for ethanol, or by the amount of sugar in the starting material.

Distilled beverages are made by distilling fermented beverages.  Broad categories of distilled beverages include [[whisky|whiskies]], distilled from fermented cereal grains; [[brandy|brandies]], distilled from fermented fruit juices, and [[rum]], distilled from fermented [[molasses]] or [[sugarcane]] juice.  [[Vodka]] and similar [[neutral grain spirits]] can be distilled from any fermented material (grain or [[potatoes]] is most common); these spirits are so thoroughly distilled that no tastes from the particular starting material remain.  Numerous other spirits and liqueurs are prepared by infusing flavors from [[fruit]]s, [[herb]]s, and [[spice]]s into distilled spirits.  A traditional example is [[gin]], the infusion of [[juniper]] berries into neutral grain alcohol.

In a few beverages, ethanol is concentrated by means other than distillation.  [[Applejack]] is traditionally made by [[freeze distillation]]: water is frozen out of fermented [[apple cider]], leaving a more ethanol-rich liquid behind.  [[Fortified wine]]s are prepared by adding brandy or some other distilled spirit to partially-fermented wine.  This kills the yeast and conserves some of the [[sugar]] in grape juice; such beverages are not only more ethanol-rich, but also sweeter than other wines.

=== Chemicals derived from ethanol ===
; Ethyl esters

In the presence of an acid catalyst (typically [[sulfuric acid]]) ethanol reacts with [[carboxylic acid]]s to produce ethyl [[ester]]s:

: CH<sub>3</sub>CH<sub>2</sub>OH + [[carboxylic acid|RCOOH]] → RCOOCH<sub>2</sub>CH<sub>3</sub> + [[water|H<sub>2</sub>O]]

The two largest-volume ethyl esters are [[ethyl acrylate]] (from ethanol and [[acrylic acid]]) and [[ethyl acetate]] (from ethanol and [[acetic acid]]).  Ethyl acrylate is a monomer used to prepare [[acrylate polymers]] for use in [[coating]]s and [[adhesive]]s.  Ethyl acetate is a common solvent used in paints, coatings, and in the pharmaceutical industry; its most familiar application in the household is as a solvent for [[nail polish]].  A variety of other ethyl esters are used in much smaller volumes as [[artificial flavoring|artificial fruit flavorings]].

; Vinegar

[[Vinegar]] is a dilute solution of [[acetic acid]] prepared by the action of ''[[Acetobacter]]'' bacteria on ethanol solutions.  Although traditionally prepared from alcoholic beverages including [[wine]], [[apple cider]], and unhopped [[beer]], vinegar can also be made from solutions of industrial ethanol.  Vinegar made from distilled ethanol is called "distilled vinegar", and is commonly used in food [[pickling]] and as a condiment.

; Ethylamines

When heated to 150&ndash;220 °C over a [[silica]]- or [[alumina]]-supported [[nickel]] catalyst, ethanol and [[ammonia]] react to produce [[ethylamine]].  Further reaction leads to [[diethylamine]] and [[triethylamine]]:

: CH<sub>3</sub>CH<sub>2</sub>OH + [[ammonia|NH<sub>3</sub>]] → [[ethylamine|CH<sub>3</sub>CH<sub>2</sub>NH<sub>2</sub>]] + [[water|H<sub>2</sub>O]]
: CH<sub>3</sub>CH<sub>2</sub>OH + [[ethylamine|CH<sub>3</sub>CH<sub>2</sub>NH<sub>2</sub>]] → [[diethylamine|(CH<sub>3</sub>CH<sub>2</sub>)<sub>2</sub>NH]] + [[water|H<sub>2</sub>O]]
: CH<sub>3</sub>CH<sub>2</sub>OH  + [[diethylamine|(CH<sub>3</sub>CH<sub>2</sub>)<sub>2</sub>NH]] → [[triethylamine|(CH<sub>3</sub>CH<sub>2</sub>)<sub>3</sub>N]] + [[water|H<sub>2</sub>O]]

The ethylamines find use in the synthesis of pharmaceuticals, agricultural chemicals, and [[surfactant]]s.

; Other chemicals

Ethanol in the past has been used commercially to synthesize dozens of other high-volume chemical commodities.  At the present, it has been supplanted in many applications by less costly petrochemical feedstocks.  However, in markets with abundant agricultural products, but a less developed petrochemical infrastructure, such as the [[People's Republic of China]], [[Pakistan]], [[India]], and [[Brazil]], ethanol can be used to produce chemicals that would be produced from petroleum in the West, including [[ethylene]] and [[butadiene]].

=== Other uses ===
Ethanol is easily [[soluble]] in [[water (molecule)|water]] in all proportions with a slight overall decrease in volume when the two are mixed.  Absolute ethanol and 95% ethanol  are themselves good [[solvent]]s, somewhat less polar than water and used in [[perfume]]s, [[paint]]s and [[tincture]]s. Other proportions of ethanol with water or other solvents can also be used as a solvent. Alcoholic drinks have a large variety of tastes because various flavor compounds are dissolved during [[brewing]]. When ethanol is produced as a mixing beverage it is a [[neutral grain spirit]].

Ethanol is used in medical wipes and in most common antibacterial hand sanitizer gels at a concentration of about 62% ([[percentage]] by weight, not volume) as an [[antiseptic]]. The peak of the disinfecting power occurs around 70% ethanol;  stronger and weaker solutions of ethanol have a lessened ability to disinfect. Solutions of this strength are often used in laboratories for disinfecting work surfaces.  Ethanol kills organisms by denaturing their [[protein]]s and dissolving their [[lipid]]s and is effective against most [[bacterium|bacteria]] and [[fungus|fungi]], and many [[virus]]es, but is ineffective against bacterial [[spore]]s. Alcohol does not act like an [[antibiotic]] and is not effective against [[infection]]s by ingestion. Ethanol in the low concentrations typically found in most alcoholic beverages does not have useful disinfectant or antiseptic properties, internally or externally.

Wine with less than 16% ethanol cannot protect itself against bacteria.  Because of this, [[port wine|port]] is often fortified with ethanol to at least 18% ethanol by volume to halt [[fermentation (food)|fermentation]] for retaining sweetness and in preparation for aging, at which point it becomes possible to prevent the invasion of bacteria into the port, and to store the port for long periods of time in wooden containers that can 'breathe', thereby permitting the port to age safely without spoiling.  Because of ethanol's disinfectant property, alcoholic beverages of 18% ethanol or more by volume can be safely stored for a very long time.

== Metabolism and toxicology ==
{{Main|Ethanol metabolism}}

Pure ethanol is a tasteless liquid with a strong and distinctive odor that produces a characteristic heat-like sensation when brought into contact with the tongue or mucous membranes.  When applied to open wounds (as for disinfection) it produces a strong stinging sensation.  Pure or highly concentrated ethanol may permanently damage living tissue on contact.  Ethanol applied to unbroken skin cools the skin rapidly through evaporation.

In the human body, ethanol is first oxidized to [[acetaldehyde]], and then to [[acetic acid]].  The first step is catalysed by the [[enzyme]] [[alcohol dehydrogenase]], and the second by [[acetaldehyde dehydrogenase]].  Some individuals have less effective forms of one or both of these enzymes, and can experience more severe symptoms from ethanol consumption than others.  Conversely, those who have acquired ethanol [[drug tolerance|tolerance]] have a greater quantity of these enzymes, and metabolize ethanol more rapidly.
{| align="right" width="250 px" class="infobox"
! BAC (mg/dL) !! Symptoms
|-
| 50          || Euphoria, talkativeness, relaxation
|-
| 100         || Central nervous system depression, impaired motor and sensory function, impaired cognition
|-
| &gt;140     || Decreased blood flow to brain
|-
| 300         || Stupefaction, possible unconsciousness
|-
| 400         || Possible death
|-
| &gt;550     || Death highly likely
|}<ref name="Pohorecky & Brick">Pohorecky, L.A., and J. Brick. (1988). "Pharmacology of ethanol." ''Pharmacology & Therapeutics'' '''36'''(3), 335-427.</ref>
The amount of ethanol in the body is typically quanitified by [[blood alcohol content]] (BAC), the [[milligram]]s of ethanol per 100 [[milliliter]]s of blood.  The table at right summarizes the symptoms of ethanol consumption.  Small doses of ethanol generally produce euphoria and relaxation; people experiencing these symptoms tend to become talkative and less inhibited, and may exhibit poor judgment.  At higher dosages (BAC &gt; 0.10), ethanol acts as a [[central nervous system]] [[depressant]], producing at progressively higher dosages, impaired sensory and motor function, slowed cognition, stupefaction, unconsciousness, and possible death.

The initial product of ethanol metabolism, acetaldehyde, is more toxic than ethanol itself. The body can quickly detoxify some acetaldehyde by reaction with [[glutathione]] and similar [[thiol]]-containing biomolecules.  When acetaldehyde is produced beyond the capacity of the body's glutathione supply to detoxify it, it accumulates in the bloodstream until further oxidized to acetic acid.  The [[headache]], [[nausea]], and [[malaise]] associated with an alcohol [[hangover]] stem from a combination of [[dehydration]] and acetaldehyde poisoning; many health conditions associated with chronic ethanol abuse, including [[liver cirrhosis]], [[alcoholism]], and some forms of [[cancer]], have been linked to acetaldehyde.{{citation needed}}  The judicial system in the United States, in a number of jurisdictions, promoted the use of [[disulfiram]], known as [[Antabuse]], for persons convicted of driving while (alcohol) intoxicated.  Disulfuram interferes with hepatic acetaldehyde metabolism, exacerbating the discomforts noted above.  Numerous deaths, said to be related to disulfuram use, led to the elimination of these court-based programs.  Some medications, including [[paracetamol]] ([[acetaminophen]]), as well as exposure to [[organochloride]]s, can deplete the body's glutathione supply, enhancing both the acute and long-term risks of even moderate ethanol consumption. Frequent use of alcoholic beverages has also been shown to be a major contributing factor in cases of elevated blood levels of [[triglycerides]]. [http://www.americanheart.org/presenter.jhtml?identifier=4778]

Ethanol has been shown to increase the growth of ''[[Acinetobacter baumannii]]'', a bacterium responsible for [[pneumonia]], [[meningitis]] and [[urinary tract infection]]s.  This finding may contradict the common misconception that drinking alcohol could kill off a budding infection. (Smith and Snyder, 2005)

== Hazards ==

* Ethanol-water solutions greater than about 50% ethanol by volume are [[Flammability|flammable]] and easily ignited.  Ethanol-water solutions below 50% ethanol by volume may also be flammable if the solution is vaporized by heating (as in some cooking methods that call for [[wine]] to be added to a hot pan, causing it to flash boil into a vapor, which is then ignited to "burn off" excessive alcohol).

== See also ==

* [[Breathalyzer]]
* [[Corn liquor]]
* [[Ethanol (data page)]]
* [[Ethanol fuel|Alcohol fuel]]
* [[Alcoholic beverage]]
* [[Effects of alcohol on the body]]
* [[Biodiesel]]
* [[Denatured alcohol]]
* [[Isopropyl alcohol]]
* [[List of energy topics]]
* [[2,2,2-Trichloroethanol]]
* [[1-Propanol]]
* [[Rubbing alcohol]]
* [[Timeline of alcohol fuel]]

== References ==
<references/>
* "Alcohol." (1911). In Hugh Chisholm (Ed.) ''Encyclopædia Britannica, 11th ed.'' [http://91.1911encyclopedia.org/A/AL/ALCOHOL.htm Online reprint]
* Lodgsdon, J.E. (1994). "Ethanol." In J.I. Kroschwitz (Ed.) ''Encyclopedia of Chemical Technology, 4th ed.'' vol. 9, pp. 812&ndash;860. New York: John Wiley & Sons.
* Smith, M.G., and M. Snyder. (2005). "Ethanol-induced virulence of ''Acinetobacter baumannii''". ''American Society for Microbiology meeting''. [[June 5]]-[[June 9]]. Atlanta.
* [http://sci-toys.com/ingredients/alcohol.html Sci-toys website explanation of US denatured alcohol designations]
* Boyce, John M., and Pittet Didier. ([[2003]]). [http://www.cdc.gov/handhygiene/ “Hand Hygiene in Healthcare Settings.”] [[Centers for Disease Control]], [[Atlanta, Georgia]], [[United States]].

== External links ==
*[http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc00/icsc0044.htm International Chemical Safety Card 0044]
*[http://www.npi.gov.au/database/substance-info/profiles/35.html National Pollutant Inventory - Ethanol Fact Sheet]
*[http://www.cdc.gov/niosh/npg/npgd0262.html NIOSH Pocket Guide to Chemical Hazards]
*[http://www.compchemwiki.org/index.php?title=Ethanol Coordinates of the ethanol molecule] on Computational Chemistry Wiki. Accessed on [[8 September]] [[2005]].
*[http://www.bluerhinos.co.uk/molview/indv.php?id=4 Molview from bluerhinos.co.uk] See Ethanol in 3D
*[http://webbook.nist.gov/cgi/cbook.cgi?Name=ethanol&Units=SI NIST Chemistry WebBook page for ethanol]
*[http://www.distill.com/specs/US-2.html Specifications]
*[http://ptcl.chem.ox.ac.uk/MSDS/ET/ethyl_alcohol.html Safety data]
{{ChemicalSources}}


[[Category:anatomical preservation]]
[[Category:Alcohol]]
[[Category:Alcohols]]
[[Category:Anxiolytics]]
[[Category:Drugs]]
[[Category:Household chemicals]]
[[Category:Solvents]]
[[Category:Teratogens]]
[[Category:Disinfectants]]

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