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[[Image:Alcohol general.svg|300px|thumb|right|[[Functional group]] of an alcohol molecule. The carbon atom is bound to [[hydrogen]] atoms and may bind to other carbon atom(s) to form a [[carbon chain]]. [[Methanol]], an alcohol with a single [[carbon]] [[atom]], is pictured. [[Ethanol]], which is drinking alcohol, has two carbon atoms.]]

An '''alcohol''' is any [[organic compound]] in which a [[hydroxyl]] [[Functional group|group]] (–OH) is bound to a [[saturation|saturated]] [[carbon]] atom,<ref name="IUPACdef">{{IUPAC class names 1995|page=1312}}.</ref><ref name="GoldBook">{{GoldBook|name=alcohols|id=A00204|accessdate=2009-08-24}}.</ref> that is the carbon atom of an [[alkyl]] or substituted alkyl group. The general formula for a simple [[Aliphatic compound|acyclic]] alcohol is C<sub>''n''</sub>H<sub>2''n''+1</sub>OH. In common terms, the word "alcohol" refers to '''[[ethanol]]''', the type of alcohol found in [[alcoholic beverages]].

Ethanol is a colorless, volatile liquid with a mild odor which can be obtained by the [[Fermentation (biochemistry)|fermentation]] of sugars. (Industrially, it is more commonly obtained by [[Ethanol#Ethylene hydration|ethylene hydration]]&mdash;the reaction of [[ethylene]] with water in the presence of [[phosphoric acid]].<ref name="ECT4 820">{{Kirk-Othmer4th | last = Lodgsdon | first = J. E. | title = Ethanol | volume = 9 | page = 820}}.</ref>) Ethanol is the most widely used [[depressant]] in the world, and has been for thousands of years. This sense underlies the term [[alcoholism]] ([[addiction]] to alcohol).

There are three major subsets of alcohols: ''primary'' (1°), ''secondary'' (2°) and ''tertiary'' (3°), based upon the number of carbon atoms the '''C-OH''' group's carbon (shown in red) is bonded to. [[Ethanol]] is a simple 'primary' alcohol. The simplest secondary alcohol is [[isopropyl alcohol]] (propan-2-ol), and the simplest tertiary alcohol is [[tert-Butanol|''tert''-butyl alcohol]] (2-methylpropan-2-ol).

==Simple alcohols==
The simplest and most commonly used alcohols are [[methanol]] and [[ethanol]]. [[Methanol]] was formerly obtained by the distillation of wood and called "wood alcohol." 

One sip of methanol (as little as 10ml) can cause permanent blindness by destruction of the [[optic nerve]].<ref name="blindness">{{citation | url = http://www.newton.dep.anl.gov/askasci/chem03/chem03561.htm | title = Methanol and Blindness | series = Ask A Scientist: Chemistry Archive | publisher = U.S. Department of Energy | date = May 2005 | accessdate = 2007-05-22}}.</ref>
Apart from its familiar role in [[alcoholic beverages]], ethanol is also used as a highly controlled industrial solvent and raw material. To avoid the high taxes on ethanol for consumption, additives are added to make it unpalatable (such as [[denatonium benzoate]]&mdash;"Bitrex") or poisonous (such as methanol). Ethanol in this form is known generally as [[denatured alcohol]]; when methanol is used, it may be referred to as [[methylated spirit]]s ("Meths") or "surgical spirits". 

Two other alcohols whose uses are relatively widespread (though not so much as those of methanol and ethanol) are [[propanol]] and [[butanol]]. Like ethanol, they can be produced by fermentation processes. (However, the fermenting agent is a bacterium, ''[[Clostridium acetobutylicum]]'', that feeds on [[cellulose]], not sugars like the [[Saccharomyces]] [[yeast]] that produces ethanol.)

==Nomenclature==
In the [[International Union of Pure and Applied Chemistry nomenclature|IUPAC]] system, the name of the alkane chain loses the terminal "e" and adds "ol", e.g. "methanol" and "ethanol".<ref name=reusch-alcohols>{{citation | first = William | last = Reusch | website = VirtualText of Organic Chemistry | webpage = Alcohols | url = http://www.cem.msu.edu/~reusch/VirtualText/alcohol1.htm#alcnom | publisher = Department of Chemistry, Michigan State University | accessdate = 2007-09-14}}.</ref> When necessary, the position of the hydroxyl group is indicated by a number between the alkane name and the "ol": [[propan-1-ol]] for CH<sub>3</sub>CH<sub>2</sub>CH<sub>2</sub>OH, [[Isopropyl alcohol|propan-2-ol]] for CH<sub>3</sub>CH(OH)CH<sub>3</sub>. In [[CAS nomenclature]], widely used in the United States, the position number is written before the name: 1-propanol and 2-propanol. If a higher priority group is present (such as an [[aldehyde]], [[ketone]] or [[carboxylic acid]]), then it is necessary to use the prefix "hydroxy",<ref name = reusch-alcohols/> for example: 1-hydroxy-2-propanone (CH<sub>3</sub>COCH<sub>2</sub>OH).

Some examples of simple alcohols and how to name them:

[[Image:Alcohol examples.gif|650px|thumb|center|Examples of alcohols & their names]]

Common names for alcohols usually takes name of the corresponding [[alkyl]] group and add the word "alcohol", e.g. [[Methyl group|methyl]] alcohol, [[Ethyl group|ethyl]] alcohol or [[Butyl|''tert''-butyl]] alcohol. [[Propyl]] alcohol may be ''n''-propyl alcohol or isopropyl alcohol depending on whether the hydroxyl group is bonded to the 1st or 2nd carbon on the propane chain. Isopropyl alcohol is also occasionally called ''sec''-propyl alcohol.

As mentioned above alcohols are classified as primary (1°), secondary (2°) or tertiary (3°), and common names often indicate this in the alkyl group prefix. For example (CH<sub>3</sub>)<sub>3</sub>COH is a tertiary alcohol is commonly known as ''tert''-butyl alcohol. This would be named 2-methylpropan-2-ol under IUPAC rules, indicating a propane chain with methyl and hydroxyl groups both attached to the middle (#2) carbon.

'''Primary alcohol (1°)'''- Have general formulas RCH<sub>2</sub>OH
'''Secondary alcohol (2°)'''- Have general formulas RR'CHOH
'''Tertiary alcohol (3°)'''- Have general formulas RR'R''COH
Hydrogen bond strength order: 1°>2°>3°
Boiling point order: 1°>2°>3°
Acidity order: 1°>2°>3°

The definition of an alcohol is specific that the hydroxy group must be attached to a [[Saturation|saturated]] carbon atom.<ref name="IUPACdef"/><ref name="GoldBook"/> When the hydroxy group is attached to an aromatic ring, the functional group is called a [[phenol (class name)|phenol]]:<ref>{{GoldBook|title=phenols|file=P04539|accessdate=2009-08-24}}.</ref> the compound named [[phenol]] is the simplest example of this class of compounds. When the hydroxy group is attached to an sp<sup>2</sup> carbon atom which is not part of an aromatic ring, the functional group is called an [[enol]]:<ref>{{GoldBook|title=enols|file=E02124|accessdate=2009-08-24}}.</ref> enols are generally unstable with respect to [[tautomerism]] to [[aldehyde]]s or [[ketone]]s, but can be very important as [[reactive intermediate]]s in organic reactions.

==Etymology==
{{Wiktionary|alcohol}}
The word ''alcohol'' appears in English in the 16th century, loaned via French from medical [[Latin]], ultimately from the [[Arabic]]  {{lang|ar|[[wikt:الكحل|الكحل]]}} (''{{lang|ar-Latn|al-kuḥl}},'' "the [[kohl (cosmetics)|kohl]], a powder used as an eyeliner"). 

{{lang|ar|[[wikt:ال|ال]]}} ''{{lang|ar-Latn|al}}'' is Arabic for the [[Article (grammar)|definitive article]], ''the'' in English.

The current Arabic name for alcohol is {{lang|ar|الكحول}} ''{{lang|ar-Latn|al-kuḥūl}}'', re-introduced from western usage.

''{{lang|ar-Latn|kuḥl}}'' was the name given to the very fine powder, produced by the [[sublimation (chemistry)|sublimation]] of the natural mineral [[stibnite]] to form [[antimony]] [[sulfide]] [[antimony|Sb]]<sub>2</sub>[[sulfur|S]]<sub>3</sub> (hence the essence or "spirit" of the substance), which was used as an [[antiseptic]] and [[Kohl (cosmetics)|eyeliner]]. 
 
[[Bartholomew Traheron]] in his 1543 translation of [[John of Vigo]] introduces the word as a term used by "barbarous" ([[Moorish]]) authors for "fine powder":
:''the barbarous auctours use alcohol, or (as I fynde it sometymes wryten) alcofoll, for moost fine poudre.''

[[William Johnson]] in his 1657 ''Lexicon Chymicum'' glosses the word as ''antimonium sive stibium''. By extension, the word came to refer to any fluid obtained by distillation, including "alcohol of wine", the distilled essence of wine. [[Libavius]] in ''Alchymia'' (1594) has ''vini alcohol vel vinum alcalisatum''. Johnson (1657) glosses ''alcohol vini'' as  ''quando omnis superfluitas vini a vino separatur, ita ut accensum ardeat donec totum consumatur, nihilque fæcum aut phlegmatis in fundo remaneat.'' 
The word's meaning became restricted to "spirit of wine" ([[ethanol]]) in the 18th century, and was again extended to the family of substances so called in modern chemistry from 1850.

==Physical and chemical properties==
Alcohols have an odor that is often described as “biting” and as  “hanging” in the nasal passages.

The [[hydroxyl group]] generally makes the alcohol molecule [[polar molecule|polar]]. Those groups can form [[hydrogen bond]]s to one another and to other compounds. This hydrogen bonding means that alcohols can be used as [[protic solvent]]s. Two opposing solubility trends in alcohols are: the tendency of the polar OH to promote solubility in water, and of the carbon chain to resist it. Thus, methanol, ethanol, and propanol are miscible in water because the hydroxyl group wins out over the short carbon chain. [[Butanol]], with a four-carbon chain, is moderately soluble because of a balance between the two trends. Alcohols of five or more carbons ([[amyl alcohol|Pentanol]] and higher) are effectively insoluble in water because of the hydrocarbon chain's dominance. All simple alcohols are miscible in organic solvents. 

Because of [[hydrogen bonding]], alcohols tend to have higher boiling points than comparable [[hydrocarbon]]s and [[ether]]s. The boiling point of the alcohol ethanol is 78.29&nbsp;°C, compared to 69&nbsp;°C for the hydrocarbon [[hexane]] (a common constituent of [[gasoline]]), and 34.6&nbsp;°C for [[diethyl ether]].

Alcohols, like water, can show either acidic or basic properties at the O-H group. With a [[pKa|p''K''<sub>a</sub>]] of around 16–19 they are generally slightly weaker [[acid]]s than [[water (molecule)|water]], but they are still able to react with strong bases such as [[sodium hydride]] or reactive metals such as [[sodium]]. The [[salt]]s that result are called [[alkoxide]]s, with the general formula [[Alkyl|R]]O<sup>-</sup>[[Metal|M]]<sup>+</sup>.

Meanwhile the oxygen atom has [[lone pair]]s of nonbonded electrons that render it weakly [[Base (chemistry)|basic]] in the presence of strong acids such as [[sulfuric acid]]. For example, with methanol:

[[Image:Methanol acid base.gif|500px|Acidity & basicity of methanol]]

Alcohols can also undergo [[oxidation]] to give [[aldehyde]]s, [[ketone]]s or [[carboxylic acid]]s, or they can be dehydrated to [[alkene]]s. They can react to form [[ester compound]]s, and they can (if activated first) undergo [[nucleophilic substitution]] reactions. The lone pairs of electrons on the oxygen of the hydroxyl group also makes alcohols nucleophiles. For more details see the [[Alcohol#Reactions|reactions of alcohols]] section below.

==Applications==
[[File:Alcohol by Country.png|thumb|200px|Total recorded [[alcohol consumption by country|alcohol per capita consumption]] (15+), in litres of pure alcohol<ref>{{citation | url = http://www.who.int/entity/substance_abuse/publications/global_status_report_2004_overview.pdf | title = Global Status Report on Alcohol 2004 | publisher = World Health Organization | year = 2004}}.</ref>]]
Alcohols can be used as a beverage ([[ethanol]] only), as fuel and for many scientific, medical, and industrial utilities. [[Ethanol]] in the form of alcoholic beverages has been consumed by humans since pre-historic times. A 50% v/v solution of [[ethylene glycol]] in water is commonly used as an [[antifreeze]]. 

Some alcohols, mainly [[ethanol]] and [[methanol]], can be used as an [[alcohol fuel]]. Fuel performance can be increased in [[forced induction]] [[internal combustion engine]]s by injecting alcohol into the air intake after the [[turbocharger]] or [[supercharger]] has pressurized the air. This cools the pressurized air, providing a denser air charge, which allows for more fuel, and therefore more power.

Alcohols have applications in industry and science as reagents or [[solvent]]s. Because of its low toxicity and ability to dissolve [[non-polar]] substances, ethanol can be used as a solvent in medical drugs, [[perfume]]s, and vegetable essences such as [[vanilla]]. In [[organic synthesis]], alcohols serve as versatile intermediates.

Ethanol can be used as an antiseptic to disinfect the skin before injections are given, often along with iodine. Ethanol-based soaps are becoming common in restaurants and are convenient because they do not require drying due to the volatility of the compound. Alcohol is also used as a [[preservative]] for specimens.

Alcohol gels have become common as [[alcohol rub|hand sanitizers]].

==Production==
Industrially alcohols are produced in several ways:
* By [[fermentation (biochemistry)|fermentation]] using [[glucose]] produced from sugar from the [[hydrolysis]] of [[starch]], in the presence of yeast and temperature of less than 37°C to produce ethanol. For instance the conversion of [[invertase]] to [[glucose]] and [[fructose]] or the conversion of [[glucose]] to [[zymase]] and [[ethanol]].
* By direct [[hydration reaction|hydration]] using [[ethylene]] ([[Ethanol#Ethylene hydration|ethylene hydration]]<ref name="ECT4 820"/> or other alkenes from [[cracking (chemistry)|cracking]] of fractions of distilled [[crude oil]].

===Endogenous===
It is inevitable that all humans always have some amount of alcohol in their bodies at all times, even if they never drink alcoholic beverages in their lives. This is because of a process called endogenous ethanol production. Many of the bacteria in the intestines use alcohol [[fermentation (food)|fermentation]] as a form of [[cellular respiration|respiration]]. This [[metabolism|metabolic]] method produces [[ethanol|alcohol]] as a waste product, in the same way that metabolism results in the formation of [[carbon dioxide]] and [[water (molecule)|water]]. Thus, human bodies always contain some quantity of alcohol produced by these benign bacteria.

==Laboratory synthesis==<!-- This section is linked from [[Organic reaction]] -->
Several methods exist for the preparation of alcohols in the laboratory.
* Primary [[alkyl halide]]s react with aqueous [[Sodium hydroxide|NaOH]] or [[Potassium hydroxide|KOH]] mainly to primary alcohols in [[nucleophilic aliphatic substitution]]. (Secondary and especially tertiary alkyl halides will give the elimination (alkene) product instead).
* [[Aldehydes]] or [[ketone]]s are [[redox|reduced]] with [[sodium borohydride]] or [[lithium aluminium hydride]] (after an acidic workup). Another reduction by aluminiumisopropylates is the [[Meerwein-Ponndorf-Verley reduction]].
* [[Alkenes]] engage in an acid catalysed [[hydration reaction]] using concentrated sulfuric acid as a catalyst which gives usually secondary or tertiary alcohols. The [[hydroboration-oxidation]] and [[oxymercuration-reduction]] of alkenes are more reliable in organic synthesis. Alkenes react with NBS and water in [[halohydrin formation reaction]]
* [[Grignard reagent]]s react with [[carbonyl]] groups to secondary and tertiary alcohols. Related reactions are the [[Barbier reaction]] and the [[Nozaki-Hiyama reaction]].
* [[Noyori asymmetric hydrogenation]] is the asymmetric reduction of β-keto-esters
* [[Amine]]s can be converted to [[diazonium salt]]s which are then hydrolyzed.
The formation of a secondary alcohol via reduction and hydration is shown:
:[[Image:Alcohol prep.gif|350px|Preparation of a secondary alcohol]]

==Reactions==<!-- This section is linked from [[Organic reaction]] -->
===Deprotonation===
Alcohols can behave as weak acids, undergoing [[deprotonation]]. The deprotonation reaction to produce an [[alkoxide]] salt is either performed with a strong base such as sodium hydride or [[butyllithium|''n''-butyllithium]], or with sodium or potassium metal.
:2R–OH + 2NaH → 2R–O<sup>-</sup>Na<sup>+</sup> + 2H<sub>2</sub> ↑
:2R–OH + 2Na → 2R–O<sup>−</sup>Na<sup>+</sup> + H<sub>2</sub> ↑
:E.g. 2CH<sub>3</sub>CH<sub>2</sub>–OH + 2Na → 2CH<sub>3</sub>-CH<sub>2</sub>-O<sup>−</sup>Na<sup>+</sup> + H<sub>2</sub> ↑

Water is similar in [[pKa|pK<Sub>a</sub>]] to many alcohols, so with [[sodium hydroxide]] there is an [[chemical equilibrium|equilibrium]] set up which usually lies to the left:
:R–OH + NaOH {{eqm}} R–O<sup>-</sup>Na<sup>+</sup> + H<sub>2</sub>O (equilibrium to the left)

It should be noted, though, that the bases used to deprotonate alcohols are strong themselves. The bases used and the alkoxides created are both highly moisture sensitive chemical reagents.

The acidity of alcohols is also affected by the overall stability of the alkoxide ion. [[Electron-withdrawing group]]s attached to the carbon containing the hydroxyl group will serve to stabilize the alkoxide when formed, thus resulting in greater acidity. On the other hand, the presence of [[electron-donating group]] will result in a less stable alkoxide ion formed. This will result in a scenario whereby the unstable alkoxide ion formed will tend to accept a proton to reform the original alcohol.

With [[alkyl halide]]s alkoxides give rise to [[ether]]s in the [[Williamson ether synthesis]].

===Nucleophilic substitution===
The OH group is not a good [[leaving group]] in [[nucleophilic substitution]] reactions, so neutral alcohols do not react in such reactions. However, if the oxygen is first protonated to give R–OH<sub>2</sub><sup>+</sup>, the leaving group ([[water (molecule)|water]]) is much more stable, and the nucleophilic substitution can take place. For instance, tertiary alcohols react with [[hydrochloric acid]] to produce tertiary [[alkyl halide]]s, where the [[hydroxyl group]] is replaced by a [[chlorine]] atom by [[unimolecular nucleophilic substitution]]. If primary or secondary alcohols are to be reacted with [[hydrochloric acid]], an activator such as [[zinc chloride]] is needed. Alternatively the conversion may be performed directly using [[thionyl chloride]].

[[Image:Alcohol reaction examples.gif|700px|Some simple conversions of alcohols to alkyl chlorides]]

Alcohols may likewise be converted to alkyl bromides using [[hydrobromic acid]] or [[phosphorus tribromide]], for example:
:3R–OH + PBr<sub>3</sub> → 3 RBr + H<sub>3</sub>PO<sub>3</sub>

In the [[Barton–McCombie deoxygenation]] an alcohol is deoxygenated to an [[alkane]] with [[tributyltin hydride]] or a [[trimethylborane]]–water complex in a [[radical substitution]] reaction.

===Dehydration===
Alcohols are themselves nucleophilic, so R–OH<sub>2</sub><sup>+</sup> can react with ROH to produce [[ether]]s and water in a [[dehydration reaction]], although this reaction is rarely used except in the manufacture of [[diethyl ether]].

More useful is the E1 [[elimination reaction]] of alcohols to produce [[alkene]]s. The reaction generally obeys [[Zaitsev's Rule]], which states that the most stable (usually the most substituted) alkene is formed. Tertiary alcohols eliminate easily at just above room temperature, but primary alcohols require a higher temperature.

This is a diagram of acid catalysed dehydration of ethanol to produce [[ethene]]:

[[Image:DehydrationOfAlcoholWithH-.png|550px]]

A more controlled elimination reaction is the [[Chugaev elimination]] with carbon disulfide and iodomethane.

===Esterification===
To form an [[ester]] from an alcohol and a [[carboxylic acid]] the reaction, known as [[Fischer esterification]], is usually performed at [[reflux]] with a [[catalyst]] of concentrated sulfuric acid:
:R–OH + R'–COOH {{eqm}} R'–COOR + H<sub>2</sub>O

In order to drive the equilibrium to the right and produce a good [[yield (chemistry)|yield]] of ester, water is usually removed, either by an excess of H<sub>2</sub>SO<sub>4</sub> or by using a [[Dean–Stark apparatus]]. Esters may also be prepared by reaction of the alcohol with an [[acid chloride]] in the presence of a base such as [[pyridine]].

Other types of ester are prepared similarly: for example [[tosyl]] (tosylate) esters are made by reaction of the alcohol with [[p-toluenesulfonyl chloride]] in pyridine.

===Oxidation===
{{Main|Oxidation of primary alcohols to carboxylic acids}}
Primary alcohols (R–CH<sub>2</sub>–OH) can be oxidized either to [[aldehyde]]s (R–CHO) or to [[carboxylic acid]]s (R–CO<sub>2</sub>H), while the oxidation of secondary alcohols (R<sup>1</sup>R<sup>2</sup>CH–OH) normally terminates at the [[ketone]] (R<sup>1</sup>R<sup>2</sup>C=O) stage. Tertiary alcohols (R<sup>1</sup>R<sup>2</sup>R<sup>3</sup>C–OH) are resistant to oxidation.

The direct oxidation of primary alcohols to carboxylic acids normally proceeds via the corresponding aldehyde, which is transformed via an [[acetal]] (R–CH(OH)<sub>2</sub>, also known as a ''gem''-diol) by reaction with water before it can be further oxidized to the carboxylic acid.

[[Image:Alcohol to aldehyde to acid.png|500px|thumb|center|Mechanism of oxidation of primary alcohols to carboxylic acids via aldehydes and aldehyde hydrates]]

Often it is possible to interrupt the oxidation of a primary alcohol at the aldehyde level by performing the reaction in absence of water, so that no aldehyde hydrate can be formed.

Reagents useful for the transformation of primary alcohols to aldehydes are normally also suitable for the oxidation of secondary alcohols to ketones. These include:
*Chromium-based reagents, such as [[Collins reagent]] (CrO<sub>3</sub>·Py<sub>2</sub>), [[pyridinium dichromate]] (PDC) or [[pyridinium chlorochromate]] (PCC).
*Activated [[dimethyl sulfoxide]] (DMSO), resulting from reaction of DMSO with an [[electrophile]] such as [[oxalyl chloride]] ([[Swern oxidation]]), a [[carbodiimide]] ([[Pfitzner–Moffatt oxidation]]) or the complex SO<sub>3</sub>·Py ([[Parikh–Doering oxidation]]).
*Hypervalent iodine compounds, such as [[Dess–Martin periodinane]] or [[2-iodoxybenzoic acid]].
*Catalytic [[Tetrapropylammonium perruthenate]] (TPAP) in presence of excess of [[N-Methylmorpholine N-oxide|''N''-methylmorpholine ''N''-oxide]] (NMO) ([[Ley oxidation]]).
*Catalytic [[TEMPO]] (2,2,6,6-tetramethylpiperidine-1-oxyl radical) in presence of excess [[bleach]] ([[NaOCl]]) ([[Anelli's oxidation]]).

[[Image:Alcohol to aldehyde or ketone.png|300px|thumb|center|Oxidation of alcohols to aldehydes and ketones]]

Allylic and benzylic alcohols can be oxidized in presence of other alcohols using certain selective oxidants such as [[manganese dioxide]] (MnO<sub>2</sub>). 

Reagents useful for the oxidation of secondary alcohols to ketones, but normally inefficient for oxidation of primary alcohols to aldehydes, include [[chromium trioxide]] (CrO<sub>3</sub>) in a mixture of sulfuric acid and [[acetone]] ([[Jones oxidation]]) and certain ketones, such as [[cyclohexanone]], in the presence of [[aluminium isopropoxide]] ([[Oppenauer oxidation]]).

The direct oxidation of primary alcohols to carboxylic acids can be carried out using:
*[[Potassium permanganate]] (KMnO<sub>4</sub>).
*[[Jones oxidation]].
*[[Pyridinium dichromate]] (PDC) in [[2,5-dimethylfuran]].
*[[Heyns oxidation]].
*[[Ruthenium tetroxide]] (RuO<sub>4</sub>).
*[[TEMPO]].

[[Image:Alcohol to acid.png|250px|thumb|center|Oxidation of primary alcohols to carboxylic acids]]

Alcohols possessing two [[hydroxy]] groups located on adjacent carbons —that is, 1,2-[[diol]]s— suffer oxidative breakage at a carbon-carbon bond with some oxidants such as [[sodium periodate]] (NaIO<sub>4</sub>) or [[lead tetraacetate]] (Pb(OAc)<sub>4</sub>), resulting in generation of two [[carbonyl]] groups.

[[Image:Oxidative breakage of 1,2-diol.png|250px|thumb|center|Oxidative breakage of carbon-carbon bond in 1,2-diols]]

==Toxicity==
{{Main|Short-term effects of alcohol|Long-term effects of alcohol}}

[[File:Possible long-term effects of ethanol.png|thumb|200px|right|Most significant of the possible [[long-term effects of ethanol]]. Additionally, in pregnant women, it causes [[fetal alcohol syndrome]].]]
[[Ethanol]] in [[alcoholic beverages]] has been consumed by humans since prehistoric times for a variety of hygienic, dietary, medicinal, religious, and recreational reasons. The consumption of large doses of ethanol causes [[drunkenness]]  (intoxication), which may lead to a [[hangover]] as its effects wear off. Depending upon the dose and the regularity of its consumption, ethanol can cause acute respiratory failure or death. Because ethanol impairs judgment in humans, it can be a catalyst for reckless or irresponsible behavior.

The [[LD50|LD<sub>50</sub>]] of [[ethanol]] in rats is 10,300&nbsp;mg/kg.<ref>{{citation | first = Robert S. | last = Gable | year = 2004 | title = Comparison of acute lethal toxicity of commonly abused psychoactive substances | journal = Addiction | volume = 99 | issue = 6 | pages = 686–96 | doi = 10.1111/j.1360-0443.2004.00744.x}}.</ref> Other alcohols are substantially more poisonous than ethanol, partly because they take much longer to be metabolized and partly because their metabolization produces substances that are even more toxic. Methanol (wood alcohol), for instance, is oxidized to the poisonous [[formaldehyde]] in the liver by [[alcohol dehydrogenase]] [[enzyme]]s; this can cause blindness or death.<ref name="blindness"/>

An effective treatment to prevent formaldehyde toxicity after methanol ingestion is to administer ethanol. Alcohol dehydrogenase has a higher affinity for ethanol, thus preventing methanol from binding and acting as a [[substrate (biochemistry)|substrate]]. Any remaining methanol will then have time to be excreted through the kidneys. Remaining formaldehyde will be converted to [[formic acid]] and excreted.<ref>{{citation | last1 = Zimmerman | first1 = H. E. | last2 = Burkhart | first2 = K. K. | last3 = Donovan | first3 = J. W. | title = Ethylene glycol and methanol poisoning: diagnosis and treatment | journal = J. Emer. Nurs. | year = 1999  | volume = 25 | issue = 2 | pages = 116–20 | pmid = 10097201}}.</ref><ref>{{citation | last = Lobert | first = S. | title = Ethanol, isopropanol, methanol, and ethylene glycol poisoning | journal = Critical Care Nurse | year = 2000 | volume = 20 | issue = 6 | pages = 41–477 | pmid = 11878258}}.</ref>

Methanol itself, while poisonous, has a much weaker [[sedative]] effect than ethanol. Some longer-chain alcohols such as [[Propan-1-ol|''n''-propanol]], [[isopropanol]], [[Butan-1-ol|''n''-butanol]], [[Tert-Butanol|''tert''-butanol]] and [[2-methylbutan-2-ol]] (''tert''-amyl alcohol) do however have stronger sedative effects, but also have higher toxicity than ethanol. These longer chain alcohols are found as contaminants in some alcoholic beverages and are known as [[fusel alcohol]]s,<ref>{{citation | last = Woo | first = Kang-Lyung | title = Determination of low molecular weight alcohols including fusel oil in various samples by diethyl ether extraction and capillary gas chromatography | journal = J. AOAC Int. | year = 2005 | volume = 88 | issue = 5 | pages = 1419–27 | pmid = 16385992 | doi = 10.5555/jaoi.2005.88.5.1419}}.</ref><ref>{{citation | last1 = Lachenmeier | first1 = Dirk W. | last2 = Haupt | first2 = Simone | last3 = Schulz | first3 = Katja | title = Defining maximum levels of higher alcohols in alcoholic beverages and surrogate alcohol products | journal = Regulat. Toxicol. Pharmacol. | year = 2008 | volume = 50 | issue = 3 | pages = 313–21 | doi = 10.1016/j.yrtph.2007.12.008}}.</ref> and are reputed to cause severe [[hangover]]s although it is unclear if the fusel alcohols are actually responsible.<ref>{{citation | last1 = Hori | first1 = Hisako | last2 = Fujii | first2 = Wataru | last3 = Hatanaka | first3 = Yutaka | last4 = Suwa | first4 = Yoshihide | title = Effects of fusel oil on animal hangover models | journal = Alcohol Clin. Exp. Res. | year = 2003 | volume = 27 | issue = 8 Suppl | pages = 37S–41S | doi = 10.1097/01.ALC.0000078828.49740.48}}.</ref> Many longer chain alcohols are used in industry as [[solvent]]s and are occasionally abused by [[alcoholic]]s, leading to a range of adverse health effects.<ref>{{citation | last1 = McKee | first1 = Martin | last2 = Sűzcs | first2 = Sándor | last3 = Sárváry | first3 = Attila | last4 = Adany | first4 = Roza | last5 = Kiryanov | first5 = Nikolay | last6 = Saburova | first6 = Ludmilla | last7 = Tomkins | first7 = Susannah | last8 = Andreev | first8 = Evgeny | last9 = Leon | first9 = David A. | title = The composition of surrogate alcohols consumed in Russia | journal = Alcohol. Clin. Exp. Res. | year = 2005 | volume = 29 | issue = 10 | pages = 1884–88 | doi = 10.1097/01.alc.0000183012.93303.90}}.</ref><ref>{{citation | last1 = Bunc | first1 = M. | last2 = Pezdir | first2 = T. | last3 = Možina | first3 = H. | last4 = Možina | first4 = M. | last5 = Brvar | first5 = M. | title = Butanol ingestion in an airport hangar | journal = Hum. Exp. Toxicol. | year = 2006 | volume = 25 | issue = 4 | page = 195–97 | doi = 10.1191/0960327106ht607oa}}.</ref>

==Occurrence in nature==
Alcohol has been found outside the Solar system. It can be found in low densities in star and planetary system forming regions of space.<ref>{{citation | last = Buhl | first = David | title = Galactic clouds of organic molecules | journal = Orig. Life Evol. Biospheres | year = 1794 | volume = 5 | issue = 1-2 | pages = 29–40 | doi = 10.1007/BF00927011}}.</ref><ref>{{citation | last = Ross | first = John E. | webpage = The Interstellar Medium | url = http://www.physics.uq.edu.au/people/ross/phys2080/ism/ism.htm | date = August 1998 | publisher = Department of Physics, University of Queensland | accessdate = 2009-08-24}}.</ref>

==References==
{{reflist}}
==Further reading==
*{{citation | title = The World in So Many Words | first = Allan A. | last = Metcalf | publisher = Houghton Mifflin | year = 1999 | isbn = 0395959209 | url =http://books.google.ca/books?id=4O0W5XyQVCYC&pg=PA123&dq=sash+etymology+arabic&lr=&as_brr=3&sig=iuzjUzyPphZKCIJLAwJZE7beIEI#PPA123,M1}}. 

[[Category:Alcohols| ]]
[[Category:Functional classes]]

{{Imported from Wikipedia|name=Alcohol|id=306676326}}