Alcohol

Alcohol

Overview

In chemistry
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....

, an alcohol is an organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

 in which the hydroxy
Hydroxy
Hydroxy can refer to:* In chemical nomenclature, the prefix "hydroxy-" shows the presence of a hydroxyl functional group '* An abbreviation for the medication hydroxyzine, which is commonly sold under the brand names Atarax, Ucerax, Serecid, and Vistaril* Hydroxy gas: A nickname for oxyhydrogen, a...

 functional group
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...

 (-O
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

H
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

) is bound to a carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

 atom. In particular, this carbon center should be saturated, having single bonds to three other atoms.

An important class of alcohols are the simple acyclic
Aliphatic compound
In organic chemistry, aliphatic compounds are acyclic or cyclic, non-aromatic carbon compounds.Thus, aliphatic compounds are opposite to aromatic compounds.- Structure :...

 alcohols, the general formula for which is CnH2n+1OH. Of those, ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

 (C2H5OH) is the type of alcohol found in alcoholic beverages, and in common speech the word alcohol refers specifically to ethanol.

Other alcohols are usually described with a clarifying adjective, as in isopropyl alcohol
Isopropyl alcohol
Isopropyl alcohol is a common name for a chemical compound with the molecular formula C3H8O. It is a colorless, flammable chemical compound with a strong odor...

(propan-2-ol) or wood alcohol (methyl alcohol, or methanol
Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...

).
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In chemistry
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....

, an alcohol is an organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

 in which the hydroxy
Hydroxy
Hydroxy can refer to:* In chemical nomenclature, the prefix "hydroxy-" shows the presence of a hydroxyl functional group '* An abbreviation for the medication hydroxyzine, which is commonly sold under the brand names Atarax, Ucerax, Serecid, and Vistaril* Hydroxy gas: A nickname for oxyhydrogen, a...

 functional group
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...

 (-O
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

H
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

) is bound to a carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

 atom. In particular, this carbon center should be saturated, having single bonds to three other atoms.

An important class of alcohols are the simple acyclic
Aliphatic compound
In organic chemistry, aliphatic compounds are acyclic or cyclic, non-aromatic carbon compounds.Thus, aliphatic compounds are opposite to aromatic compounds.- Structure :...

 alcohols, the general formula for which is CnH2n+1OH. Of those, ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

 (C2H5OH) is the type of alcohol found in alcoholic beverages, and in common speech the word alcohol refers specifically to ethanol.

Other alcohols are usually described with a clarifying adjective, as in isopropyl alcohol
Isopropyl alcohol
Isopropyl alcohol is a common name for a chemical compound with the molecular formula C3H8O. It is a colorless, flammable chemical compound with a strong odor...

(propan-2-ol) or wood alcohol (methyl alcohol, or methanol
Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...

). The suffix -ol appears in the IUPAC chemical name
IUPAC nomenclature of organic chemistry
The IUPAC nomenclature of organic chemistry is a systematic method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry . Ideally, every possible organic compound should have a name from which an unambiguous structural formula can be drawn. ...

 of all substances where the hydroxyl group is the functional group with the highest priority; in substances where a higher priority group is present the prefix hydroxy- will appear in the IUPAC name. The suffix -ol in non-systematic names (such as paracetamol
Paracetamol
Paracetamol INN , or acetaminophen USAN , is a widely used over-the-counter analgesic and antipyretic . It is commonly used for the relief of headaches and other minor aches and pains and is a major ingredient in numerous cold and flu remedies...

 or cholesterol
Cholesterol
Cholesterol is a complex isoprenoid. Specifically, it is a waxy steroid of fat that is produced in the liver or intestines. It is used to produce hormones and cell membranes and is transported in the blood plasma of all mammals. It is an essential structural component of mammalian cell membranes...

) also typically indicates that the substance includes a hydroxyl functional group and, so, can be termed an alcohol. But many substances, particularly sugars (examples glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

 and sucrose
Sucrose
Sucrose is the organic compound commonly known as table sugar and sometimes called saccharose. A white, odorless, crystalline powder with a sweet taste, it is best known for its role in human nutrition. The molecule is a disaccharide composed of glucose and fructose with the molecular formula...

) contain hydroxyl functional groups without using the suffix.

Simple alcohols



The most commonly used alcohol is ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

, , with the ethane
Ethane
Ethane is a chemical compound with chemical formula C2H6. It is the only two-carbon alkane that is an aliphatic hydrocarbon. At standard temperature and pressure, ethane is a colorless, odorless gas....

 backbone. Ethanol has been produced and consumed by humans for millennia, in the form of fermented and distilled alcoholic beverages. It is a clear flammable liquid that boils at 78.4 °C, which is used as an industrial solvent, car fuel
Alcohol fuel
Although fossil fuels have become the dominant energy resource for the modern world, alcohol has been used as a fuel throughout history. The first four aliphatic alcohols are of interest as fuels because they can be synthesized chemically or biologically, and they have characteristics which allow...

, and raw material in the chemical industry. In the US
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 and some other countries, because of legal and tax restrictions on alcohol consumption, ethanol destined for other uses often contains additives that make it unpalatable (such as 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
Methylated spirit
Denatured alcohol or methylated spirits is ethanol that has additives to make it more poisonous or unpalatable, and thus, undrinkable. In some cases it is also dyed....

s or "surgical spirits".

The simplest alcohol is methanol
Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...

, , which was formerly obtained by the distillation of wood and, therefore, is called "wood alcohol". It is a clear liquid resembling ethanol in smell and properties, with a slightly lower boiling point (64.7 °C), and is used mainly as a solvent, fuel, and raw material. Unlike ethanol, methanol is extremely toxic: One sip (as little as 10 ml) can cause permanent blindness by destruction of the optic nerve
Optic nerve
The optic nerve, also called cranial nerve 2, transmits visual information from the retina to the brain. Derived from the embryonic retinal ganglion cell, a diverticulum located in the diencephalon, the optic nerve doesn't regenerate after transection.-Anatomy:The optic nerve is the second of...

 and 30 ml (one fluid ounce) is potentially fatal.

Two other alcohols whose uses are relatively widespread (though not so much as those of methanol and ethanol) are propanol
Propanol
Propanol may refer to:*Propan-1-ol, or n-propanol: CH3CH2CH2OH, the most common meaning*Propan-2-ol, or isopropyl alcohol, or isopropanol: 2CHOH...

 and butanol
N-Butanol
n-Butanol or n-butyl alcohol or normal butanol is a primary alcohol with a 4-carbon structure and the molecular formula C4H9OH. Its isomers include isobutanol, 2-butanol, and tert-butanol...

. Like ethanol, they can be produced by fermentation processes. (However, the fermenting agent is a bacterium, Clostridium acetobutylicum
Clostridium acetobutylicum
Clostridium acetobutylicum, ATCC 824, is included in the genus Clostridium, is a commercially valuable bacterium sometimes called the "Weizmann Organism", after Jewish-Russian born Chaim Weizmann, then senior lecturer at the University of Manchester, England, used them in 1916 as a bio-chemical...

, that feeds on cellulose
Cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....

, not sugars like the Saccharomyces
Saccharomyces
Saccharomyces is a genus in the kingdom of fungi that includes many species of yeast. Saccharomyces is from Greek σάκχαρ and μύκης and means sugar fungus. Many members of this genus are considered very important in food production. One example is Saccharomyces cerevisiae, which is used in making...

 yeast
Yeast
Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...

 that produces ethanol.) Saccharomyces
Saccharomyces
Saccharomyces is a genus in the kingdom of fungi that includes many species of yeast. Saccharomyces is from Greek σάκχαρ and μύκης and means sugar fungus. Many members of this genus are considered very important in food production. One example is Saccharomyces cerevisiae, which is used in making...

 yeast
Yeast
Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...

 are known to produce these higher alcohols at temperatures above 75 °F (23.9 °C). These alcohols are called fusel alcohols or fusel oils in brewing
Brewing
Brewing is the production of beer through steeping a starch source in water and then fermenting with yeast. Brewing has taken place since around the 6th millennium BCE, and archeological evidence suggests that this technique was used in ancient Egypt...

 and tend to have a spicy or peppery flavor. They are considered a fault in most styles of beer
Beer
Beer is the world's most widely consumed andprobably oldest alcoholic beverage; it is the third most popular drink overall, after water and tea. It is produced by the brewing and fermentation of sugars, mainly derived from malted cereal grains, most commonly malted barley and malted wheat...

.

Simple alcohols, in particular, ethanol and methanol, possess denaturing
Denaturation (biochemistry)
Denaturation is a process in which proteins or nucleic acids lose their tertiary structure and secondary structure by application of some external stress or compound, such as a strong acid or base, a concentrated inorganic salt, an organic solvent , or heat...

 and inert rendering properties, leading to their use as anti-microbial agents in medicine, pharmacy, and industry.

Systematic names


In the IUPAC system, the name of the alkane chain loses the terminal "e" and adds "ol", e.g., "methanol" and "ethanol". When necessary, the position of the hydroxyl group is indicated by a number between the alkane name and the "ol": propan-1-ol
Propan-1-ol
1-Propanol is a primary alcohol with the molecular formula of C3H8O, and a structural formula of CH3CH2CH2OH. It is also known as propan-1-ol, 1-propyl alcohol, n-propyl alcohol, n-propanol, or simply propanol. It is an isomer of isopropanol . It is used as a solvent in the pharmaceutical...

 for CH3CH2CH2OH, propan-2-ol
Isopropyl alcohol
Isopropyl alcohol is a common name for a chemical compound with the molecular formula C3H8O. It is a colorless, flammable chemical compound with a strong odor...

 for CH3CH(OH)CH3. Sometimes, the position number is written before the IUPAC name: 1-propanol and 2-propanol. If a higher priority group is present (such as an aldehyde
Aldehyde
An aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....

, ketone
Ketone
In organic chemistry, a ketone is an organic compound with the structure RCR', where R and R' can be a variety of atoms and groups of atoms. It features a carbonyl group bonded to two other carbon atoms. Many ketones are known and many are of great importance in industry and in biology...

, or carboxylic acid
Carboxylic acid
Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...

), then it is necessary to use the prefix "hydroxy", for example: 1-hydroxy-2-propanone (CH3COCH2OH).



The IUPAC nomenclature is used in scientific publications and where precise identification of the substance is important. In other less formal contexts, an alcohol is often called with the name of the corresponding alkyl group followed by the word "alcohol", e.g., methyl
Methyl group
Methyl group is a functional group derived from methane, containing one carbon atom bonded to three hydrogen atoms —CH3. The group is often abbreviated Me. Such hydrocarbon groups occur in many organic compounds. The methyl group can be found in three forms: anion, cation and radical. The anion...

 alcohol, ethyl
Ethyl group
In chemistry, an ethyl group is an alkyl substituent derived from ethane . It has the formula -C2H5 and is very often abbreviated -Et.Ethylation is the formation of a compound by introduction of the ethyl functional group, C2H5....

 alcohol. Propyl
Propyl
In organic chemistry, propyl is a three-carbon alkyl substituent with chemical formula -C3H7. It is the substituent form of the alkane propane...

 alcohol may be n-propyl alcohol
Propanol
Propanol may refer to:*Propan-1-ol, or n-propanol: CH3CH2CH2OH, the most common meaning*Propan-2-ol, or isopropyl alcohol, or isopropanol: 2CHOH...

 or isopropyl alcohol
Isopropyl alcohol
Isopropyl alcohol is a common name for a chemical compound with the molecular formula C3H8O. It is a colorless, flammable chemical compound with a strong odor...

, depending on whether the hydroxyl group is bonded to the 1st or 2nd carbon on the propane
Propane
Propane is a three-carbon alkane with the molecular formula , normally a gas, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used as a fuel for engines, oxy-gas torches, barbecues, portable stoves, and residential central...

 chain.

Alcohols are classified into primary, secondary, and tertiary, based upon the number of carbon atoms connected to the carbon atom that bears the hydroxyl group. The primary alcohols have general formulas RCH2OH; secondary ones are RR'CHOH; and tertiary ones are RR'R"COH, where R, R', and R" stand for alkyl groups. Ethanol and n-propyl alcohol are primary alcohols; isopropyl alcohol is a secondary one. The prefixes sec- (or s-) and tert- (or t-), conventionally in italics, may be used before the alkyl group's name to distinguish secondary and tertiary alcohols, respectively, from the primary one. For example, isopropyl alcohol is occasionally called sec-propyl alcohol, and the tertiary alcohol (CH3)3COH, or 2-methylpropan-2-ol in IUPAC nomenclature is commonly known as tert-butyl alcohol
Tert-Butanol
tert-Butanol, or 2-methyl-2-propanol, is the simplest tertiary alcohol. It is one of the four isomers of butanol. tert-Butanol is a clear liquid with a camphor-like odor. It is very soluble in water and miscible with ethanol and diethyl ether...

 or tert-butanol.

Common Names

! Chemical Formula 
! IUPAC Name 
! Common Name 
|-
|align="center" colspan="3" |Monohydric alcohols
|-
|CH3OH
|Methanol
Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...


|Wood alcohol
|-
|C2H5OH
|Ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...


|Grain alcohol
|-
|C3H7OH
|Isopropyl alcohol
Isopropyl alcohol
Isopropyl alcohol is a common name for a chemical compound with the molecular formula C3H8O. It is a colorless, flammable chemical compound with a strong odor...


|Rubbing alcohol
|-
|C5H11OH
|Pentanol
|Amyl alcohol
Amyl alcohol
An amyl alcohol is any of 8 alcohols with the formula C5H11OH. A mixture of amyl alcohols can be obtained from fusel alcohol. Amyl alcohol is used as a solvent and in esterfication for example in the production of amyl acetate...


|-
|C16H33OH
|Hexadecan-1-ol
|Cetyl alcohol
Cetyl alcohol
Cetyl alcohol, also known as 1-hexadecanol and palmityl alcohol, is a fatty alcohol with the chemical formula CH315OH. At room temperature, cetyl alcohol takes the form of a waxy white solid or flakes....


|-
|align="center" colspan="3" |Polyhydric alcohols
|-
|C2H4(OH)2
|Ethane-1,2-diol
|Ethylene glycol
Ethylene glycol
Ethylene glycol is an organic compound widely used as an automotive antifreeze and a precursor to polymers. In its pure form, it is an odorless, colorless, syrupy, sweet-tasting liquid...


|-
|C3H5(OH)3
|Propane-1,2,3-triol
|Glycerin
|-
|C4H6(OH)4
|Butane-1,2,3,4-tetraol
|Erythritol
Erythritol
Erythritol is a sugar alcohol that has been approved for use as a food additive in the United States and throughout much of the world. It was discovered in 1848 by British chemist John Stenhouse. It occurs naturally in some fruits and fermented foods...


|-
|C5H7(OH)5
|Pentane-1,2,3,4,5-pentol
|Xylitol
Xylitol
Xylitol is a sugar alcohol sweetener used as a naturally occurring sugar substitute. It is found in the fibers of many fruits and vegetables, and can be extracted from various berries, oats, and mushrooms, as well as fibrous material such as corn husks and sugar cane bagasse, and birch...


|-
|C6H8(OH)6
|Hexane-1,2,3,4,5,6-hexol
|Mannitol
Mannitol
Mannitol is a white, crystalline organic compound with the formula . This polyol is used as an osmotic diuretic agent and a weak renal vasodilator...

, Sorbitol
Sorbitol
Sorbitol, also known as glucitol, Sorbogem® and Sorbo®, is a sugar alcohol that the human body metabolizes slowly. It can be obtained by reduction of glucose, changing the aldehyde group to a hydroxyl group. Sorbitol is found in apples, pears, peaches, and prunes...


|-
|C7H9(OH)7
|Heptane-1,2,3,4,5,6,7-heptol
|Volemitol
Volemitol
Volemitol is a naturally occurring seven-carbon sugar alcohol. It is a substance widely distributed in plants, red algae, fungi, mosses, and lichens. It was also found in lipopolysaccharides from E. coli. In certain higher plants, such as Primula, volemitol plays several important physiological roles...


|-
|align="center" colspan="3" |Unsaturated aliphatic alcohols
|-
|C3H5OH
|Prop-2-ene-1-ol
|Allyl alcohol
Allyl alcohol
Allyl alcohol is an organic compound with the structural formula CH2=CHCH2OH. Like many alcohols,it is a water soluble, colourless liquid, but it is more toxic than typical small alcohols. Allyl alcohol is used as a raw material for the production of glycerol, but is used as a precursor to many...


|-
|C10H17OH
|3,7-Dimethylocta-2,6-dien-1-ol
|Geraniol
Geraniol
Geraniol is a monoterpenoid and an alcohol. It is the primary part of rose oil, palmarosa oil, and citronella oil . It also occurs in small quantities in geranium, lemon, and many other essential oils. It appears as a clear to pale-yellow oil that is insoluble in water, but soluble in most common...


|-
|C3H3OH
|Prop-2-in-1-ol
|Propargyl alcohol
Propargyl alcohol
Propargyl alcohol, or 2-propyn-1-ol, is an organic compound which is a simple alcohol containing an alkyne functional group . Propargyl alcohol is a clear colorless viscous liquid that is miscible with water and most polar organic solvents. It is insoluble in most hydrocarbon solvents...


|-
|align="center" colspan="3" |Alicyclic alcohols
|-
|C6H6(OH)6
|Cyclohexane-1,2,3,4,5,6-hexol
|Inositol
Inositol
Inositol or cyclohexane-1,2,3,4,5,6-hexol is a chemical compound with formula 6126 or 6, a sixfold alcohol of cyclohexane. It exists in nine possible stereoisomers, of which the most prominent form, widely occurring in nature, is cis-1,2,3,5-trans-4,6-cyclohexanehexol, or myo-inositol...


|-
|C10H19OH
|2 - (2-propyl)-5-methyl-cyclohexane-1-ol
|Menthol
Menthol
Menthol is an organic compound made synthetically or obtained from peppermint or other mint oils. It is a waxy, crystalline substance, clear or white in color, which is solid at room temperature and melts slightly above. The main form of menthol occurring in nature is -menthol, which is assigned...


|}>

History and Etymology



Alcohol was discovered by Rhazes.

The word alcohol appears in English in the 16th century, loaned via French from medical Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

, ultimately from the Arabic  (, "the kohl
Kohl (cosmetics)
Kohl is an ancient eye cosmetic. It was made by grinding galena and other ingredients. It is widely used in South Asia, the Middle East, North Africa, the Horn of Africa, and parts of West Africa to darken the eyelids and as mascara for the eyelashes...

, a powder used as an eyeliner").

is Arabic for the definitive article
Article (grammar)
An article is a word that combines with a noun to indicate the type of reference being made by the noun. Articles specify the grammatical definiteness of the noun, in some languages extending to volume or numerical scope. The articles in the English language are the and a/an, and some...

, the in English.

The current Arabic name for alcohol is , re-introduced from western usage.

was the name given to the very fine powder, produced by the sublimation of the natural mineral stibnite
Stibnite
Stibnite, sometimes called antimonite, is a sulfide mineral with the formula Sb2S3. This soft grey material crystallizes in an orthorhombic space group. It is the most important source for the metalloid antimony...

 to form antimony
Antimony
Antimony is a toxic chemical element with the symbol Sb and an atomic number of 51. A lustrous grey metalloid, it is found in nature mainly as the sulfide mineral stibnite...

 sulfide
Sulfide
A sulfide is an anion of sulfur in its lowest oxidation state of 2-. Sulfide is also a slightly archaic term for thioethers, a common type of organosulfur compound that are well known for their bad odors.- Properties :...

 Sb
Antimony
Antimony is a toxic chemical element with the symbol Sb and an atomic number of 51. A lustrous grey metalloid, it is found in nature mainly as the sulfide mineral stibnite...

2S
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

3 (hence the essence or "spirit" of the substance), which was used as an antiseptic
Antiseptic
Antiseptics are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction...

 and eyeliner
Kohl (cosmetics)
Kohl is an ancient eye cosmetic. It was made by grinding galena and other ingredients. It is widely used in South Asia, the Middle East, North Africa, the Horn of Africa, and parts of West Africa to darken the eyelids and as mascara for the eyelashes...

.

Bartholomew Traheron
Bartholomew Traheron
-Life:Born about 1510, he is said to have been a native of Cornwall. Bartholomew was early left an orphan, and was brought up under the care of Richard Tracy of Toddington, Gloucestershire....

 in his 1543 translation of John of Vigo
John of Vigo
John of Vigo was a Spanish Renaissance pioneer of chirurgy....

 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
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

) 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. Ethanol has a slightly sweeter odor than the other alcohols.

In general, the hydroxyl group makes the alcohol molecule polar. Those groups can form hydrogen bond
Hydrogen bond
A hydrogen bond is the attractive interaction of a hydrogen atom with an electronegative atom, such as nitrogen, oxygen or fluorine, that comes from another molecule or chemical group. The hydrogen must be covalently bonded to another electronegative atom to create the bond...

s to one another and to other compounds (except in certain large molecules
2,2,4,4-Tetramethyl-3-t-butyl-pentane-3-ol
2,2,4,4-Tetramethyl-3-t-butyl-pentane-3-ol is an organic compound with formula C13H28O, or 3COH. It is an alcohol whose molecule can be viewed as a tridecane isomer where the central hydrogen has been replaced by a hydroxyl group -OH.The bulky tert-butyl groups 3C- groups attached to the central...

 where the hydroxyl is protected by steric hindrance of adjacent groups). This hydrogen bonding means that alcohols can be used as protic solvent
Protic solvent
In chemistry a protic solvent is a solvent that has a hydrogen atom bound to an oxygen or a nitrogen . In general terms, any molecular solvent that contains dissociable H+ is called a protic solvent. The molecules of such solvents can donate an H+...

s. Two opposing solubility trends in alcohols are: the tendency of the polar OH to promote solubility in water, and the tendency 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
N-Butanol
n-Butanol or n-butyl alcohol or normal butanol is a primary alcohol with a 4-carbon structure and the molecular formula C4H9OH. Its isomers include isobutanol, 2-butanol, and tert-butanol...

, with a four-carbon chain, is moderately soluble because of a balance between the two trends. Alcohols of five or more carbons (pentanol
Amyl alcohol
An amyl alcohol is any of 8 alcohols with the formula C5H11OH. A mixture of amyl alcohols can be obtained from fusel alcohol. Amyl alcohol is used as a solvent and in esterfication for example in the production of amyl acetate...

 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
Hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....

s and ether
Ether
Ethers are a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R'. A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether"...

s. The boiling point of the alcohol ethanol is 78.29 °C, compared to 69 °C for the hydrocarbon hexane
Hexane
Hexane is a hydrocarbon with the chemical formula C6H14; that is, an alkane with six carbon atoms.The term may refer to any of four other structural isomers with that formula, or to a mixture of them. In the IUPAC nomenclature, however, hexane is the unbranched isomer ; the other four structures...

 (a common constituent of gasoline
Gasoline
Gasoline , or petrol , is a toxic, translucent, petroleum-derived liquid that is primarily used as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. Some gasolines also contain...

), and 34.6 °C for diethyl ether
Diethyl ether
Diethyl ether, also known as ethyl ether, simply ether, or ethoxyethane, is an organic compound in the ether class with the formula . It is a colorless, highly volatile flammable liquid with a characteristic odor...

.

Alcohols, like water, can show either acidic or basic properties at the -OH group. With a pKa
PKA
PKA, pKa, or other similar variations may stand for:* pKa, the symbol for the acid dissociation constant at logarithmic scale* Protein kinase A, a class of cAMP-dependent enzymes* Pi Kappa Alpha, the North-American social fraternity...

 of around 16-19, they are, in general, slightly weaker acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...

s than water, but they are still able to react with strong bases such as sodium hydride
Sodium hydride
Sodium hydride is the chemical compound with the empirical formula NaH. It is primarily used as a strong base in organic synthesis. NaH is representative of the saline hydrides, meaning it is a salt-like hydride, composed of Na+ and H− ions, in contrast to the more molecular hydrides such as...

 or reactive metals such as sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...

. The salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...

s that result are called alkoxide
Alkoxide
An alkoxide is the conjugate base of an alcohol and therefore consists of an organic group bonded to a negatively charged oxygen atom. They can be written as RO−, where R is the organic substituent. Alkoxides are strong bases and, when R is not bulky, good nucleophiles and good ligands...

s
, with the general formula RO-M
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

+.

Meanwhile, the oxygen atom has lone pair
Lone pair
In chemistry, a lone pair is a valence electron pair without bonding or sharing with other atoms. They are found in the outermost electron shell of an atom, so lone pairs are a subset of a molecule's valence electrons...

s of nonbonded electrons that render it weakly basic
Base (chemistry)
For the term in genetics, see base A base in chemistry is a substance that can accept hydrogen ions or more generally, donate electron pairs. A soluble base is referred to as an alkali if it contains and releases hydroxide ions quantitatively...

 in the presence of strong acids such as sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

. For example, with methanol:

Alcohols can also undergo oxidation to give aldehyde
Aldehyde
An aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....

s, ketone
Ketone
In organic chemistry, a ketone is an organic compound with the structure RCR', where R and R' can be a variety of atoms and groups of atoms. It features a carbonyl group bonded to two other carbon atoms. Many ketones are known and many are of great importance in industry and in biology...

s, or carboxylic acid
Carboxylic acid
Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...

s, or they can be dehydrated to alkene
Alkene
In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...

s. They can react to form ester compounds, and they can (if activated first) undergo nucleophilic substitution
Nucleophilic substitution
In organic and inorganic chemistry, nucleophilic substitution is a fundamental class of reactions in which an electron nucleophile selectively bonds with or attacks the positive or partially positive charge of an atom or a group of atoms called the leaving group; the positive or partially positive...

 reactions. The lone pairs of electrons on the oxygen of the hydroxyl group also makes alcohols nucleophiles. For more details, see the reactions of alcohols section below.

As one moves from primary to secondary to tertiary alcohols with the same backbone, the hydrogen bond strength, the boiling point, and the acidity typically decrease.

Applications



Alcohols can be used as a beverage (ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

 only), as fuel and for many scientific, medical, and industrial utilities. Ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

 in the form of alcoholic beverages has been consumed by humans since pre-historic times. A 50% v/v solution of ethylene glycol
Ethylene glycol
Ethylene glycol is an organic compound widely used as an automotive antifreeze and a precursor to polymers. In its pure form, it is an odorless, colorless, syrupy, sweet-tasting liquid...

 in water is commonly used as an antifreeze
Antifreeze
Antifreeze is a freeze preventive used in internal combustion engines and other heat transfer applications, such as HVAC chillers and solar water heaters....

.

Some alcohols, mainly ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

 and methanol
Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...

, can be used as an alcohol fuel
Alcohol fuel
Although fossil fuels have become the dominant energy resource for the modern world, alcohol has been used as a fuel throughout history. The first four aliphatic alcohols are of interest as fuels because they can be synthesized chemically or biologically, and they have characteristics which allow...

. Fuel performance can be increased in forced induction
Forced induction
Forced induction is the process of compressing air on the intake of an internal combustion engine . A forced induction engine uses a gas compressor to increase the pressure, temperature and density of the air...

 internal combustion engine
Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...

s by injecting alcohol into the air intake after the turbocharger
Turbocharger
A turbocharger, or turbo , from the Greek "τύρβη" is a centrifugal compressor powered by a turbine that is driven by an engine's exhaust gases. Its benefit lies with the compressor increasing the mass of air entering the engine , thereby resulting in greater performance...

 or supercharger
Supercharger
A supercharger is an air compressor used for forced induction of an internal combustion engine.The greater mass flow-rate provides more oxygen to support combustion than would be available in a naturally aspirated engine, which allows more fuel to be burned and more work to be done per cycle,...

 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
Solvent
A solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent at a specified temperature...

s. Because of its low toxicity and ability to dissolve non-polar substances, ethanol can be used as a solvent in medical drugs, perfume
Perfume
Perfume is a mixture of fragrant essential oils and/or aroma compounds, fixatives, and solvents used to give the human body, animals, objects, and living spaces "a pleasant scent"...

s, and vegetable essences such as vanilla
Vanilla
Vanilla is a flavoring derived from orchids of the genus Vanilla, primarily from the Mexican species, Flat-leaved Vanilla . The word vanilla derives from the Spanish word "", little pod...

. In organic synthesis
Organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...

, 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
Preservative
A preservative is a naturally occurring or synthetically produced substance that is added to products such as foods, pharmaceuticals, paints, biological samples, wood, etc. to prevent decomposition by microbial growth or by undesirable chemical changes....

 for specimens.

Alcohol gels have become common as hand sanitizers.

Production


In industry, alcohols are produced in several ways:
  • By fermentation
    Fermentation (biochemistry)
    Fermentation is the process of extracting energy from the oxidation of organic compounds, such as carbohydrates, using an endogenous electron acceptor, which is usually an organic compound. In contrast, respiration is where electrons are donated to an exogenous electron acceptor, such as oxygen,...

     using glucose
    Glucose
    Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

     produced from sugar from the hydrolysis
    Hydrolysis
    Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...

     of starch
    Starch
    Starch or amylum is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store...

    , in the presence of yeast and temperature of less than 37 °C to produce ethanol, for instance, the conversion of invertase
    Invertase
    Invertase is an enzyme that catalyzes the hydrolysis of sucrose . The resulting mixture of fructose and glucose is called inverted sugar syrup. Related to invertases are sucrases. Invertases and sucrases hydrolyze sucrose to give the same mixture of glucose and fructose...

     to glucose
    Glucose
    Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

     and fructose
    Fructose
    Fructose, or fruit sugar, is a simple monosaccharide found in many plants. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed directly into the bloodstream during digestion. Fructose was discovered by French chemist Augustin-Pierre Dubrunfaut in 1847...

     or the conversion of glucose
    Glucose
    Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

     to zymase
    Zymase
    Zymase is an enzyme complex that catalyzes the fermentation of sugar into ethanol and carbon dioxide. They occur naturally in yeasts...

     and ethanol
    Ethanol
    Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

    .
  • By direct hydration
    Hydration reaction
    In organic chemistry, a hydration reaction is a chemical reaction in which a hydroxyl group and a hydrogen cation are added to the two carbon atoms bonded together in the carbon-carbon double bond which makes up an alkene functional group. The reaction usually runs in a strong acidic, aqueous...

     using ethylene
    Ethylene
    Ethylene is a gaseous organic compound with the formula . It is the simplest alkene . Because it contains a carbon-carbon double bond, ethylene is classified as an unsaturated hydrocarbon. Ethylene is widely used in industry and is also a plant hormone...

     (ethylene hydration) or other alkenes from cracking
    Cracking (chemistry)
    In petroleum geology and chemistry, cracking is the process whereby complex organic molecules such as kerogens or heavy hydrocarbons are broken down into simpler molecules such as light hydrocarbons, by the breaking of carbon-carbon bonds in the precursors. The rate of cracking and the end products...

     of fractions of distilled crude oil.

Endogenous


Several of the benign bacteria in the intestine use fermentation
Fermentation (food)
Fermentation in food processing typically is the conversion of carbohydrates to alcohols and carbon dioxide or organic acids using yeasts, bacteria, or a combination thereof, under anaerobic conditions. Fermentation in simple terms is the chemical conversion of sugars into ethanol...

 as a form of anaerobic respiration
Anaerobic respiration
Anaerobic respiration is a form of respiration using electron acceptors other than oxygen. Although oxygen is not used as the final electron acceptor, the process still uses a respiratory electron transport chain; it is respiration without oxygen...

. This metabolic
Metabolism
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...

 reaction produces ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

 as a waste product, just like aerobic respiration produces carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 and water. Thus, human bodies contain some quantity of alcohol endogenously produced by these bacteria.

Substitution


Primary alkyl halides react with aqueous NaOH or KOH
Potassium hydroxide
Potassium hydroxide is an inorganic compound with the formula KOH, commonly called caustic potash.Along with sodium hydroxide , this colorless solid is a prototypical strong base. It has many industrial and niche applications. Most applications exploit its reactivity toward acids and its corrosive...

 mainly to primary alcohols in nucleophilic aliphatic substitution. (Secondary and especially tertiary alkyl halides will give the elimination (alkene) product instead). Grignard reagents react with carbonyl
Carbonyl
In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups....

 groups to secondary and tertiary alcohols. Related reactions are the Barbier reaction
Barbier reaction
The Barbier reaction is an organic reaction between an alkyl halide and a carbonyl group as an electrophilic substrate in the presence of magnesium, aluminium, zinc, indium, tin or its salts. The reaction product is a primary, secondary or tertiary alcohol...

 and the Nozaki-Hiyama reaction.

Reduction


Aldehydes or ketone
Ketone
In organic chemistry, a ketone is an organic compound with the structure RCR', where R and R' can be a variety of atoms and groups of atoms. It features a carbonyl group bonded to two other carbon atoms. Many ketones are known and many are of great importance in industry and in biology...

s are reduced
Redox
Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....

 with sodium borohydride
Sodium borohydride
Sodium borohydride, also known as sodium tetrahydridoborate, is an inorganic compound with the formula NaBH4. This white solid, usually encountered as a powder, is a versatile reducing agent that finds wide application in chemistry, both in the laboratory and on a technical scale. Large amounts are...

 or lithium aluminium hydride
Lithium aluminium hydride
Lithium aluminium hydride, commonly abbreviated to LAH or known as LithAl, is an inorganic compound with the chemical formula LiAlH4. It was discovered by Finholt, Bond and Schlesinger in 1947. This compound is used as a reducing agent in organic synthesis, especially for the reduction of esters,...

 (after an acidic workup). Another reduction by aluminiumisopropylates is the Meerwein-Ponndorf-Verley reduction
Meerwein-Ponndorf-Verley reduction
The Meerwein-Ponndorf-Verley Reduction in organic chemistry is the reduction of ketones and aldehydes to their corresponding alcohols utilizing aluminumalkoxide catalysis in the presence of a sacrificial alcohol...

. Noyori asymmetric hydrogenation
Noyori asymmetric hydrogenation
The Noyori asymmetric hydrogenation is a chemical reaction described as an asymmetric reduction of β-keto-esters.Both enantiomers of BINAP are commercially available and widely used...

 is the asymmetric reduction of β-keto-esters.

Hydrolysis


Alkenes engage in an acid catalysed hydration reaction
Hydration reaction
In organic chemistry, a hydration reaction is a chemical reaction in which a hydroxyl group and a hydrogen cation are added to the two carbon atoms bonded together in the carbon-carbon double bond which makes up an alkene functional group. The reaction usually runs in a strong acidic, aqueous...

 using concentrated sulfuric acid as a catalyst that 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
Halohydrin formation reaction
The halohydrin formation reaction is a chemical reaction in which a halogen is added to an alkene in aqueous solution to form a halohydrin. The reaction is a form of electrophilic addition; it is similar to the halogen addition reaction....

. Amine
Amine
Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...

s can be converted to diazonium salts, which are then hydrolyzed.

The formation of a secondary alcohol via reduction and hydration is shown:

Deprotonation


Alcohols can behave as weak acids, undergoing deprotonation
Deprotonation
Deprotonation is the removal of a proton from a molecule, forming the conjugate base.The relative ability of a molecule to give up a proton is measured by its pKa value. A low pKa value indicates that the compound is acidic and will easily give up its proton to a base...

. The deprotonation reaction to produce an alkoxide
Alkoxide
An alkoxide is the conjugate base of an alcohol and therefore consists of an organic group bonded to a negatively charged oxygen atom. They can be written as RO−, where R is the organic substituent. Alkoxides are strong bases and, when R is not bulky, good nucleophiles and good ligands...

 salt is performed either with a strong base such as sodium hydride or n-butyllithium
N-Butyllithium
n-Butyllithium is an organolithium reagent. It is widely used as a polymerization initiator in the production of elastomers such as polybutadiene or styrene-butadiene-styrene...

 or with sodium or potassium metal.
2 R-OH + 2 NaH
Sodium hydride
Sodium hydride is the chemical compound with the empirical formula NaH. It is primarily used as a strong base in organic synthesis. NaH is representative of the saline hydrides, meaning it is a salt-like hydride, composed of Na+ and H− ions, in contrast to the more molecular hydrides such as...

 → 2 R-O-Na+ + 2H2
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...


2 R-OH + 2 Na
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...

 → 2 R-ONa+ + H2

2 CH3CH2-OH
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

 + 2 Na → 2 CH3-CH2-O+ + H2


Water is similar in pKa
PKA
PKA, pKa, or other similar variations may stand for:* pKa, the symbol for the acid dissociation constant at logarithmic scale* Protein kinase A, a class of cAMP-dependent enzymes* Pi Kappa Alpha, the North-American social fraternity...

 to many alcohols, so with sodium hydroxide there is an equilibrium
Chemical equilibrium
In a chemical reaction, chemical equilibrium is the state in which the concentrations of the reactants and products have not yet changed with time. It occurs only in reversible reactions, and not in irreversible reactions. Usually, this state results when the forward reaction proceeds at the same...

 set-up, which usually lies to the left:
R-OH + NaOH ⇌ R-O-Na+ + H2O (equilibrium to the left)


It should be noted, however, 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 groups 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 halides alkoxides give rise to ether
Ether
Ethers are a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R'. A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether"...

s in the Williamson ether synthesis
Williamson ether synthesis
The Williamson ether synthesis is an organic reaction, forming an ether from an organohalide and an alcohol. This reaction was developed by Alexander Williamson in 1850. Typically it involves the reaction of an alkoxide ion with a primary alkyl halide via an SN2 reaction...

.

Nucleophilic substitution


The OH group is not a good leaving group
Leaving group
In chemistry, a leaving group is a molecular fragment that departs with a pair of electrons in heterolytic bond cleavage. Leaving groups can be anions or neutral molecules. Common anionic leaving groups are halides such as Cl−, Br−, and I−, and sulfonate esters, such as para-toluenesulfonate...

 in nucleophilic substitution
Nucleophilic substitution
In organic and inorganic chemistry, nucleophilic substitution is a fundamental class of reactions in which an electron nucleophile selectively bonds with or attacks the positive or partially positive charge of an atom or a group of atoms called the leaving group; the positive or partially positive...

 reactions, so neutral alcohols do not react in such reactions. However, if the oxygen is first protonated to give R−OH2+, the leaving group (water) is much more stable, and the nucleophilic substitution can take place. For instance, tertiary alcohols react with hydrochloric acid
Hydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....

 to produce tertiary alkyl halides, where the hydroxyl group is replaced by a chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

 atom by unimolecular nucleophilic substitution. If primary or secondary alcohols are to be reacted with hydrochloric acid
Hydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....

, an activator such as zinc chloride
Zinc chloride
Zinc chloride is the name of chemical compound with the formula ZnCl2 and its hydrates. Zinc chlorides, of which nine crystalline forms are known, are colorless or white, and are highly soluble in water. ZnCl2 itself is hygroscopic and even deliquescent. Samples should therefore be protected from...

 is needed. In alternative fashion, the conversion may be performed directly using thionyl chloride
Thionyl chloride
Thionyl chloride is an inorganic compound with the formula SOCl2. It is a reactive chemical reagent used in chlorination reactions. It is a colorless, distillable liquid at room temperature and pressure that decomposes above 140 °C. Thionyl chloride is sometimes confused with sulfuryl...

.[1]

Alcohols may, likewise, be converted to alkyl bromides using hydrobromic acid
Hydrobromic acid
Hydrobromic acid is a strong acid formed by dissolving the diatomic molecule hydrogen bromide in water. "Constant boiling" hydrobromic acid is an aqueous solution that distills at 124.3 °C and contains 47.6% HBr by weight, which is 8.89 mol/L. Hydrobromic acid has a pKa of −9, making it a...

 or phosphorus tribromide
Phosphorus tribromide
Phosphorus tribromide is a colourless liquid with the formula PBr3. It fumes in air due to hydrolysis and has a penetrating odour. It is widely used in the laboratory for the conversion of alcohols to alkyl bromides.-Preparation:...

, for example:
3 R-OH + PBr3 → 3 RBr + H3PO3


In the Barton-McCombie deoxygenation
Barton-McCombie deoxygenation
The Barton–McCombie deoxygenation is an organic reaction in which an hydroxy functional group in an organic compound is replaced by a hydride to give an alkyl group . It is named for the British chemists Sir Derek Harold Richard Barton and Stuart W. McCombie.This deoxygenation reaction is a...

 an alcohol is deoxygenated to an alkane
Alkane
Alkanes are chemical compounds that consist only of hydrogen and carbon atoms and are bonded exclusively by single bonds without any cycles...

 with tributyltin hydride
Organotin
Organotin compounds or stannanes are chemical compounds based on tin with hydrocarbon substituents. Organotin chemistry is part of the wider field of organometallic chemistry. The first organotin compound was diethyltin diiodide, discovered by Edward Frankland in 1849...

 or a trimethylborane
Organoborane
Organoborane or organoboron compounds are chemical compounds that are organic derivatives of BH3, for example trialkyl boranes. Organoboron chemistry or organoborane chemistry is the chemistry of these compounds...

-water complex in a radical substitution
Radical substitution
In organic chemistry, a radical substitution reaction is a substitution reaction involving free radicals as a reactive intermediate.The reaction always involves at least two steps, and possibly a third....

 reaction.

Dehydration


Alcohols are themselves nucleophilic, so R−OH2+ can react with ROH to produce ether
Ether
Ethers are a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R'. A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether"...

s and water in a dehydration reaction
Dehydration reaction
In chemistry and the biological sciences, a dehydration reaction is usually defined as a chemical reaction that involves the loss of water from the reacting molecule. Dehydration reactions are a subset of elimination reactions...

, although this reaction is rarely used except in the manufacture of diethyl ether
Diethyl ether
Diethyl ether, also known as ethyl ether, simply ether, or ethoxyethane, is an organic compound in the ether class with the formula . It is a colorless, highly volatile flammable liquid with a characteristic odor...

.

More useful is the E1 elimination reaction
Elimination reaction
An elimination reaction is a type of organic reaction in which two substituents are removed from a molecule in either a one or two-step mechanism...

 of alcohols to produce alkene
Alkene
In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...

s. The reaction, in general, obeys Zaitsev's Rule
Zaitsev's rule
In chemistry, Zaitsev's rule, Saytzeff's rule or Saytsev's rule named after Alexander Mikhailovich Zaitsev is a rule that states that if more than one alkene can be formed during dehalogenation by an elimination reaction, the more stable alkene is the major product...

, 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:



A more controlled elimination reaction is the Chugaev elimination
Chugaev elimination
The Chugaev elimination is a chemical reaction that involves the elimination of water from alcohols to produce alkenes. The intermediate is a xanthate. It is named for its discoverer, the Russian chemist Lev Aleksandrovich Chugaev....

 with carbon disulfide and iodomethane.

Esterification


To form an ester
Ester
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...

 from an alcohol and a carboxylic acid
Carboxylic acid
Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...

 the reaction, known as Fischer esterification
Fischer esterification
Fischer esterification or Fischer–Speier esterification is a special type of esterification by refluxing a carboxylic acid and an alcohol in the presence of an acid catalyst. The reaction was first described by Emil Fischer and Arthur Speier in 1895. Most carboxylic acids are suitable for the...

, is usually performed at reflux
Reflux
Reflux is a technique involving the condensation of vapors and the return of this condensate to the system from which it originated. It is used in industrial and laboratory distillations...

 with a catalyst of concentrated sulfuric acid:
R-OH + R'-COOH → R'-COOR + H2O


In order to drive the equilibrium to the right and produce a good yield
Yield (chemistry)
In chemistry, yield, also referred to as chemical yield and reaction yield, is the amount of product obtained in a chemical reaction. The absolute yield can be given as the weight in grams or in moles...

 of ester, water is usually removed, either by an excess of H2SO4 or by using a Dean-Stark apparatus
Dean-Stark apparatus
For the video game character, see Wild Arms 5thumb|right|A Dean-Stark apparatus in use; aluminum foil is used to reduce radiative heat lossesThe Dean-Stark apparatus or Dean-Stark receiver or distilling trap is a piece of laboratory glassware used in synthetic chemistry to collect water from a...

. Esters may also be prepared by reaction of the alcohol with an acid chloride in the presence of a base such as pyridine
Pyridine
Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one C-H group replaced by a nitrogen atom...

.

Other types of ester are prepared in a similar manner — for example, tosyl
Tosyl
A tosyl group is CH3C6H4SO2. This group is usually derived from the compound 4-toluenesulfonyl chloride, CH3C6H4SO2Cl, which forms esters and amides of toluenesulfonic or tosylic acid...

 (tosylate) esters are made by reaction of the alcohol with p-toluenesulfonyl chloride in pyridine.

Oxidation



Primary alcohols (R-CH2-OH) can be oxidized either to aldehyde
Aldehyde
An aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....

s (R-CHO) or to carboxylic acid
Carboxylic acid
Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...

s (R-CO2H), while the oxidation of secondary alcohols (R1R2CH-OH) normally terminates at the ketone
Ketone
In organic chemistry, a ketone is an organic compound with the structure RCR', where R and R' can be a variety of atoms and groups of atoms. It features a carbonyl group bonded to two other carbon atoms. Many ketones are known and many are of great importance in industry and in biology...

 (R1R2C=O) stage. Tertiary alcohols (R1R2R3C-OH) are resistant to oxidation.

The direct oxidation of primary alcohols to carboxylic acids
Oxidation of primary alcohols to carboxylic acids
The oxidation of primary alcohols to carboxylic acids is an important oxidation reaction in organic chemistry.When a primary alcohol is converted to a carboxylic acid, the terminal carbon atom increases its oxidation state by four...

 normally proceeds via the corresponding aldehyde, which is transformed via an aldehyde hydrate (R-CH(OH)2) by reaction with water before it can be further oxidized to the carboxylic acid.

Reagents useful for the transformation of primary alcohols to aldehydes are normally also suitable for the oxidation of secondary alcohols to ketones
Oxidation of secondary alcohols to ketones
The oxidation of secondary alcohols to ketones is an important oxidation reaction in organic chemistry.When a secondary alcohol is oxidised, it is converted to a ketone. The hydrogen from the hydroxyl group is lost along with the hydrogen bonded to the second carbon. The remaining oxygen then...

. These include Collins reagent
Collins reagent
Collins reagent is the complex of chromium oxide with pyridine in dichloromethane. It is used to selectively oxidize primary alcohols to the aldehyde, and will tolerate many other functional groups within the molecule....

 and Dess-Martin periodinane
Dess-Martin periodinane
Dess–Martin periodinane is a chemical reagent used to oxidize primary alcohols to aldehydes and secondary alcohols to ketones. This periodinane has several advantages over chromium- and DMSO-based oxidants that include milder conditions , shorter reaction times, higher yields, simplified workups,...

. The direct oxidation of primary alcohols to carboxylic acids can be carried out using potassium permanganate
Potassium permanganate
Potassium permanganate is an inorganic chemical compound with the formula KMnO4. It is a salt consisting of K+ and MnO4− ions. Formerly known as permanganate of potash or Condy's crystals, it is a strong oxidizing agent. It dissolves in water to give intensely purple solutions, the...

 or the Jones reagent.

Toxicity



Ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

 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
Drunkenness
Alcohol intoxication is a physiological state that occurs when a person has a high level of ethanol in his or her blood....

 (intoxication), which may lead to a hangover
Hangover
A hangover describes the sum of unpleasant physiological effects following heavy consumption of alcoholic beverages. The most commonly reported characteristics of a hangover include headache, nausea, sensitivity to light and noise, lethargy, dysphoria, diarrhea and thirst, typically after the...

 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 of ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

 in rats is 10.3 g/kg.

Other alcohols are substantially more poisonous than ethanol, partly because they take much longer to be metabolized and partly because their metabolism produces substances that are even more toxic. Methanol (wood alcohol), for instance, is oxidized to formaldehyde
Formaldehyde
Formaldehyde is an organic compound with the formula CH2O. It is the simplest aldehyde, hence its systematic name methanal.Formaldehyde is a colorless gas with a characteristic pungent odor. It is an important precursor to many other chemical compounds, especially for polymers...

 and then to the poisonous formic acid
Formic acid
Formic acid is the simplest carboxylic acid. Its chemical formula is HCOOH or HCO2H. It is an important intermediate in chemical synthesis and occurs naturally, most notably in the venom of bee and ant stings. In fact, its name comes from the Latin word for ant, formica, referring to its early...

 in the liver by alcohol dehydrogenase
Alcohol dehydrogenase
Alcohol dehydrogenases are a group of dehydrogenase enzymes that occur in many organisms and facilitate the interconversion between alcohols and aldehydes or ketones with the reduction of nicotinamide adenine dinucleotide...

 and formaldehyde dehydrogenase
Formaldehyde dehydrogenase
In enzymology, a formaldehyde dehydrogenase is an enzyme that catalyzes the chemical reactionThe 3 substrates of this enzyme are formaldehyde, NAD+, and H2O, whereas its 3 products are formate, NADH, and H+....

 enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

s, respectively; accumulation of formic acid can lead to blindness or death. Likewise, poisoning due to other alcohols such as ethylene glycol
Ethylene glycol
Ethylene glycol is an organic compound widely used as an automotive antifreeze and a precursor to polymers. In its pure form, it is an odorless, colorless, syrupy, sweet-tasting liquid...

 or diethylene glycol
Diethylene glycol
Diethylene glycol is an organic compound with the formula 2O. It is a colorless, practically odorless, poisonous, and hygroscopic liquid with a sweetish taste. It is miscible in water, alcohol, ether, acetone, and ethylene glycol. DEG is a widely used solvent...

 are due to their metabolites, which are also produced by alcohol dehydrogenase. An effective treatment to prevent toxicity after methanol or ethylene glycol ingestion is to administer ethanol. Alcohol dehydrogenase has a higher affinity for ethanol, thus preventing methanol from binding and acting as a substrate
Substrate (biochemistry)
In biochemistry, a substrate is a molecule upon which an enzyme acts. Enzymes catalyze chemical reactions involving the substrate. In the case of a single substrate, the substrate binds with the enzyme active site, and an enzyme-substrate complex is formed. The substrate is transformed into one or...

. Any remaining methanol will then have time to be excreted through the kidneys.

Methanol itself, while poisonous, has a much weaker sedative
Sedative
A sedative or tranquilizer is a substance that induces sedation by reducing irritability or excitement....

 effect than ethanol. Some longer-chain alcohols such as n-propanol, isopropanol, n-butanol
N-Butanol
n-Butanol or n-butyl alcohol or normal butanol is a primary alcohol with a 4-carbon structure and the molecular formula C4H9OH. Its isomers include isobutanol, 2-butanol, and tert-butanol...

, t-butanol, and 2-methyl-2-butanol
2-Methyl-2-butanol
2-Methyl-2-butanol, also known as tert-amyl alcohol or amylene hydrate, is one of the isomers of amyl alcohol. It is a clear, colorless liquid with a strong odor of peppermint or camphor. In humans it possesses sedative, hypnotic, and anticonvulsant effects similar to ethanol through ingestion or...

 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
Fusel alcohol
Fusel alcohols, also sometimes called fusel oils, or potato oil in Europe, are higher-order alcohols formed by fermentation and present in cider, mead, beer, wine, and spirits to varying degrees....

s, and are reputed to cause severe hangover
Hangover
A hangover describes the sum of unpleasant physiological effects following heavy consumption of alcoholic beverages. The most commonly reported characteristics of a hangover include headache, nausea, sensitivity to light and noise, lethargy, dysphoria, diarrhea and thirst, typically after the...

s although it is unclear if the fusel alcohols are actually responsible. Many longer chain alcohols are used in industry as solvent
Solvent
A solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent at a specified temperature...

s and are occasionally abused by alcoholics, leading to a range of adverse health effects.

Occurrence in nature


Alcohol has been found outside the Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...

. It can be found in low densities in star and planetary system forming regions of space.

See also


  • Blood alcohol content
    Blood alcohol content
    Blood alcohol content , also called blood alcohol concentration, blood ethanol concentration, or blood alcohol level is most commonly used as a metric of alcohol intoxication for legal or medical purposes....

  • Breathalyzer
    Breathalyzer
    A breathalyzer or breathalyser is a device for estimating blood alcohol content from a breath sample...

  • Cooking with alcohol
    Cooking with alcohol
    -As ingredient:Many foods contain alcoholic beverages that are later incorporated into the food itself, rather than being consumed separately by drinking them. Such dishes include coq au vin, hunter style chicken, and boeuf bourguignon. More modern examples are beer grilled chicken and bratwursts...

  • Enol
    Enol
    Enols are alkenes with a hydroxyl group affixed to one of the carbon atoms composing the double bond. Alkenes with a hydroxyl group on both sides of the double bond are called enediols. Deprotonated anions of enols are called enolates...

  • Fatty alcohol
    Fatty alcohol
    Fatty alcohols are aliphatic alcohols consisting of a chain of 8 to 22 carbon atoms. Fatty alcohols usually have even number of carbon atoms and a single alcohol group attached to the terminal carbon. Some are unsaturated and some are branched...

  • History of alcoholic beverages
  • List of countries by alcohol consumption
  • Phenols
    Phenols
    In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of a hydroxyl group bonded directly to an aromatic hydrocarbon group...

  • Polyol
    Polyol
    A polyol is an alcohol containing multiple hydroxyl groups. In two technological disciplines the term "polyol" has a special meaning: food science and polymer chemistry.- Polyols in food science :...

  • Rubbing alcohol
    Rubbing alcohol
    Rubbing alcohol, USP / B.P. is a liquid prepared and used primarily for topical application. It is prepared from a special denatured alcohol solution and contains 97.5-100% by volume of pure, concentrated ethanol or isopropyl alcohol...

  • Sugar alcohol
    Sugar alcohol
    A sugar alcohol is a hydrogenated form of carbohydrate, whose carbonyl group has been reduced to a primary or secondary hydroxyl group . Sugar alcohols have the general formula Hn+1H, whereas sugars have HnHCO...

  • Surrogate alcohol
    Surrogate alcohol
    Surrogate alcohol is a term for any substance containing ethanol that is consumed but is not meant for human consumption. Most people turn to these as a last resort either out of desperation or being unable to afford consumable alcoholic beverages....

  • Transesterification
    Transesterification
    In organic chemistry, transesterification is the process of exchanging the organic group R″ of an ester with the organic group R′ of an alcohol. These reactions are often catalyzed by the addition of an acid or base catalyst...