Alcohol

Ball-and-stick model of the hydroxyl (-OH) functional group in an alcohol molecule (R3COH). The three "R's" stand for carbon substituents or hydrogen atoms.[1]
The hydroxyl (-OH) functional group with bond angle

In chemistry, an alcohol is any organic compound in which the hydroxyl functional group (–OH) is bound to a carbon.[2] The term alcohol originally referred to the primary alcohol ethanol (ethyl alcohol), which is used as a drug and is the main alcohol present in alcoholic beverages.

The suffix -ol appears in the IUPAC chemical name 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 International Union of Pure and Applied Chemistry (IUPAC) name. The suffix -ol in non-systematic names (such as paracetamol or cholesterol) 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 and sucrose) contain hydroxyl functional groups without using the suffix. An important class of alcohols, of which methanol and ethanol are the simplest members is the alcohols, the general formula for which is CnH2n+1OH. It is these simple monoalcohols that are the subject of this article.

History and nomenclature

Alcohol distillation was known to Islamic chemists as early as the eighth century.[3][4] The Arab chemist, al-Kindi, unambiguously described the distillation of wine in a treatise titled as "The Book of the chemistry of Perfume and Distillations".[5][6][7]

The Persian Rhazes (854 CE – 925 CE)[8] is credited with the discovery of ethanol.[9][10]

Etymology

The word "alcohol" is from the Arabic kohl (Arabic: الكحل‎, translit. al-kuḥl), a powder used as an eyeliner.[11] Al- is the Arabic definite article, equivalent to the in English. Alcohol was originally used for the very fine powder produced by the sublimation of the natural mineral stibnite to form antimony trisulfide Sb
2
S
3
, hence the essence or "spirit" of this substance. It was used as an antiseptic, eyeliner, and cosmetic. The meaning of alcohol was extended to distilled substances in general, and then narrowed to ethanol, when "spirits" was a synonym for hard liquor.[12]

Bartholomew Traheron, in his 1543 translation of John of Vigo, introduces the word as a term used by "barbarous" (Moorish) authors for "fine powder." Vigo wrote: "the barbarous auctours use alcohol, or (as I fynde it sometymes wryten) alcofoll, for moost fine poudre."[13]

The 1657 Lexicon Chymicum, by William Johnson glosses the word as "antimonium sive stibium."[14] 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) refers to "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" (the chemical known today as ethanol) in the 18th century and was extended to the class of substances so-called as "alcohols" in modern chemistry after 1850.[13]

The term ethanol was invented 1892, combining the word ethane with the "-ol" ending of "alcohol".[15]

Systematic names

IUPAC nomenclature is used in scientific publications and where precise identification of the substance is important, especially in cases where the relative complexity of the molecule does not make such a systematic name unwieldy. In the IUPAC system, in naming simple alcohols, the name of the alkane chain loses the terminal "e" and adds "ol", e.g., as in "methanol" and "ethanol".[16] 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
3
CH
2
CH
2
OH
, propan-2-ol for CH
3
CH(OH)CH
3
. If a higher priority group is present (such as an aldehyde, ketone, or carboxylic acid), then the prefix "hydroxy" is used,[16] e.g., as in 1-hydroxy-2-propanone (CH
3
C(O)CH
2
OH
).[17]

Some examples of simple alcohols and how to name them
CH3–CH2–CH2–OH Propan-2-ol displayed.svg Cyclohexanol displayed.svg 2-methylpropan-1-ol displayed.svg 2-methylbutan-2-ol displayed.svg
Propan-1-ol.svg 2-Propanol.svg Cyclohexanol acsv.svg Isobutanol.svg 2-Methyl-2-butanol FormulaV1-Seite001.svg
n-propyl alcohol,
propan-1-ol, or
1-propanol
isopropyl alcohol,
propan-2-ol, or
2-propanol
cyclohexanol isobutyl alcohol,
2-methylpropan-1-ol, or
2-methyl-1-propanol
tert-amyl alcohol,
2-methylbutan-2-ol, or
2-methyl-2-butanol
A primary alcohol A secondary alcohol A secondary alcohol A primary alcohol A tertiary alcohol

In cases where the OH functional group is bonded to an sp2 carbon on an aromatic ring the molecule is known as a phenol, and is named using the IUPAC rules for naming phenols.[18]

Common names

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 alcohol, ethyl alcohol. Propyl alcohol may be n-propyl alcohol or isopropyl alcohol, depending on whether the hydroxyl group is bonded to the end or middle carbon on the straight propane chain. As described under systematic naming, if another group on the molecule takes priority, the alcohol moiety is often indicated using the "hydroxy-" prefix.[19]

Alcohols are then classified into primary, secondary (sec-, s-), and tertiary (tert-, t-), based upon the number of carbon atoms connected to the carbon atom that bears the hydroxyl functional group. (The respective numeric shorthands 1°, 2°, and 3° are also sometimes used in informal settings.[20]) The primary alcohols have general formulas RCH2OH. The simplest primary alcohol is methanol (CH3OH), for which R=H, and the next is ethanol, for which R=CH3, the methyl group. Secondary alcohols are those of the form RR'CHOH, the simplest of which is 2-propanol (R=R'=CH3). For the tertiary alcohols the general form is RR'R"COH. The simplest example is tert-butanol (2-methylpropan-2-ol), for which each of R, R', and R" is CH3. In these shorthands, R, R', and R" represent substituents, alkyl or other attached, generally organic groups.

 Chemical formula   IUPAC Name   Common name 
Monohydric alcohols
CH3OH methanol wood alcohol
C2H5OH ethanol alcohol
C3H7OH propan-2-ol isopropyl alcohol, rubbing alcohol
C4H9OH butan-1-ol butanol, butyl alcohol
C5H11OH pentan-1-ol pentanol, amyl alcohol
C16H33OH hexadecan-1-ol cetyl alcohol
Polyhydric alcohols
C2H4(OH)2 ethane-1,2-diol ethylene glycol
C3H6(OH)2 propane-1,2-diol propylene glycol
C3H5(OH)3 propane-1,2,3-triol glycerol
C4H6(OH)4 butane-1,2,3,4-tetraol erythritol, threitol
C5H7(OH)5 pentane-1,2,3,4,5-pentol xylitol
C6H8(OH)6 hexane-1,2,3,4,5,6-hexol mannitol, sorbitol
C7H9(OH)7 heptane-1,2,3,4,5,6,7-heptol volemitol
Unsaturated aliphatic alcohols
C3H5OH Prop-2-ene-1-ol allyl alcohol
C10H17OH 3,7-Dimethylocta-2,6-dien-1-ol geraniol
C3H3OH Prop-2-yn-1-ol propargyl alcohol
Alicyclic alcohols
C6H6(OH)6 cyclohexane-1,2,3,4,5,6-hexol inositol
C10H19OH 2 – (2-propyl)-5-methyl-cyclohexane-1-ol menthol
Other Languages
Afrikaans: Alkohol
Alemannisch: Alkohole
العربية: كحول
aragonés: Alcohol
armãneashti: Alcoolu
অসমীয়া: এলক'হল
asturianu: Alcohol
azərbaycanca: Spirtlər
تۆرکجه: الکول
Bân-lâm-gú: Alcohol
башҡортса: Спирт
беларуская: Спірты
беларуская (тарашкевіца)‎: Сьпірт
български: Алкохол
bosanski: Alkohol
brezhoneg: Alkool
català: Alcohol
čeština: Alkoholy
Cymraeg: Alcohol
Deutsch: Alkohole
eesti: Alkoholid
Ελληνικά: Αλκοόλες
español: Alcohol
Esperanto: Alkoholo
euskara: Alkohol
فارسی: الکل
Fiji Hindi: Alcohol
føroyskt: Alkohol
français: Alcool (chimie)
Gaeilge: Alcóil
Gaelg: Alcoal
Gàidhlig: Alcol
galego: Alcohol
ગુજરાતી: આલ્કોહોલ
한국어: 알코올
Հայերեն: Սպիրտ
हिन्दी: अल्कोहल
hrvatski: Alkoholi
Ilokano: Alkohol
Bahasa Indonesia: Alkohol
interlingua: Alcohol
íslenska: Alkóhól
italiano: Alcoli
עברית: כוהל
Basa Jawa: Alkohol
ქართული: სპირტი
қазақша: Алкогольдер
Kiswahili: Alkoholi
Kreyòl ayisyen: Alkòl
kurdî: Alkol
Кыргызча: Алкоголяттар
Ladino: Alkól
Latina: Alcohol
latviešu: Spirti
Lëtzebuergesch: Alkoholen
lietuvių: Alkoholis
Limburgs: Alcohol
lingála: Lotoko
lumbaart: Alcol
magyar: Alkoholok
македонски: Алкохол
Bahasa Melayu: Alkohol
မြန်မာဘာသာ: အယ်လ်ကိုဟော
नेपाली: अल्कोहल
日本語: アルコール
norsk: Alkoholer
norsk nynorsk: Alkohol
occitan: Alcòl
oʻzbekcha/ўзбекча: Spirtlar
ਪੰਜਾਬੀ: ਅਲਕੋਹਲ
پنجابی: الکحل
Patois: Alkoal
Plattdüütsch: Alkohol
polski: Alkohole
português: Álcool
Ripoarisch: Alkohol
română: Alcool
Runa Simi: Alkul
русиньскый: Алкоголы
русский: Спирты
Scots: Alcohol
shqip: Alkooli
sicilianu: Alcool
Simple English: Alcohol
slovenščina: Alkohol
کوردی: ئەلکھول
српски / srpski: Алкохол
srpskohrvatski / српскохрватски: Alkoholi
Basa Sunda: Alkohol
suomi: Alkoholit
svenska: Alkoholer
Tagalog: Alkohol
தமிழ்: மதுசாரம்
татарча/tatarça: Спиртлар
తెలుగు: ఆల్కహాలు
Türkçe: Alkol
українська: Спирти
اردو: الکحل
Tiếng Việt: Ancol
文言:
West-Vlams: Alcool
Winaray: Arkohol
吴语:
ייִדיש: אלקאהאל
Yorùbá: Ọtí
粵語: 酒精
žemaitėška: Alkuoguolis
中文:
Kabɩyɛ: Alɩkɔɔlɩ