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Alcohol

Alcohol

In general usage, alcohol (from Arabic al-ghawl الغول) refers almost always to ethanol, also known as grain alcohol, and often to any beverage that contains ethanol (see alcoholic beverage). This sense underlies the term alcoholism (addiction to alcohol). Other forms of alcohol are usually described with a clarifying adjective, as in isopropyl alcohol or by the suffix -ol, as in isopropanol. In chemistry, alcohol is a more general term, applied to any organic compound in which a hydroxyl group (-O H) is bound to a carbon atom, which in turn is bound to other hydrogen and/or carbon atoms. The general formula for a simple acyclic alcohol is C_nH_2n+1OH. As a drug, common alcohol (ethanol) is known to have a depressing effect that decreases the responses of the central nervous system.

Structure

central nervous system The functional group of an alcohol is a hydroxyl group bonded to an sp³ hybridized carbon. It can therefore be regarded as a derivative of water, with an alkyl group replacing one of the hydrogens. If an aryl group is present rather than an alkyl, the compound is generally called a phenol rather than an alcohol. The oxygen in an alcohol has a bond angle of around 109° (c.f. 104.5° in water), and two nonbonded electron pairs. The O-H bond in methanol (CH₃OH) is around 96 picometres long.

Primary, secondary, and tertiary alcohols

There are three major subsets of alcohols- 'primary' (1°), 'secondary' (2°) and 'tertiary' (3°), based upon the number of carbons the C-OH carbon (shown in red) is bonded to. Methanol is the simplest 'primary' alcohol. The simplest secondary alcohol is isopropanol (propan-2-ol), and a simple tertiary alcohol is tert-butanol (2-methylpropan-2-ol). butanol

Methanol & ethanol

The simplest and most commonly used alcohols are methanol and ethanol (common names methyl alcohol and ethyl alcohol, respectively), which have the structures shown above. Methanol was formerly obtained by the distillation of wood, and was called "wood alcohol". It is now a cheap commodity chemical produced by the high pressure reaction of carbon monoxide with hydrogen. In common usage, "alcohol" often refers simply to ethanol or "grain alcohol". Methylated spirits ("Meths"), also called "surgical spirits", is a form of ethanol rendered undrinkable by the addition of methanol. Aside from its major use in alcoholic beverages, ethanol is also used (though highly controlled) as an industrial solvent and raw material.

Uses

Alcohols are in wide use in industry and science as reagents, solvents, and fuels. Ethanol and methanol can be made to burn more cleanly than gasoline or diesel. Because of its low toxicity and ability to dissolve non-polar substances, ethanol is often used as a solvent in medical drugs, perfumes, and vegetable essences such as vanilla. In organic synthesis, alcohols frequently serve as versatile intermediates. Ethanol is also commonly used in beverages after fermentation to promote flavor or induce a euphoric intoxication commonly known as "drunkenness" or "being drunk". The use of ethanol for this purpose is illegal in some jurisdictions.

Sources

Many alcohols can be created by fermentation of fruits or grains with yeast, but only ethanol is commercially produced this way, chiefly for fuel and drink. Other alcohols are generally produced by synthetic routes from natural gas, petroleum, or coal feed stocks, for example via acid catalyzed hydration of alkenes. For more details see Chemistry of alcohols

Nomenclature

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 for CH₃CH₂CH₂OH, propan-2-ol 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, ketone or carboxylic acid), then it is necessary to use the prefix "hydroxy", for example: 1-hydroxy-2-propanol (CH₃COCH₂OH). Some examples of simple alcohols and how to name them: carboxylic acid Common names for alcohols usually take the name of the corresponding alkyl group and add the word "alcohol", e.g. methyl alcohol, ethyl alcohol or 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 (CH₃)₃COH 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. An alcohol with two hydroxyl groups is commonly called a "glycol", e.g. HO-CH₂-CH₂-OH is ethylene glycol. The IUPAC name is ethane-1,2-diol, "diol" indicating two hydroxyl groups, and 1,2 indicating their bonding positions. Geminal glycols (with the two hydroxyls on the same carbon atom), such as ethane-1,1-diol, are generally unstable. For three or four groups, "triol" and "tetraol" are used.

Etymology

The word "alcohol" almost certainly comes from the Arabic language (the "al-" prefix being the Arabic definite article); however, the precise origin is unclear. It was introduced into Europe, together with the art of distillation and the substance itself, around the 12th century by various European authors who translated and popularized the discoveries of Islamic alchemists. A popular theory, found in many dictionaries, is that it comes from الكحل = ALKHL = al-kuhul, originally the name of very finely powdered antimony sulfide Sb₂S₃ used as an antiseptic and eyeliner. The powder is prepared by sublimation of the natural mineral stibnite in a closed vessel. According to this theory, the meaning of alkuhul would have been first extended to distilled substances in general, and then narrowed to ethanol. This conjectured etymology has been circulating in England since 1672 at least (OED). However, this derivation is suspicious since the current Arabic name for alcohol, الكحول = ALKHWL = al???, does not derive from al-kuhul. The Qur'an in verse 37:47 uses the word الغول = ALGhWL = al-ghawl — properly meaning "spirit" ("spiritual being") or "demon" — with the sense "the thing that gives the wine its headiness". The word al-ghawl also originated the English word "ghoul", and the name of the star Algol. This derivation would, of course, be consistent with the use of "spirit" or "spirit of wine" as synonymous of "alcohol" in most Western languages. (Incidentally, the etymology "alcohol" = "the devil" was used in the 1930s by the U.S. Temperance Movement for propaganda purposes.) According to the second theory, the popular etymology and the spelling "alcohol" would not be due to generalization of the meaning of ALKHL, but rather to Western alchemists and authors confusing the two words ALKHL and ALGhWL, which have indeed been transliterated in many different and overlapping ways.

Physical and chemical properties

The hydroxyl group generally makes the alcohol molecule polar. Those groups can form hydrogen bonds to one another and to other compounds. 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 (Pentanol and higher) are effectively insoluble because of the hydrocarbon chain's dominance. Because of hydrogen bonding, alcohols tend to have higher boiling points than comparable hydrocarbons and ethers. All simple alcohols are miscible in organic solvents. This hydrogen bonding means that alcohols can be used as protic solvents. The lone pairs of electrons on the oxygen of the hydroxyl group also makes alcohols nucleophiles. Alcohols, like water, can show either acidic or basic properties at the O-H group. With a pK_a of around 16-19 they are generally slightly weaker acids than water, but they are still able to react with strong bases such as sodium hydride or reactive metals such as sodium. The salts that result are called alkoxides, with the general formula RO^- M⁺. Meanwhile the oxygen atom has lone pairs of nonbonded electrons that render it weakly basic in the presence of strong acids such as sulfuric acid. For example, with methanol: sulfuric acid Alcohols can also undergo oxidation to give aldehydes, ketones or carboxylic acids, or they can be dehydrated to alkenes. They can react to form ester compounds, and they can (if activated first) undergo nucleophilic substitution reactions. For more details see the #Chemistry of alcohols section below.

Toxicity

Alcohols often have an odor described as 'biting' that 'hangs' in the nasal passages. Ethanol in the form of alcoholic beverages has been consumed by humans since pre-historic times, for a variety of hygienic, dietary, medicinal, religious, and recreational reasons. While infrequent consumption of ethanol in small quantities may be harmless or even beneficial, larger doses result in a state known as drunkenness or intoxication and, depending on the dose and regularity of use, can cause acute respiratory failure or death and with chronic use has medical repercussions. Other alcohols are substantially more poisonous than ethanol, partly because they take much longer to be metabolized, and often their metabolism produces even more toxic substances. Methanol, or wood alcohol, for instance, is oxidized by alcohol dehydrogenase enzymes in the liver to the poisonous formaldehyde, which can cause blindness or death. Interestingly, an effective treatment to prevent formaldehyde toxicity after methanol ingestion is to administer ethanol. This will bind to alcohol dehydrogenase, preventing methanol from binding and thus acting as a substrate. Any formaldehyde will be converted to formic acid and excreted before it causes damage.

Chemistry of alcohols

Preparation

Laboratory

There are three common methods:
- From alkyl halides: react with aqueous NaOH or KOH (mainly 1° alcohols). :R-Br + KOH → R-OH + KBr
- From aldehydes or ketones: reduction with sodium borohydride or lithium aluminium hydride. :R-CHO - [O] → R-OH
- From alkenes: an acid catalysed hydration reaction using concentrated sulfuric acid as a catalyst (gives usually 2° or 3° alcohols). :C₂H₄ + H₂SO₄ (l) → C₂H₅-HSO₄ :C₂H₅-HSO₄ + H₂O → C₂H₅OH + H₂SO₄ The formation of a secondary alcohol via the last two methods is shown: sulfuric acid

Industrial

- Fermentation: using glucose produced from sugar from the hydrolysis of starch, in the presence of yeast and temperature of <37°C to produce ethanol. :C₁₂H₂₂O₁₁ → C₆H₁₂O₆ + C₆H₁₂O₆ :Invertase → glucose + fructose :C₆H₁₂O₆ + H₂O → C₂H₅OH + CO₂ :Glucose → zymase + ethanol
- Direct hydration: using ethene or other alkenes from cracking of fractions of distilled crude oil. Uses a catalyst of phosphoric acid under high temperature and pressure.
- Methanol from water gas: It is manufactured from synthesis gas, where CO + 2 H₂ are combined to produce methanol using a Cu, ZnO and Al₂O₃ catalyst at 250°C and a pressure of 50-100 atm. :[CO + H₂] + H₂O (g) → CH₃OH

Reactions

See the physical and chemical properties section above for a general overview.

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 n-butyllithium, or with sodium or potassium metal. : 2 R-OH + 2 NaH → 2 R-O^-Na⁺ + H₂↑ : 2 R-OH + 2Na → 2R-O⁻Na⁺ : e.g. 2 CH₃CH₂-OH + 2 Na → 2 CH₃-CH₂-O⁻Na⁺ Water is similar in pK_a to many alcohols, so with sodium hydroxide there is an equilibrium set up which usually lies to the left: : R-OH + NaOH <=> R-O^-Na⁺ + H₂O (equilibrium to the left)

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−OH₂⁺, the leaving group (water) is much more stable, and nucleophilic substitution can take place. For instance, tertiary alcohols react with hydrochloric acid to produce tertiary alkyl halides, where the hydroxyl group is replaced by a chlorine atom. 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.^[1] thionyl chloride Alcohols may likewise be converted to alkyl bromides using hydrobromic acid or phosphorus tribromide, for example: : 3 R-OH + PBr₃ → 3 RBr + H₃PO₃ 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−OH₂⁺ can react with ROH to produce ethers and water, although this reaction is rarely used except in the manufacture of diethyl ether. More useful is the E1 elimination reaction of alcohols to produce alkenes. 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 requre a higher temperature. This is a diagram of acid catalysed dehydration of ethanol to produce ethene: 550px

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

\Leftrightarrow

R'-COOR + H₂O In order to drive the equilibrium to the right and produce a good yield of ester, water is usually removed, either by an excess of H₂SO₄ 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 p-toluenesulfonate (tosylate) esters are made by reaction of the alcohol with p-toluenesulfonyl chloride in pyridine.

Oxidation

Primary alcohols generally give aldehydes or carboxylic acids upon oxidation, while secondary alcohols give ketones. Traditionally strong oxidants such as the dichromate ion or potassium permanganate are used, under acidic conditions, for example: :3 CH₃-CH(-OH)-CH₃ + K₂Cr₂O₇ + 4 H₂SO₄ → 3 CH₃-C(=O)-CH₃ + Cr₂(SO₄)₃ + K₂SO₄ + 7 H₂O Frequently in aldehyde preparations these reagents cause a problem of over-oxidation to the carboxylic acid. To avoid this, other reagents such as PCC, Dess-Martin periodinane, IBX acid, TPAP or methods such as Swern oxidation are now preferred. Alcohols with a methyl group attached to the alcohol carbon can also undergo a haloform reaction (such as the iodoform reaction) in the presence of the halogen and a base such as sodium hydroxide. Tertiary alcohols resist oxidation, but can be oxidised by reagents such as 2,3-dichloro-5,6-dicyano-1,4-benzoquinone.

External links

- [http://www.french-paradox.net/fpbksb1.html What Is Alcohol, Anyway?] Interesting information about alcohols.
- Category:Drugs Category:Antiseptics Category:Arabic words Category:functional groups ja:アルコール simple:Alcohol

Arabic language

The Arabic language (; , less formally, ) is the largest member of the Semitic branch of the Afro-Asiatic language family (classification: South Central Semitic) and is closely related to Hebrew and Aramaic. It is spoken throughout the Arab world and is widely studied and known throughout the Islamic world. Arabic has been a literary language since at least the 6th century and is the liturgical language of Islam.

Literary and Modern Standard Arabic

The term "Arabic" may refer either to literary Arabic, which no Arab speaks as a mother tongue, or Modern Standard Arabic or to the many spoken varieties of Arabic commonly called "colloquial Arabic." Arabs consider literary Arabic as the standard language and tend to view everything else as mere dialects. Literary Arabic, (Literally: "the most eloquent Arabic language" — ) refers both to the language of present-day media across North Africa and the Middle East and to the more archaic language of the Qur'an. (The expression media here includes most television and radio, and all written matter, including all books, newspapers, magazines, documents of every kind, and reading primers for small children.) "Colloquial" or "dialectal" Arabic refers to the many national or regional dialects/languages derived from Classical Arabic, spoken daily across North Africa and the Middle East, which constitute the everyday spoken language. These sometimes differ enough to be mutually incomprehensible. These dialects are not typically written, although a certain amount of literature (particularly plays and poetry) exists in many of them. They are often used to varying degrees in informal spoken media, such as soap operas and talk shows. Literary Arabic or classical Arabic, is the official language of all Arab countries and is the only form of Arabic taught in schools at all stages. The sociolinguistic situation of Arabic in modern times provides a prime example of the linguistic phenomenon of Diglossia -the normal use of two separate varieties of the same language, usually in different social situations. In the case of Arabic, educated Arabs of whatever nationality can be assumed to speak both their local dialect and their school-taught literary Arabic (to an equal or lesser degree). This diglossic situation facilitates code switching in which a speaker switches back and forth unaware between the two varieties of the language, sometimes even within the same sentence. In instances in which Arabs of different nationalities engage in conversation only to find their dialects mutually unintelligible (e.g. a Moroccan speaking with a Lebanese), both should be able to code switch into Literary Arabic for the sake of communication. Since the written Arabic of today differs from the written Arabic of the Qur'anic era, it has become customary in western scholarship and among non-Arab scholars of Arabic to refer to the language of the Qur'an as Classical Arabic and the modern language of the media and of formal speeches as Modern Standard Arabic. Arabs, on the other hand, often use the term to refer to both forms, thus placing greater emphasis on the similarities between the two. The difference between Arabic of the Qur'anic era and today's Classical Arabic is only in the degree of eloquance. The vocabulary, the syntatic and grammatical rules are the same. Quite a few English words are ultimately derived from Arabic, often through other European languages, especially Spanish, among them every-day vocabulary like sugar (sukkar), cotton (qutn) or magazine (). More recognizable are words like algorithm, algebra, alchemy, alcohol, azimuth, nadir, and zenith (see List of English words of Arabic origin). The Maltese language spoken on the Mediterranean island of Malta is the only surviving European language to derive primarily from Arabic (a North African dialect), though it contains a large number of Italian and English borrowings.

Arabic and Islam

It is sometimes difficult to translate Islamic concepts, and concepts specific to Arab culture, without using the original Arabic terminology. The Qur'an is expressed in Arabic and traditionally Muslims deem it impossible to translate in a way that would adequately reflect its exact meaning—indeed, until recently, some schools of thought maintained that it should not be translated at all. A list of Islamic terms in Arabic covers those terms which are too specific to translate in one phrase. While Arabic is strongly associated with Islam (and is the language of salah), it is also spoken by Arab Christians, Oriental (Sephardic) Jews, and smaller sects such as Iraqi Mandaeans. Even so, a majority of the world's Muslims do not actually speak Arabic, but only know some fixed phrases of Arabic, such as those used in Islamic prayer. However, to counteract this, there is great encouragement for non-Arabic-speaking Muslims to learn the language.

Dialects

See Varieties of Arabic for a fuller overview. "Colloquial Arabic" is a collective term for the spoken languages or dialects of people throughout the Arab world, which, as mentioned, differ radically from the literary language. The main dialectal division is between the Maghreb dialects and those of the Middle East, followed by that between sedentary dialects and the much more conservative Bedouin dialects. Maltese, though descended from Arabic, is considered a separate language. Speakers of some of these dialects are unable to converse with speakers of another dialect of Arabic; in particular, while Middle Easterners can generally understand one another, they often have trouble understanding Maghrebis (although the converse is not true, due to the popularity of Middle Eastern—especially Egyptian—films and other media). One factor in the differentiation of the dialects is influence from the languages previously spoken in the areas, which have typically provided a significant number of new words, and have sometimes also influenced pronunciation or word order; however, a much more significant factor for most dialects is, as among Romance languages, retention (or change of meaning) of different classical forms. Thus Iraqi aku, Levantine fiih, and North African kayen all mean "there is", and all come from Arabic (yakuun, fiihi, kaa'in respectively), but now sound very different. The major groups are:
- Egyptian Arabic (Egypt) Considered the most widely understood and used "second dialect"
- Maghreb Arabic (Algerian Arabic, Moroccan Arabic, Tunisian Arabic and western Libyan)
- Levantine Arabic (Western Syrian, Lebanese, Palestinian, and western Jordanian, Cypriot Maronite Arabic)
- Iraqi Arabic or Gulf Arabic (Iraqi, Eastern Syrian, Kuwaiti, Saudi Arabian, Persian Gulf coast from Iraq to Oman including much of Saudi Arabia's Eastern Province, and minorities on the other side) Other varieties include:
- (in Mauritania and Western Sahara)
- Andalusi Arabic (extinct, but important role in literary history)
- Maltese
- Sudanese Arabic (with a dialect continuum into Chad)
- Hijazi Arabic (West Cost of Saudi Arabia, Northern Saudi Arabia, eastern Jordan, Western Iraq)
- Najdi Arabic (Najd region of central Saudi Arabia)
- Yemeni Arabic (Yemen to southern Saudi Arabia)

Phonology

The consonant phonemes below reflect the pronunciation of Standard Arabic, which has only three vowels, in short and long variants, namely and . Naturally, considerable allophony occurs.

Consonants

Standard Arabic has 28 consonants: See Arabic alphabet for explanations on the IPA phonetic symbols found in this chart. # is pronounced as by some speakers. This is especially characteristic of the Egyptian and southern Yemeni dialects. In many parts of North Africa and in the Levant, it is pronounced as . # is pronounced only in , the name of God, i.e. Allah. # is usually a phonetic approximant. # In many varieties (if not most), are actually epiglottal (despite what is reported in many earlier works).

Emphatic Consonants

The consonants traditionally known as "emphatic" are either velarised or pharyngealised . In some transcription systems, emphasis is shown by capitalizing the letter e.g. is written ‹D›; in others the letter is underlined or has a dot below it e.g. ‹ḍ›.

Long Consonants

Vowels and consonants can be (phonologically) short or long. Long (geminate) consonants are normally written doubled in Latin transcription (i.e. bb, dd, etc.), reflecting the presence of the Arabic diacritic mark shaddah, which marks lengthened consonants. Such consonants are held twice as long as short consonants. This consonant lengthening is phonemically contrastive: e.g. qabala "he received" and qabbala "he kissed".

Syllable Shape

Arabic has two kinds of syllable: open syllables (CV) and (CVV) - and closed syllables (CVC), (CVVC) and (CVCC). Every syllable begins with a consonant - or else a consonant is borrowed from a previous word through elision – especially in the case of the definite article THE, al (used when starting an utterance) or _l (when following a word), e.g. baytu –l mudiir “house (of) the director”, which becomes bay-tul-mu-diir when divided syllabically. By itself, definite mudiir would be pronounced .

Word Stress

Although word stress is not phonemically contrastive in Standard Arabic, it does bear a strong relationship to vowel length and syllable shape, and correct word stress aids intelligibility. In general, "heavy" syllables attract stress (i.e. syllables of longer duration - a closed syllable or a syllable with a long vowel). In a word with a syllable with one long vowel, the long vowel attracts the stress (e.g. ki-'taab and ‘kaa-tib). In a word with two long vowels, the second long vowel attracts stress (e.g.ma-kaa-'tiib). In a word with a "heavy" syllable where two consonants occur together or the same consonant is doubled, the (last) heavy syllable attracts stress (e.g. ya-ma-’niyy, ka-'tabt, ka-‘tab-na, ma-‘jal-lah, ‘mad-ra-sah, yur-‘sil-na). This last rule trumps the first two: ja-zaa-i-‘riyy. Otherwise, word stress typically falls on the first syllable: ‘ya-man, ‘ka-ta-bat, etc. The Cairo (Egyptian Arabic) dialect, however, has some idiosyncrasies in that a heavy syllable may not carry stress more than two syllables from the end of a word, so that mad-‘ra-sah carries the stress on the second-to-last syllable, as does qaa-‘hi-rah.

Dialectical Phonologies

In some dialects, there may be more or fewer phonemes than those listed in the chart above. For example, non-Arabic is used in the Maghreb dialects as well in the written language mostly for foreign names. Semitic became extremely early on in Arabic before it was written down; a few modern Arabic dialects, such as Iraqi (influenced by Persian) distinguish between and . Interdental fricatives ( and ) are rendered as stops and in some dialects (principally Levantine and Egyptian) and as and in "learned" words from the Standard language. Early in the expansion of Arabic, the separate emphatic phonemes and coallesced into a single phoneme, becoming one or the other. Predictably, dialects without interdental fricatives use exclusively, while those with such fricatives use . Again, in "learned" words from the Standard language, is rendered as in dialects without interdental fricatives. Another key distinguishing mark of Arabic dialects is how they render Standard (a voiceless uvular stop): it retains its original pronunciation in widely scattered regions such as Yemen and Morocco (and among the Druze), while it is rendered in Gulf Arabic, Iraqi Arabic, Upper Egypt and less urban parts of the Levant (e.g. Jordan) and as a glottal stop in many prestige dialects, such as those spoken in Cairo, Beirut and Damascus. Thus, Arabs instantly give away their geographical (and class) origin by their pronunciation of a word such as qamar "moon": , or .

Grammar

See Arabic grammar

Alphabet

Arabic alphabet

Main article: Arabic alphabet The Arabic alphabet derives from the Aramaic script (which variety - Nabataean or Syriac - is a matter of scholarly dispute), to which it bears a loose resemblance like that of Coptic or Cyrillic script to Greek script. Traditionally, there were several differences between the Western (Maghrebi) and Eastern version of the alphabet—in particular, the fa and qaf had a dot underneath and a single dot above respectively in the Maghreb, and the order of the letters was slightly different (at least when they were used as numerals). However, the old Maghrebi variant has been abandoned except for calligraphic purposes in the Maghreb itself, and remains in use mainly in the Quranic schools (zaouias) of West Africa. Arabic, like other Semitic languages, is written from right to left.

Calligraphy

See Arabic calligraphy for a fuller overview. After the definitive fixing of the Arabic script around 786, by Khalil ibn Ahmad al Farahidi, many styles were developed, both for the writing down of the Qur'an and other books, and for inscriptions on monuments as decoration. Kufic font Arabic calligraphy has not fallen out of use as in the Western world, and is still considered by Arabs as a major art form; calligraphers are held in great esteem. Being cursive by nature, unlike the Latin alphabet, Arabic script is used to write down a verse of the Qur'an, a Hadith, or simply a proverb, in a spectacular composition. The composition is often abstract, but sometimes the writing is shaped into an actual form such as that of an animal. Two of the current masters of the genre are Hassan Massoudy and [http://arabworld.nitle.org/gallery.php?module_id=7 Khaled Al Saa’i].

Arabic using the Latin alphabet

See Arabic transliteration and Arabic Chat Alphabet for more information. There are a number of different standards of Arabic transliteration: methods of accurately and efficently representing Arabic with the Latin alphabet. The more scientific standards allow the reader to recreate the exact word using the Arabic alphabet. However, these systems are heavily reliant on diacritical marks, which may be difficult to pronounce at first sight. Other, less scientific, systems often use digraphs (like sh and kh), which are usually more simple to read, but sacrifice the definiteness of the scientific systems. During the last few decades and especially since the 1990s, Western-invented text communication technologies have become prevalent in the Arab world, such as personal computers, the World Wide Web, email, Bulletin board systems, IRC, instant messaging and mobile phone text messaging. Most of these technologies originally had the ability to communicate using the Latin alphabet only, and some of them still do not have the Arabic alphabet as an optional feature. As a result, Arabic speaking users communicated in these technologies by transliterating the Arabic text using the Latin script. To handle those Arabic letters that do not have an approximate equivalent in the Latin script, numerals and other characters were appropriated. E.g., the Latin numeral "3" is used to represent the Arabic letter "ع" ("ayn"). There is no universal name for this type of transliteration, but some have named it Arabic Chat Alphabet.

External links

- [http://arabic-media.com/ Arabic-Media] on-line access to Arabic newspapers, radio, and television
- [http://st-takla.org/Learn_Languages/01_Learn_Arabic-ta3leem-3araby/Learn-Arabic_00-index_El-Fehres.html Learn Arabic language online with audio pronunciation] from [http://St-Takla.org St. Takla Egyptian Church]
- [http://www.nicoweb.com/sirpus/learn%20arabic%20course%20mp3.htm Arabic Writing and Reading with MP3]. Arabic Writing and Reading Course Online with MP3 audio.
- [http://pince31.free.fr/lang/arabic/liens.htm Links to learn Arabic language with online course]
- [http://www.madinaharabic.com Arabic language learning course with audio]
- [http://www.dailystar.com.lb/article.asp?edition_id=10&categ_id=4&article_id=6173 "Antonyms in Arabic are a strange phenomenon" by Tamim al-Barghouti]
- [http://arabworld.nitle.org/texts.php?module_id=1&reading_id=17 "The Development of Classical Arabic" by Kees Versteegh]
- [http://arabworld.nitle.org/audiovisual.php?module_id=1&selected_feed=118 Wellesley College Professor of Arabic on the forms and dialects of the language]
- [http://www.uga.edu/islam/arabic_windows.html Multilingual Computing in Arabic with Windows, major word processors, web browsers, Arabic keyboards, and Arabic transliteration fonts]
- [http://www.gomideast.com/arabic/index.htm gomideast - Learning to Speak Arabic phrases]
- [http://language-directory.50webs.com/languages/arabic.htm List of online Arabic-related resources] Web references and examples:
- [http://transliteration.org/quran/Pronunciation/Letters/TashP.htm Arabic language pronunciation applet] with audio samples
- [http://www.sunna.info/teaching/ Learn Arabic]
- [http://www.everything2.com/index.pl?node_id=1289272 E2 article]
- [http://www.sprachprofi.de.vu/english/ar.htm Sprachprofi]
- [http://www.websters-online-dictionary.org/definition/Arabic-english/ Arabic - English Dictionary]: from [http://www.websters-online-dictionary.org Webster's Online Dictionary] - the Rosetta Edition.
- [http://www.ethnologue.com/show_language.asp?code=arb SIL's Ethnologue]
- [http://www.nitle.org/arabworld/texts.php?module_id=1&reading_id=113 Dialects of Arabic]
- [http://www.muftah-alhuruf.com Muftah-Alhuruf.com]: Write and send Arabic emails without having an Arabic keyboard or operating system. Arabic languages samples:
- [http://www.language-museum.com/a/arabic.php Arabic]
- [http://www.language-museum.com/a/arabic-chadian-spoken.php Arabic Chadian Spoken]
- [http://www.language-museum.com/a/arabic-judeo-iraqi.php Arabic Judeo Iraqi]
- [http://www.language-museum.com/a/arabic-north-levantine-spoken.php Arabic North Levantine Spoken]
- [http://arabworld.nitle.org/texts.php?module_id=1&reading_id=17 "The Development of Classical Arabic" by Kees Versteegh]
- Category:Arab ko:아랍어 ms:Bahasa Arab ja:アラビア語 simple:Arabic language th:ภาษาอาหรับ

Ethanol

Ethanol, also known as ethyl alcohol or grain alcohol, is a flammable, colorless chemical compound, one of the alcohols that is most often found in alcoholic beverages. In common parlance, it is often referred to simply as alcohol. Its chemical formula is C₂H₅OH, also written as C₂H₆O. This article is mostly about ethanol as a chemical compound. For beverages containing ethanol, see alcoholic beverage. For the use of ethanol as a fuel, see alcohol fuel.

History

Ethanol has been used by humans since prehistory as the intoxicating ingredient in alcoholic beverages. Dried residues on 9000-year-old pottery found in northern China imply the use of alcoholic beverages even among Neolithic peoples. Its isolation as a relatively pure compound was first achieved by Islamic alchemists who developed the art of distillation during the Abbasid caliphate. The writings of Jabir Ibn Hayyan (Geber) (721-815) mention the flammable vapors of boiled wine. Al-Kindī (801-873) unambiguously described the distillation of wine. Distillation of ethanol from water yields a product that is at most 96% ethanol. Absolute ethanol was first obtained in 1796 by Johann Tobias Lowitz, by filtering distilled ethanol through charcoal. Antoine Lavoisier described ethanol as a compound of carbon, hydrogen, and oxygen, and in 1808, Nicolas-Théodore de Saussure determined ethanol's chemical formula. In 1858, Archibald Scott Couper published a structural formula for ethanol: this places ethanol among the first chemical compounds to have their chemical structures determined. Ethanol was first prepared synthetically in 1826, through the independent efforts of Henry Hennel in Britain and S.G. Sérullas in France. Michael Faraday prepared ethanol by the acid-catalysed hydration of ethylene in 1828, in a process similar to that used for industrial ethanol synthesis today.

Production

ethylene Ethanol is produced both as a petrochemical, through the hydration of ethylene, and biologically, by fermenting sugars with yeast.

Ethylene hydration

Ethanol for use as industrial feedstock and is most often made from petroleum feedstocks, typically by the acid-catalysed hydration of ethylene, represented by the chemical equation : H₂C=CH₂ + H₂O → CH₃CH₂OH The catalyst is most commonly phosphoric acid, adsorbed onto a porous support such as diatomaceous earth or charcoal; this catalyst was first used for large-scale ethanol production by the Shell Oil Company in 1947. Solid catalysts, mostly various metal oxides, have also been mentioned in the chemical literature. In an older process, first practised on the industrial scale in 1930 by Union Carbide, but now almost entirely obsolete, ethylene was hydrated indirectly by reacting it with concentrated sulfuric acid to product ethyl sulfate, which was then hydrolyzed to yield ethanol and regenerate the sulfuric acid: : H₂C=CH₂ + H₂SO₄ → CH₃CH₂OSO₃H : CH₃CH₂OSO₃H + H₂O → CH₃CH₂OH + H₂SO₄ Ethanol for industrial use is normally made unfit for human consumption ("denatured") by the inclusion of small amounts of substances that are either toxic (such as methanol) or unpleasant (such as denatonium), thus avoiding the applicable taxes or inventory controls. Denatured ethanol has the UN number UN 1987 and toxic denatured ethanol has UN 1986.

Fermentation

Ethanol for use in alcoholic beverages, and the vast majority of ethanol for use as fuel, is produced by fermentation: when certain species of yeast (most importantly, Saccharomyces cerevisiae) metabolize sugar in the absence of oxygen, they produce ethanol and carbon dioxide. The overall chemical reaction conducted by the yeast may be represented by the chemical equation : C₆H₁₂O₆ → 2 CH₃CH₂OH + 2 CO₂ The process of culturing yeast under conditions to produce alcohol is referred to as brewing. Yeasts can grow in the presence of up to about 20% alcohol, but the concentration of alcohol in the final product can be increased by distillation. In order to produce ethanol from starchy materials such as cereal grains, the starch must first be broken down into sugars. In brewing beer, this has traditionally been accomplished allowing the grain to germinate, or malt. In the process of germination, the seed produces enzymes that can break its starches into sugars. For fuel ethanol, this hydrolysis of starch into glucose is accomplished more rapidly by treatment with dilute sulfuric acid, fungal amylase enzymes, or some combination of the two. Potentially, glucose for fermentation into ethanol could also be obtained from cellulose. Cellulosic ethanol is a blend of normal ethanol that can be produced from a great diversity of biomass including waste from urban, agricultural, and forestry sources. There are at least two methods of production of cellulosic ethanol - enzymatic hydrolysis and synthesis gas fermentation. Neither process generates toxic emissions when it produces ethanol. The technology is very new and exists in pilot configurations where testing is ongoing. Realization of this enzymatic hydrolysis would turn a number of cellulose-containing agricultural byproducts, such as corncobs, straw, and sawdust, into renewable energy resources. Until recently, the cost of the cellulase enzymes that could hydrolyse cellulose was prohibitive. The Canadian firm Iogen brought the first cellulose-based ethanol plant on-stream in 2004. In April 2004, Iogen became the first business to commercially sell cellulosic ethanol. The primary consumer thus far has been the Canadian government, which, along with the United States government (particularly the Department of Energy's National Renewable Energy Laboratory), has invested millions of dollars into assisting the commercialization of cellulosic ethanol. [http://www.genencor.com/ Genencor] and [http://www.novozymes.com/ Novozymes] are two other companies that have received United States government Department of Energy funding for research into reducing the cost of cellulase, a key enzyme in the production cellulosic ethanol by enzymatic hydrolysis. [http://www.brienergy.com/ BRI Energy, LLC] is a company whose pilot plant in Fayetteville, Arkansas is currently using synthesis gas fermentation to convert a broad variety of urban, agricultural, and forestry waste into ethanol. Fossil fuels and virtually any blend of biomass could also be used as feedstock. After gasification, anaerobic bacteria (Clostridium ljungdahlii) are used to convert the syngas (CO, CO2, and H2) into ethanol. The heat generated by gasification is also used to co-generate excess electricity. According to US Department of Energy studies conducted by the Argonne Laboratories of the University of Chicago, one of the benefits of cellulosic ethanol is that it reduces [greenhouse gas emissions] (GHG) by 85% over reformulated gasoline. By contrast, sugar-fermented ethanol reduces GHG emissions by 18% to 29% over gasoline. At petroleum prices like those that prevailed through much of the 1990s, ethylene hydration was a decidedly more economical process than fermentation for producing purified ethanol. Recent increases in petroleum prices, coupled with perennial uncertainty in agricultural prices, make forecasting the relative production costs of fermented versus petrochemical ethanol difficult at the present time.

Purification

For a mixture of ethanol and water, there is a maximum boiling azeotrope at 96% ethanol and 4% water. For this reason, fractional distillation of ethanol-water mixtures (of less than 96% ethanol) cannot yield ethanol purer than 96%. Therefore, 95% ethanol in water is a fairly common solvent. Several competing approaches may be used to produce absolute ethanol. To break the azeotrope for performing distillation, a small amount of benzene can be added, and the mixture is again fractionally distilled. Benzene forms a tertiary azeotrope with water and ethanol to remove the last of the water, and a binary azeotrope with ethanol removes most of the benzene. The resulting ethanol is water free, for processes that require it. However, several parts per million of benzene remain, so consumption by humans leads to distinctive liver damage. Nowadays benzene as entrainer is replaced by cyclohexane to avoid the health hazards. Alternatively, a molecular sieve can be used to selectively absorb the water from the 96% ethanol solution. Synthetic zeolite in pellet form can be used, as well as corn grits. The zeolite approach is especially of value, for it is possible to recycle the zeolite in a closed system essentially an unlimited number of times, through drying it with a blast of heated CO₂. Absolute ethanol produced this way has no residual benzene, and can be used as fuel, or, when diluted, can even be used to fortify port and sherry in traditional winery operations. Also possible is the method of pressure swing distillation, which is still a topic of current researches. The idea of pressure swing distillation is, to distillate at 2 different pressure, due to the pressure dependence of the azeotropic composition. For example the first distillation step would be proceeded at a pressure at which the azeotropic composition is above 96% for example 97% afterwards a distillation at a pressure with a lower azeotropic composition would follow. By this it is possible to purify ethanol without the use of an entrainer.

Use

zeolite, USA).]]

As a fuel

Main article: alcohol fuel The largest single use of ethanol is as a motor fuel and fuel additive. The largest national fuel ethanol industries exist in Brazil and the United States. The Brazilian ethanol industry is based on sugarcane; as of 2004, Brazil produces 14 billion liters annually, enough to replace about 40% of its gasoline demand. Most new cars sold in Brazil are flexible-fuel vehicles that can run on ethanol, gasoline, or any blend of the two. The United States fuel ethanol industry is based largely on maize. As of 2005, its capacity is 15 billion liters annually, although the Energy Policy Act of 2005 requires U.S. fuel ethanol production to increase to 7.5 billion gallons (28 billion liters) by 2012. In the United States, ethanol is most commonly blended with gasoline as a 10% ethanol blend nicknamed "gasohol". This blend is widely sold throughout the U.S. Midwest, and in cities required by the 1990 Clean Air Act to oxygenate their gasoline during the winter. Many states mandate that an oxygenate be blended into all gasoline sold in the state to reduce CO2 emissions. MTBE used to be the most common oxygenate but because of groundwater contamination problems it has been replaced with ethanol. In California, for instance, 5.6% of its gasoline blend is ethanol.

Chemicals derived from ethanol

; Ethyl esters In the presence of an acid catalyst (typically sulfuric acid) ethanol reacts with carboxylic acids to produce ethyl esters: : CH₃CH₂OH + RCOOH → RCOOCH₂CH₃ + H₂O The two largest-volume ethyl esters are ethyl acrylate (from ethanol and acrylic acid) and ethyl acetate (from ethanol and acetic acid). Ethyl acrylate is a monomer used to prepare acrylate polymers for use in coatings and adhesives. Ethyl acetate is a common solvent used in paints, coatings, and in the pharmaceutical industry; its most familiar application in the household is as a solvent for nail polish. A variety of other ethyl esters are used in much smaller volumes as artificial fruit flavorings. ; Vinegar Vinegar is a dilute solution of acetic acid prepared by the action of Acetobacter bacteria on ethanol solutions. Although traditionally prepared from alcoholic beverages including wine, apple cider, and unhopped beer, vinegar can also be made from solutions of industrial ethanol. Vinegar made from distilled ethanol is called "distilled vinegar," and is commonly used in food pickling and as a condiment. ; Ethylamines When heated to 150–220 °C over a silica- or alumina-supported nickel catalyst, ethanol and ammonia react to produce ethylamine. Further reaction leads to diethylamine and triethylamine: : CH₃CH₂OH + NH₃ → CH₃CH₂NH₂ + H₂O : CH₃CH₂OH + CH₃CH₂NH₂ → (CH₃CH₂)₂NH + H₂O : CH₃CH₂OH + (CH₃CH₂)₂NH → (CH₃CH₂)₃N + H₂O The ethylamines find use in the synthesis of pharmaceuticals, agricultural chemicals, and surfactants. ; Other chemicals Ethanol is a versatile chemical feedstock, and in the past has been used commercially to synthesize dozens of other high-volume chemical commodities. At the present, it has been supplanted in many applications by less costly petrochemical feedstocks. However, in markets with abundant agricultural products, but a less developed petrochemical infrastructure, such as China, India, and Brazil, ethanol can be used to produce chemicals that would be produced from petroleum in the West, including ethylene and butadiene.

Other uses

Ethanol is also used in antifreeze products for its low freezing point. It is easily soluble in water in all proportions with a slight overall decrease in volume when the two are mixed. Absolute ethanol and 95% ethanol are themselves good solvents, somewhat less polar than water and used in perfumes, paints and tinctures. Other proportions of ethanol with water or other solvents can also be used as a solvent. Alcoholic drinks have a large variety of tastes because various flavor compounds are dissolved during brewing. When ethanol is produced as a mixing beverage it is a neutral grain spirit. A solution of 70% of ethanol is commonly used as a disinfectant. Ethanol is also used in most common antibacterial hand sanitizer gels at a concentration of about 62%. Oddly enough, the peak of the disinfecting power occurs around 70% ethanol; stronger and weaker solutions of ethanol have a lessened ability to disinfect. Ethanol kills organisms by denaturing their proteins and dissolving their lipids and is effective against most bacteria and fungi, and many viruses, but is ineffective against bacterial spores. Wine with less than 16% ethanol cannot protect itself against bacteria. Because of this, port is often fortified with ethanol to at least 18% ethanol by volume to halt fermentation for retaining sweetness and in preparation for aging, at which point it becomes possible to prevent the invasion of bacteria into the port, and to store the port for long periods of time in wooden containers that can 'breathe', thereby permitting the port to age safely without spoiling. Because of ethanol's disinfectant property, alcoholic beverages of 18% ethanol or more by volume can be safely stored for a very long time. The hydroxyl group on the ethanol molecule is an extremely weak acid, but upon treatment alkali metal or a very strong base, an H⁺ can be removed to form an ethoxide ion, C₂H₅O^-.

Hazards

- Ethanol and mixtures with water greater than about 50% ethanol are flammable and easily ignited, although there are some solvents and organic compounds which are even more flammable.
- Ethanol within the human body is converted into acetaldehyde by alcohol dehydrogenase and then into acetic acid by acetaldehyde dehydrogenase. The product of the first step of this breakdown, acetaldehyde, is more toxic than ethanol. Acetaldehyde is linked to most of the clinical effects of alcohol. It has been shown to increase the risk of contracting cirrhosis of the liver, multiple forms of cancer, and alcoholism. The characteristic flushing reaction in some Asians is due to the accumulation of acetaldehyde in individuals who have a relative deficiency of acetaldehyde dehydrogenase.
- Although ethanol is not highly toxic, death from ethyl alcohol consumption is possible when blood alcohol level reaches 0.4%. A blood level of 0.5% or more is commonly fatal. Levels of even less than 0.1% can cause intoxication, with unconsciousness often occurring at 0.3-0.4%. There are often drunk driving laws governing the acceptable levels in the blood while driving or operating heavy machinery, usual limits being 0.05% or 0.08%. Methyl alcohol or methanol, on the other hand, is very toxic, regardless of whether it is unintentionally consumed, absorbed through the skin, or inhaled.
- Ethanol has been shown to increase the growth of Acinetobacter baumannii, the bacteria responsible for pneumonia, meningitis and urinary tract infections. This finding may contradict the common misconception that drinking alcohol can kill off a budding infection. (Smith and Snyder, 2005)

References

- "Alcohol." (1911). In Hugh Chisholm (Ed.) Encyclopædia Britannica, 11th ed. [http://91.1911encyclopedia.org/A/AL/ALCOHOL.htm Online reprint]
- Al-Hassan, A.Y. [http://www.gabarin.com/ayh/Notes/Notes%207.htm "Alcohol and the Distillation of Wine in Arabic Sources."] Accessed 14 November 2005.
- Couper, A.S. (1858). "On a new chemical theory." Philosophical magazine 16, 104–116. [http://web.lemoyne.edu/~giunta/couper/couper.html Online reprint]
- Hennell, H. (1828). "On the mutual action of sulphuric acid and alcohol, and on the nature of the process by which ether is formed." Philosophical Transactions 118, 365–371.
- Lodgsdon, J.E. (1994). "Ethanol." In J.I. Kroschwitz (Ed.) Encyclopedia of Chemical Technology, 4th ed. vol. 9, pp. 812–860. New York: John Wiley & Sons.
- Ritter, S.K. (May 31, 2004). "Biomass or Bust." Chemical & Engineering News 82(22), 31–34.
- Roach, J. (July 18, 2005) [http://news.nationalgeographic.com/news/2005/07/0718_050718_ancientbeer.html "9,000-Year-Old Beer Re-Created From Chinese Recipe."] National Geographic News. Accessed 14 November 2005.
- Smith, M.G., and M. Snyder. (2005). "Ethanol-induced virulence of Acinetobacter baumannii". American Society for Microbiology meeting. June 5-9. Atlanta.

External links

- [http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc00/icsc0044.htm International Chemical Safety Card 0044]
- [http://www.cdc.gov/niosh/npg/npgd0262.html NIOSH Pocket Guide to Chemical Hazards]
-
- [http://www.compchemwiki.org/index.php?title=Ethanol Coordinates of the ethanol molecule] on Computational Chemistry Wiki. Accessed on 8 September 2005.
- Ethanol as a Source of Renewable Energy
- [http://www.rengen.info/?p=17 Essay]
- [http://issct.intnet.mu/cpabs.htm Abstracts]
- [http://business.guardian.co.uk/story/0,16781,1648504,00.html Sugar powers a Revolution on Brazil's roads] Category:Over-the-counter substances Category:Alcohol Category:Alcohols Category:Teratogens Category:Solvents Category:Household chemicals ms:Etanol ja:エタノール

Alcoholic beverage

ian alcoholic beverage.]] Alcoholic beverages are drinks containing ethanol. Alcoholic beverages have been widely consumed since prehistoric times by people around the world, seeing use as a component of the standard diet, for hygienic or medical reasons, for their relaxant and euphoric effects, for recreational purposes, for artistic inspiration, as aphrodisiacs, and for other reasons. Some have been invested with symbolic or religious significance suggesting the mystical use of alcohol, e.g., by Greco-Roman religion in the ecstatic rituals of Dionysus (also called Bacchus), god of drink and revelry; in the Christian Eucharist; and at the Jewish Passover. Moderate consumption of alcohol, defined by the U.S. Department of Agriculture and the Dietary Guidelines for Americans as no more than one to two drinks for men and one drink for women per day, is consistently shown as being beneficial for the heart and circulatory system (the UK equivalent is 3-4 units per day for men and 2-3 units for women). Moderate consumers statistically have fewer heart attacks and strokes, live longer, have lower blood pressure, and generally report better overall health. However, some people are prone to developing a chemical dependency to alcohol, alcoholism. The results of alcoholism are considered a major health problem in many nations. Frequent excessive consumption can harmfully interfere with the user's well-being. The neurological effects of alcohol use are often a factor in deadly motor vehicle accidents and fights. People under the influence of alcohol sometimes find themselves in dangerous or compromising situations where they would not be had they remained sober. Operating a motor vehicle or heavy machinery under the influence of alcohol is serious crime in almost all developed nations. Some religions—most notably Islam, Latter-day Saints, the Nikaya and most Mahayana schools of Buddhism and some Protestant sects of Christianity—forbid or discourage the consumption of alcoholic beverages for these and other reasons. Most governments regulate or restrict the sale and use of alcohol.

Chemistry

The ethanol (CH₃CH₂OH) in alcoholic beverages is almost always produced by fermentation, which is the metabolism of carbohydrates (usually sugars) by certain species of yeast in the absence of oxygen. The process of culturing yeast under conditions that produce alcohol is referred to as brewing. It should be noted that in chemistry, alcohol is a general term for any organic compound in which a hydroxyl group (-O H) is bound to a carbon atom, which in turn is bound to other hydrogen and/or carbon atoms. Other alcohols such as propylene glycol and the sugar alcohols may appear in food or beverages regularly, but these alcohols do not make them alcoholic. It has been suggested that alcoholic impurities, congeners, are the cause of hangovers. Alcoholic beverages with a concentration of about 50% ethanol or greater (100 proof) are flammable liquids and easily ignited. See also: ethanol

Alcoholic content

The concentration of alcohol in an alcoholic beverage may be specified in percent alcohol by volume (ABV), in percentage by weight (sometimes abbreviated w/w for weight for weight), or in proof. The 'proof' measurement roughly corresponds in a 2:1 ratio to percent alcoholic content by volume (e.g. 80 proof = 40% ABV). Common distillation cannot exceed 192 proof because at that point ethanol is an azeotrope with water. Alcohols of this purity are commonly referred to as grain alcohol and are not meant for human consumption, with the notable exception of neutral grain spirits. Most yeasts cannot grow when the concentration of alcohol is higher than about 18% by volume, so that is a practical limit for the strength of fermented beverages such as wine, beer, and sake. Strains of yeast have been developed that can survive in solutions of up to 25% alcohol by volume, but these were bred for ethanol fuel production, not beverage production. Liquors are produced by distillation of a fermented product, concentrating the alcohol and eliminating some of the by-products. Many wines are fortified wines with additional grain alcohol to achieve higher ABV than is easily reached using fermentation alone.

Flavoring

Ethanol is a moderately good solvent for many "fatty" substances and essential "oils", and thus facilitates the inclusion of several coloring, flavoring, and aromatic compounds to alcoholic beverages, especially to distilled ones. These flavoring ingredients may be naturally present in the starting material, or may be added before fermentation, before distillation, or before bottling the distilled product. Sometimes the flavor is obtained by allowing the beverage to stand for months or years in barrels made of special wood, or in bottles where scented twigs or fruits — or even insects — have been inserted. A well-stocked bar will include a selection of beers and wines, along with the typical liquors of vodka, rum, gin, tequila, and whisky; each in varying qualities from "well" quality (off brand) to premium quality (name brand) to "top shelf" (usually very expensive, ranging from $50 to several hundred USD per 750 ml bottle). Alcoholic beverages can be combined at the time of serving, sometimes with other ingredients, to create cocktails or mixed drinks. Small servings of pure liquor (shots) are also common, with whisky and tequila being traditionally popular selections.

History

Fermented beverages

Fermented alcoholic beverages have been known since pre-historical times. Beer was certainly known in Mesopotamia before 4000 BC, as attested to by recipes found on clay tablets and art that shows individuals using straws to drink from large vats. Wine was consumed in Classical Greece at breakfast or at symposia, and in the 1st century BC it was part of the diet of most Roman citizens. However, both Greeks and Romans generally consumed their wine watered (from 1 parts of wine to 1 part of water, to 1 part of wine to 4 parts of water). The transformation of water into wine at a wedding feast is one of the miracles attributed to Jesus in the New Testament, and his symbolic use of wine in the Last Supper led to it becoming an essential part of the Catholic Eucharist rite. In spite of the Qur'anic ban on alcoholic beverages, wine (usually sold by Christian tavern-keepers) remained fairly popular in Islamic lands over the centuries, as revealed in the verses of Persian mathematician Omar Khayyám (1040–1131): :"Here with a Loaf of Bread beneath the Bough, :A Flask of Wine, a Book of Verse—and Thou :Beside me singing in the Wilderness— :And Wilderness is Paradise enow." [http://www.armory.com/~thrace/ev/siir/Omar_Khayyam.html] In Europe during the Middle Ages, beer was consumed by the whole family, thanks to a triple fermentation process — the men had the strongest, then women, then children. A document of the times mentions nuns having an allowance of six pints of ale a day. Cider and pomace wine were also widely available, while grape wine was the prerogative of the higher classes. After the collapse of the Roman Empire, wine production in Europe appears to have been sustained chiefly by monasteries. By the time the Europeans reached the Americas in the 15th century, several native civilizations had developed alcoholic beverages. According to a post-Conquest Aztec document, consumption of the local "wine" (pulque) was generally restricted to religious ceremonies, but freely allowed to those over 70 years old (possibly the all-time record for legal drinking age). The natives of South America manufactured a beer-like product from cassava or maize (cauim, chicha), which had to be chewed before fermentation in order to turn the starch into sugars. (Curiously, the same technique was used in ancient Japan to make sake from rice and other starchy crops.) The medicinal use of alcoholic beverages was mentioned in Sumerian and Egyptian texts dated from 2100 BC or earlier. The Hebrew Bible recommends giving alcoholic drinks to those who are dying or depressed, so that they can forget their misery.

Distilled beverages

Main article: Distilled beverage Beer and wine are typically limited to a maximum 15 percent alcohol, although brewers have reached 25% alcohol. Beyond this limit yeast is adversely affected and cannot ferment. Since the fourth millennium BC in Babylonia, higher levels of alcohol have been obtained in a number of ways. It was not until the still was invented by Islamic alchemists in the 8th or 9th centuries that the history of distilled beverages began. Alcohol appeared first in Europe in the mid 12th century and by the early 14th century it had spread throughout Europe. It also spread eastward, mainly by the Mongols, and was practiced in China by the 14th century. However, recent archeological evidence has supported the idea that China has had wines and distilled beverages dating back to 5000 BC. Paracelsus gave alcohol its modern name, taking it from the Arabic word which means "finely divided", a reference to distillation.

Uses

In many countries, alcoholic beverages are commonly consumed at the major daily meals (lunch and dinner). Most early beers were in fact highly nutritional and served as a means of calorie distribution. Beer can be stored longer than grain or bread without fear of pest infestation or rotting, and drinking beer avoided the tooth-destroying grit that was present in hand-ground or early mill-ground flours. In places and eras with poor public sanitation, such as Medieval Europe, consumption of alcoholic beverages (particularly weak or "small" beer) was one method of avoiding water-borne diseases such as the cholera. Though strong alcohol kills bacteria, the low concentration in beer or even wine will have only a limited effect. Probably the boiling of water, which is required for the brewing of beer, and the growth of yeast, which would tend to crowd out other micro-organisms, were more important than the alcohol itself. In any case, the ethanol (and possibly other ingredients) of alcoholic beverages allows them to be stored for months or years in simple wood or clay containers without spoiling, which was certainly a major factor in their popularity. In colder climates, strong alcoholic beverages are popularly seen as a way to "warm up" the body, possibly because ethanol is a quickly absorbed source of food energy and dilates peripheral blood vessels (Peripherovascular dilation). This however is a dangerous myth, and people experiencing hypothermia should avoid alcohol. Although a drunk may feel warmer, the body loses heat and body temperature decreases, which may cause hypothermia, and eventually death. This is because of the dilation of blood vessels not in the core of the body; because of this increased bloodflow, the body loses its heat out of its less protected outer extremities. In many cultures, both contemporary and historical, alcoholic beverages — mostly because of their neurological effects — have also played an important role in various kinds of social interaction, providing a form of "liquid courage" (those who consume it "gain" confidence and lose discretion) While other psychoactive drugs (such as opium, coca, khat, cannabis, kava-kava, etc.) also have millennial traditions of social use, only coffee, tea and tobacco have been as universally used and accepted as ethanol is today.

Legal considerations

tobacco]] Most countries have rules forbidding the sale of alcoholic beverages to children. For example, in the Netherlands and Germany, one has to be 16 to buy beer or wine and 18 to buy distilled alcoholic beverages. However, possession of alcoholic beverages is not illegal for minors in Germany. Law here is directed at the potential sellers of alcoholic beverages and not at the minors. German law puts control concerning the consumption of alcoholic beverage into the hands of custodial persons and persons with parental power. See [http://www.bmfsfj.de/RedaktionBMFSFJ/Abteilung5/Pdf-Anlagen/juSchGenglisch,property=pdf.pdf] In law, sometimes the term "intoxicating agent" is used for a category of substances which includes alcoholic beverages and some drugs. Giving any of these substances to a person to create an abnormal condition of the mind (such as drunkenness), in order to facilitate committing a crime, may be an additional crime. Some countries may forbid the commerce, consumption or advertising of alcoholic beverages, or restrict them in various ways. During the period known as Prohibition, from 1919 to 1933, it was illegal to manufacture, transport, import, export, or sell alcoholic beverages in the United States. Many Muslim countries, such as Saudi Arabia, continue to prohibit alcohol for religious reasons. In the United States there are still communities with a ban on alcohol sales. Most countries have laws against drunk driving, driving with a certain concentration of ethanol in the blood. The legal threshold of blood alcohol content ranges from 0.0% to 0.05% or 0.08%, according to local law. Most countries also specify a legal drinking age, below which the consumption of alcohol is prohibited. In the US, the legal age in every state has been 21 since the passage of the National Minimum Drinking Age Act in 1984, which tied federal highway funds to states' raising their minimum drinking age to 21. In many countries, production of alcoholic beverages requires a license, and alcohol production is taxed. In the U.S., the Bureau of Alcohol, Tobacco, Firearms, and Explosives and the Alcohol and Tobacco Tax and Trade Bureau (formerly one organization known as the Bureau of Alcohol, Tobacco and Firearms) enforce federal laws and regulations related to alcohol, though most regulations regarding serving and selling alcoholic beverages are made by the individual states. For example, in the state of Washington, one can only buy bottles of spirits in state-run stores, whereas in many other states, these can be bought in supermarkets. There also exist intrastate regulatory differences, as between Montgomery County, Maryland and the rest of the state. In the UK the Customs and Excise department issues distilling licences. In New Zealand it is legal to produce alcohol for personal use. This has made the sale and use of home distillation equipment popular.

Types of alcoholic beverages

Alcoholic beverages include low-alcohol-content beverages produced by fermentation of sugar- or starch-containing products, and high-alcohol-content beverages produced by distillation of the low-alcohol-content beverages. Sometimes, the alcohol content of low-alcohol-content beverages is increased by adding distilled products, particularly in the case of wines. Such fortified wines include Port wine and Sherry. The process involved (as well as the resulting alcohol content) defines the finished product. A "beer" involves a relatively short (incomplete) fermentation process and an equally short aging process (a week or two) resulting in an alcohol content generally between 3-8%, as well as natural carbonation. A "wine" involves a longer (complete) fermentation process, and a relatively long aging process (months or years -- sometimes decades) resulting in an alcohol content between 7-18%. (Note that sparkling wine is generally made by adding a small amount of sugar before bottling). Distilled products are generally not made from a "beer" that would normally be palatable as fermentation is normally completed, but no aging is involved until after distillation. Most distilled liquors are 40% alcohol by volume. Standard drinks of alcoholic beverages in the United States all contain equivalent amounts of alcohol, about 0.6 ounce each. A U.S. standard drink is a 12 ounce can or bottle of beer, a five ounce glass of dinner wine, or a 1.5 ounce drink of 80 proof distilled spirits (either straight or in a mixed drink). This means that there is no drink of moderation, only behaviors of moderation. Standard drinks of beer, wine and liquor are all the same to a Breathalyzer.

Non-distilled beverages

- Beer
- Ales
- Barleywine
- Bitter ale
- Mild ale
- Pale ale
- Porter
- Stout
- Real ale
- Stock ale
- Fruit Beer
- Lager beer
- Bock
- Dry beer
- Oktoberfest Märzen
- Pilsener
- Schwarzbier
- Small beer
- Wheat beer
- Cauim
- Chicha
- Cider
- Kumis
- Lappish Hag's Love Potion
- Mead
- Perry
- Pulque
- Sake
- Wine
- Spritzer
- Palm wine
- Wine cooler
- Fruit wine

Distilled beverages

- Cocktails
- Liqueurs
- Spirits The names of some beverages are determined by the source of the material fermented: Note that in common speech, wine or brandy is made from grapes unless the fruit is specified: "plum wine" or "cherry brandy" for example, although in some cases grape-derived alcohol is added. In the USA and Canada, cider often means unfermented apple juice (see the article on cider), while fermented cider is called hard cider. Unfermented cider is sometimes called sweet cider. Also, applejack was originally made by a freezing process described in the article on cider which was equivalent to distillation but more easily done in the cold climate of New England. In the UK, cider is always alcoholic, and in Australia it can be either. Beer is generally made from barley, but can sometimes contain a mix of other grains. Whisky is sometimes made from a blend of different grains, especially Irish whiskey which may contain several different grains. The style of whisky (Scotch, Rye, Bourbon) generally determines the primary grain used, with additional grains usually added to the blend (most often barley, and sometimes oats). Two common distilled beverages are vodka and gin. Vodka can be distilled from any source (grain and potatoes being the most common, also industrial cellulose for the cheapest!) but the main characteristic of vodka is that it is so thoroughly distilled as to exhibit none of the flavors derived from its source material. Gin is a similar distillate which has been flavored by contact with herbs and other plant products, especially juniper berries. The name comes from the Dutch liquor genever, which in turn takes it's name from the Dutch word for juniper.

Addiction

Addiction is a compulsion to repeat a behavior regardless of its consequences. A person who is addicted is sometimes called an addict. Many drugs (sometimes called hard drugs) or behaviors are seen to precipitate an addiction, or a chronic pattern of behaviour, which includes a craving for more of the drug, or of the initial behavior, increased physiological tolerance to exposure, and withdrawal symptoms in the absence of the stimulus. Most drugs and behaviors that directly provide either pleasure or relief from pain pose a risk of dependency. Addictions can also be formed due to opponent process reactions. For example the terror of jumping out of an airplane is rewarded with intense pleasure when the parachute opens. Because of this opponent process, criminal behavior, running, stealing, violence, acting, and test taking can become habit forming.

Terminology and usage

The medical community now makes a careful theoretical distinction between physical dependence (characterized by symptoms of withdrawal) and psychological addiction (or simply addiction). Addiction is now narrowly defined as "uncontrolled, compulsive use despite harm"; if there is no harm being suffered by, or damage done to, the patient or another party, then clinically it may be considered compulsive, but within this narrow definition it is not categorized as "addiction". In practice, however, the two kinds of addiction are not always easy to distinguish. Addictions often have both physical and psychological components. There is also a lesser known situation called pseudo-addiction, where a patient will exhibit drug-seeking behaviour reminiscent of psychological addiction, however in this case, the patients tend to have genuine pain or other symptoms that have been undertreated. Unlike true psychological addiction, however, these behaviours tend to stop as soon as their pain is adequately treated. The obsolete term physical addiction is deprecated because of its pejorative connotations, especially in modern pain management with opioids where physical dependence is nearly universal but addiction is rare. Also, it should be noted that some highly addictive drugs (so-called hard drugs), such as cocaine, induce relatively little physical dependence, whilst other drugs (so-called soft drugs) such as magic mushrooms and peyote are not normally considered to give rise to any significant degree of addiction or dependence. Not all doctors do agree on what addiction or dependency is, particularly because traditionally, addiction has been defined as being possible only to a psychoactive substance (for example alcohol, tobacco, or drugs), which is ingested, crosses the blood-brain barrier, and alters the natural chemical behaviour of the brain temporarily. Many people, both psychology professionals and laypersons, now feel that there should be accommodation made to include psychological dependency on such things as gambling, food, sex, pornography, computers, work, and shopping / spending. However, these are things or tasks which, when used or performed, cannot cross the blood-brain barrier and hence, do not fit into the traditional view of addiction. Symptoms mimicking withdrawal may occur with abatement of such behaviours; however, it is said by those who adhere to a traditionalist view that these withdrawal-like symptoms are not strictly reflective of an addiction, but rather of a behavioural disorder. In spite of traditionalist protests and warnings that overextension of definitions may cause the wrong treatment to be used (thus failing the person with the behavioural problem), popular media, and some members of the field, do represent the aforementioned behavioural examples as addictions.

Varied forms of addiction

Physical dependency

Physical dependency on a substance is defined by the appearance of characteristic withdrawal symptoms when the drug is suddenly discontinued. While opioids, benzodiazepines, barbiturates, alcohol and nicotine are all well known for their ability to induce physical dependence, other drugs share this property that are not considered addictive: cortisone, beta-blockers and most antidepressants are examples. So while physical dependency can be a major factor in the psychology of addiction, the primary attribute of an addictive drug is its ability to induce euphoria while causing harm. Some drugs induce physical dependence or physiological tolerance - but not addiction - for example many laxatives, which are not psychoactive; nasal decongestants, which can cause rebound congestion if used for more than a few days in a row; and some antidepressants, most notably Effexor and Paxil, as they have quite short half-lives, so stopping them abruptly causes a more rapid change in the neurotransmitter balance in the brain than many other antidepressants. Many non-addictive prescription drugs should not be suddenly stopped, so a doctor should be consulted before abruptly discontinuing them. The speed with which a given individual becomes addicted to various substances varies with the substance, the frequency of use, the means of ingestion, and the individual. Some alcoholics report they exhibited alcoholic tendencies from the moment of first intoxication, while most people can drink socially without ever becoming addicted. Because of this variation, some people hypothesise that physical dependency and addiction are in large part genetically moderated. Nicotine is considered by many to be the most addictive substance in the world, although there has been no way found to determine this. Caffeine, ingested by more than 80% of human adults, is the most popular psychoactive substance in the world.

Psychological addiction

Psychological addictions are a dependency of the mind, and lead to psychological withdrawal symptoms. Addictions can theoretically form for any rewarding behavior, or as a habitual means to avoid undesired activity, but typically they only do so to a clinical level in individuals who have emotional, social, or psychological dysfunctions, taking the place of normal positive stimuli not otherwise attained (see Rat Park). While eating disorders, like other behavioral addictions, are usually considered primarily psychological disorders, they are sometimes treated as addictions, especially if they include elements of addictive behavior. Sufferers may experience withdrawal or withdrawal-like symptoms if they alter their diet suddenly. This suggests that some common food substances, especially chocolate, sugar and salt, may have the potential for addiction. In addition, frequent overeating can also be considered an addiction.

Addiction and drug control legislation

Most countries have legislation which brings vari