In chemistry Chemistry (from Arabic: كيمياء Latinized: chem , meaning "earth") is the science concerned with the composition, behavior, structure, and properties of matter, as well as the changes it undergoes during chemical reactions. It is a physical science for studies of various atoms, molecules, crystals and other aggregates of matter, an alcohol is any organic compound An organic compound is any member of a large class of chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of compounds such as carbonates, simple oxides of carbon and cyanides, as well as the allotropes of carbon, are considered inorganic. The distinction between "organic" and " in which a hydroxyl In chemistry, hydroxyl is a compound containing an oxygen atom bound covalently with a hydrogen atom. The neutral form of this group is a hydroxyl radical. The hydroxyl anion is called hydroxide; it is a diatomic ion with a single negative electronic charge. In discussions of synthetic methods in organic chemistry the hydroxyl group (–OH) is 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. However, its relative reactivity can be (-O Oxygen , from the Greek roots ὀξύς (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter), is the element with atomic number 8 and represented by the symbol O. It is a member of the chalcogen group on the periodic table, and is a highly reactive nonmetallic period 2 element that H Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an atomic weight of 1.00794 u, hydrogen is the lightest and most abundant chemical element, constituting roughly 75 % of the Universe's elemental mass. Stars in the main sequence are mainly composed of hydrogen in its plasma state. Naturally occurring) is bound to a 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. There are three naturally occurring isotopes, with 12C and 13C being stable, while 14C is radioactive, decaying with a half-life of atom, usually connected to other carbon or hydrogen atoms.
An important class are the simple acyclic In organic chemistry, compounds composed of carbon and hydrogen are divided into two classes: aromatic compounds, which contain benzene rings or similar rings of atoms, and aliphatic compounds , which do not contain aromatic rings alcohols, the general formula for which is CnH2n+1OH. Of those, ethanol Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a potent psychoactive drug, best known as the type of alcohol found in alcoholic beverages and in modern thermometers. Ethanol is one of the oldest recreational drugs. In common usage, it is often referred to (C2H5OH) is the type of alcohol found in alcoholic beverages An alcoholic beverage is a drink that contains ethanol . Alcoholic beverages are divided into three general classes: beers, wines, and spirits, 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 is a common name for a colorless, flammable chemical compound with a strong odor. It has the molecular formula C3H8O. It is the simplest example of a secondary alcohol, where the alcohol carbon is attached to two other carbons sometimes shown as (CH3)2CHOH. It is an isomer of propanol (propan-2-ol) or wood alcohol (methyl alcohol, or methanol Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with formula C ). The suffix -ol appears in the IUPAC chemical name 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 organic compound should have a name from which an unambiguous structural formula can be drawn. There is also an IUPAC nomenclature of inorganic chemistry of all alcohols.
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Simple alcohols
The most commonly used alcohol is ethanol, C2H5OH, with the 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 millenia, in the form of fermented and distilled alcoholic beverages An alcoholic beverage is a drink that contains ethanol . Alcoholic beverages are divided into three general classes: beers, wines, and spirits, and was isolated by the Persian alchemist Rāzi (Rhazes) Abū Bakr Muhammad ibn Zakariyā Rāzī , known as Rhazes or Rasis after medieval Latinists, (August 26, 865, Rayy— 925, Rayy) was a Persian alchemist, chemist, physician, philosopher and scholar. He is recognised as a polymath and often referred to as "probably the greatest and most original of all the physicians, and one of the most around 900 AD. It is a clear flammable liquid that boils at 78.4 °C, which is used as an industrial solvent, car 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 biologically, and they have characteristics which allow them to be used in current engines. One advantage shared by all, and raw material in the chemical industry. In the US ^ b. English is the de facto language of American government and the sole language spoken at home by 80% of Americans age five and older. Spanish is the second most commonly spoken language 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 Denatonium, usually available as denatonium benzoate and as denatonium saccharide, is the most bitter chemical compound known. It was discovered in 1958 during research on local anesthetics by Macfarlan Smith of Edinburgh, Scotland, and registered under the trademark Bitrex. Dilutions of as little as 10 ppm are unbearably bitter to most humans) or poisonous (such as methanol). Ethanol in this form is known generally as denatured alcohol Denatured alcohol is ethanol that has additives to make it poisonous and/or unpalatable, and thus, undrinkable. In some cases it is also dyed; when methanol is used, it may be referred to as methylated spirits Denatured alcohol is ethanol that has additives to make it poisonous and/or unpalatable, and thus, undrinkable. In some cases it is also dyed ("Meths") or "surgical spirits".
The simplest alcohol is methanol Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with formula C , CH3OH, 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 The optic nerve is the second of twelve paired cranial nerves but is considered to be part of the central nervous system as it is derived from an outpouching of the diencephalon during embryonic development. Consequently, the fibres are covered with myelin produced by oligodendrocytes rather than the Schwann cells of the peripheral nervous system and 30 ml (one fluid ounce) is potentially fatal.[1]
Two other alcohols whose uses are relatively widespread (though not so much as those of methanol and ethanol) are propanol and butanol. Like ethanol, they can be produced by fermentation processes. (However, the fermenting agent is a bacterium, Clostridium acetobutylicum Clostridium acetobutylicum, included in the genus Clostridium, is a commercially valuable bacterium. It is sometimes called the "Weizmann Organism", after Chaim Weizmann, who in 1916 helped discover how C. acetobutylicum culture could be used to produce acetone, butanol, and ethanol from starch using the ABE process for industrial, that feeds on cellulose Cellulose is an organic compound with the formula n, a polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4) linked D-glucose units, not sugars like the Saccharomyces Saccharomyces is a genus in the kingdom of fungi that includes many species of yeast. Saccharomyces is from Latin meaning sugar fungi. Many members of this genus are considered very important in food production. One example is Saccharomyces cerevisiae, which is used in making wine, bread, and beer. Other members of this genus include Saccharomyces yeast Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with about 1,500 species currently described; they dominate fungal diversity in the oceans. Most reproduce asexually by budding, although a few do so by binary fission. Yeasts are unicellular, although some species with yeast forms may become multicellular through the formation that produces ethanol.)
Nomenclature
Systematic names
In the IUPAC IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. It is developed and kept up to date under the auspices of the International Union of Pure and Applied Chemistry . The rules for naming organic and inorganic compounds are contained in two publications, known as the Blue Book and the system, the name of the alkane chain loses the terminal "e" and adds "ol", e.g. "methanol" and "ethanol".[2] 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 is a primary alcohol with the molecular formula of C3H8O. It is also known as 1-propanol, 1-propyl alcohol, n-propyl alcohol, or simply propanol. It is an isomer of propan-2-ol. It is used as a solvent in the pharmaceutical industry, and for resins and cellulose esters. It is formed naturally in small amounts during many fermentation for CH3CH2CH2OH, propan-2-ol Isopropyl alcohol is a common name for a colorless, flammable chemical compound with a strong odor. It has the molecular formula C3H8O. It is the simplest example of a secondary alcohol, where the alcohol carbon is attached to two other carbons sometimes shown as (CH3)2CHOH. It is an isomer of propanol 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 An aldehyde is an organic compound containing a terminal carbonyl group. This functional group, which consists of a carbon atom bonded to a hydrogen atom and double-bonded to an oxygen atom , is called the aldehyde group. The aldehyde group is also called the formyl or methanoyl group, ketone In organic chemistry, a ketone is a type of compound that features one carbonyl group (C=O) bonded to two other carbon atoms, i.e., R3CC or carboxylic acid Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the formula -COH, usually written -COOH or -CO2H. Carboxylic acids are Brønsted-Lowry acids — they are proton donors. Salts and anions of carboxylic acids are called carboxylates), then it is necessary to use the prefix "hydroxy",[2] for example: 1-hydroxy-2-propanone (CH3COCH2OH).
Some examples of simple alcohols and how to name themThe 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 In chemistry, a methyl group is a hydrophobic alkyl functional group named after methane (C alcohol, ethyl In chemistry, an ethyl group is an alkyl functional group derived from ethane . It has the formula -C2H5 and is very often abbreviated -Et alcohol. 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 or isopropyl alcohol Isopropyl alcohol is a common name for a colorless, flammable chemical compound with a strong odor. It has the molecular formula C3H8O. It is the simplest example of a secondary alcohol, where the alcohol carbon is attached to two other carbons sometimes shown as (CH3)2CHOH. It is an isomer of propanol depending on whether the hydroxyl group is bonded to the 1st or 2nd carbon on the propane Propane is a three-carbon alkane, normally a gas, but compressible to a transportable liquid. It is derived from other petroleum products during oil or natural gas processing. It is commonly used as a fuel for engines, oxy-gas torches, barbecues, portable stoves and residential central heating chain.
Alcohols are classified into primary, secondary and tertiary, based upon the number of carbon atoms conected to the carbon atom that bears the hydroxyl group. Namely, 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, 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. It is unique among the isomers of butanol because it tends to be a solid at room temperature, with a or tert-butanol.
Common Names
Etymology
| Look up alcohol in Wiktionary, the free dictionary. |
The word alcohol appears in English in the 16th century, loaned via French from medical Latin, ultimately from the Arabic الكحل (al-kuḥl, "the kohl, a powder used as an eyeliner").
ال al is Arabic for the definitive article, the in English.
The current Arabic name for alcohol is الكحول al-kuḥūl, re-introduced from western usage.
kuḥl was the name given to the very fine powder, produced by the sublimation of the natural mineral stibnite to form antimony sulfide Sb2S3 (hence the essence or "spirit" of the substance), which was used as an antiseptic and eyeliner.
Bartholomew Traheron in his 1543 translation of John of Vigo introduces the word as a term used by "barbarous" (Moorish) authors for "fine powder":
- the barbarous auctours use alcohol, or (as I fynde it sometymes wryten) alcofoll, for moost fine poudre.
William Johnson in his 1657 Lexicon Chymicum glosses the word as antimonium sive stibium. By extension, the word came to refer to any fluid obtained by distillation, including "alcohol of wine", the distilled essence of wine. Libavius in Alchymia (1594) has vini alcohol vel vinum alcalisatum. Johnson (1657) glosses alcohol vini as quando omnis superfluitas vini a vino separatur, ita ut accensum ardeat donec totum consumatur, nihilque fæcum aut phlegmatis in fundo remaneat. The word's meaning became restricted to "spirit of wine" (ethanol) in the 18th century, and was again extended to the family of substances so called in modern chemistry from 1850.
Physical and chemical properties
Alcohols have an odor that is often described as “biting” and as “hanging” in the nasal passages.
The hydroxyl group generally makes the alcohol molecule polar. Those groups can form hydrogen bonds to one another and to other compounds (except in certain large molecules where the hydroxyl is protected by steric hindrance of adjacent groups[3]). This hydrogen bonding means that alcohols can be used as protic solvents. 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 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 hydrocarbons and ethers. The boiling point of the alcohol ethanol is 78.29 °C, compared to 69 °C for the hydrocarbon Hexane (a common constituent of gasoline), and 34.6 °C for Diethyl ether.
Alcohols, like water, can show either acidic or basic properties at the O-H group. With a pKa 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:
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. 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
Total recorded alcohol per capita consumption (15+), in litres of pure alcohol[4]Alcohols can be used as a beverage (ethanol only), as fuel and for many scientific, medical, and industrial utilities. Ethanol in the form of alcoholic beverages has been consumed by humans since pre-historic times. A 50% v/v solution of ethylene glycol in water is commonly used as an antifreeze.
Some alcohols, mainly ethanol and methanol, can be used as an alcohol fuel. Fuel performance can be increased in forced induction internal combustion engines by injecting alcohol into the air intake after the turbocharger or supercharger has pressurized the air. This cools the pressurized air, providing a denser air charge, which allows for more fuel, and therefore more power.
Alcohols have applications in industry and science as reagents or solvents. Because of its low toxicity and ability to dissolve non-polar substances, ethanol can be used as a solvent in medical drugs, perfumes, and vegetable essences such as vanilla. In organic synthesis, alcohols serve as versatile intermediates.
Ethanol can be used as an antiseptic to disinfect the skin before injections are given, often along with iodine. Ethanol-based soaps are becoming common in restaurants and are convenient because they do not require drying due to the volatility of the compound. Alcohol is also used as a preservative for specimens.
Alcohol gels have become common as hand sanitizers.
Production
Industrially alcohols are produced in several ways:
- By fermentation using glucose produced from sugar from the hydrolysis of starch, in the presence of yeast and temperature of less than 37°C to produce ethanol. For instance the conversion of invertase to glucose and fructose or the conversion of glucose to zymase and ethanol.
- By direct hydration using ethylene (ethylene hydration)[5] or other alkenes from cracking of fractions of distilled crude oil.
Endogenous
Several of the benign bacteria in the intestine use fermentation as a form of anaerobic respiration. This metabolic reaction produces ethanol as a waste product, just like aerobic respiration produces carbon dioxide and water. Thus, human bodies inevitably contain some quantity of alcohol endogenously produced by these bacteria.
Laboratory synthesis
Several methods exist for the preparation of alcohols in the laboratory.
- Primary alkyl halides react with aqueous NaOH or KOH mainly to primary alcohols in nucleophilic aliphatic substitution. (Secondary and especially tertiary alkyl halides will give the elimination (alkene) product instead).
- Aldehydes or ketones are reduced with sodium borohydride or lithium aluminium hydride (after an acidic workup). Another reduction by aluminiumisopropylates is the Meerwein-Ponndorf-Verley reduction.
- Alkenes engage in an acid catalysed hydration reaction using concentrated sulfuric acid as a catalyst which gives usually secondary or tertiary alcohols. The hydroboration-oxidation and oxymercuration-reduction of alkenes are more reliable in organic synthesis. Alkenes react with NBS and water in halohydrin formation reaction
- Grignard reagents react with carbonyl groups to secondary and tertiary alcohols. Related reactions are the Barbier reaction and the Nozaki-Hiyama reaction.
- Noyori asymmetric hydrogenation is the asymmetric reduction of β-keto-esters
- Amines can be converted to diazonium salts which are then hydrolyzed.
The formation of a secondary alcohol via reduction and hydration is shown:
Reactions
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 + 2Na → 2R-O−Na + H2
- E.g. 2 CH3CH2-OH + 2 Na → 2 CH3-CH2-O−Na + H2
Water is similar in pKa 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)
It should be noted, though, that the bases used to deprotonate alcohols are strong themselves. The bases used and the alkoxides created are both highly moisture sensitive chemical reagents.
The acidity of alcohols is also affected by the overall stability of the alkoxide ion. Electron-withdrawing 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 ethers in the Williamson ether synthesis.
Nucleophilic substitution
The OH group is not a good leaving group in nucleophilic substitution reactions, so neutral alcohols do not react in such reactions. However, if the oxygen is first protonated to give R−OH2+, the leaving group (water) is much more stable, and the 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 by unimolecular nucleophilic substitution. If primary or secondary alcohols are to be reacted with hydrochloric acid, an activator such as zinc chloride is needed. Alternatively the conversion may be performed directly using thionyl chloride.[1]
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 in a dehydration reaction, although this reaction is rarely used except in the manufacture of diethyl ether.
More useful is the E1 elimination reaction of alcohols to produce 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 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 with carbon disulfide and iodomethane.
Esterification
To form an ester from an alcohol and a carboxylic acid the reaction, known as Fischer esterification, is usually performed at reflux with a catalyst of concentrated sulfuric acid:
- R-OH + R'-COOH → 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 tosyl (tosylate) esters are made by reaction of the alcohol with p-toluenesulfonyl chloride in pyridine.
Oxidation
Main article: Oxidation of primary alcohols to carboxylic acidsPrimary alcohols (R-CH2-OH) can be oxidized either to aldehydes (R-CHO) or to carboxylic acids (R-CO2H), while the oxidation of secondary alcohols (R1R2CH-OH) normally terminates at the ketone (R1R2C=O) stage. Tertiary alcohols (R1R2R3C-OH) are resistant to oxidation.
The direct oxidation of primary alcohols to carboxylic acids normally proceeds via the corresponding aldehyde, which is transformed via an aldehyde hydrate (R-CH(OH)2) by reaction with water before it can be further oxidized to the carboxylic acid.
Mechanism of oxidation of primary alcohols to carboxylic acids via aldehydes and aldehyde hydratesOften it is possible to interrupt the oxidation of a primary alcohol at the aldehyde level by performing the reaction in absence of water, so that no aldehyde hydrate can be formed.
Reagents useful for the transformation of primary alcohols to aldehydes are normally also suitable for the oxidation of secondary alcohols to ketones. These include:
- Chromium-based reagents, such as Collins reagent (CrO3·Py2), PDC or PCC.
- Activated DMSO, resulting from reaction of DMSO with electrophiles, such as oxalyl chloride (Swern oxidation), a carbodiimide (Pfitzner-Moffatt oxidation) or the complex SO3·Py (Parikh-Doering oxidation).
- Hypervalent iodine compounds, such as Dess-Martin periodinane or 2-Iodoxybenzoic acid.
- Catalytic TPAP in presence of excess of NMO (Ley oxidation).
- Catalytic TEMPO in presence of excess bleach (NaOCl) (Anelli's oxidation).
Allylic and benzylic alcohols can be oxidized in presence of other alcohols using certain selective oxidants such as manganese dioxide (MnO2).
Reagents useful for the oxidation of secondary alcohols to ketones, but normally inefficient for oxidation of primary alcohols to aldehydes, include chromium trioxide (CrO3) in a mixture of sulfuric acid and acetone (Jones oxidation) and certain ketones, such as cyclohexanone, in the presence of aluminium isopropoxide (Oppenauer oxidation).
The direct oxidation of primary alcohols to carboxylic acids can be carried out using:
- Potassium permanganate (KMnO4).
- Jones oxidation.
- PDC in DMF.
- Heyns oxidation.
- Ruthenium tetroxide (RuO4).
- TEMPO.
Alcohols possessing two hydroxy groups located on adjacent carbons —that is, 1,2-diols— suffer oxidative breakage at a carbon-carbon bond with some oxidants such as sodium periodate (NaIO4) or lead tetraacetate (Pb(OAc)4), resulting in generation of two carbonyl groups.
Oxidative breakage of carbon-carbon bond in 1,2-diolsToxicity
Main articles: Short-term effects of alcohol and Long-term effects of alcohol Most significant of the possible long-term effects of ethanol. Additionally, in pregnant women, it causes fetal alcohol syndrome.Ethanol in alcoholic beverages has been consumed by humans since prehistoric times for a variety of hygienic, dietary, medicinal, religious, and recreational reasons. The consumption of large doses of ethanol causes drunkenness (intoxication), which may lead to a hangover as its effects wear off. Depending upon the dose and the regularity of its consumption, ethanol can cause acute respiratory failure or death. Because ethanol impairs judgment in humans, it can be a catalyst for reckless or irresponsible behavior. The LD50 of ethanol in rats is 10.3 g/kg.[6]
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 and then to the poisonous formic acid in the liver by alcohol dehydrogenase and formaldehyde dehydrogenase enzymes respectively; accumulation of formic acid can lead to blindness or death.[7] Similarly poisoning due to other alcohols such as ethylene glycol or diethylene glycol are due to their metabolites which are also produced by alcohol dehydrogenase.[8][9] 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. Any remaining methanol will then have time to be excreted through the kidneys.[7][10][11]
Methanol itself, while poisonous, has a much weaker sedative effect than ethanol. Some longer-chain alcohols such as n-propanol, isopropanol, n-butanol, t-butanol and 2-methyl-2-butanol do however have stronger sedative effects, but also have higher toxicity than ethanol.[12][13] These longer chain alcohols are found as contaminants in some alcoholic beverages and are known as fusel alcohols,[14][15] and are reputed to cause severe hangovers although it is unclear if the fusel alcohols are actually responsible.[16] Many longer chain alcohols are used in industry as solvents and are occasionally abused by alcoholics,[17][18] leading to a range of adverse health effects.[19]
Occurrence in nature
Alcohol has been found outside the Solar system. It can be found in low densities in star and planetary system forming regions of space.
See
- http://www.springerlink.com/content/u3p6612j611w2hqv/
- http://www.physics.uq.edu.au/people/ross/phys2080/ism/ism.htm (species found)
- Astrophysical maser (species found)
See also
| Wikiquote has a collection of quotations related to: Alcohol |
| Look up alcohol in Wiktionary, the free dictionary. |
- Alcohol fuel
- Alcoholic beverage
- Blood alcohol content
- Breathalyzer
- Fatty alcohol
- Fetal alcohol syndrome
- History of alcohol
- List of countries by alcohol consumption
- Long-term effects of alcohol
- Oxidation of primary alcohols to carboxylic acids
- Oxidation of secondary alcohols to ketones
- Phenols
- Rubbing alcohol
- Sugar alcohol
- Surrogate alcohol
- Transesterification
- Cooking with alcohol
References
- ^ Vale A (2007). "Methanol". Medicine 35 (12): 633–4. doi:10.1016/j.mpmed.2007.09.014.
- ^ a b William Reusch. "Alcohols". VirtualText of Organic Chemistry. http://www.cem.msu.edu/~reusch/VirtualText/alcohol1.htm#alcnom. Retrieved 2007-09-14.
- ^ Irena Majerza, Ireneusz Natkaniec (2006), ' Experimental and theoretical IR, R, and INS spectra of 2,2,4,4-tetramethyl-3-t-butyl-pentane-3-ol Journal of Molecular Structure, Volume 788, Issues 1-3, Pages 93-101 {{doi:10.1016/j.molstruc.2005.11.022}}
- ^ Global Status Report on Alcohol 2004
- ^ Lodgsdon, J.E. (1994). "Ethanol." In J.I. Kroschwitz (Ed.) Encyclopedia of Chemical Technology, 4th ed. vol. 9, p. 820. New York: John Wiley & Sons.
- ^ Robert S. Gable (2004). "Comparison of acute lethal toxicity of commonly abused psychoactive substances" (reprint). Addiction 99 (6): 686–696. doi:10.1111/j.1360-0443.2004.00744.x. http://web.cgu.edu/faculty/gabler/toxicity%20Addiction%20offprint.pdf.
- ^ a b Schep LJ, Slaughter RJ, Vale JA, Beasley DM (Sep 30 2009). "A seaman with blindness and confusion". BMJ 339: b3929. doi:10.1136/bmj.b3929. PMID 19793790. http://www.bmj.com/cgi/content/full/339/sep30_1/b3929.
- ^ Brent J (May 2009). "Fomepizole for ethylene glycol and methanol poisoning". N. Engl. J. Med. 360 (21): 2216–23. doi:10.1056/NEJMct0806112. ISSN 0028-4793. PMID 19458366.
- ^ Schep LJ, Slaughter RJ, Temple WA, Beasley DM (July 2009). "Diethylene glycol poisoning". Clin Toxicol (Phila) 47 (6): 525–35. doi:10.1080/15563650903086444. ISSN 1556-3650. PMID 19586352.
- ^ Zimmerman HE, Burkhart KK, Donovan JW. Ethylene glycol and methanol poisoning: diagnosis and treatment. Journal of Emergency Nursing. 1999 Apr;25(2):116-20. PMID 10097201
- ^ Lobert S. Ethanol, isopropanol, methanol, and ethylene glycol poisoning. Critical Care Nurse. 2000 December;20(6):41-7. PMID 11878258
- ^ McKee M, Suzcs S, Sárváry A, Adany R, Kiryanov N, Saburova L, Tomkins S, Andreev E, Leon DA. The composition of surrogate alcohols consumed in Russia. Alcoholism, Clinical and Experimental Research. 2005 October;29(10):1884-8. PMID 16269919
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Bibliography
- Metcalf, Allan A. (1999). The World in So Many Words. Houghton Mifflin. ISBN 0395959209.
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Categories: Alcohols | Antiseptics | Arabic loanwords | Functional groups
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