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==Production== ===Hydroxylation=== Many alcohols are produced by [[hydroxylation]], i.e., the installation of a hydroxy group using oxygen or a related oxidant. Hydroxylation is the means by which the body processes many [[xenobiotic|poisons]], converting lipophilic compounds into hydrophilic derivatives that are more readily excreted. Enzymes called [[hydroxylase]]s and [[oxidase]]s facilitate these conversions. Many industrial alcohols, such as [[cyclohexanol]] for the production of [[nylon]], are produced by hydroxylation. ===Ziegler and oxo processes=== In the [[Ziegler process]], linear alcohols are produced from ethylene and [[triethylaluminium]] followed by oxidation and hydrolysis.<ref name="Falbe"/> An idealized synthesis of [[1-octanol]] is shown: :{{chem2 | Al(C2H5)3 + 9 C2H4 -> Al(C8H17)3 }} :{{chem2 | Al(C8H17)3 + 3O + 3 H2O -> 3 HOC8H17 + Al(OH)3 }} The process generates a range of alcohols that are separated by [[distillation]]. Many higher alcohols are produced by [[hydroformylation]] of alkenes followed by hydrogenation. When applied to a [[terminal alkene]], as is common, one typically obtains a linear alcohol:<ref name="Falbe"/> :{{chem2 | RCH\dCH2 + H2 + CO -> RCH2CH2CHO }} :{{chem2 | RCH2CH2CHO + 3 H2 -> RCH2CH2CH2OH }} Such processes give [[fatty alcohol]]s, which are useful for detergents. ===Hydration reactions=== Some low molecular weight alcohols of industrial importance are produced by the addition of water to alkenes. Ethanol, isopropanol, 2-butanol, and ''tert''-butanol are produced by this general method. Two implementations are employed, the direct and indirect methods. The direct method avoids the formation of stable intermediates, typically using acid catalysts. In the indirect method, the alkene is converted to the [[sulfate ester]], which is subsequently hydrolyzed. The direct [[hydration reaction|hydration]] uses [[ethylene]] ([[Ethanol#Hydration|ethylene hydration]])<ref name="Lodgsdon-1994">{{cite book |author =Lodgsdon J.E. |year=1994 |chapter=Ethanol |editor=Kroschwitz J.I. |title=Encyclopedia of Chemical Technology| edition=4th |volume=9 |page=820 |location=New York |publisher=John Wiley & Sons |isbn=978-0-471-52677-3}}</ref> or other alkenes from [[cracking (chemistry)|cracking]] of fractions of distilled [[crude oil]]. Hydration is also used industrially to produce the diol [[ethylene glycol]] from [[ethylene oxide]]. ===Fermentation=== Ethanol is obtained by [[fermentation (biochemistry)|fermentation]] of [[glucose]] (which is often obtained from [[starch]]) in the presence of yeast. Carbon dioxide is cogenerated. Like ethanol, [[n-Butanol|butanol]] can be produced by fermentation processes. ''Saccharomyces'' yeast are known to produce these higher alcohols at temperatures above {{convert|75|°F|°C|abbr=on}}. The bacterium ''[[Clostridium acetobutylicum]]'' can feed on [[cellulose]] (also an alcohol) to produce butanol on an industrial scale.<ref name="Zverlov-2006">{{cite journal|last1=Zverlov|first1=W|last2=Berezina|first2=O|last3=Velikodvorskaya|first3=GA|last4=Schwarz|first4=WH|s2cid=24074264|title=Bacterial acetone and butanol production by industrial fermentation in the Soviet Union: use of hydrolyzed agricultural waste for biorefinery.|journal=Applied Microbiology and Biotechnology|date=August 2006|volume=71|issue=5|pages=587–97|doi=10.1007/s00253-006-0445-z|pmid=16685494}}</ref> ===Substitution=== Primary [[alkyl halide]]s react with aqueous [[Sodium hydroxide|NaOH]] or [[Potassium hydroxide|KOH]] to give alcohols in [[nucleophilic aliphatic substitution]]. Secondary and especially tertiary alkyl halides will give the elimination (alkene) product instead. [[Grignard reagent]]s react with [[carbonyl]] groups to give secondary and tertiary alcohols. Related reactions are the [[Barbier reaction]] and the [[Nozaki–Hiyama–Kishi reaction]]. ===Reduction=== [[Aldehydes]] or [[ketone]]s are [[redox|reduced]] with [[sodium borohydride]] or [[lithium aluminium hydride]] (after an acidic workup). Another reduction using [[aluminium isopropoxide]] is the [[Meerwein–Ponndorf–Verley reduction]]. [[Asymmetric hydrogenation|Noyori asymmetric hydrogenation]] is the asymmetric reduction of β-keto-esters. ===Hydrolysis=== [[Alkenes]] engage in an acid catalyzed [[hydration reaction]] using concentrated sulfuric acid as a catalyst that gives usually secondary or tertiary alcohols. Formation of a secondary alcohol via [[Hydration reaction#Alkenes|alkene reduction and hydration]] is shown: :[[File:Secondary alcohol formation-diagram.svg|class=skin-invert-image|frameless|upright=1.6|Preparation of a secondary alcohol]] The [[hydroboration-oxidation]] and [[oxymercuration-reduction]] of alkenes are more reliable in organic synthesis. Alkenes react with [[N-Bromosuccinimide|''N''-bromosuccinimide]] and water in [[halohydrin formation reaction]]. [[Amine]]s can be converted to [[diazonium salt]]s, which are then hydrolyzed.
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