| Revision as of 02:22, 7 June 2005 edit~K (talk | contribs)Extended confirmed users2,339 editsm changed Category:Organic reaction to Category:Organic reactions← Previous edit |
Latest revision as of 09:23, 18 August 2024 edit undoChristian75 (talk | contribs)Extended confirmed users, New page reviewers, Pending changes reviewers, Rollbackers114,675 edits Same target but to section: Acetal#AcetalisationTag: Redirect target changed |
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'''Acetalisation''' is an ] that involves is the formation of an ] or ]. One way of acetal formation is the ] of an ] to a ] or an ]. Acetalisation is often used in ] to create a ] because it is a reversible reaction. |
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{{Redirect category shell|1= |
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=== Acetalisation of carbonyl groups by alcohols=== |
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{{R to section}} |
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{{R with history}} |
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Acetalisation is ] ] with elimination of water. The reaction can be driven to the acetal when water is removed from the reaction system either by ] or trapping water with ]s or ]. The general reaction mechanism for acetalisation of a carbonyl group is shown below. |
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The carbonyl group in '''1''' abstracts a proton from ]. The protonated carbonyl group 2 is activated for nucleophilic addition of the alcohol. The structures '''2a''' and '''2b''' are ]s. After ] of '''3''' by water the ] or ] '''4''' is formed. The hydroxyl group in '''4''' is protonated leading to the ] '''6''' which accepts a second alcohol group to '''7''' with a final deprotonation to the acetal '''8'''. The reverse reaction takes place by adding water in the same acidic medium. Acetals are stable towards ] media. |
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Typical reaction in organic chemistry: |
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A solution of ] in ] is slowly added over a stirred mixture of ] ('''1''') and ] at ]. After workup 3-bromo-3-methyl-butan-2-one ('''2''') is dissolved in ] and ] ] and ] are added. A ] device is fitted to remove generated water and the reaction is ]ed for 4.5 h. The crude reaction is worked up by washing with saturated ] and ] and the organic layer dried over anhydrous ], after that, ] is added to evaporate the ] under reduced pressure. The residue is purified by ] (0.15 mmHg, 32 ºC) to yield the dioxolane compound '''3''' (62% from 1) as a colorless liquid. <sup></sup> |
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Examples: |
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* acetalisation in ] |
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* acetalisation in ] |
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== References == |
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<sup></sup> 2-(1-Bromo-1-methyl-ethyl)-2-methyl-dioxolane Juan M. Castro, Pablo J. Linares-Palomino, Sofia Salido, Joaquan Altarejos Manuel Nogueras, Adolfo Sanchez ] 2004, M387 ] publication. |
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{{reaction-stub}} |
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