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#REDIRECT ] |
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{{mergeto|acetal|date=February 2011}} |
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{{unreferenced|date=August 2011}} |
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'''Acetalisation''' is an ] that involves 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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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 to the right. |
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{{R with history}} |
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}} |
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The carbonyl group in '''1''' abstracts a proton from ]. The protonated carbonyl group 2 is activated for ] 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. In a '''transacetalisation''' or '''crossacetalisation''' a diol reacts with an acetal or two different acetals react with each other. Again this is possible because all the reaction steps are equilibria. |
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== See also== |
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* ] |
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* ] |
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==References== |
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{{Reflist}} |
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