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Nierenstein reaction
Chemical reaction From Wikipedia, the free encyclopedia
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The Nierenstein reaction is an organic reaction describing the conversion of an acid chloride into a haloketone with diazomethane.[1][2] It is an insertion reaction in that the methylene group from the diazomethane is inserted into the carbon-chlorine bond of the acid chloride.
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Reaction mechanism
The reaction proceeds through a diazonium salt intermediate formed when diazomethyl anion displaces the chloride:
Excess diazomethane can act as a base, abstracting a hydrogen from the diazonium intermediate. The results are a neutral diazoketone, which does not react further; and methyldiazonium chloride, which decomposes to chloromethane. The unreactive diazoketone can, however, be re-activated with hydrogen chloride to give the Nierenstein product:
In even some cases with limited diazomethane, the reaction process can stall into the diazoketone pathway, requiring reparative HCl gas.[3]
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Examples
Nierenstein's original 1924 publication:[4]
A reaction from benzoyl bromide going haywire and forming the dioxane dimer:[5]
See also
- Maximilian Nierenstein
- Curtius rearrangement
- Wolff rearrangement
- Arndt–Eistert reaction: where acid chlorides react with diazomethane to give chain extended carboxylic acids via a rearrangement
References
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