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13.17 : Loss of Carboxy Group as CO2: Decarboxylation of Malonic Acid Derivatives

Just like β-keto acids—which upon thermal decarboxylation form ketones—β-dicarboxylic acids undergo decarboxylation to generate monocarboxylic acids with the liberation of carbon dioxide.

Decarboxylation reaction diagram; β-keto acid to methyl ketone; chemical equation.

The mechanism initiates with an internal electronic redistribution, resulting in a cyclic six-membered transition state. This is followed by a C–C bond cleavage to produce an enol by releasing carbon dioxide gas. Next, the enol rapidly tautomerizes under the acidic conditions to yield a more stable monocarboxylic acid.

Chemical reaction mechanism; acetoacetic ester tautomerization; structural formulas; reaction arrows.

In malonic ester synthesis, the key step is the decarboxylation of malonic acid, wherein alkyl halides are converted to monocarboxylic acids.

Kinetic resolution reaction diagram; ester to alcohol conversion; chemical reaction steps.

Tags

DecarboxylationMalonic Acid DerivativesCarbon Dioxide LiberationKeto AcidsDicarboxylic AcidsMonocarboxylic AcidsCyclic Transition StateC C Bond CleavageEnol FormationTautomerizationAcidic ConditionsMalonic Ester SynthesisAlkyl Halides

来自章节 13:

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