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The malonic ester synthesis is a chemical reaction where diethyl malonate or another ester of malonic acid is alkylated at the carbon alpha (directly adjacent) to both carbonyl groups, and then converted to a substituted acetic acid. [2] Reaction formula
Malonic acid is a dicarboxylic acid with structure CH 2 (COOH) 2. The ionized form of malonic acid, as well as its esters and salts , are known as malonates . For example, diethyl malonate is malonic acid's diethyl ester .
One of the principal uses of this compound is in the malonic ester synthesis. The carbanion (2) formed by reacting diethyl malonate (1) with a suitable base can be alkylated with a suitable electrophile. This alkylated 1,3-dicarbonyl compound (3) readily undergoes decarboxylation with loss of carbon dioxide, to give a substituted acetic acid (4):
Dimethyl malonate is a diester derivative of malonic acid. It is a common reagent for organic synthesis used, for example, as a precursor for barbituric acid. It is also used in the malonic ester synthesis. It can be synthesized from dimethoxymethane and carbon monoxide. [2]
A notable method for synthesizing acetamidomalon ester is described in a 1950 patent, [1] which cites a procedure previously featured in Organic Syntheses. [2] The synthesis procedure involves the preparation of malonic acid diethyl ester in acetic acid combined with sodium nitrite (NaNO 2), resulting in diethyl isonitrosomalonate (also known as α-oximinomalonic acid diethyl ester).
Sodium ethoxide is commonly used as a base in the Claisen condensation [7] and malonic ester synthesis. [8] Sodium ethoxide may either deprotonate the α-position of an ester molecule, forming an enolate, or the ester molecule may undergo a nucleophilic substitution called transesterification. If the starting material is an ethyl ester, trans ...
Unlike other malonic esters that are derived via malonic ester synthesis, diethyl phenylmalonate is typically indirectly derived via a Claisen condensation with diethyl oxalate and ethyl phenylacetate followed by decarbonylation. [2]
Common examples include a CH 2 group flanked by two carbonyls or nitriles (see for example the Knoevenagel condensation and the first steps of the malonic ester synthesis and acetoacetic ester synthesis). Otherwise, the most acidic carbonyls are typically also the most active electrophiles: first aldehydes, then ketones, then esters, and ...