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Diethyl malonate, also known as DEM, is the diethyl ester of malonic acid. It occurs naturally in grapes and strawberries as a colourless liquid with an apple-like odour, and is used in perfumes. It is also used to synthesize other compounds such as barbiturates, artificial flavourings, vitamin B1, and vitamin B6.
Malonic acid is a rather simple dicarboxylic acid, with two carboxyl groups close together in its molecule. In forming diethyl malonate from malonic acid, the hydroxyl group (-OH) on both of the carboxyl groups is replaced by an ethoxy group (-OEt; -OCH2CH3). The methylene group (-CH2-) in the middle of the malonic part of the diethyl malonate molecule is neighboured by two carbonyl groups (-C(=O)-).
This carbanion can be made from treating diethyl malonate with a base such as sodium ethoxide in ethanol. If aqueous sodium hydroxide were used, base hydrolysis of the ester can happen giving sodium malonate and ethanol. When sodium ethoxide is used, instead, any nucleophilic attack at the carboxylate by the ethoxide will not give any side product. Thus sodium ethoxide is preferred.
Other examples of 1,3-diketo compounds with labile hydrogens include acetylacetone, acetoacetate esters. Synthetically, malonic esters are often used in Claisen ester condensations because unwanted self-condensation reactions are avoided. Another malonate reaction is the Malonic ester synthesis:
forming a monosubstituted acetic acid.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Diethyl_malonate". A list of authors is available in Wikipedia.|