HOME

TheInfoList



OR:

Diethyl malonate, also known as DEM, is the diethyl
ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glyceride ...
of
malonic acid Malonic acid (IUPAC systematic name: propanedioic acid) is a dicarboxylic acid with structure CH2(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 aci ...
. It occurs naturally in
grape A grape is a fruit, botanically a berry, of the deciduous woody vines of the flowering plant genus '' Vitis''. Grapes are a non- climacteric type of fruit, generally occurring in clusters. The cultivation of grapes began perhaps 8,000 years ag ...
s and
strawberries The garden strawberry (or simply strawberry; ''Fragaria × ananassa'') is a widely grown hybrid species of the genus '' Fragaria'', collectively known as the strawberries, which are cultivated worldwide for their fruit. The fruit is widely ap ...
as a colourless
liquid A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, ...
with an
apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple trees are cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, where its wild ancestor ...
-like odour, and is used in
perfume Perfume (, ; french: parfum) is a mixture of fragrant essential oils or aroma compounds (fragrances), fixatives and solvents, usually in liquid form, used to give the human body, animals, food, objects, and living-spaces an agreeable scent. T ...
s. It is also used to synthesize other compounds such as
barbiturate Barbiturates are a class of depressant drugs that are chemically derived from barbituric acid. They are effective when used medically as anxiolytics, hypnotics, and anticonvulsants, but have physical and psychological addiction potential as w ...
s, artificial flavourings, vitamin B1, and vitamin B6.


Structure and properties

Malonic acid is a rather simple dicarboxylic acid, with two the
carboxyl group In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxyli ...
s close together. In forming diethyl malonate from malonic acid, the
hydroxyl In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...
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)−). The hydrogen atoms on the carbon adjacent to the carbonyl group in a molecule is significantly more
acidic In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a se ...
than hydrogen atoms on a carbon adjacent to
alkyl groups In organic chemistry, an alkyl group is an alkane missing one hydrogen. The term ''alkyl'' is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula of . A cycloalkyl is derived from a cyclo ...
(up to 30 orders of magnitude). (This is known as the α position with respect to the carbonyl.) The hydrogen atoms on a carbon adjacent to two carbonyl groups are even more acidic because the carbonyl groups help stabilize the
carbanion In organic chemistry, a carbanion is an anion in which carbon is trivalent (forms three bonds) and bears a formal negative charge (in at least one significant resonance form). Formally, a carbanion is the conjugate base of a carbon acid: :R ...
resulting from the removal of a proton from the methylene group between them. : The extent of resonance stabilization of this compound's conjugate base is depicted by the three resonance forms below: :


Preparation

Diethyl malonate may be prepared by reacting the sodium salt of chloroacetic acid with
sodium cyanide Sodium cyanide is a poisonous compound with the formula Na C N. It is a white, water-soluble solid. Cyanide has a high affinity for metals, which leads to the high toxicity of this salt. Its main application, in gold mining, also exploits its hig ...
, followed by base hydrolysis of the resultant
nitrile In organic chemistry, a nitrile is any organic compound that has a functional group. The prefix ''cyano-'' is used interchangeably with the term ''nitrile'' in industrial literature. Nitriles are found in many useful compounds, including ...
to give the sodium salt of the malonic acid. Fischer esterification gives diethyl malonate: :


Reactions


Malonic ester synthesis

One of the principal uses of this compound is in the
malonic ester synthesis 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. The major ...
. The carbanion (2) formed by reacting diethyl malonate (1) with a suitable base can be alkylated with a suitable
electrophile In chemistry, an electrophile is a chemical species that forms bonds with nucleophiles by accepting an electron pair. Because electrophiles accept electrons, they are Lewis acids. Most electrophiles are positively charged, have an atom that carri ...
. This alkylated 1,3-dicarbonyl compound (3) readily undergoes
decarboxylation Decarboxylation is a chemical reaction that removes a carboxyl group and releases carbon dioxide (CO2). Usually, decarboxylation refers to a reaction of carboxylic acids, removing a carbon atom from a carbon chain. The reverse process, which ...
with loss of carbon dioxide, to give a substituted acetic acid (4): : In general, salts of the alkoxide anion whose alkyl part corresponds to the one used in the above alkylation are preferred as the base. The use of a conventional base may give base hydrolysis products – for example, sodium hydroxide would simply produce sodium malonate and the alcohol, while other alkoxide salts will cause scrambling by
transesterification In organic chemistry, transesterification is the process of exchanging the organic group R″ of an ester with the organic group R' of an alcohol. These reactions are often catalyzed by the addition of an acid or base catalyst. The reaction can ...
. Only the "same" alkoxide anion as the one that one used to alkylate the deprotonated active methylenic site will prevent both base hydrolysis and transesterification.


Other reactions

Like many other esters, this compound undergoes the Claisen ester condensations. The advantage of using this compound is that unwanted self-condensation reactions are avoided. Like other esters, this compound undergoes bromination at the alpha position. Diethyl malonate can be nitrosated with excess sodium nitrite in acetic acid to afford diethyl oximinomalonate, catalytic
hydrogenolysis Hydrogenolysis is a chemical reaction whereby a carbon–carbon or carbon– heteroatom single bond is cleaved or undergoes lysis (breakdown) by hydrogen.Ralph Connor, Homer Adkins. Hydrogenolysis Of Oxygenated Organic Compounds. J. Am. Chem. S ...
of which in ethanol over Pd/C affords diethyl aminomalonate (DEAM). DEAM can be acetylated to produce diethyl acetamidomalonate (useful in amino-acid synthesis), or can be added with 3-substituted 2,4-diketones to boiling acetic acid to afford in maximal yield variously substituted ethyl pyrrole-2-carboxylates of interest for porphyrin synthesis.


References

{{reflist Flavors Malonate esters Perfume ingredients Ethyl esters