Diethyl malonate

Description

Diethyl malonate is a diester derivative of malonic acid, a dicarboxylic acid with two carboxyl groups (-COO-) separated by one methylene group (-CH2-). Diethyl malonate is formed by the replacement of the hydroxyl groups (-OH) of malonic acid with ethoxy groups (-OCH2CH3). The hydrogen atoms on the methylene carbon between the two carboxyl groups make this compound acidic. Because of its unique structure, diethyl malonate is reactive and functions as a reagent for organic synthesis and to make products such as barbiturates, pigments, and agrochemicals. Volatile esters are known to have fruity scents and are often used as fragrances and flavorings. Diethyl malonate is a volatile diester that occurs naturally in fruits such as grapes, strawberries, guava, melon, pineapple, and blackberries.

Odor

A colourless liquid with an apple-like odour.

Chemical properties

Diethyl malonate has a faint, pleasant, aromatic odor.

Occurence

Diethyl malonate occurs naturally in grapes and strawberries.

Occurrence

Reported found in pineapple, bilberry, Cape gooseberry, cognac, malt whiskey, apple brandy, grape brandy, port, cider, sherry and red, white, strawberry and bilberry wines.

The Uses of Diethyl malonate

Diethyl Malonate occurs naturally in grapes and strawberries. It is used in the preparation of barbiturates, artificial flavourings, vitamin B1, and vitamin B6 as well as in perfumes.

The Uses of Diethyl malonate

manufacture of barbiturates.

The Uses of Diethyl malonate

Diethyl malonate is used in organic synthesis for the preparation of alpha-aryl malonates, mono-substituted and di-substituted acetic acid, barbiturates and artificial flavorings. It is also involved in the synthesis of pharmaceuticals like chloroquine, butazolidin and barbital. It acts as intermediate in the synthesis of vitamin B1, vitamin B6, non-steroidal anti-inflammatory agents agrochemicals and perfumes. In Knoevenagel condensation reaction, it reacts with benzaldehyde to get diethyl benzylidenemalonate.

Preparation

Reacting chloroacetic acid to cyanoacetic acid using sodium cyanide and subsequent saponification; malonic acid is finally esterified by azeotropic distillation with ethanol in benzene

Definition

ChEBI: Ethyl malonate is a dicarboxylic acid.

Preparation

Diethyl malonate is produced from the reaction of the sodium salt of chloroacetic acid with sodium cyanide, which produces the nitrile. This intermediate is then treated with ethanol in the presence of acid catalyst:

ClCH2CO2Na + NaCN → NCCH2CO2Na + NaCl

Taste threshold values

Taste characteristics at 50 ppm: sweet and fruity with apple and pineapple nuances.

Synthesis Reference(s)

The Journal of Organic Chemistry, 46, p. 3151, 1981 DOI: 10.1021/jo00328a041
Tetrahedron Letters, 36, p. 3997, 1995 DOI: 10.1016/0040-4039(95)00697-B

General Description

Diethyl malonate is diethyl ester of malonic acid. Acylation of diethyl malonate using magnesium chloride and triethylamine is reported. K₂CO₃-catalyzed 1,4-addition reaction of diethyl malonate with various substituted 1,2-allenic ketones yields polyfunctionalized β,γ-unsaturated enones.

Safety Profile

Mildly toxic by ingestion. A skin irritant. Combustible liquid when exposed to heat or flame; can react with oxidizing materials. To fight fire, use water to blanket fire, foam, CO2, dry chemical. When heated to decomposition it emits acrid smoke and irritating fumes. See also ESTERS.

Metabolism

When the ester was fed to chicks at a level of 5% in the diet, 32% of the energy from diethyl malonate was available (Yoshida et al. 1970). Hydrolysis of diethyl malonate would produce ethanol and malonic acid, which is a relatively strong acid and acts as an inhibitor of enzymes, including succinic dehydrogenase (Fassett, 1963). Malonic acid injected into rats or rabbits is excreted largely unchanged, but also causes increased excretion of citric and a-ketoglutaric acids (Krebs, Salvin & Johnson, 1938). Some malonate may be metabolized through the tricarboxylic acid cycle, with decarboxylation to acetate followed by transformation to succinate, which has been detected in rat urine (Lee & Lifson, 1951). Diethyl malonate was hydrolysed by adipose-tissue lipase (Lynn & Perryman, 1960) and to the monoester by α-chymotrypsin (Cohen & Crossely, 1964). It was oxidized in 110 min to the extent of 34% by the homogenized mycelium of urethane-grown Streptomyces nitrifica (Schatz, Trelawny, Schatz & Mohan, 1957).

Purification Methods

If too impure (IR, NMR) the ester (250g) is heated on a steam bath for 36hours with absolute EtOH (125mL) and conc H2SO4 (75mL), then fractionally distilled under reduced pressure. Otherwise fractionally distil it under reduced pressure and collect the steady boiling middle fraction. [Beilstein 2 IV 1881.]