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Malonic acid
(also called Propanedioic Acid ) is a white crystalline C-3 dicarboxylic acid;
melting at 135 -136 C; readily soluble in water, alcohol and ether; solution in
water is medium-strong acidic. It can be derived by oxidizing malic acid or by
the hydrolysis of cyanacetic acid. Malonic acid itself is rather unstable and
has few applications. It's diethyl ester (diethyl malonate) is more important
commercially. Diethyl malonate, a colourless, fragrant liquid boiling at 199 C,
is prepared by the reaction of monochloroacetatic acid with methanol, carbon
monoxide or by the reaction cyanoacetic acid (the half nitriled-malonic acid)
with ethyl alcohol. Malonic acid and its esters contain active methylene groups
which have relatively acidic alpha-protons due to H atoms adjacent to two
carbonyl groups. The reactivity of its methylene group provide the sequence of
reactions of alkylation, hydrolysis of the esters and decarboxylation resulting
in substituted ketones. The methylene groups in 1,3-dicarboxylic acid utilize
the synthesis of barbiturates; a hydrogen atom is removed by sodium ethoxide,
and the derivative reacts with an alkyl halide to form a diethyl alkylmalonate.
The diethyl dialkylmalonates are converted to barbiturates by reaction with
urea. Malonic acid and its esters are characterized by the large number of
condensation products. They are important intermediates in syntheses of vitamins
B1 and B6, barbiturates, non-steroidal anti-inflammatory agents, other numerous
pharmaceuticals, agrochemicals and flavors & fragrances
compounds.
Methylpropanedioic acid
is a vital
intermediate in the metabolism of fat and protein. Abnormalities in
methylmalonic acid metabolism lead to an inherited disorder called methylmalonic aciduria
which makes the body unable to process certain proteins
and lipids properly due to a block in the enzymatic conversion of methylmalonyl
CoA to succinyl CoA.
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