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Malonic acid is a dicarboxylic acid with structure CH2(COOH)2. The form of malonic acid, as well as its and salts, are known as malonates. For example, is malonic acid's . The name originates from the word μᾶλον ( malon) meaning 'apple'.


History
Malonic acid is a naturally occurring substance found in many fruits and vegetables. There is a suggestion that fruits produced in contain higher levels of malonic acid than fruits produced in conventional agriculture.

Malonic acid was first prepared in 1858 by the French chemist Victor Dessaignes via the oxidation of .

and Hugo Müller independently discovered how to synthesize malonic acid from , and decided to publish their results back-to-back in the Chemical Society journal in 1864. This led to priority dispute with Hans Hübner and who had independently published preliminary results on related reactions.


Structure and preparation
The structure has been determined by X-ray and extensive property data including for condensed phase thermochemistry are available from the National Institute of Standards and Technology. A classical preparation of malonic acid starts from chloroacetic acid:

generates the sodium salt, which is then reacted with to provide the sodium salt of via a nucleophilic substitution. The group can be with to sodium malonate, and acidification affords malonic acid. Industrially, however, malonic acid is produced by hydrolysis of dimethyl malonate or . It has also been produced through of .


Reactions
Malonic acid reacts as a typical carboxylic acid forming , ester, and derivatives.
(2025). 9780471740032
Malonic anhydride can be used as an intermediate to mono-ester or amide derivatives, while is most useful to obtain diesters or diamides. In a well-known reaction, malonic acid condenses with to form . Malonic acid may also be condensed with to form Meldrum's acid, a versatile intermediate in further transformations. The esters of malonic acid are also used as a CH2COOH in the malonic ester synthesis.


Briggs–Rauscher reaction
Malonic acid is a key component in the Briggs–Rauscher reaction, the classic example of an oscillating chemical reaction.


Knoevenagel condensation
Malonic acid is used to prepare a,b-unsaturated carboxylic acids by condensation and decarboxylation. are prepared in this way:
In this, the so-called Knoevenagel condensation, malonic acid condenses with the group of an or , followed by a . When malonic acid is condensed in hot pyridine, the condensation is accompanied by , the so-called Doebner modification.


Preparation of carbon suboxide
Malonic acid does not readily form an , dehydration gives instead:
The transformation is achieved by warming a dry mixture of phosphorus pentoxide () and malonic acid. It reacts in a similar way to malonic anhydride, forming malonates.


Applications
Malonic acid is a precursor to specialty . It can be converted into 1,3-propanediol for use in polyesters and polymers (whose usefulness is unclear though). It can also be a component in , which are used in a number of coatings applications for protecting against damage caused by UV light, oxidation, and corrosion. One application of malonic acid is in the coatings industry as a crosslinker for low-temperature cure powder coatings, which are becoming increasingly valuable for heat sensitive substrates and a desire to speed up the coatings process. The global coatings market for automobiles was estimated to be $18.59 billion in 2014 with projected combined annual growth rate of 5.1% through 2022.

It is used in a number of manufacturing processes as a high value specialty chemical including the electronics industry, flavors and fragrances industry, specialty solvents, polymer crosslinking, and pharmaceutical industry. In 2004, annual global production of malonic acid and related diesters was over 20,000 metric tons. Potential growth of these markets could result from advances in industrial biotechnology that seeks to displace petroleum-based chemicals in industrial applications.

In 2004, malonic acid was listed by the US Department of Energy as one of the top 30 chemicals to be produced from biomass.

In food and drug applications, malonic acid can be used to control acidity, either as an excipient in pharmaceutical formulation or natural preservative additive for foods.

Malonic acid is used as a building block chemical to produce numerous valuable compounds,Hildbrand, S.; Pollak, P. Malonic Acid & Derivatives. March 15, 2001. Ullmann's Encyclopedia of Industrial Chemistry including the flavor and fragrance compounds gamma-nonalactone, , and the pharmaceutical compound .

Malonic acid (up to 37.5% w/w) has been used to cross-link corn and potato starches to produce a biodegradable thermoplastic; the process is performed in water using non-toxic catalysts. Starch-based polymers comprised 38% of the global biodegradable polymers market in 2014 with food packaging, foam packaging, and compost bags as the largest end-use segments.

Eastman Kodak company and others use malonic acid and derivatives as a surgical adhesive.


Pathology
If elevated malonic acid levels are accompanied by elevated methylmalonic acid levels, this may indicate the metabolic disease combined malonic and methylmalonic aciduria (CMAMMA). By calculating the malonic acid to methylmalonic acid ratio in blood plasma, CMAMMA can be distinguished from classic methylmalonic acidemia.
(2025). 9783662536810, Springer.


Biochemistry
Malonic acid is the precursor in mitochondrial fatty acid synthesis (mtFAS), in which it is converted to by acyl-CoA synthetase family member 3 (ACSF3).

Additionally, the derivative of malonate, malonyl-CoA, is an important precursor in fatty acid biosynthesis along with . Malonyl CoA is formed there from acetyl CoA by the action of acetyl-CoA carboxylase, and the malonate is transferred to an acyl carrier protein to be added to a fatty acid chain.

Malonic acid is the classic example of a competitive inhibitor of the succinate dehydrogenase (complex II), in the respiratory electron transport chain. It binds to the of the enzyme without reacting, competing with the usual substrate but lacking the −CH2CH2− group required for dehydrogenation. This observation was used to deduce the structure of the active site in succinate dehydrogenase. Inhibition of this enzyme decreases cellular respiration. Since malonic acid is a natural component of many foods, it is present in mammals including humans.


Salts and esters
Malonic acid is diprotic; that is, it can donate two protons per molecule. Its first pK_a is 2.8 and the second is 5.7. Thus the malonate can be or . Malonate or propanedioate compounds include salts and of malonic acid, such as


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