Malonic acid

  (Redirected from Malonate)

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 acid's diethyl ester. The name originates from the Greek word μᾶλον (malon) meaning 'apple'.

Malonic acid
Skeletal formula of malonic acid
Ball-and-stick model of the malonic acid molecule
IUPAC name
Malonic acid
Preferred IUPAC name
Propanedioic acid
Other names
Methanedicarboxylic acid
3D model (JSmol)
ECHA InfoCard 100.005.003 Edit this at Wikidata
Molar mass 104.061 g·mol−1
Density 1.619 g/cm3
Melting point 135 to 137 °C (275 to 279 °F; 408 to 410 K) (decomposes)
Boiling point decomposes
763 g/L
Acidity (pKa) pKa1 = 2.83[1]
pKa2 = 5.69[1]
-46.3·10−6 cm3/mol
Related compounds
Other anions
Oxalic acid
Propionic acid
Succinic acid
Fumaric acid
Related compounds
Dimethyl malonate
Safety data sheet External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references


Malonic acid[2] is a naturally occurring substance found in many fruits and vegetables.[3] There is a suggestion that citrus fruits produced in organic farming contain higher levels of malonic acid than fruits produced in conventional agriculture.[4]

Malonic acid was first prepared in 1858 by the French chemist Victor Dessaignes via the oxidation of malic acid.[2][5]

Structure and preparationEdit

The structure has been determined by X-ray crystallography[6] and extensive property data including for condensed phase thermochemistry are available from the National Institute of Standards and Technology.[7] A classical preparation of malonic acid starts from chloroacetic acid:[8]

Preparation of malonic acid from chloroacetic acid.

Sodium carbonate generates the sodium salt, which is then reacted with sodium cyanide to provide the sodium salt of cyanoacetic acid via a nucleophilic substitution. The nitrile group can be hydrolyzed with sodium hydroxide to sodium malonate, and acidification affords malonic acid. Industrially, however, malonic acid is produced by hydrolysis of dimethyl malonate or diethyl malonate.[9] It has also been produced through fermentation of glucose.[10]

Organic reactionsEdit

Malonic acid reacts as a typical carboxylic acid: forming amide, ester, anhydride, and chloride derivatives.[11] Malonic anhydride can be used as an intermediate to mono-ester or amide derivatives, while malonyl chloride is most useful to obtain diesters or diamides. In a well-known reaction, malonic acid condenses with urea to form barbituric acid. Malonic acid may also condensed be with acetone to form Meldrum's acid, a versatile intermedate in further transformations. The esters of malonic acid are also used as a CH2COOH synthon in the malonic ester synthesis.

Additionally, the coenzyme A derivative of malonate, malonyl-CoA, is an important precursor in fatty acid biosynthesis along with acetyl CoA. Malonyl CoA is formed 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.

Briggs–Rauscher reactionEdit

Malonic acid is a key component in the Briggs–Rauscher reaction, the classic example of an oscillating chemical reaction.[12]

Knoevenagel condensationEdit

In Knoevenagel condensation, malonic acid or its diesters are reacted with the carbonyl group of an aldehyde or ketone, followed by a dehydration reaction.

Z=COOH (malonic acid) or Z=COOR' (malonate ester)

When malonic acid itself is used, it is normally because the desired product is one in which a second step has occurred, with loss of carbon dioxide, in the so-called Doebner modification.[13]

The Doebner modification of the Knoevenagel condensation.

Thus, for example, the reaction product of acrolein and malonic acid in pyridine is trans-2,4-Pentadienoic acid with one carboxylic acid group and not two.[14]

Preparation of carbon suboxideEdit

Carbon suboxide is prepared by warming a dry mixture of phosphorus pentoxide (P
) and malonic acid.[15] It reacts in a similar way to malonic anhydride, forming malonates.[16]


Malonic acid is a precursor to specialty polyesters. It can be converted into 1,3-propanediol for use in polyesters and polymers and a projected market size of $621.2 million by 2021.[citation needed] It can also be a component in alkyd resins, 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.[17] 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.[18]

It is used in a number of manufacturing processes as a high value specialty chemical including the electronics industry, flavors and fragrances industry,[3] specialty solvents, polymer crosslinking, and pharmaceutical industry. In 2004, annual global production of malonic acid and related diesters was over 20,000 metric tons.[19] Potential growth of these markets could result from advances in industrial biotechnology that seeks to displace petroleum-based chemicals in industrial applications.

Malonic acid was listed as one of the top 30 chemicals to be produced from biomass by the US Department of Energy.[20]

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.[3]

Malonic acid is used as a building block chemical to produce numerous valuable compounds,[21] including the flavor and fragrance compounds gamma-nonalactone, cinnamic acid, and the pharmaceutical compound valproate.

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.[22][23] 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.[24]

Eastman Kodak company and others use malonic acid and derivatives as a surgical adhesive.[25]


Malonic acid is the classic example of a competitive inhibitor of the enzyme succinate dehydrogenase (complex II), in the respiratory electron transport chain.[26] It binds to the active site of the enzyme without reacting, competing with the usual substrate succinate 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.[27][28] Since malonic acid is a natural components of many foods, it is present in mammals including humans.[29]

Salts and estersEdit

Chemical structure of the malonate dianion.

Malonic acid is diprotic; that is, it can donate two protons per molecule. Its first   is 2.8 and the second is 5.7.[1] Thus the malonate ion can be HOOCCH
or CH
. Malonate or propanedioate compounds include salts and esters of malonic acid, such as


  1. ^ a b c pKa Data Compiled by R. Williams (pdf; 77 kB) Archived 2010-06-02 at the Wayback Machine
  2. ^ a b Chisholm, Hugh, ed. (1911). "Malonic Acid" . Encyclopædia Britannica. 17 (11th ed.). Cambridge University Press. p. 495.
  3. ^ a b c "Propanedioic acid". The Good Scents Company. Retrieved 2020-10-07.
  4. ^ Duarte, A.M.; Caixeirinho, D.; Miguel, M.G.; Sustelo, V.; Nunes, C.; Fernandes, M.M.; Marreiros, A. (2012). "Organic Acids Concentration in Citrus Juice from Conventional Versus Organic Farming". Acta Horticulturae. 933 (933): 601–606. doi:10.17660/actahortic.2012.933.78. hdl:10400.1/2790. ISSN 0567-7572.
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  6. ^ Srinivasa Gopalan, R.; Kumaradhas, P.; Kulkarni, G.U.; Rao, C.N.R. (2000). "An experimental charge density study of aliphatic dicarboxylic acids". Journal of Molecular Structure. 521 (1–3): 97–106. Bibcode:2000JMoSt.521...97S. doi:10.1016/S0022-2860(99)00293-8.
  7. ^ NIST Chemistry WebBook. "Propanedioic acid".
  8. ^ Nathan Weiner. "Malonic acid". Organic Syntheses.; Collective Volume, 2, p. 376
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  12. ^ Csepei, L.I.; Bolla, C. "The Effect of Salicylic Acid on the Briggs-Rauscher Oscillating Reaction" (PDF). Studia UBB Chemia. 1: 285–300.
  13. ^ Doebner, O. (1902). "Ueber die der Sorbinsäure homologen, ungesättigten Säuren mit zwei Doppelbindungen". Berichte der deutschen chemischen Gesellschaft. 35: 1136–36. doi:10.1002/cber.190203501187.
  14. ^ Peter J. Jessup, C. Bruce Petty, Jan Roos, and Larry E. Overman (1988). "1-N-Acylamino-1,3-dienes from 2,4-pentadienoic acids by the Curtius rearrangement: benzyl trans-1,3-butadiene-1-carbamate". Organic Syntheses.CS1 maint: multiple names: authors list (link); Collective Volume, 6, p. 95
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  17. ^ Fäcke, T., Subramanian R., Dvorchak, M., Feng, S. Diethylmalonate Blocked Isocyanates As Crosslinkers For Low Temperature Cure Powder Coatings. 2004 International Waterborne, High-Solids, and Powder Coatings Symposium.
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External linksEdit