3-Oxopropanoic acid (also malonic semialdehyde or formylacetic acid) is an organic chemical compound that carries both a carboxylic acid function and an aldehyde function.

Natural occurence

In nature, 3-oxopropanoic acid occurs as a

metabolic intermediate Metabolic intermediates are compounds produced during the conversion of substrates (starting molecules) into final products in biochemical reactions within cells. Although these intermediates are of relatively minor direct importance to cell ...

. It is formed, for example, by the reversible oxidation of 3-hydroxypropionyl-CoA with

nicotinamide adenine dinucleotide Nicotinamide adenine dinucleotide (NAD) is a Cofactor (biochemistry), coenzyme central to metabolism. Found in all living cell (biology), cells, NAD is called a dinucleotide because it consists of two nucleotides joined through their phosphat ...

(NAD). A bacterial strain of the species ''

Pseudomonas fluorescens ''Pseudomonas fluorescens'' is a common Gram-negative, rod-shaped bacterium. It belongs to the ''Pseudomonas'' genus; 16S rRNA analysis as well as phylogenomic analysis has placed ''P. fluorescens'' in the ''P. fluorescens'' group within the genu ...

'' is known to survive on

propiolic acid Propiolic acid is the organic compound with the formula HC2CO2H. It is the simplest acetylenic carboxylic acid. It is a colourless liquid that crystallises to give silky crystals. Near its boiling point, it decomposes. It is soluble in water a ...

as its sole carbon and energy source. 3-Oxopropanoic acid is an important metabolic intermediate: it is formed by hydration of acetylenic acid and is converted into

acetyl-CoA Acetyl-CoA (acetyl coenzyme A) is a molecule that participates in many biochemical reactions in protein, carbohydrate and lipid metabolism. Its main function is to deliver the acetyl group to the citric acid cycle (Krebs cycle) to be oxidation, o ...

by decarboxylation. It also occurs as a metabolic intermediate in a strain of ''

Escherichia coli ''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Escherichia'' that is commonly fo ...

'' that can grow on

uracil Uracil () (nucleoside#List of nucleosides and corresponding nucleobases, symbol U or Ura) is one of the four nucleotide bases in the nucleic acid RNA. The others are adenine (A), cytosine (C), and guanine (G). In RNA, uracil binds to adenine via ...

as its sole nitrogen source. 3-Oxopropanoic acid also occurs in atmospheric aerosols along with various other organic acids (especially

oxalic acid Oxalic acid is an organic acid with the systematic name ethanedioic acid and chemical formula , also written as or or . It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colorless solution in water. Its name i ...

). It has been detected as an aerosol component at various stations during a circumnavigation of the globe by ship. The compound has also been found in aerosol analyses in the Arctic, the North Pacific, India, and Tokyo.

Synthesis

3-Oxopropanoic acid is highly reactive. It is often generated in situ by reacting

malic acid Malic acid is an organic compound with the molecular formula . It is a dicarboxylic acid that is made by all living organisms, contributes to the sour taste of fruits, and is used as a food additive. Malic acid has two stereoisomeric forms ( ...

with concentrated

sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, ...

. This process releases

formic acid Formic acid (), systematically named methanoic acid, is the simplest carboxylic acid. It has the chemical formula HCOOH and structure . This acid is an important intermediate in chemical synthesis and occurs naturally, most notably in some an ...

, water, and

carbon monoxide Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...

. A readily storable precursor to the compound is ethyl 3-oxopropionate diethyl acetal. This can be prepared by condensation of

ethyl acetate Ethyl acetate commonly abbreviated EtOAc, ETAC or EA) is the organic compound with the formula , simplified to . This flammable, colorless liquid has a characteristic sweet smell (similar to pear drops) and is used in glues, nail polish removers, ...

and

ethyl formate Ethyl formate is an ester formed when ethanol (an alcohol) reacts with formic acid (a carboxylic acid). Ethyl formate has the characteristic smell of rum and is partially responsible for the flavor of raspberries, occurring naturally in some plan ...

, followed by acetalization with

hydrogen chloride The Chemical compound, compound hydrogen chloride has the chemical formula and as such is a hydrogen halide. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor. Hyd ...

absolute ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an alcohol, with its formula also written as , or EtOH, where Et is the pseudoelement symbol fo ...

. The 3-oxopropanoic acid can also be obtained from it by hydrolysis with dilute sulfuric acid followed by neutralization.

Reactions

Reaction with a

phenol Phenol (also known as carbolic acid, phenolic acid, or benzenol) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile and can catch fire. The molecule consists of a phenyl group () ...

yields

coumarin Coumarin () or 2''H''-chromen-2-one is an aromatic organic chemical compound with formula . Its molecule can be described as a benzene molecule with two adjacent hydrogen atoms replaced by an unsaturated lactone ring , forming a second six-me ...

. The enol form, which is initially formed during the preparation from

and

, can condense with

urea Urea, also called carbamide (because it is a diamide of carbonic acid), is an organic compound with chemical formula . This amide has two Amine, amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest am ...

to form

Isocytosine Isocytosine or 2-aminouracil is a pyrimidine base that is an isomer of cytosine. It is used in combination with isoguanine in studies of unnatural nucleic acid analogues of the normal base pairs in DNA. In particular, it is used as a nucleobas ...

was prepared analogously, using

guanidine hydrochloride Guanidinium chloride or guanidine hydrochloride, usually abbreviated GdmCl and sometimes GdnHCl or GuHCl, is the hydrochloride salt of guanidine. Structure Guanidinium chloride on a weighing boat Guanidinium chloride crystallizes in orthorhomb ...

instead of urea.{{cite journal , last1=Caldwell , first1=William T. , last2=Kime , first2=Harry B. , title=A New Synthesis of Isocytosine , journal=

Journal of the American Chemical Society The ''Journal of the American Chemical Society'' (also known as JACS) is a weekly peer-reviewed scientific journal that was established in 1879 by the American Chemical Society. The journal has absorbed two other publications in its history, the ...

, date=1 September 1940 , volume=62 , issue=9 , pages=2365 , doi=10.1021/ja01866a028 , bibcode=1940JAChS..62.2365C , url=https://pubs.acs.org/doi/abs/10.1021/ja01866a028 , access-date=17 June 2025 , issn=0002-7863

References

Aldehydes Alkanoic acids