Aconitic acid is an organic acid. The two

isomers In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...

are ''cis''-aconitic acid and ''trans''-aconitic acid. The

conjugate base A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid donates a proton () to a base—in other words, it is a base with a hydrogen ion added to it, as in the reverse reaction it loses a ...

of ''cis''-aconitic acid, ''cis''-aconitate is an intermediate in the

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...

ization of citrate to

isocitrate Isocitric acid is a structural isomer of citric acid. Since citric acid and isocitric acid are structural isomers, they share similar physical and chemical properties. Due to these similar properties, it is difficult to separate the isomers. Salt ...

in the

citric acid cycle The citric acid cycle (CAC)—also known as the Krebs cycle or the TCA cycle (tricarboxylic acid cycle)—is a series of chemical reactions to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins ...

. It is acted upon by the enzyme

aconitase Aconitase (aconitate hydratase; ) is an enzyme that catalyses the stereo-specific isomerization of citrate to isocitrate via ''cis''- aconitate in the tricarboxylic acid cycle, a non-redox-active process. Image:Citrate wpmp.png, Image:Cis- ...

. Aconitic acid can be synthesized by dehydration of

citric acid Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in t ...

using

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

: :(HO₂CCH₂)₂C(OH)CO₂H → HO₂CCH=C(CO₂H)CH₂CO₂H + H₂O A mixture of isomers are generated in this way. It was first prepared by thermal dehydration.

References

{{Citric acid cycle Tricarboxylic acids Enoic acids