Aconitic Acid

Title: Aconitic Acid
CAS Registry Number: 499-12-7
CAS Name: 1-Propene-1,2,3-tricarboxylic acid
Additional Names: equisetic acid; citridic acid; achilleic acid
Molecular Formula: C6H6O6
Molecular Weight: 174.11
Percent Composition: C 41.39%, H 3.47%, O 55.14%
Literature References: Found in leaves and tubers of Aconitum napellus L., Ranunculaceae, in various species of Achillea (Compositae) and Equisetum (Equisetaceae), in beet root, and in sugar cane. Can be prepd commercially from calcium magnesium aconitate recovered from sugar cane juice: McCalip, Seibert, Ind. Eng. Chem. 33, 637 (1941); from molasses: Regna, Bruins, ibid. 48, 1268 (1956). Most of the commercial aconitic acid is, however, manufactured by sulfuric acid dehydration of citric acid: Bruce, Org. Synth. coll. vol. II, p 12 (1943); by using methanesulfonic acid instead of sulfuric: Cranston, US 2727066 (1955 to Daniel F. Kelly). Aconitic acid prepd by any of the above methods has the trans-configuration which is the form described here.
Properties: Leaflets, plates from water. Decompn 198-199° (capillary inserted in oil bath at 190°); decompn 204-205° (capillary in oil bath at 195°); decompn 209° (electrically heated bar). K1 at 25° = 1.58 ´ 10-3; K2 = 3.5 ´ 10-5. One gram dissolves in 5.5 ml water at 13°, in 2 ml water at 25°. Soluble in 2 parts of 88% alcohol at 12°. Slightly sol in ether.
Derivative Type: Triethyl ester
Properties: bp5 155°.
Boiling point: bp5 155°
Derivative Type: Tributyl ester
Properties: bp3 190°.
Boiling point: bp3 190°
Use: Manuf itaconic acid. As plasticizer for buna rubber and plastics. Used in form of triethyl or tributyl ester.
Aconitine Aconitine, Amorphous Aconitum Ferox Acranil? Acridine

cis-Aconitic acid (top) and trans-Aconitic acid (bottom)[1]
cis-Aconitic acid
trans-Aconitic acid
Identifiers
CAS number 499-12-7 YesY
PubChem 309
ChemSpider 303 YesY
UNII 93371T1BXP YesY
MeSH Aconitate
ChEBI CHEBI:22211 YesY
Jmol-3D images Image 1
Properties
Molecular formula C6H6O6
Molar mass 174.11 g mol−1
Appearance Colorless crystals
Melting point 190 °C (decomp) (trans isomer), 122 °C (cis isomer)
Acidity (pKa) 2.80, 4.46 (trans isomer)[2]
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Aconitic acid is an organic acid. The two isomers are cis-aconitic acid and trans-aconitic acid. The conjugate base of cis-aconitic acid, cis-aconitate is an intermediate in the isomerization of citrate to isocitrate in the citric acid cycle. It is acted upon by the enzyme aconitase.

Aconitic acid can be synthesized by dehydration of citric acid using sulfuric acid:[3]

(HO2CCH2)2COH(CO2H) → HO2CCH=C(CO2H)CH2CO2H + H2O

It was first prepared by thermal dehydration.[4]