In 1825, Croconic acid and potassium croconate dihydrate were discovered by Leopold Gmelin, who named the compounds from Greek meaning "saffron" or "egg yolk". In 1964, the structure of ammonium croconate was determined by Baenziger et al. . The structure of K₂C₅O₅ . 2H₂O was determined by J. D. Dunitz in 2001.

The Croconic acid, with the CAS registry number 488-86-8, is also known as UNII-6HGY35UXAA. This chemical's molecular formula is C₅H₂O₅ and molecular weight is 142.07. Its IUPAC name is called 4,5-dihydroxycyclopent-4-ene-1,2,3-trione. Croconic acid also forms esters such as dimethyl croconate.

Physical properties of Croconic acid: (1)ACD/LogP: -2.23; (2)ACD/LogD (pH 5.5): -6.72; (3)ACD/LogD (pH 7.4): -6.72; (4)ACD/BCF (pH 5.5): 1; (5)ACD/BCF (pH 7.4): 1; (6)ACD/KOC (pH 5.5): 1; (7)ACD/KOC (pH 7.4): 1; (8)#H bond acceptors: 5; (9)#H bond donors: 2; (10)#Freely Rotating Bonds: 2; (11)Index of Refraction: 1.798; (12)Molar Refractivity: 26.22 cm³; (13)Molar Volume: 61.4 cm³; (14)Surface Tension: 197.1 dyne/cm; (15)Density: 2.311 g/cm³; (16)Flash Point: 144.4 °C; (17)Enthalpy of Vaporization: 61.63 kJ/mol; (18)Boiling Point: 291.7 °C at 760 mmHg; (19)Vapour Pressure: 0.000206 mmHg at 25°C.

Uses of Croconic acid: it can be used to produce 1,3-bis-(2-dimethylamino-5-thienyl)croconine with dimethyl-thiophen-2-yl-amine by heating. This reaction will need solvents butan-1-ol and toluene. The yield is about 55%.

When you are using this chemical, please be cautious about it as the following:
This chemical may cause inflammation to the skin or other mucous membranes. It is irritating to eyes, respiratory system and skin. In case of contact with eyes, you should rinse immediately with plenty of water and seek medical advice. Whenever you will contact it, please wear suitable protective gloves and eye/face protection.

You can still convert the following datas into molecular structure:
(1)Canonical SMILES: C1(=C(C(=O)C(=O)C1=O)O)O
(2)InChI: InChI=1S/C5H2O5/c6-1-2(7)4(9)5(10)3(1)8/h6-7H
(3)InChIKey: RBSLJAJQOVYTRQ-UHFFFAOYSA-N