Cyclopropanetrione or trioxocyclopropane is a little-known oxide of carbon with formula C3O3. It consists of a ring of three carbon atoms each attached to an oxygen atom with a double bond. Alternately it can be thought as a trimer of carbon monoxide. This compound is thermodynamically unstable, and has not been produced in bulk.[1] However it has been detected using mass spectrometry.[2][3]

It is the neutral equivalent of the deltate anion C3O32−, known since 1975.[4] An equivalent hydrate hexahydroxycyclopropane or cyclopropane-1,1,2,2,3,3-hexol, (-C(OH)2-)3 also exists. This contains geminal hydroxy groups.[5]

IUPAC name
3D model (JSmol)
Molar mass 84.03 g/mol
Related compounds
Related compounds
deltic acid oxopropandial
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).


  1. ^ Corkran, Greg; David W. Ball (2004). "The relative energies of cyclopropanone, cyclopropanedione, and cyclopropanetrione. Hartree–Fock, density-functional, G2, and CBS calculations". Journal of Molecular Structure: THEOCHEM. 668 (2–3): 171–178. doi:10.1016/j.theochem.2003.10.026. ISSN 0166-1280.
  2. ^ Schröder, Detlef; Helmut Schwarz; Suresh Dua; Stephen J. Blanksby; John H. Bowie (1999). "Mass spectrometric studies of the oxocarbons CnOn (n = 3–6)". International Journal of Mass Spectrometry. 188 (1–2): 17–25. Bibcode:1999IJMSp.188...17S. doi:10.1016/S1387-3806(98)14208-2. ISSN 1387-3806.
  3. ^ Eggerding, David; Robert West (1975). "Synthesis of dihydroxycyclopropenone (deltic acid)". Journal of the American Chemical Society. 97 (1): 207–208. doi:10.1021/ja00834a047. ISSN 0002-7863.
  4. ^ Eggerding, David; Robert West (1976). "Synthesis and properties of deltic acid (dihydroxycyclopropenone) and the deltate ion". Journal of the American Chemical Society. 98 (12): 3641–3644. doi:10.1021/ja00428a043. ISSN 0002-7863.
  5. ^ Skujins, S.; J. Delderfield, G.A. Webb (1968). "A mass spectrometric study of some monocyclic polycarbonyl compounds". Tetrahedron. 24 (13): 4805–4817. doi:10.1016/S0040-4020(01)98676-4. ISSN 0040-4020.

An oxocarbon or oxide of carbon is a chemical compound consisting only of carbon and oxygen.The simplest and most common oxocarbons are carbon monoxide (CO) and carbon dioxide (CO2) with IUPAC names carbon(II) oxide and carbon(IV) oxide respectively. Many other stable (practically if not thermodynamically) or metastable oxides of carbon are known, but they are rarely encountered, such as carbon suboxide (C3O2 or O=C=C=C=O) and mellitic anhydride (C12O9).

While textbooks will often list only the first three, and rarely the fourth, a large number of other oxides are known today, most of them synthesized since the 1960s. Some of these new oxides are stable at room temperature. Some are metastable or stable only at very low temperatures, but decompose to simpler oxocarbons when warmed. Many are inherently unstable and can be observed only momentarily as intermediates in chemical reactions or are so reactive that they can exist only in the gas phase or under matrix isolation conditions.

The inventory of oxocarbons appears to be steadily growing. The existence of graphene oxide and of other stable polymeric carbon oxides with unbounded molecular structures suggests that many more remain to be discovered.


A triketone or trione is a molecule containing three ketone groups.

Simple cyclic triketones include cyclopropanetrione, barbituric acid and the triazine cyanuric acid. Croconic acid also has hydroxy groups. In ninhydrin one of the ketone groups is normally hydrated.

Linear triketones include triuret. Compounds with three adjacent carbonyl groups include mesoxalic acid, and dioxosuccinic acid, however these can be considered as dicarboxylic acids or ketonic acids. Triketones known by 1901 include diphenyltriketone, diphenyltetraketone, and triketopentane.

Common oxides
Exotic oxides
Compounds derived from oxides


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