Tetracarbon dioxide

Tetracarbon dioxide is an oxide of carbon, a chemical compound of carbon and oxygen, with chemical formula C4O2 or O=C=C=C=C=O. It can be regarded as butatriene dione, the double ketone of butatriene — more precisely 1,2,3-butatriene-1,4-dione.[1]

Butatriene dione is the fourth member of the family of linear carbon dioxides O(=C)n=O, that includes carbon dioxide CO2 or O=C=O, ethylene dione C2O2 or O=C=C=O, carbon suboxide C3O2 or O=C=C=C=O, pentacarbon dioxide C5O2 or O=C=C=C=C=C=O, and so on.

The compound was obtained in 1990 by Maier and others, by flash vacuum pyrolysis of cyclic azaketones in a frozen argon matrix.[2] It was also obtained in the same year by Sülzle and Schwartz through impact ionization of ((CH3-)2(C4O2)(=O)2=)2 in the gas phase.[3] Although theoretical studies indicated that the even-numbered members of the O(=C)n=O family should be inherently unstable,[4] C4O2 is indefinitely stable in the matrix, but is decomposed by light into tricarbon monoxide C3O and carbon monoxide CO.[2][1] It has a triplet ground state.[1]

Tetracarbon dioxide
Full structural formula of tetracarbon dioxide
Space-filling model of the tetracarbon dioxide molecule
IUPAC name
3D model (JSmol)
Molar mass 80.042
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).


  1. ^ a b c J.I.G. Codagan, John Buckingham, Finlay J. MacDonald, P. H. Rhodes (1996), Dictionary of Organic Compounds. CRC Press, ISBN 0-412-54090-8, ISBN 978-0-412-54090-5. 9000 pages.
  2. ^ a b Günther Maier, Hans Peter Reisenauer, Heinz Balli, Willy Brandt, Rudolf Janoschek(1990), C4O2 (1,2,3-Butatriene-1,4-dione), the First Dioxide of Carbon with an Even Number of C Atoms. Angewandte Chemie International Edition, volume 29, p. 905–908.
  3. ^ Detlev Sülzle, Helmut Schwartz (1990), Identification of Butatrienedione, Its Radical Anion, and Its Radical Cation in the Gas Phase. Angewandte Chemie International Edition, volume 29, p. 908–909.
  4. ^ V. Krishnamurthy and V. H. Rawal (1997), J. Org. Chem., volume 62, 1572.
  • François Diederich and Yves Rubin (2003), Synthetic Approaches toward Molecular and Polymeric Carbon Allotropes. Angewandte Chemie International Edition, Volume 31 Issue 9, Pages 1101–1123.

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.

Tricarbon monoxide

Tricarbon monoxide C3O is a reactive radical oxocarbon molecule found in space, and which can be made as a transient substance in the laboratory. It can be trapped in an inert gas matrix or made as a short lived gas. C3O can be classified as a ketene or an oxocumulene a kind of heterocumulene.

Common oxides
Exotic oxides
Compounds derived from oxides


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