Tetracarbon dioxide explained

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

References

• 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.

Notes and References

1. J.I.G. Codagan, John Buckingham, Finlay J. MacDonald, P. H. Rhodes (1996), Dictionary of Organic Compounds. CRC Press,, . 9000 pages
2. 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.
3. V. Krishnamurthy and V. H. Rawal (1997), J. Org. Chem., volume 62, 1572.
4. 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.