Pentacarbon dioxide, officially penta-1,2,3,4-tetraene-1,5-dione, is an oxide of carbon (an oxocarbon) with formula C5O2 or O=C=C=C=C=C=O.
The compound is the third member of the series CnO2 with odd n, the first two members being carbon dioxide (CO2) and carbon suboxide (C3O2). The compound was described in 1988 by G. Maier and others, who obtained it by pyrolysis of 1,3,5-cyclohexanetrione (phloroglucin, the tautomeric form of phloroglucinol). It has also been obtained by flash vapor pyrolysis of 2,4,6-tris(diazo)cyclohexane-1,3,5-trione (C6N6O3).:p.97 It is stable at room temperature in solution. The pure compound is stable up to −96 °C, when it polymerizes.
- ^ a b Maier, G.; Reisenauer, H. P.; Schäfer, U.; Balli, H. (1988). "C5O2 (1,2,3,4-Pentatetraene-1,5-dione), a New Oxide of Carbon". Angewandte Chemie International Edition 27 (4): 566–568. doi:10.1002/anie.198805661.
- ^ a b Eastwood, F. W. (1997). "Gas Phase Pyrolytic Methods for the Preparation of Carbon-Hydrogen and Carbon-Hydrogen-Oxygen Compounds". In Vallée, Y. Gas Phase Reactions in Organic Synthesis. CRC Press. ISBN 90-5699-081-0.