Carbon suboxide

Other names: propa-1,2-diene-1,3-dione

C₃O₂

28/50 common

Carbon suboxide is a volatile, colorless gas with a remarkably linear molecular structure consisting of three carbon atoms and two oxygen atoms (O=C=C=C=O). It is one of the four stable oxocarbons under standard conditions, alongside the ubiquitous carbon dioxide and carbon monoxide and the esoteric mellitic anhydride. Carbon suboxide has a pungent, irritating odor often compared to mustard or horseradish. However, it may be as a useful building block in organic synthesis, particularly for introducing ketene functionality. Exposed to light or heat, it spontaneously polymerizes to form a deep red-brown solid with complex cyclic and linear structures. Its unusual 'heterocumulene' structure makes it of theoretical interest for understanding carbon-oxygen multiple bond systems; as modeled by Melville et al.