Oxocarbon

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). Many other stable 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.