High Quality Content by WIKIPEDIA articles! Ethylene dione or ethylenedione, also called dicarbon dioxide, ethenedione, or ethene 1,2-dione, is the name given to a hypothetical chemical compound with the formula C2O2 or O=C=C=O. It would be an oxide of carbon (an oxocarbon), specifically a dimer of carbon monoxide (CO). It can be thought of as ketene of glyoxylic acid (OHCCOOH).