CO''

Carbonyl Car"bon*yl, n. [Carbon + -yl.] (Chem.) The radical {(CO)''}, occuring, always combined, in many compounds, as the aldehydes, the ketones, urea, carbonyl chloride, etc. [1913 Webster]

Note: Though denoted by a formula identical with that of carbon monoxide, it is chemically distinct, as carbon seems to be divalent in carbon monoxide, but tetravalent in carbonyl compounds. [1913 Webster]

{Carbonyl chloride} (Chem.), a colorless gas, {COCl2}, of offensive odor, and easily condensable to liquid. It is formed from chlorine and carbon monoxide, under the influence of light, and hence has been called {phosgene}, or {phosgene gas}; -- called also {carbon oxychloride}. It is used in chemical synthesis, and was also used as a poison gas in World War I. [1913 Webster +PJC]