This gradually brought clarity about the constitution of alkylated ketene dimers. Isopropenyl acetate is prepared by treating acetone with ketene. It is the simplest member of the ketene class. The ketone then undergoes Wolff rearrangement to ketene 6. The first step involves conversion of the isobutyric acid or its anhydride into the ketene. As for related organic cumulenes (e.g. ketene), CO obeys the octet rule. A specific example is derived from the dimerization of the ketene of stearic acid. An inherent problem with mCPBA is its inability to oxidize silyl ketene acetals. This reaction is called the Schmidlin ketene synthesis. The name may also refers to the specific compound ethenone , the simplest ketene. CO can be classified as a ketene or an oxocumulene a kind of heterocumulene. The application is similar to that for alkyl ketene dimers. Such reactions will often proceed via ketene. Alternatively, nitric acid adds to ketene. The reversion reaction, the [2+2] cycloaddition of ketene and ethylene, has never been observed.