Prepn from ketene + acetone: Hull, Agett; Hagemeyer, US 2481669; US 2476860 (both 1949 to Eastman Kodak); Young, US 2461016; US 2511423 (1949, 1950 both to Carbide & Carbon Chem.); Mawer, US 2684980 (1954 to I.C.I.); Buttner, Enk, US 2867653 (1959 to Wacker-Chemie). Use as reagent for acylation of potential enols: Hagemeyer, Hull, Ind. Eng. Chem. 41, 2920 (1949); Hull, Agett, US 2482066 (1949 to Eastman Kodak); Jeffery, Satchell, J. Chem. Soc. 1962, 1876, 1906. Toxicity study: Smyth et al., J. Ind. Hyg. Toxicol. 31, 60 (1949).