Recent efforts in this laboratory to prepare new ketenes by the pyrolysis of substituted malonic anhydrides' or of mixed anhydrides' derived from diphenylacetic acid and substituted malonic acids led to a desire to improve these classical synthetic methods. The substituted malonic anhydrides had formerly been obtained from the malonic acids by treatment with acetic anhydridej2 or from the malonyl chlorides by various methods, but ...
