Distinguishing Between Methyl Ketone and Ethyl Ketone: A simple test can be carried out using Iodoform Test. The reaction with iodine and sodium hydroxide will form a yellow precipitate of Iodoform (CHI) for methyl ketones, such as ace- tophenone (CHCOCH), but will not give this result for ethyl ketones, such as phenylethanecar- bonyl (CHCOCHCH).
C6H5COCH3 + I2 + NaOH → Iodoform (yellow precipitate)
Ethanal to But-2-enal