Chem

ussion:

    The 2,4-dinitrophenylhydrazine test produced a yellow precipitate. 2,4-DNPH reacts via an imine formation mechanism, reacting with aldehydes and ketones but not with alcohols. This meant that the unknown compound was either an aldehyde or ketone. The yellow color of the precipitate also suggested that the carbonyl group of the unknown was unconjugated. The precipitate was used as a solid derivative to determine the melting point of the unknown. The Schiff test had no change in color, giving a negative result. Schiff’s reagent is very bulky, and as such will only be able to react with molecules which have enough space. Ketones are unable to react with the reagent due to its size, so only aldehydes will react and show a change in color. This meant that the unknown present was a ketone. Lastly, the iodoform test was performed to determine if the unknown was or was not a methyl ketone.