The derivatives are created to help further identify the compound by determining the melting point of a solid. Since it is hard to determine the boiling point of a small amount of liquid, it is easier to determine the melting point of a solid. This is helpful when you are trying to determine the identity of multiple compounds that are producing the same positive tests and have similar melting points. Turning them into a derivative makes them different than other regular compounds (derivative MP is different than regular MP). More test answers on https://studyhippo.com/aldehydes-ketones/