Aldehydes + Ketones Flashcards
What is the difference between aldehydes and ketones?
The position of the carbonyl group (C=O)
What is an aldehyde?
A compound where the carbonyl group is at the end of a carbon and all aldehydes end in –al
What is a ketone?
A compound where the carbonyl group is on an inner carbon and all ketones end in –one
What happens when you oxidise aldehydes?
They are oxidised to carboxylic acids using an oxidising agent
What happens when you oxidise ketones?
Nothing as ketones cannot be oxidised
What reagents are used to distinguish between aldehydes and ketones?
Tollens reagent
Fehling’s Solution
How do aldehydes react with Tollens reagent?
Tollens is reduced to silver forming a silver precipitate
How do ketones react with Tollens reagent?
No precipitate is formed
What conditions are needed when testing using Tollens?
Use a hot water bath and not a Bunsen burner as aldehydes and ketones are flammable
What is Fehling’s solution?
An oxidising agent (has Cu2+) that can be used to distinguish between aldehydes and ketones
How does Fehling’s solution react with Aldehydes?
It goes from a blue solution to a brick red precipitate
How does Fehling’s solution react with Ketones?
It doesn’t so it remains blue
How do you represent reducing agents?
[H]
Name a reducing agent used to reduce Aldehydes and Ketones?
NaBH4 – Sodium Borohydride dissolved in methanol and water
What are aldehydes reduced to?
Primary Alcohols
