Aldehydes and ketones Flashcards
Where is the carbonyl group located on ketones?
They have the carbonyl group on an inner carbon.
What are aldehydes oxidised into?
Carboxylic acids.
Which test is able to distinguish between aldehydes and ketones?
Add tollen’s reagent ( {Ag (NH3)2}+ ) in a warm water bath. If aldehyde is present a silver mirror is formed as Ag is reduced. Ketone no silver precipitate is formed.
Which reducing agent can reduce aldehydes and ketones?
Sodium borohydride (NaBH4) dissolved in methanol and water.
How can you represent oxidising and reducing agents?
{O} {H}
What type of alcohols are ketones and aldehydes reduced to?
Aldehydes are reduced to primary alcohols, whilst ketones are reduced to secondary alcohols.
What type of mechanism is the reduction of aldehydes and ketones?
A nucleophilic addition reaction. The H- ion is a nucleophile and attacks delta positive C.
What type of molecule is formed when potassium cyanide (acidic) reacts with aldehydes or ketones?
Hydroxynitriles (a molecule containing OH and CN group).
What happens when we use an unsymmetrical ketone or aldehyde (apart from methanal) in a reaction with potassium cyanide?
A mixture of enantiomers are formed.
What risks are associated with potassium cyanide and how to lower these risks?
Potassium cyanide is an irritant, therefore, is dangerous if ingested or inhaled. If reacted with moisture it can form toxic gas, hydrogen cyanide. Use goggles, a fume cupboard, gloves.
