Carbonyl compounds

Aldehydes and ketones production: oxidation from alcohols by distillation

Reagents: acidified K₂Cr₂O₇ and KMnO₄

Conditions: heat

primary alcohol → aldehyde

secondary alcohol → ketone

Reduction of aldehydes and ketones → alcohols

Reagents: LiAlH₄ and NaBH₄

aldehyde → primary alcohol

ketone → secondary alcohol

nucleophilic addition of aldehydes with HCN

Reagents: HCN

Conditions: heat, catalyst KCN

nucleophilic addition of ketones with HCN

Reagents: HCN

Conditions: heat, catalyst KCN

test for aldehydes and ketone using 2,4 - DNPH

positive result (aldehyde and ketone present) → orange ppt

negative result → no color change

does not give positive result to carboxylic acids or esters (also contains carbonyl)

test using fehling’s solution

positive result (aldehyde present) → red ppt

• aldehydes are oxidise → carboxylic acids by fehling’s

negative result (ketone) → clear blue of Cu²⁺

test using tollen’s reagent

positive result (aldehyde present) → silver mirror of Ag

• aldehydes are oxidise → carboxylic acids by tollen’s

negative result (ketone) → no silver mirror (Ag⁺ present)

test of alkaline I₂ (aq)