Aldehydes and Ketones Flashcards
What type of bonding Do carbonyls have?
Pure carbonyls cannot hydrogen bond to themselves.
They are attached by permanent dipole forces.
Describe the solubility of carbonyls in water
Smaller carbonyls are soluble in water because they can form hydrogen bonds with water.
Describe oxidation of aldehydes
Product: carboxylic acid
Reagent: acidified potassium dichromate
Conditions: heat under reflux
What is the equation for the reaction that occurs when Tollens’ reagent is added to aldehydes?
CH3CHO + 2Ag+ +H2O -> CH3COOH +2Ag +2H+
What is the equation for oxidation of aldehydes?
3RCHO + (Cr2O7)2- +8H+ -> 3RCOOH + 4H2O + 2Cr3+
What is the equation for the reaction that occurs Fehling’s solution is added to aldehydes?
CH3CHO +2Cu2+ +2H2O -> CH3COOH + Cu2O + 4H+
Describe the reduction of carbonyls
Reagent: NaBH4 in aqueous ethanol
Condition: room temperature and pressure
Product: alcohol (primary or secondary)
Type of reaction: Nucleophilic Addition
Describe catalytic hydrogenation
Reagent: hydrogen and nickel catalyst
Condition: high pressure
Product: alcohol
Describe addition of hydrogen cyanide to carbonyls
Product: hydroxynitrile
Reagent: KCN and dilute sulfuric acid
Conditions: Room temperature and pressure
Mechanism: Nucleophilic addition
How is a racemic mixture formed when KCN reacts with carbonyls?
The carbonyl group has a planar shape, so the nucleophile can attack from both sides with equal probability, so forms equal amounts of each enantiomer and no optical activity is seen.
