17b - carbonyl compounds Flashcards
what are carbonyls?
compounds with c=o bonds
what are the trend in solubility of carbonyls with chain length?
higher chain length = lower solubility
- smaller carbonyls could H-bond with water as they have similar intermolecular forces)
- stronger london forces as chain length increases (which outweighs? H2O)
what is the trend in boiling point with increasing chain length?
higher chain length = higher bp
- stronger IM forces
what are the conditions and reagents of oxidation of aldehydes? what is the product?
carboxylic acid
- heat under reflux
- K2Cr2O7 & dilute H2SO4
what would be the observations of oxidation of aldehydes?
orange Cr2O7(2-) reduced to green Cr3(3+)
what compound could be tested with fehling’s solution? state the conditions, reagents & observation.
aldehydes
condition: heat gently
reagents: solution with Cu2+ ions
observation: Cu2+ ions reduced to CuO (red ppt)
(& aldehydes oxidised to carboxylic acids)
what compound could be tested with tollen’s reagent? state the conditions, reagents & observation.
aldehydes
condition: heat gently
reagents: aq, NH3 + AgNO3 -> complex ion [Ag(NH3)2]+
observation: silver mirror forms as Ag+ (aq) reduced to Ag(s))
(& aldehydes oxidised to carboxylic acids)
what is the reagents & conditions of reduction of carbonyls?
reagents: LiAlH4 in dry ether / reduction agent
conditions: room temp. & Pa
what would aldehydes & ketones be reduced to?
aldehyde: primary alcohols
ketones: secondary alcohols
what are the general formulas of reduction of carbonyls?
R-CHO + 2[H] -> R-COOH
R1-CO-R2 + 2[H] -> R1-CH(OH)-R2
what are formed with nucleophillic addition of carbonyls?
hydroxynitriles
what are the reagents & conditions of nucleophillic addition of carbonyls? draw the mechanism.
reagent: HCN in presence of KCN
conditions: room temp. & Pa
what is the KCN used for in nucleophillic addition of carbonyls?
extra KCN increases concentration of CN- ion as nucleophile needed
why would a mixture of enantiomers be produced from addition of carbonyls?
CN- could attack both sides
what does 2,4-dnph test for? what observation will be formed?
C=O bond in carbonyls, forms bright orange ppt
