*6.1.2 carbonyls

aldehyde (al ending, at the end) and ketones (one ending, in middle of chain)

smaller carbonyls are soluble as they can form hydrogen bonds with water pure carbonyls cannot hydrogen bond but bond with permanent dipole forces

C=O bond polarised as O is more electronegative than carbon positive carbon atom attracts nucleophiles in comparison to C=C bond in alkenes, C=O is stronger and doesn’t undergo addition reactions easily (electrophiles attracted to C=C)

K2Cr2O7 oxidising agent oxidising alcohols and aldehydes primary alc > aldehydes > carboxylic acid secondary alc > ketones tertiary alc > don’t oxidise

aldehyde > carboxylic acid reagent: potassium dichromate (VI) solution and dilute H2SO4 3CH3CHO + (Cr2O7)2- + 8H+ > 3 CH3CO2H + 4H2O + 2Cr3+ orange dichromate ion (Cr2O7)2- reduced to green Cr3+

tollens reagent (aqueous ammonia and silver nitrate) - [Ag(NH3)2]+ heat gently aldehydes oxidised by tollens reagent into carboxylic acid - silver (I) ions reduced to silver atoms silver mirror forms coating inside of test tube - ketones have no change CH3CHO + 2Ag+ + H2O > CH3COOH + 2Ag + 2H+

NaBH4 in aqueous ethanol room temperature and pressure reducing agents e.g. NaBH4 and LiAlH4 reduce carbonyls to alcohols aldehydes > primary alcohols ketones > secondary alcohols

contains a source of nucleophilic hydride ions (H-) which are attracted to positive carbon in C=O bond

catalytic hydrogenation reagent: hydrogen and nickel catalyst high pressure

Carbonyl > hydroxynitrile NaCN and dilute H2SO4 Room temp Nucleophilic substitution

Aqueous ammonia + silver nitrate [Ag(NH3)2] Heat gently Aldehydes oxidised into carboxylic acid - silver (I) ions reduced to silver atoms Aldehydes - silver mirror forms , ketones no change CH3CHO + 2Ag+ + H2O > CH3COOH + 2Ag + 2H+