aldehydes and ketones

where is the C=O in aldehydes

on the end

where is the C=O in ketones

not on the last carbon

solubility in water of carbonyls

The smaller carbonyls are soluble in water because they can form hydrogen bonds with water.

intermolecular forces in carbonyls

Pure carbonyls cannot hydrogen bond to themselves, but are attracted instead by permanent dipole forces.

why is the C=O polarised

because O is more electronegative than carbon. The positive carbon atom attracts nucleophiles

what are aldehydes oxidised into

carboxylic acids

reagent for oxidation of aldehydes

potassium dichromate (VI) solution and dilute sulfuric acid

equation for oxidation of aldehydes (structural formula)

full equation for oxidation of aldehydes

observation after oxidation of aldehydes

goes from orange to green

how is Tollen’s reagent made

by mixing aqueous ammonia and silver nitrate

what are aldehydes oxidised into with Tollen’s reagent and Fehling’s solution

carboxylic acids

observation after mixing Tollen’s reagent with aldehydes or ketones

aldehydes - silver mirror

ketones - no visible change

observation after mixing Fehling’s solution with aldehydes or ketones

aldehydes - brick red precipitate is formed

ketones - no visible change

what are aldehydes reduced into

primary alcohols

what are ketones reduced to

secondary alcohols

what is the reducing agent for aldehydes and ketones

NaBH₄

equation for reduction of aldehydes (structural formula)

equation for reduction of ketones (structural formula)

mechanism for nucleophilic addition for ketones (making alcohol)

why does nucleophilic addition work with NaBH₄

it contain a source of nucleophilic hydride ions (:H-) which are attracted to the positive carbon in the C=O bond.

nucleophilic addition mechanism for ketones (making hydroxynitriles)

what is a racemic mixture

a 50:50 mixture of 2 enantiomers

why is racemic mixture produced as a result of nucleophilic addition using HCN

the planar carbonyl group is approached equally from both sides by the HCN