ChemistryCode 9701
Aldehydes and ketones
What this topic asks you to be able to do
- recall the reagents and conditions that produce aldehydes and ketones: (a) oxidising a primary alcohol with acidified K2Cr2O7 or acidified KMnO4, distilling the product to give an aldehyde (b) oxidising a secondary alcohol with acidified K2Cr2O7 or acidified KMnO4, distilling the product to give a ketone
- describe: (a) reducing aldehydes and ketones with NaBH4 or LiAlH4 to form alcohols (b) reacting aldehydes and ketones with HCN, using KCN as a catalyst and heating, to form hydroxynitriles, with ethanal and propanone as examples
- describe the nucleophilic addition mechanism by which hydrogen cyanide reacts with aldehydes and ketones, as in 17.1.2(b)
- describe the way 2,4-dinitrophenylhydrazine (2,4-DNPH reagent) is employed in establishing whether carbonyl compounds are present
- deduce whether an unknown carbonyl compound is an aldehyde or a ketone from the outcomes of simple tests, namely Fehling’s and Tollens’ reagents and ease of oxidation
- deduce that an aldehyde or ketone, CH3CO–R, contains a CH3CO– group, based on its reaction with alkaline I2(aq) that forms a yellow precipitate of tri-iodomethane and an ion, RCO2–