3.3.11 Amines Flashcards
base properties, synthesis of amines, etc. (11 cards)
what are quaternary ammonium salts used for
cleaning products e.g. shampoo and laundry detergent
how do quaternary ammonium salts remove grease from clothing?
- non-polar tail is attracted to the oil/grease
- polar head is attracted to the water
- allows the water + oil to mix -> grease removed
what are quaternary ammonium salts made up of?
has a positive end which is attracted to negative ions; ones that have a hydrocarbon tail are called a ‘cationic surfactant’
what are cationic surfactants used in and why?
- hair conditioner + fabric softener
- the positive ammonium ion is attracted to negatively charged fibres and hair
what is the order of base strength from weakest to strongest?
aromatic amines -> ammonia -> primary amine -> secondary amine -> tertiary amine
why are aromatic amines the weakest base?
- benzene = electron withdrawing group -> pulls electron density away from the N atom into the delocalised ring -> lone pair on the N atom is less readily available -> less basicity
why are primary aliphatic amines stronger bases than aromatic amines?
- alkyl groups = electron donating group (or ‘positive indcuctive effect) -> donates electron density to the N atom -> lone pair on the N atom is more readily available -> more basicity
why is using nucleophilic substitution to prepare amines inefficient? how can we make it more efficient?
mixture of products are formed (primary, secondary, tertiary, etc.)
- use excess ammonia to prevent this
how can we prepare aliphatic amines? [2 ways]
- nucleophilic substitution of haloalkanes (using excess ammonia)
- hydrogenation - ‘reduction of nitriles’ (using hydrogen gas and a nickel/platinum catalyst, could also use LiAlH4 as a reducing agent)
how can we prepare aromatic amines?
- redution of nitrobenzene using a tin catalyst and concentrated HCl (heat under reflux)
- can be reacted with an alkali like NaOH to produce phenylamine
