amines Flashcards
Base Properties of amines
Primary aliphatic amines act as Bronsted-Lowry Bases because the lone pair of electrons on the nitrogen is readily available for forming a dative covalent bond with a H+ and so accepting a proton. They are weak bases as only a low concentration of hydroxide ions is produced.
CH3NH2 +H2O ⇌ CH3NH3+ +OH-
Primary aliphatic amines are stronger bases than ammonia as the alkyl groups are electron releasing and push electrons towards the nitrogen atom and so make it a stronger base
NH3 (aq) +H2O (l) ⇌ NH4+ (aq) +OH-
Base strength of aromatic amines
Primary aromatic amines such as phenylamine do not form basic solutions because the lone pair of electrons on the nitrogen delocalise with the ring of electrons in the benzene ring. This means the N is less able to accept protons
Overall order of base strength
Amiens reactions with acids
Making a basic buffer from an amine
Basic buffers can be made from combining a weak base with a salt of that weak base
e.g. Ammonia and ammonium chloride
Methylamine and methylammonium chloride Ethylamine and ethylammonium chloride
Forming a primary amine in a one-step reaction of halogenoalkanes with ammonia
Nucleophilic properties
Reaction forming secondary amine
Reaction forming a tertiary amine
Reaction forming a quaternary ammonium salt
Where RX is the haloalkane+ AMINE
Some questions will involve substituting an amine onto a halogenoalkane which has a different length of carbon chain from the amine
Preparing amines from nitriles in a 2 step reaction
Reducing nitroarenes to aromatic amines
acyl chloride to secondary amide
acid anhydride to secondary amide
