Amines Flashcards
How are Amines produced?
when one or more hydrogen atoms in ammonia is replaced with an alkyl group
Can be classified by primary, secondary and tertiary amines, depending on how many alkyl groups are bonded to the nitrogen atom
What do amines form when they react with water?
alkaline solution. The lone pair of electrons on the amine’s nitrogen atom can accept a hydrogen from a water molecule, therefore acting as a base. This release OH- ions into the solution
What do amines form when they react with an acid? (Dilute acid like HCl dilute)
ammonium salt. Amine acts as a base and accepts a proton to form a quaternary ammonium salt.
How are aliphatic amines prepared?
Nucleophilic substitution
Between a haloalkane and excess ethanol in ammonia (ethanol is the solvent) in a sealed test tube
One mole of halogenoalkane reacts with two moles of ammonia.
This produces a primary amine and an ammonium salt. (Ammonium ion bonded to a halide ion).
The substitution reaction can continue until all the hydrogen atoms have been replaced with amine groups
Following this, an additional substitution can occur, producing a quaternary ammonium salt.
Draw the mechanism of a Nucleophilic substitution reaction of bromoethane with ammonia
Check pmt
Multiple possible substitutions mean that a mixture of products is produced. What are the problems with this and how can it be controlled?
The reaction has a low efficiency
Reaction conditions has to be changed so that only a single substitution occurs.
Ammonia can be added in excess in order to form only the primary amine, or the mixture of products can be separated using fractional distillation.
How are aliphatic amines produced from the reduction of nitriles?
Draw an equation showing this
hydrogenation
Requires hydrogen with a nickel catalyst (catalytic hydrogenation)
Check equation on pmt
How are aromatic amines prepared?
reduction of nitrobenzene
Using concentrated HCl and a tin catalyst.
Aromatic amines consist of an amine group and a benzene ring
