amines Flashcards
are amines acids or bases
aliphatic amines are bases
how do aliphatic amines act as bronsted bases
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.
what is a stronger base ammonia or aliphatic amines
aliphatic amines
why are aliphatic amines stronger bases
the alkyl groups are electron releasing and push electrons towards the nitrogen
atom
and so making the lone pair of electrons on the nitrogen more readily available to accept protons.
bases are electron donors or acceptors
acceptors
what are stronger secondary amines or primary amines
secondary amines
why are secondary amines stronger than primary amines
Secondary amines are stronger bases than primary amines because they have more alkyl groups that are
substituted onto the N atom in place of H atoms.
Therefore more electron density is pushed onto the N atom (as the inductive effect of alkyl groups is greater than that of H atoms), so making the lone pair of electrons on the nitrogen more readily available.
What is the order of base strength for the types of amines
Aromatic amines < ammonia< primary amines< tertiary amines< secondary amines
When amines reacts with acid they form
Ammonium salts
What is used to convert ammonium salt into amine
Sodium hydroxide
What is the ionic equation when primary amine reacts with acid
CH3NH2 + H+ —>CH3NH3+
When ammonium salts form it makes the compound
Solubl
What is a reaction which forms a primary amine
Nucleophilc substitution with ammonia
How are secondary amines formed
When a primary amine with lone pair reacts with halogenoalkane
What effect does using excess ammonia have in nucleophilic substitution
Can limit the further subsequent reactions and maximise the amount of primary amine formed
What effect does adding excess of the halogenoalkane have
Will promote the formation of the quaternary salt
What are the uses of the quaternary salts
Cationic surfactants
How can you prepare amine using a nitrile
Convert halogenoalkane into a nitrile using KCN in aqueous solution
Reduce nitrile to amine using LiALH4 by reducing with H2 using a nickel catalyst
What reagents are involved in forming amine using nitrile
KCN
Aqueous ethanol
LiAlH4
Nickel catalyst
Why is better to use nitriles to form amine
Reacting halogenoalkane with ammonia leads to further substitution reaction
Doesn’t form a high yield of primary amine
What is a disadvantage of using KCN to form amine
KCN is toxic
Two step reaction so low yield
How are aromatic amines formed
Nitroarene(nitrobenzene) is reduced using Sn and HCl
Or Fe and HCl
Bases are proton
Acceptors
Bases are electron
Donors
