Amines Flashcards
What are amines
Substituted ammonia compounds (NH3)
How many R groups does primary amines have
1
How many R groups does secondary amines have
2
How many R groups does tertiary amines have
3
What are the 4y amines called
Ammonium salt
2 ways 1y amines can be prepared
From halogenoalkanes by nucleophilic substitution
Reduction of aliphatic nitriles and aryl nitrates
Which is most reliable method of preparing 1y amines
Reduction
How is ammonia used in nucleophilic substitution
It has a lone pair of electrons so it acts as a nucleophile and a base
Define a nucleophile
Electron pair donor
What is a base
Proton acceptor
When may a side reaction occur from halogenoalkanes
If ammonia isn’t present in sufficient quantities to trap the startin material (haloalkane) as the amine still has a lone pair on the N (nucleophile)
What is limited if there is excess NH3
Limited haloalkane
What are the reducing agents that can be used to produce 1y amines
LiAlH4 [H] and dilute acid (HCl)
Ni catalyst with H2(g)
What are the reagents for reduction of aryl nitrates to produce 1y amines
Fe/Sn
With concentrated HCl
What is use of aryl amines
Azo dyes
How can amines behave with transition metals
Why
As ligands due to the lone pair of electrons
What bases are amines (protons acceptors)
Bronstead-Lowry bases
What acids are amines (electron pair donor)
Lewis Acid
What is formed between the lone pair on nitrogen and the proton when an amine accepts a proton
A dative covalent bond
In water the solution of amines is what ph
Why
Alkaline
Hydroxide ions are generated
the amines dissolve in dilute acid due to the formation of what
A soluble ionic salt
Behave as bases and react as acids to form salts
When may an amine have a stronger base strength
If the lone pair on the N is more available (electron dense)
What type of amine is most likely to bond with H+
Tertiary
What bases are more likely to accept a proton
Stronger bases
What increases the ability for an amine to accept a H+
The inductive effect that pushes electron density towards the N
In (aromatic) aryl amines why is the lone pair less available to bond with a H+
As the lone pair interacts with delocalised pi electrons of the benzene ring and gets incorporated in the ring (partially delocalised in ring)
What amines are weaker than ammonia
Aryl amines
Why is phenylmethyl amine aromatic but has a base strength more similar to the aliphatic amines
As the lone pair of the N is too far away from the benzene ring
What are quaternary ammonium salts used as
How
Catonic surfactants in fabric and hair conditioners
Coating surface with positive charges, reducing static
What are amines used in the manufacture of (2)
Polymers
Drugs (tranquillisers / painkillers)
What 2 things can amines react with
Acyl chlorides and acid anhydrides
What is used as the solvent in nucleophilic substitution
Why
Ethanol
Prevents any substitution of the haloalkane by water to produce alcohols
How is phenylamine made
Reduction of nitrobenzene
Heated under reflux with tin and HCl
How is a 2y amine obtained from an ammonium salt
Reacting with NaOH
