11: Amines Flashcards
Give the formula of an ammonium ion.
NH4+
Give the shape of an ammonium ion.
Tetrahedral
What is formed when a hydrogen in ammonia is replaced by an alkyl or aromatic group?
Amine
If one hydrogen in ammonia is replaced with a different organic functional group, what is formed?
Primary amine
If two hydrogens in ammonia is replaced with a different organic functional group, what is formed?
Secondary amine
If three hydrogens in ammonia are replaced with a different organic functional group, what is formed?
Tertiary amine
What does the NH2 functional group smell of?
Rotten fish
Generally how do we name amines?
Amine is the suffix, the prefix depends on the organic groups attached
Give 2 uses of amines.
Used in drugs to treat malaria
Used to make plastics
Give a use of quaternary amine salts.
To make detergents.
Why are amines considered bronsted-lowry bases?
They accept protons by forming a coordinate bond with them.
When acids react with amines, what is produced?
Salt
What does the strength of amines as bases depend on?
The availability of the lone pair on the nitrogen.
Are primary aromatic amines strong or weak bases? Why?
Weak
The benzene ring draws electrons towards itself and the nitrogen’s lone pair gets partially delocalised onto the ring.
Are ammonia molecules strong or weak bases? Why?
They are in between strong and weak. They do not have an aromatic group to pull electrons away from the amine or they don’t have an alkyl group to push the lone pair of electrons forward and make the lone pair more available.
Are primary aliphatic amines strong or weak bases? Why?
Strong bases. The alkyl group pushes electrons away from itself towards the hydrogen, making them more available for a proton to bind to.
What is an inductive effect?
The ability of an atom in a molecule to pull electrons towards itself, increasing the negative charge.
Why are secondary aliphatic amines stronger bases than primary amines?
They have 2 inductive effects.
Amides are derivatives of what organic molecule?
Carboxylic acids
Give the formula of the group that amides contain.
CONH2
In CONH2, what does the carbonyl group doto NH2’s electrons?
Pulls electrons away from the NH2.
Generally, how do we name amides?
Amide is always the suffix.
The prefix comes from the length of the RCO chain.
Name the mechanism that forms amines from halogenoalkanes.
Nucleophilic substitution
Why are there a mixture of primary/secondary/tertiary and quaternary ammonium salts produced from nucleophilic substitution of haloalkanes?
More than one hydrogen in the halogenoalkane is likely to be substituted.
Describe the mechanism of nucleophilic substitution of halogenoalkanes to produce amines.
- NH3 attacks slightly positive carbon bonded to halogen.
- Halogen breaks off as a halide ion.
- NH3 binds and the N is positive
- Another NH3 attacks a hydrogen bonded to the positive nitrogen and breaks off.
- The broken off hydrogen bonds with the NH3 and produces an NH4+ ion
Why does nucleophilic substitution keep occurring on the amine molecule produced?
It has a lone pair, so is still a nucleophile.
Briefly, how can we produce amines from nitriles?
By reducing the nitrile using a strong reducing agent (such as LiAlH4 in dry ether), followed by dilute acid
Why do we not use reduction of nitriles to produce amines in industry?
Too expensive
Give the conditions for the production of amines from nitriles in industry.
Nickel or platinum catalyst
High temperature and pressure
Name the mechanism that produces primary amides from acyl chlorides.
Nucleophilic addition elimination
Describe the nucleophilic addition elimination mechanism to produce amides from acyl chloride and ammonia.
- Lone pair on nitrogen in ammonia ttacks the slightly positive carbon in the acyl chloride
- A pair of electrons from C=O is transferred onto the oxygen, so the bond is now single.
- The pair of electrons on the oxygen reform the double bond and the Cl is removed
- This leaves the amide ion positively charged and the Cl-
- The Cl- bonds to a hydrogen on the N atom, the hydrogen breaks off, forming HCl
- This leaves an amide and HCl is eliminated.
When acid anhydrides react with primary amines, what 2 things are formed?
N-substituted amide and carboxylic acid
When acid anhydrides react with ammonia, what 2 things are formed?
Primary amide and a carboxylic acid.
Explain how aromatic amines a produced,
A mixture of a nitrocompound, tin and conc HCl is heated under reflux to produce a salt.
An alkali is added to the mixture (such as NaOH) which turns the salt into an aromatic amine.
What are N-Substituted amides?
Amides where one of the hydrogens attached to nitrogen has been substituted with an alkyl group
How do we name N substituted amides?
Add N-(alkyl group) for example, N-propylamide.
