3.11 Amines Flashcards
Name the aliphatic amine and state the type of amine it is
Name the aliphatic amine and state the type of amine it is
Name the aliphatic amine and state the type of amine it is
Name the aliphatic amine and state the type of amine it is
Name the aromatic amine and state the type of amine it is
Explain how a quaternary ammonium ion forms
Lone pair of electrons on nitrogen atom in tertiary amine can also bond with 4th organic group
Explain how quaternary ammonium salts form
Quaternary ammonium ions are positively charged ∴ form bonds around with -ve ions & form complexes (quaternary ammonium salts)
What type of quaternary ammonium salts are used as cationic surfactants?
Quaternary ammonium salts with at least 1 long hydrocarbon chain
What products are cationic surfactants used in?
Fabric cleaners (e.g. fabric conditioner) and hair products (e.g. conditioner)
Describe and explain why cationic surfactants are useful in fabric cleaners and hair products
- Hydrocarbon tail binds to non-polar substances like grease & cationic head dissolves in water
- Positively charged part (ammonium ion) will bind to negatively charged surfaces e.g. hair and fibre
- Gets rid of static
Why do amines act as (weak) bases?
∵ accept protons
Explain how amines can accept protons
Lone pair of electrons on nitrogen atom can form dative covalent (coordinate) bond with H+ ion
What does the strength of a base depend on (for amines)?
Depends on how available nitrogen’s lone pair of electrons is
More available the lone pair is = more likely amine is to accept proton & stronger base it’ll be
When is a lone pair of electrons more available?
When its electron density is high
Order the amines from the weakest to strongest base
Ammonia, aliphatic amines, aromatic amines
- Aromatic amines (weakest)
- Ammonia
- Aliphatic amines (strongest)
Explain why primary aromatic amines (e.g. phenylamine) act as very weak bases
- Benzene ring draws electrons towards itself and nitrogen lone pair gets partially delocalised onto the ring
- ∴ the electron density on nitrogen ↓, making lone pair much less available
Explain why primary aliphatic amines act as strong bases
- Alkyl groups push electrons onto attached groups
- ∴ electron density on nitrogen atom ↑
- Makes lone pair more available
Why are amines considered nucleophiles?
∵ have lone pair of electrons
Name the 2 mechanisms that amines partake in. Include the reactants.
- React with halogenoalkanes in nucleophilic substitution
- React with acyl chlorides and acid anhydrides in nucleophilic addition-elimination
Name 2 ways you can make aliphatic amines
- Heating halogenoalkane with excess ammonia
- Reducing a nitrile (to a primary amine)
Draw the mechanism to show how ethylamine can be made by reacting ammonia with bromoethane
When heating halogenoalkane with ammonia, what mixture of products do you get?
Mixture of primary, secondary, tertiary amines + quaternary ammonium salts
Explain how heating halogenoalkane with ammonia results in a mixture of primary, secondary, tertiary amines and quaternary ammonium salts
- Primary amine 1st produced has lone pair of electrons = nucleophile
- ∴ can react with any remaining halogenoalkane in nucleophilic substitution reaction
- Further substitutions take place as long as there’s remaining halogenoalkane
- Happens up to quaternary ammonium salt = can’t react further ∵ has no lone pair
Write an equation for when a primary amine acts as a nucleophile with CH2CH2Br
Mechanism is similar to reaction of ammonia + halogenoalkane: 2 amine molecules react with halogenoalkane in succession to form more substituted amine (e.g. primary amine forms secondary amine) & ammonium salt with similar structure to original amine
Describe 2 ways you can reduce a nitrile to a primary amine
- Use lithium aluminium hydride (LiAlH4 - strong reducing agent) in non-aqueous solvent e.g. dry ether followed by dilute acid
- Catalytic hydrogenation: Reduced using hydrogen gas with metal catalyst e.g. platinum or nickel at high temperature and pressure
Why is the LiAlH4 method good in a lab but not good for industrial use?
LiAlH4 is too expensive
(industry uses catalytic hydrogenation)
Write an equation representing the reduction of a nitrile to a primary amine using lithium aluminium hydride
Write an equation representing the reduction of a nitrile to a primary amine via catalytic hydrogenation
State how you can produce aromatic amines
Reduce nitro compound e.g. nitrobenzene
Describe how you can produce an aromatic amine by reducing nitro compound (e.g. nitrobenzene)
- Heat mixture of nitro compound, tin metal & concentrated HCl under reflux
- Makes salt
- e.g. using nitrobenzene, salt formed = C6H5NH3+Cl-
- To turn salt into aromatic amine, add alkali e.g. NaOH solution
Write an equation representing the reduction of nitrobenzene into an aromatic amines
Give an example of how aromatic amines are useful compounds in organic synthesis
Are starting molecules for lots of dyes and pharmaceuticals
Amides are _______ ___ derivates
Amides are carboxylic acid derivates
State the functional group of amides
-CONH2
Why do amides behave differently from amines?
Carbonyl group pulls electrons away from NH2 group
Draw an amide
Draw an N-substituted amide
Define the inductive effect
Ability of alkyl group to release electrons towards nitrogen atom
Give the formula of an organic compound that forms an alkaline buffer solution when added to a solution of ethylamine
CH3CH2NH3Cl
- (weak base + salt = alkaline buffer solution)
- (ethylamine + amine hydrochloride = alkaline buffer solution)
- (add HCl to ethylamine to get salt)
Name the following compound
Name the following compound
N-ethylpropanamide
Write an ionic equation for the reaction between propylamine and hydrochloric acid
CH3CH2CH2NH2 + H+ → CH3CH2CH2NH3+
(original equation: CH3CH2CH2NH2 + HCl → CH3CH2CH2NH3Cl)
Propylamine reacts with bromoethane under specific conditions, to give a compound with the formula C9H22NBr. Draw the structure of the compound with the formula C9H22NBr.
