topic 18B Flashcards
amine functional group
-yl
- e.g. propylamine
amide functional froup
-amide
- e.g. ethanamide
identifying an amino acid
aliphatic amines
- non-aromatic amines are aliphatic amines
how is an aliphatic amine formed
- either by reacting a halogenoalkane with excess ammonia
- or by reducing a nitrile
why do primary aliphatic amines act as Bronsted-Lowry bases?
- the lone pair of electrons on the nitrogen is readily available to form a dative covalent bond with a H+
- it is accepting a proton
why are primary aliphatic amines stronger bases than ammonia?
- primary aliphatic amines are stronger bases than ammonia
- the alkyl groups are electron releasing and push electrons towards the nitrogen atom
- making it a stronger base
what’s the stronger base - primary or secondary amine and why?
- secondary are stronger
- they have more alkyl groups
- more electron density is pushed onto the N atom
what’s the stronger base - secondary or tertiary amine
- secondary
reaction of primary aliphatic amines with water
- small amines can form hydrogen bonds with water
- forming an alkaline solution
reaction of primary aliphatic amines with water example
CH3CH2NH2 + water –> CH2CH2NH3+ + OH-
reaction of primary aliphatic amines with acids
- react with acids to form salts
reaction of primary aliphatic amines with acids - example
CH3NH2 + HCl -> CH3NH3+Cl-
methylamine + HCl -> mehtylammonium chloride
reaction of primary aliphatic amines with ethanoyl chloride - type of reaction?
addition-elimination reaction
- two molecules join together and a small molecule is eliminated
reaction of primary aliphatic amines with ethanoyl chloride - example
CH3CH2NH2 + CH3COCl -> CH3CONH
what does the reaction with ethanoyl chloride lead to
- it leads to the formation of a new functional group
- carbonyl group is next to the NH group
reaction of primary aliphatic amines with halogenoalkanes - type of reaction
- halogenoalkanes undergo nucelophilic substitution
- form secondary amines
reaction of primary aliphatic amines with halogenoalkanes - example
butylamine + chloroethane -> N-ethylbutylamine + HCl
reaction of primary aliphatic amines with copper (II) ions - what is formed
complex ions
how are these complex ions formed
- lone pair of electrons on the nitrogen allows amines to act as ligands
- hence they form dative covalent bonds inot transition metal ions to form coloured complex ions
reaction of primary aliphatic amines with copper (II) ions - example
4 CH3CH2NH2 + Cu(H2O)6 2+ ⇌ [Cu(CH3CH2NH2)4(H2O2)2]2+ + 4 H2O
reaction of primary aliphatic amines with copper (II) ions - example (ammonia as the ligand)
4NH3 + Cu(H2O)6 2+ ⇌ [Cu(NH3)4(H2O)2]2+ + 4H2O
light blue solution ⇌ deep blue solution
do primary aromatic amines for basic solutions?
- no
- the lone pair of electrons on the nitrogen delocalise with the ring of electrons on the benzene ring
- N is less acceptable to protons
difference in basicity of ammonia, primary aliphatic amines and primary aromatic amines
- ammonia is more basic than aromatic amines - there is no partial delocalisation of N lone pair
- aliphatic amines are more basic than both ammonia and aromatic amines - alkyl groups have an inductive effect on the N lone pair
what is meant by inductive effect
The effect on electron density in one portion of a molecule
formation of primary aliphatic amines from halogenoalkanes
- reagents
- conditions
- type of reaction
- excess ammonia
- ethanol and heat
- nucleophilic substitution
formation of primary aliphatic amines from halogenoalkanes details
- the nitrogen lone pair on the ammonia acts as a nucleophile and replaces the halogen on the halogenoalkane
- when halogenoalkane is reacted with excess ammonia, hot ethanol under pressure, a primary amine is formed
formation of primary aliphatic amines from the reduction of nitriles
- reagents
- conditions
- type of reaction
- aqueous ethanol, LiAlH4 in dry ether, nickel catlayst
- heat under reflux
- reduction
formation of primary aliphatic amines from the reduction of nitriles details
- nitriles contain a -CN group which can be reduced to an -NH2 group
- nitrile vapour and H2 gas are passed over a nickel catlayst or LiAlH4 in dry ether and can be used to form a primary amine
how can aromatic nitroarenes be reduced to form amines?
- reagents
- conditions
- mechanism
- tin and HCl
- iron and HCl
- heating
- reduction
preparing amides
- change in functional group
- reagent
- condition
- acyl chloride to secondary amide
- primary amine
- room temperature