topic 18B

Question 1

amine functional group

Answer 1

-yl
- e.g. propylamine

Question 2

amide functional froup

Answer 2

-amide
- e.g. ethanamide

Question 3

identifying an amino acid

Question 4

aliphatic amines

Answer 4

• non-aromatic amines are aliphatic amines

Question 5

how is an aliphatic amine formed

Answer 5

• either by reacting a halogenoalkane with excess ammonia
• or by reducing a nitrile

Question 6

why do primary aliphatic amines act as Bronsted-Lowry bases?

Answer 6

• 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

Question 7

why are primary aliphatic amines stronger bases than ammonia?

Answer 7

• 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

Question 8

what’s the stronger base - primary or secondary amine and why?

Answer 8

• secondary are stronger
• they have more alkyl groups
• more electron density is pushed onto the N atom

Question 9

what’s the stronger base - secondary or tertiary amine

Answer 9

• secondary

Question 10

reaction of primary aliphatic amines with water

Answer 10

• small amines can form hydrogen bonds with water
• forming an alkaline solution

Question 11

reaction of primary aliphatic amines with water example

Answer 11

CH3CH2NH2 + water –> CH2CH2NH3+ + OH-

Question 12

reaction of primary aliphatic amines with acids

Answer 12

• react with acids to form salts

Question 13

reaction of primary aliphatic amines with acids - example

Answer 13

CH3NH2 + HCl -> CH3NH3+Cl-

methylamine + HCl -> mehtylammonium chloride

Question 14

reaction of primary aliphatic amines with ethanoyl chloride - type of reaction?

Answer 14

addition-elimination reaction
- two molecules join together and a small molecule is eliminated

Question 15

reaction of primary aliphatic amines with ethanoyl chloride - example

Answer 15

CH3CH2NH2 + CH3COCl -> CH3CONH

Question 16

what does the reaction with ethanoyl chloride lead to

Answer 16

• it leads to the formation of a new functional group
• carbonyl group is next to the NH group

Question 17

reaction of primary aliphatic amines with halogenoalkanes - type of reaction

Answer 17

• halogenoalkanes undergo nucelophilic substitution
• form secondary amines

Question 18

reaction of primary aliphatic amines with halogenoalkanes - example

Answer 18

butylamine + chloroethane -> N-ethylbutylamine + HCl

Question 19

reaction of primary aliphatic amines with copper (II) ions - what is formed

Answer 19

complex ions

Question 20

how are these complex ions formed

Answer 20

• 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

Question 21

reaction of primary aliphatic amines with copper (II) ions - example

Answer 21

4 CH3CH2NH2 + Cu(H2O)6 2+ ⇌ [Cu(CH3CH2NH2)4(H2O2)2]2+ + 4 H2O

Question 22

reaction of primary aliphatic amines with copper (II) ions - example (ammonia as the ligand)

Answer 22

4NH3 + Cu(H2O)6 2+ ⇌ [Cu(NH3)4(H2O)2]2+ + 4H2O

light blue solution ⇌ deep blue solution

Question 23

do primary aromatic amines for basic solutions?

Answer 23

• 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

Question 24

difference in basicity of ammonia, primary aliphatic amines and primary aromatic amines

Answer 24

• 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

Question 25

what is meant by inductive effect

Answer 25

The effect on electron density in one portion of a molecule

Question 26

formation of primary aliphatic amines from halogenoalkanes - reagents - conditions - type of reaction

Answer 26

- excess ammonia - ethanol and heat - nucleophilic substitution

Question 27

formation of primary aliphatic amines from halogenoalkanes details

Answer 27

- 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

Question 28

formation of primary aliphatic amines from the reduction of nitriles - reagents - conditions - type of reaction

Answer 28

- aqueous ethanol, LiAlH4 in dry ether, nickel catlayst - heat under reflux - reduction

Question 29

formation of primary aliphatic amines from the reduction of nitriles details

Answer 29

- 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

Question 30

how can aromatic nitroarenes be reduced to form amines? - reagents - conditions - mechanism

Answer 30

- tin and HCl - iron and HCl - heating - reduction

Question 31

preparing amides - change in functional group - reagent - condition

Answer 31

- acyl chloride to secondary amide - primary amine - room temperature