Chapter 27 - Amines, Amino Acids + Polymers

amines

-derived from ammonia

-primary, secondary + tertiary = refer to number of alkyl groups attached to nitrogen

naming amines

-primary = when NH2 group is on end, suffix = -amine

-primary = when NH2 group is in middle, prefix = number + amino

-secondary + tertiary = same length side chains attached to nitrogen, ‘di’ or ‘tri’ alkylamine

-secondary + tertiary = different length side chains attached to nitrogen, prefix = shorter chain with N for position, longest chain = stem + amine e.g. N-methylbutylamine

properties of amines

-act as bases = lone pair of N can accept a H+ from a dilute acid to form a salt = neutralisation
-phenyl amine is a weaker base as the electrons in lone pair are partially delocalised into ring so not fully available to accept H+

if 3 groups bonded to N = neutral

if 4 things bonded to N = 1+ charge

preparation of PRIMARY amines (write equation of CH₃Cl)

reagents = haloalkane + ammonia

conditions = ethanol + excess ammonia - needs to be in excess so the salt is more likely to form from the excess ammonia instead

CH3Cl + 2NH3 → CH3NH2 + NH4Cl

preparation of SECONDARY amines (write equation of CH₃CH₂Cl + 2CH₃CH₂NH₂)

reagents = haloalkane + primary amine

conditions = excess primary amine + ethanol OR can then also use NaOH after

CH₃CH₂Cl + 2CH₃CH₂NH₂ → (CH₃CH₂)₂NH + CH₃CH₂NH₃⁺Cl^-

preparation of AROMATIC amines

reagents = nitrobenzene

conditions = Sn (tin) + conc HCl

-reduction reaction [H], heated under reflux, product collected using NaOH

NO₂ is a 3,5 directing group while NH₂ is 2,4 directing group

amides

-derived from acyl chlorides reacted with ammonia if primary or amine if secondary

-difference with amine - has C=O

-primary, secondary + tertiary = refer to the 1 alkyl group attached to carbon ADD number of alkyl groups attached to nitrogen

properties of amides 

can react as they:
-have lone pair on ammonia/amine

-can behave as nucleophile

-have polar bond on acyl chloride

preparations of amides (write equation for CH₃COCl)

reagents = acyl chloride + excess ammonia/amine

conditions = excess ammonia/amine

CH₃COCl + 2NH₃ → CH₃CONH₂ + NH₄Cl

properties of amino acids (DRAW)

-can behave as acids due to -COOH group and as bases due to -NH₂ group

-soluble in water as they can form hydrogen bonds with both groups

reactions of amino acids

with HCl = NH₂ group reacts to make ammonium salt + halide ion

with NaOH = COOH group reacts to make carboxylate salt + water

with alcohol = COOH group reacts to make ester + water 

(if there is a COOH or NH₂ group on R group it can also react)

optical isomerism of amino acids (DRAW)

.

chiral carbons

-carbon has 4 different groups bonded to it

-pair of isomers for every chiral carbon

addition polymerisation (DRAW ethene → polyethene)

monomers containing alkene functional group are added together by breaking of double bond

condensation polymerisation - FUNCTIONAL GROUPS involved

-COOH or -COCl groups - the OH or Cl atoms are lost

AND

-OH or -NH2 groups - the H atom is lost

condensation polymerisation -PRODUCTS FORMED

-2 possible by products = H2O if COOH or HCl if COCl

-2 types of polymers = polyesters if OH or polyamides if NH2

-when writing balanced equations need to write (2n-1) H₂O or HCl

hydrolysis of polymers

-breaking apart with water

-bond always breaks after C of C=O

in alkali: Na, O, H atoms added on, products = carboxylate salt + alcohol or amine

in acid: H, H, O atoms added on, products = carboxylic acid + alcohol or amine - but acid reacts with amine to form NH₃⁺