amines, amino acids and polymers Flashcards
amines are derived from…
ammonia
2 types of amines
aliphatic
aromatic
aliphatic amine
nitrogen attached to at least one straight or branched carbon chain
aromatic amine
nitrogen attached to at least one aromatic carbon ring
why do amines behave as bases?
lone pair of electrons on N atom can accept a proton, forming dative covalent bond
amine + acid ->
salt and water
formation of primary aliphatic amines
- ammonia (nucleophile) undergoes substitution reaction with haloalkane, producing ammonium salt
- ammonium salt then reacted with excess ammonia to generate amine
conditions required for formation of primary aliphatic amines
- ethanol as solvent to prevent further substitution of haloalkane with water to produce alcohols
- excess ammonia used to reduce further substitution of amine group to form secondary + tertiary amines
2 overall stages for formation of primary aliphatic amines
- salt formatin
- amine formation
formation for secondary and tertiary amines
- primary amine reacted with haloalkane, and undergoes substitution as it still has a lone pair of electrons on N
2 overall stages for formation of secondary and tertiary aliphatic amines
- salt formation
- amine formation
production of aromatic amines
- form ammonium salt by reacting nitrobenzene under reflux with tin + HCl
- react w excess NaOH to produce phenylamine
why is methylamine a stronger base than ammonia?
- alkyl group (-CH3) pushes electrons away, making the charge on the N more negative, therefore meaning H-ions can be attracted more easily
- ion formed is more stable, as alkyl group spreads positive charge through molecule
why is phenylamine a weaker base than ammonia?
- lone pair on N touches and partially dissociates into electron ring of phenol, and becoming delocalised with them, meaning the pair cannot fully combine with H-ions, intensity of charge is decreased
- if lone pair joins to H-ion, there must be a disruption in delocalisation (making the molecule more unstable) which requires energy + doesn’t occur easily
amino acid
substance containing both amine and carboxylic acid functional groups
how many amino acids in the body
20
what is an α-amino acid
an amino acid where amine group is attached to α-carbon (2nd carbon atom, next to carbonyl group)
general amino acid formula
RCH(NH2)COOH
why do amino acids have reactions similar to both acids and amines?
because they contain both carb. acid and amine functional groups
3 main reactions of amino acids
- w. HCl
- w. aqueous alkalis
- w. alcohols
product of reaction between amino acid and HCl
ammonium salt
product of reaction between amino acid and aqueous alkali
salt and water
product of reaction between amino acid and alcohol
ester and water
amide
product of reaction between acyl chloride w. ammonia and amines
chiral center
a carbon atom attached to 4 different atoms/groups of atoms
optical isomers
2 non-superimposable mirror image structures
how many optical isomers for a chiral carbon
1 pair
only α-amino acid which doesn’t contain a chiral carbon
glycine - H2NCH2COOH
condensation polymerisation
joining of monomers with loss of a small molecule, usually water or hydrogen chloride
how many functional groups needed for condensation polymerisation
2
polyesters
2 monomers joined by ester linkages
2 ways of making a polyester
- 1 monomers, containing both carb acid and alcohol functional group
- 2 monomers, one containing carb acid group and the other containing alcohol group
why is lactic acid a good monomer to use in making polyesters?
it is derived from maize, making it more sustainable then polymers from fossil fuels
2 monomers needed for polmerisations of polyesters
- 1 diol - 2 hydroxyl groups
- 1 dicarboxylic acid - 2 carboxylic acid groups
uses of polyesters (3)
- clothing
- electrical insulation
- plastic bottles
polyamides
monomers joined together by amide linkages
2 ways of making a polyamide
- 1 monomers, containing both carb acid/acyl chloride and amine functional group
- 2 monomers, one containing carb acid/acyl chloride group and the other containing amine group
how to hydrolyse condensation polymers
using hot aqueous alkali or acid
ligand
molecule/ion which can donate a pair of electrons to the transition metal ion
coordination number
total number of coordinate bonds formed between central metal ion and ligands
stereoisomer
same molecular formula, different arrangement in space
enantiomer
2 non-superimposable mirror image structures (same as optical isomer)
type of reaction making aromatic amine from benzene
reduction
