38542
Organic nitrogen compounds:
Amines, Amides, A.A, proteins
- Preparation of Amines
- Ammonia heated under pressure with halogenoalkane
- 1-3 H substituted by an aryl or alkyl group
- 1-3 H substituted by an aryl or alkyl group
- Reduction of aromatic nitro-compounds to form aryl amines *
- Reduction of Nitrobenzene using tin and HCl under reflux: -NO2 → NH2
- Cool, +NaOH → redissolve tin(IV) hydroxide
- Steam distillation
- Separate phenylamine and water
- Salting out
- Solvent extraction
- Drying agent: Potassium hydroxide
- Final distillation
- Final distillation
- Drying agent: Potassium hydroxide
- Solvent extraction
- Separate phenylamine and water
- Steam distillation
- Cool, +NaOH → redissolve tin(IV) hydroxide
- Reduction of Nitrobenzene using tin and HCl under reflux: -NO2 → NH2
- Ammonia heated under pressure with halogenoalkane
- Properties
- Aryl amines
- Less volatile, usually liquid
- Dissolve in organic solvents,
only slightly in water
- Less volatile, usually liquid
- Alkyl amines
- H-bond → higher m.p
- Lower members are gases or volatile liquids
- H-bond → higher m.p
- Strong Bases: lone pair on N
- e- shift from alkyl group →
primary alkyl amines better that
ammonia
- aryl amine: e- on N interact with delocalised pi e- → weaker base than NH3
- e- shift from alkyl group →
primary alkyl amines better that
ammonia
- Aryl amines
- Reactions
- NS: With Halogenoalkanes → substituted ammine
- A-E: With AC → N substituted amides
- Condensation polymers: polyamides
- Condensation polymers: polyamides
- Amines form complex ions in similar way to NH3
- ES of phenylamine → 4-aminobenzenesulfonamide
- Sulfonamides destroy bacteria
- Sulfonamides destroy bacteria
- NS: With Halogenoalkanes → substituted ammine
- Amino Acids
- Contain NH2 and COOH and R group
- Acidic and basic properties
- In alkaline soln: acid
- In acidic son: base
- In neutral soln: zwitterion formed
- aa can exist as zwitterions in solid state → high
mp, dissolve in water. Don't dissolve in organic
solvent
- aa can exist as zwitterions in solid state → high
mp, dissolve in water. Don't dissolve in organic
solvent
- In alkaline soln: acid
- 20
- Peptide bond C-N in
condensation
reaction
- Proteins made up of particular sequence of aa
- Can determine structure of protein, e.g. Insulin by Frederick Sanger
- Difficult for chemists to synthesise proteins
- Longer chain = more difficult
- Longer chain = more difficult
- Can determine structure of protein, e.g. Insulin by Frederick Sanger
- Hydrolysis of proteins
- Reflux with d.HCl
- aa neutralised
- aa separated by paper chromatography
- Invisible, so spray with ninhydrin in fume
cupboard and dry → purple spots
- Rf value to identify aa
- Rf value to identify aa
- Sometimes electrophoresis is used
- Invisible, so spray with ninhydrin in fume
cupboard and dry → purple spots
- aa separated by paper chromatography
- aa neutralised
- Reflux with d.HCl
- Optical activity
- Most aa form optical isomers
- aa in living organisms are L enentiomers
- Laboratory synthesis of aa tends to produce
racemic mixture of L and D enantiomers
- Most aa form optical isomers
- Contain NH2 and COOH and R group
- Ecstasy (an amine) causes
release of serotonin and
dopamine in the brain
- Paracetamol
- Phenol is nitrated using H2SO4 and Sodium nitrate
- 2-nitrophenol and 4-nitrophenol
- Fractional distillation
- 4-nitrophenol is reduced → 4-aminophenol
- Using Sodium tetrahydridoborate(III) in alkaline soln
- + ethanoic anhydride →paracetamol
- Using Sodium tetrahydridoborate(III) in alkaline soln
- 4-nitrophenol ↑bp
- 4-nitrophenol is reduced → 4-aminophenol
- 2-nitrophenol and 4-nitrophenol
- No chiral centres → simpler
- Phenol is nitrated using H2SO4 and Sodium nitrate
- Azodyes
- Phenylamine + nitrous acid (made in situ) +HCl
- <5 degrees
- benzenediazonium chloride + water
- Diazonium compound reactions
- NS: N evolved
- Is strong electrophile
- Coupling → strong coloured
compounds, no N produced
- Diazo-compounds are extremely stable and unreactive
- Extensive delocalised
e- system → bright
colours
- Dye
- Dye
- Diazo-compounds are extremely stable and unreactive
- Coupling → strong coloured
compounds, no N produced
- NS: N evolved
- Diazonium compound reactions
- <5 degrees
- Phenylamine + nitrous acid (made in situ) +HCl
- Polymers
- Nylon
- Wallace Hume Carothers
- Made from 2 monomers
- Hexanedioic acid + 1,6-diaminohexane → nylon-6,6
- Obtained via phenol or cyclohexane
- Hexanedioic acid + 1,6-diaminohexane → nylon-6,6
- Uses: tights, carpets, ropes
- Wallace Hume Carothers
- Kevlar
- 1st used in 1970s as a replacement
for steel in racing car tyres
- Resists high temp,
low thermal
conductivity, high
tensile strength,
flame, chemical and
cut resistant
- Uses: cables, tyres, bullet proof vests, ropes, adhesives
- 1st used in 1970s as a replacement
for steel in racing car tyres
- Addition polymerisation
- 2-propanamide → Poly(propanamide)
- Crossed linked → gel which absorbs water → soft contact lenses
- Non-cross-linked → thickener and filler in facial surgery
- Crossed linked → gel which absorbs water → soft contact lenses
- Ester exchange: Poly(ethylethanoate) + methanol → poly(ethanol) + methylethanoate
- Solubility varies
- uses: disposable laundry bags (bags
dissolve in wash cycle), viscoelastic gel
- Solubility varies
- Properties of polyamides
- Links vulnerable to
attack under acidic or
alkaline conditions
- Addition polymers of
just C and H are
difficult to break down
→ pollution
- Links vulnerable to
attack under acidic or
alkaline conditions
- 2-propanamide → Poly(propanamide)
- Nylon
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