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Amines - Coggle Diagram
Amines
Structure
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diamine
compound containing 2 amino groups
(remember e e.g. butane-1,4-diamine)
Boiling Point
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amines ability
to H bond
2° lower BP
- still form H bonds
- but each N atom only 1 H atom which can form H bonds
or
- N bonded to 2 alkyl groups
- ∴ less available to H bond
3° even lower BP
- H bonding IMPOSSIBLE
- aren't ANY H atoms attached directly to N
- only held by VDW
or
- less likely to H bond
- N bonded to 3 alkyl groups
- ∴ even less available to H bond
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Preparation
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Prep of
Phenylamine
overall
- reducing nitrobenzene
- w tin + conc HCl
STAGE 1
- nitrobenzene reduced
- by refluxing
- with tin + conc HCl
- produces phenylammonium salt
(containing C6H5NH3+ ion)
STAGE 2
- treated w NaOH solution
- liquid phenylamine released
- STEAM DISTILLATION = gets phenylamine
- (can decompose close to its BP)
- steam = allows phenylamine to boil off @ lower temp
method
1.nitrobenzene & granulated tin
- added to flask
- w/ reflux condenser
2.conc hydrochloric acid added
- flask heated in
boiling water bath
4.flask cooled in water
- apparatus moved = form
Steam Distillation
- phenylamine only slightly soluble in water
- most separates as oily drops in distilled water
- salt added (get more phenylamine)
- SHAKE
- ether added to distillate + SHAKE
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6.layers allowed to separate
- lower aq layer run off + discarded
- ether layer run into conical flask
7.powdered potassium hydroxide added to flask
- left in until ether = CLEAR
- mix filtered + ether distilled off
9.remaining phenylamine steam distilled
- fraction BP 180-185°C collected
conditions
- tin + conc HCl
- heat under reflux
- addition of conc NaOH solution
(liberate amine from its salt)
Solubility
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as size of alkyl group increases
amines become less soluble in water
- long hydrocarbon chain
- force way between H2O molecules
- hinders formation of hydrogen bonds
solubility decreases
- primary
- secondary
- tertiary
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Physical
Properties
amines with low molecular mass
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