Zusammenfassung der Ressource
Benzene
and
amine
- Benzene
- Benzene is an aromatic
compound with a formula
of C6H6.
- It has a cyclic planar
strucuture
- Each Carbon has a free electron on its p subshell and
these electrons form a ring of delocalized electrons
above and below the benzene. They are free to
move.
- If benzene did have three double
bonds, it would be called
cyclohexa-1,3,5-triene, but this doesn't
actually exist.
- Reasons why it does not have
3 double bonds which C6H6 is
meant to have
- 1. All of its bond lengths are the same
of 140 pm, unlike the length of a
double bond.
- 2. If it had double bonds, it would have no
delocalized electrons as there would be C=C
bonds where the e-'s would remain.
- 3. The enthalpy of cyclohexene
(has 1 double bond) is -120 kJ/mol.
If benzene had 3 double bonds,
you would expect its enthalpy to
be 3 times higher of -360 kJ/mol.
- But benzene has a bond enthalpy of -208
kJ/mol, so it cannot have double bonds.
- Finally, if benzene had 3 double
bonds, it would undergo electrophilic
addition.
- But it undergoes electrophilic substitution.
- Naming benzene
- If a halogen, an alkyl group, or a
nitrate ion (NO2-) is joined to benzene, the
functional group will be the prefix
and benzene is the suffix.
- For example, nitrobenzene.
- However, if an hydroxyl group (OH), an amine
group (NH2, an acyl group or an alkene is
joined to benzene, phyl- or phenol will be the
prefix and the group willl be suffix.
- Two types of
electrophilic
substitution.
- Friedel-Crafts
acylation
- This is when you add an acyl
group (-C(=O)R-). R is just an
alkyl group.
- This has to be done under
reflux and using AlCl3 as a
catalyst
- The products are a
phenylketone and
Hydrochloric acid.
- Nitration
- You just need to add a
nitronium ion to a
benzene ring to
replace a Hydrogen.
- To form the nitronium ion,
mix nitric acid with sulfuric
acid.
- You will get HSO4-, NH2+
and water.
- The sulfuric acid acts as a
catalyst. it reforms by the
following reaction:
- H+ + HSO4- makes H2SO4.
- This process can be used
to make TNT explosives.
- Amines
- Naming them is
easy.
- If it is primary, secondary or
tertiary amine, alkyl goes at
the front and the suffix is
amine.
- If it has more than one functional group,
the prefix goes in alphabetical order
- There can also be
quarternary ammonium ions.
- Methylamine, propylamine, decylamine,
decylpentylamine etc.
- Cationic surfactants are
compounds which are
partially soluble and
insoluble in water.
- These are ammonium salts with a long
hydrocarbon chain.
- The long chain is insoluble and the
ammonium head is soluble.
- This allows them to be
used in detergents to
remove grease
- Bases
- Amines can act as bases
as they have a lone pair of
e-'s on the Nitrogen
- The availability of the lone pair depends
on the alkyl group which pushes it so it is
more available...
- ... Or the benzene ring which attracts
the lone pair by it e- ring, making it
less available.
- Amides
- These are basically carboxylic
acids but with the o-H group
replaced at the end by NH2
- The amide is always the suffix
and the prefix depends on the
acyl(R-C=O) group.
Anmerkungen:
- If there are 3 carbon, the prefix would be propan-, if there is four, butan- etc.
- Prpanamide, pentanamide,
decanethanamid