Cyclic Hydrocarbons
compounds that contain hydrocarbon
rings.
rings of 3 to 20 are found in nature
5 and 6 are most abundant
Naming:
place the prefix cyclo out front
ex - cyclopentane
general formula same as for an alkene
Name each:
cyclooctane C8H16
cyclohexane C6H12
same
cyclobutene C4H6
Benzene C6H6
know this
Resonance - when one or more valid structures can be
drawn. This makes a very stable molecule. Not as reactive
as other 6 carbon alkenes
Benzene is perfectly flat. Bending or twisting disrupts the
double bonds. Chemist often use a circle to show the
resonance in benzene.
terms
Aliphatic compounds
hydrocarbons that do not contain rings
Arenes
unsaturated cyclic hydrocarbons
Aromatic
old name for arenes
used because arenes smell good
now used to describe compounds that
have bonding like benzene
Naming compounds with benzene
If a hydrogen has been replaced with a
substituent, name the substituent
followed by the name benzene.
Examples CH3
CH3
CH3
methylbenzene
1,2-dimthylbenzene
Naming compounds with benzene
If the benzene ring is a substituent of a
carbon chain (an alkyl group) the name
is changed to phenyl.
Example -
C-C-C-C-C
3-phenylpentane
cyclohexane
phenylbenzene
ethylbenzene
1-ethyl-3-propylbenzene
propylbenzene
2-phenylpropane
Natural gas and petroleum
Natural gas and petroleum are 2
important fossil fuels
They contain mostly aliphatic
hydrocarbons
What is the major component of natural
gas?
It is the same gas we use in the lab and
to heat your domicile (home).
Methane - CH4
Combustion reactions (a review)
Complete Combustion
CxHy + O2 --> CO2 + H2O
Incomplete Combustion
CxHy + O2 --> CO2 + H2O + C + CO
You will be expected to be able to write
balanced equations for combustion
reactions.
A combustion reaction
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Petroleum
Crude oil is refined before it is used. We just
don’t use it directly out of the ground.
It is separated on the physical property of
boiling points. This lab technique is called
distillation.
The parts of crude oil are called fractions.
The process of breaking large hydrocarbons
into smaller useful molecules is called
cracking.
Petrochemicals - chemical used to make other
products
oil distillation
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Coal - another important fossil fuel
Coal consists of condensed ring compounds
of extremely high molar mass.
Due to the high proportion of these aromatic
compound, coal leaves more soot. So,
burning petroleum has an environmental
advantage. However, you get more energy
out of coal.
Coal contains sulfur which produces SO2 and
SO3, which in turn makes acid rain.
Coal can be distilled to make
coal gas
hydrogen, methane, carbon monoxide
all are flammable
coal tar
petrochemicals - benzene, toluene (methyl
benzene), napthalene, phenol, pitch
Coke - a fuel used in industry
pure carbon - produces little smoke and burns
with an intense heat
ammonia - cleaning product as well as being
converted to ammonium sulfate for use as a
fertilizer
Wouldn’t it be nice your car ran on water?
watch video
Info for demo. Read it.