Transcript Organic Chemistry PowerPoint

Organic “Carbon” Chemistry
Chapter 13-14
Science 10
CT03D01
Resource:
Brown, Ford, Ryan, IB Chem
Organic “Carbon” Chemistry
Chemistry for you, Lawrie Ryan
Chapter 13
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Pages 159-177
Hydrocarbons, Fossil Fuels, Distillation of
Crude Oil, Cracking, Plastics, Polymers
Chapter 14
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Pages 178-185
Alcohols, Isomers, Ethanol, Alcohol
Reactions, Carboxylic Acids
13.1 - Hydrocarbons
A hydrocarbon is a compound containing only
hydrogen and carbon
Crude Oil, which is very important to the survival
Venezuela is a mixture of many hydrocarbons
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Not only vital for fuels but also the starting materials for
plastics and other polymers
13.1 - Alkanes
The most common hydrocarbon found in crude oil is an
alkane
An alkane contains a ‘backbone’ of single-bonded carbon
atoms and is saturated with hydrogen atoms
Natural gas, methane, CH4, is the shortest alkane
Alkane
Methane, CH4
Ethane, C2H6
Propane, C3H8
Butane, C4H10
Pentane, C5H12
Hexane, C6H14
Heptane, ______
Octane, _______
13.2 – Fossil Fuels
Most common fuels are fossil fuels
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Coal, crude oil, natural gas, etc
Coal, although it’s not a hydrocarbon, does contain
carbon and hydrogen, as well as oxygen in some of
it’s molecules
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From organic material (like trees) that died and were buried
below swamps
Crude oil, hydrocarbons

Formed from tiny animals and plants which lived in the sea
Takes millions of years to form fossil fuels
 In reality the energy comes from the sun to produce
fossil fuels, but it simply takes so long to produce
13.2 – Finding Oil
Crude oil today was made from mainly plankton that died about
150 million years ago. Their bodies did not decay normally due
to lack of oxygen and with high pressures and temperatures,
formed oil and natural gas.
We can find oil by surveying the land and it’s topography
 Look for dome shaped layers (cap rock or anti-cline)
 Seismic survey
13.3 – Distilling Crude Oil
When crude oil reaches the refinery it’s a thick,
black, and smelly liquid

This liquid contains long hydrocarbon chains
At the refinery the long chains can be sorted out into
groups of useful substances called fractions

We can separate these substances by fractional
distillation which separates substances based on their
boiling point
Fraction
Length
Color
Thickness
Reactivity
Low BP (up to
80C)
Short
Clear
Runny
Easily lit (flammable, clean
flame)
Medium BP (80- Medium
150C)
Yellow
Thicker
Harder to light, some smoke
High BP (above
150C)
Dark orange Thick
Long
Difficult to light, smoky flame
13.4 – Fractional Distillation in Industry
Fraction
Length of
Carbon Chain
Petroleum gas
C1-C4
Petrol
C4-C12
Kerosine
C11-C15
Diesel
C15-C19
Lubricating Oil
C20-C30
Fuel Oil
C30-C40
Bitumen
C50 +
13.5 - Cracking
After distillation of crude oil companies are
still left with long hydrocarbons and the
need is for shorter chains like petrol
The solution is cracking meaning big
molecules are broken down by heating
them over a catalyst

This is competed inside a cracker
13.6 - Plastics
When oil companies crack large molecules into
smaller ones, ethene is made

Ethene is just like ethane, but with a double bond making
it unsaturated
vs
ethene

This ethene molecule is the starting material for plastics.
When the double bond is broken, new bonds can form
between several molecules forming polymers
 Lots of small, reactive molecules called monomers join together to
make a polymer
13.7 – Ethene and the Alkenes
Alkenes, which are also hydrocarbons, are very
similar to alkanes, but are not saturated. They
have at least one double bond and less hydrogen
atoms which makes them unsaturated.
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Their names end in –ene instead of –ane
Contain double bonds
Alkane
Methane, CH4
Very reactive
Ethane, C2H6
Building block for polymers
Propane, C3H8
Also react with
 Br, Cl, I, F water
 Strong acids
 Water and sulfuric adid
Alkene
Ethene, C2H4
Propene, C3H6
Butane, C4H10
Butene, C4H8
Pentane, C5H12
Pentene, C5H10
Hexane, C6H14
Hexene, C6H12
Heptane, ______
Heptene, ______
Octane, _______
Octene, _______
13.8 - Polymerization
There are two types of reactions that make
polymers
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Addition – where at least two things simply join
together
Condensation – where water is given off in the
process of joining molecules. Also known as
dehydration synthesis
13.8 – Addition Polymerization
Addition Reactions
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Monomers have at least one double bond
The polymer is the only material formed in the reaction
Easiest example is ethene used to make poly(ethene)
 n C2H4  -[-C2H4-]-n
 Where n = large number

The double bonds open up to form single bonds to the
adjacent monomer
R can be just
about anything
13.9 – Condensation Polymerization
Nylon is an example of a polymer formed through
condensation
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Fumes are given off as the different monomers react
together. These small molecules given off could be H2O,
HCl, etc. It depends on the ends of the monomers.
The monomers have reactive parts at both ends and join
end-to-end to make long chain polymers
+ H2O
13.10 – Properties of Plastics
Many materials are made out of plastics
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PVC piping, bags, surfaces, protective films, bottles, etc
Plastics often have advantages over the use of
metal compounds and cost much less
When we run out of oil we will also run out of
access to cheap plastics
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This is why recycling our plastics is so important!!
Chapter 14 – Organic Molecules
Nomenclature!
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How do we name organic compounds?
 Alkane vs alkene
 Saturated vs unsaturated
 Functional groups
 Length of chain
14.1 – Types of Organics
Types of Organic Molecules
Saturated
•Compounds which contain only single bonds
•For example: alkanes
Aliphatics
•Compounds which do not contain a benzene
ring; may be saturated or unsaturated
•For example: alkanes, alkenes
Unsaturated
•Compounds which contain double or triple
bonds
•For example: alkenes, arenes
Arenes
•Compounds which contain a benzene ring;
they are all unsaturated compounds
•For example: benzene, phenol
14.2 - Members of Homologous
Series
Differ by a CH2
Can be represented by the same
general formula
Show gradation in physical properties
Have similar chemical properties
14.2 - Members of Homologous Series…
… differ by a –CH2 group
14.2 - Members of Homologous Series…
… can be represented by the same general formula
Formula
Name
CH4OH
Methan-1-ol
C2H5OH
Ethan-1-ol
C3H7OH
Propan-1-ol
C4H9OH
Butan-1-ol
C5H11OH
Pentan-1-ol
C6H13OH
Hexan-1-ol
C7H15OH
Heptan-1-ol
C8H17OH
Octan-1-ol
14.2 - Members of Homologous Series…
… show gradation in physical properties
Alkane
Boiling Point
Methane, CH4
-164
Ethane, C2H6
-89
Propane, C3H8
-42
Butane, C4H10
-0.5
Pentane, C5H12
36
Hexane, C6H14
69
Heptane, C7H16
98
Octane, C8H18
125
Since the series differ by one –CH2 they have
successively longer carbon chains
Results in gradual trend of phy. Props
Not always a linear growth
Density and viscosity are other examples
14.2 - Members of Homologous Series…
… show similar chemical properties
As the have the same functional group
Ex.1 – the alcohols have a functional –OH
group, which can be oxidized to form organic
acids
Ex. 2 – the –COOH functional group, present
in the homologous series of the carboxylic
acids, is responsible for the acidic properties
of these compounds
14.3 – Organic Formulas
Emperical formula
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Simplest whole number ratio
Ethane CH3
Molecular formula
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Actual number of atoms
Ethane C2H6
Structural Formula
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Full, condensed, steriochemical
14.3 - Emperical Formula
The simplest whole number ratio of the
atoms it contains. For example, the
emperical formula of ethane, C2H6, is
CH3. This formula can be derived from
percentage composition data obtained
from combustion analysis. It is, however,
of rather limited use on it’s own, as it
does not tell us the actual number of
atoms in the molecule.
14.3 - Molecular Formula
Actual number of atoms of each element
present. For example, the molecular
formula of ethane is C2H6. It is therefore
a multiple of the emperical formula, and
so can be deduced if we know both the
emperical formula and the relative
molecular mass Mr.
14.3 - Full Structural Formula
Graphic formula or displayed formula –
shows every bonded atom. Usually 90o
and 180o angles are used to show the
bonds because this is the clearest 2-D
representation, although it is not the true
geometry of the molecule
14.3 - Condensed Structural Formula
Often omits bonds where they can be
assumed, and groups atoms together.
It contains the minimum information
needed to describe the molecule nonambiguously – in other words there is
only one possible structure that could
be described by its formula.
14.4 – IUPAC Nomenclature
Nomenclature for Organic Compounds:
the IUPAC system
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International Union of Pure and Applied
Chemistry
Rule 1: Identify the longest straight chain of
carbons
Rule 2: Identify the functional group
Rule 3: Identify the side chains or
substituent groups
14.4 - IUPAC Rule 1: Longest Chain
# C atoms in longest Stem in IUPAC name Example
1
meth-
CH4
methane
2
eth-
C2H6 ethane
3
prop-
C3H8 propane
4
but-
C4H10 octane
5
pent-
C5H12 pentane
6
hex-
C6H14 hexane
Note: ‘straight chain’ does not mean just 180o angles or unbranched chains of
carbon atoms. Be careful, do not be confused by the way the molecule may
appear on paper because of free rotation around the carbon-carbon single
bonds. Example, all three below are the same….
15.4 - IUPAC Rule 2: Functional Group
The functional group is described by a
specific ending (or suffix) to the name,
that replaces the –ane ending of the
name of the parent alkane. The suffixes
used for some common functional
groups are in the slides to follow. Those
marked * will have slides with further
information.
14.4 - Functional Groups
Homologous
Series
Suffix in IUPAC
name
Example of
compound
Alkane
-ane
C3H8 propane
Alkene
-ene
CH3CH=CH2
propene
Alcohol
-anol
C3H7OH propanol
chloro, Fluoro,
bromo
chloromethane
Halogen
Functional Group
-Cl -F -Br
14.4 - IUPAC Rule 3: Side Chains
Side Chain
Prefix in
IUPAC
Example of Compound
-CH3
methly-
CH3CH(CH3)CH3
2-methylpropane
-C2H5
ethly-
CH(C2H5)3
3-ethlypentane
-C3H7
proply-
CH(C3H7)3
4-propylheptane
-F , -Cl , -Br ,
-I
fluoro- ,
chloro- ,
bromo- , iodo-
CCl4
Tetrachloromethane
-NH2
amino-
CH2(NH2)COOH
2-aminoethanoic acid
14.5 - Structural Isomers
Different arrangements of the same atoms make
different molecules
Molecular formula shows the atoms that are present
in a molecule, but gives no information on how they
are arranged. Consider, for example, C4H10
Each isomer is a distinct compound, having unique
physical and chemical properties.
14.5 - Structural Isomers of Alkenes
14.6 - Alkanes as Fuels
Release significant amounts of energy when
they burn, highly exothermic, because large
amount of energy released when forming..
Double bonds of CO2
 Bonds in H2O
C3H8 + 5O2  3CO2 + 4H2O ΔH = -2200 kJ/mol
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However, when O2 is limited…..
2C3H8 + 7O2  6CO + 8H2O
when O2 is extremely limited…..
C3H8 + 2O2  3C + 4H2O
These are examples of the incomplete combustion of fossil
fuels which makes them an environmental concern