Topics for Today

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Welcome Back!
2
Topics for Today

• Gasoline additives (MTBE, ethanol, and
  oxygenates) Part II!

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Readings for Today

• 4.10 Newer fuels and other sources

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Topics for Today

• The other part of crude oil
• Uses of polyethylene

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Readings for Today

• 9.1 Polymers The long, long chain
• 9.2 The Big Six
• 9.3 Addition polymerization
• 9.4 Polyethylene

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Topics for Wednesday

• Where Do We Find Other Addition Polymers?
• PETE (A Polyester)!

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Readings for Today

• 9.2 The Big Six
• 9.3 Addition polymerization
• 9.5 Condensation Polymers

8
Topics for Today

• Gasoline additives (MTBE, ethanol, and
  oxygenates) Part II!

9
2) Less direct impact if spilled
Whats good about using ethanol?
1) Reduced CO emissions
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Problems with ethanol?
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Air Pollution Implications
- means decreased emission means increased
emission
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Problems with ethanol?
1) Air pollution compromise
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Problems with ethanol?
2) We eat corn!
1) Air pollution compromise
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What is ethanol currently made from?
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Reducing supply of sweet corn!
Increased prices of corn
Over the past year, corn prices have doubled!
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Problems with ethanol?
2) We eat corn!
1) Air pollution compromise
3) Energy requirement
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Compared to the energy we get out of the fuel
We would have to use 75 gallons of ethanol to
make 100 gallons
For gasoline, we use 6 gallons.
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For equal volumes of ethanol and gasoline
This leads to reduced gas mileage
Which contains more energy?
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Problems with ethanol?
2) We eat corn!
1) Air pollution compromise
3) Energy requirement
4) More corrosive than gasoline
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Cannot use the same pipelines used to transport
gasoline
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Why do we use fuel additives?
1) To increase the octane number
2) To make a cleaner fuel
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Oxygenate 2
MTBE
An ether

• CH3
• CH3 O C CH3
• CH3

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Alcohol R O H Ether R O R
R some hydrocarbon group (methyl, ethyl, etc)
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Oxygenate 2
MTBE
An ether

• CH3
• CH3 O C CH3
• CH3

Octane rating 116
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Oxygenate 2
MTBE
An ether

• CH3
• CH3 O C CH3
• CH3

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Oxygenates

• CH3
• CH3 O C CH3
• CH3

M methyl T tert or tertiary B butyl E
ether
KNOW
KNOW
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Review
Where have we seen an ether before?
CH3 O CH3

Dimethyl ether
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Name?
Isomers?
CH3 O CH2 CH3

ethyl methyl ether
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Why can MTBE be added at the refinery?
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H H H C C
OH H H
Which is more polar?
CH3
CH3 O C CH3
CH3
Which will better dissolve in gasoline?
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MTBE
Why not?

• Replaced TEL in 1979

Not used much anymore
11 by volume
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Distinct odor at very low levels
Leaks into the ground water
Health effects uncertain
How does it leak into the groundwater?
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Underground Storage Tanks
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Underground Storage Tanks
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Prior to MTBE

• Remove leaking tank,
• Spill some gasoline.
• (insoluble in groundwater)
• Gasoline degrades quickly.

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After MTBE

• Remove leaking tank,
• Spill some gasoline.
• (insoluble in groundwater)
• Gasoline degrades quickly.
• But MTBE persists in the water.

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So far, we have only been focusing on making fuel
from crude oil
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What else can we do with crude oil?
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A closer look
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Where do we find plastics?
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Everywhere!!
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Just the beginning!
Assignment 4 due Wed the 18th!
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Chemically speaking, what are plastics?
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Polymers!!
Really, really big molecules made up of smaller
ones
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Polymers!!
The smaller molecules are called monomers.
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Where have we seen a polymer in Chem 108?
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Cellulose

• A chain (polymer) of glucose molecules.

Glucose C6H12O6
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Cellulose
The monomer is glucose!
Other natural polymers?
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Other natural polymers?
Spider Webs and Silk
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Other natural polymers?
Wool
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Other natural polymers?
Fur and Hair
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Other natural polymers?
Beaks Feathers Claws Fingernails
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Other natural polymers?
Proteins!
Starch!
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Some synthetic (manmade) polymers?
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• Teflon
• Kevlar
• Nylon
• Gore-Tex
• Polyester
• Rayon
• And many, many more!

Other synthetic polymers
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• Polyethylene
• Polypropylene
• Polyvinyl Chloride
• Polystyrene

Other synthetic polymers
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Fig.09.01a
Table 9.1 (p. 401)
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Fig.09.01b
Table 9.1 (p. 401)
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Polyethylene
Table 9.1 (p. 401)
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How do we make PE?
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Polyethylene
Ethylene double bond
Whered the double bond go?
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Monomer for PE
Name?
H
H
How do we get PE from ethene?
C
C
H
H
Ethene (or ethylene) C2H4
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Free Radical Polymerization!1. Initiation
Reaction
H
H
C
C
R.

H
H
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Free Radical Polymerization!1. Initiation
Reaction
H
H
H
H
..
..
..
..
..
..
..
R
C
C
..
C
C.
R.

..
..
..
..
H
H
H
H
Free Radical
Ethylene
New Radical
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Free Radical Polymerization!1. Initiation
Reaction
What happens to a nearby ethylene molecule?
H
H
H
H
..
..
..
..
..
..
..
R
C
C
..
C
C.
R.

..
..
..
..
H
H
H
H
Free Radical
Ethylene
New Radical
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H
H
H
H
..
..
..
..
..
..
R

..
C
C.
C
C
..
..
..
..
..
H
H
H
H
New Radical
Ethylene
H
H
H
H
..
..
..
..
..
..
..
C.
R
C
C
C
..
..
..
..
..
H
H
H
H
Then what happens?
Newer Radical
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Figure 9.5, page 407
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Polyethylene
How else can we write this?
This will go on for 1000s of units
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Polyethylene
Repeating Unit
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Polyethylene
Easier way to write PE!
H
H
C
C
n can be in the 1000s and higher
H
H
n
OR
CH2
CH2
n
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Polyethylene formation

n
H
H
R
CH2CH2
n
C C
H
H
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Addition Polymerization!!

• Initiated by a free radical.
• No by-products!

Animation!
http//chemincontext.eppg.com/chapter9/cic_interfa
ce9.swf
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PE comes in more than 1 form!
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Types of Polyethylene
Figure 9.7 (p. 409)
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Different chemical structures different
chemical properties
Why does HDPE have a slightly higher density?
Branched 0.93 g / mL
Linear 0.96 g / mL