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Topics for Today Gasoline additives (MTBE, ethanol, and oxygenates) Part II!

Readings for Today 4.10 Newer fuels and other sources

Topics for Today The “other” part of crude oil Uses of polyethylene

Readings for Today 9.1 Polymers: The long, long chain 9.2 The “Big Six” 9.3 Addition polymerization 9.4 Polyethylene

Topics for Wednesday Where Do We Find Other Addition Polymers? PETE (A Polyester)!

Readings for Today 9.2 The “Big Six” 9.3 Addition polymerization 9.5 Condensation Polymers

Topics for Today Gasoline additives (MTBE, ethanol, and oxygenates) Part II!

What’s good about using ethanol? 1) Reduced CO emissions * 2) Less direct impact if spilled

Problems with ethanol?

Air Pollution Implications CO (tons / day) NO x (tons / day) VOCs (tons / day) Emissions compared to today means decreased emission + means increased emission

Problems with ethanol? 1) Air pollution compromise

Problems with ethanol? 1) Air pollution compromise 2) We eat corn!

What is ethanol currently made from?

Reducing supply of sweet corn! Increased prices of corn Over the past year, corn prices have doubled!

Problems with ethanol? 1) Air pollution compromise 3) Energy requirement … 2) We eat corn!

For gasoline, we use 6 gallons. Compared to the energy we get out of the fuel… We would have to use 75 gallons of ethanol to make 100 gallons

For equal volumes of ethanol and gasoline Which contains more energy? This leads to reduced gas mileage…

Problems with ethanol? 1) Air pollution compromise 3) Energy requirement … 4) More corrosive than gasoline 2) We eat corn!

Cannot use the same pipelines used to transport gasoline

Why do we use fuel additives? 1) To increase the octane number 2) To make a cleaner fuel

Oxygenate #2 CH 3 | CH 3 – O – C – CH 3 | CH 3 An ether MTBE

Alcohol R – O – H Ether R – O – R R = some hydrocarbon group (methyl, ethyl, etc…)

Oxygenate #2 CH 3 | CH 3 – O – C – CH 3 | CH 3 An ether MTBE Octane rating = 116

Oxygenate #2 CH 3 | CH 3 – O – C – CH 3 | CH 3 An ether MTBE

Oxygenates M = methyl T = “tert” or tertiary B = butyl E = ether CH 3 | CH 3 – O – C – CH 3 | CH 3 KNOW

Review: Where have we seen an ether before? CH 3 – O – CH 3 Dimethyl ether

CH 3 – O – CH 2 – CH 3 Name? ethyl methyl ether Isomers?

Why can MTBE be added at the refinery?

CH 3 | CH 3 – O – C – CH 3 | CH 3 H H | | H – C – C – OH | | H H Which is more polar? Which will better dissolve in gasoline?

MTBE Replaced TEL in 1979 ~11% by volume Not used much anymore… Why not?

Leaks into the ground water… Health effects uncertain Distinct odor at very low levels How does it leak into the groundwater?

Underground Storage Tanks…

Prior to MTBE Remove leaking tank, … Spill some gasoline. (insoluble in groundwater) Gasoline degrades quickly.

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

So far, we have only been focusing on making fuel from crude oil…

What else can we do with crude oil?

A closer look…

Where do we find plastics?

Everywhere! !

Just the beginning! Assignment #4 due Wed the 18 th !

Chemically speaking, what are plastics?

Polymers!! Really, really big molecules made up of smaller ones

Polymers!! The smaller molecules are called monomers.

Where have we seen a polymer in Chem 108?

Cellulose A chain (polymer) of glucose molecules. Glucose: C 6 H 12 O 6

Cellulose The monomer is glucose! Other natural polymers?

Spider Webs and Silk

Other natural polymers? Wool

Other natural polymers? Fur and Hair

Beaks Feathers Claws Fingernails Other natural polymers?

Proteins! Other natural polymers? Starch!

Some synthetic (manmade) polymers?

Teflon Kevlar Nylon Gore-Tex Polyester Rayon And many, many more! Other synthetic polymers

Polyethylene Polypropylene Polyvinyl Chloride Polystyrene Other synthetic polymers

Fig.09.01a Table 9.1 (p. 401)

Fig.09.01b Table 9.1 (p. 401)

Polyethylene Table 9.1 (p. 401)

How do we make PE?

Polyethylene Ethylene = double bond… Where’d the double bond go?

Monomer for PE CC HH H H Name? Ethene (or ethylene) C 2 H 4 How do we get PE from ethene?

Free Radical Polymerization! 1. Initiation Reaction CC H H H H R.R. +

CC H H H H R.R. +.. CC.C. HH HH R Free Radical EthyleneNew Radical

Free Radical Polymerization! 1. Initiation Reaction CC H H H H R.R. +.. CC.C. HH HH R Free Radical EthyleneNew Radical What happens to a nearby ethylene molecule?

CC.C. HH HH.. R New Radical CC H H H H +.. Ethylene CC HH HH.. R C HH HH C.C. Newer Radical Then what happens?

Figure 9.5, page 407

Polyethylene This will go on for 1000s of units… How else can we write this?

Polyethylene Repeating Unit

Polyethylene CC HH HH n Easier way to write PE! “n” can be in the 1000s and higher OR CH 2 n

Polyethylene formation [ ]n]n –CH 2 –CH 2 – n C = C H HH H R·R·

Addition Polymerization!! Initiated by a free radical. No by-products! Animation !

PE comes in more than 1 form!

Types of Polyethylene Figure 9.7 (p. 409)

Why does HDPE have a slightly higher density? Different chemical structures = different chemical properties… Linear ~0.96 g / mL Branched ~0.93 g / mL