1. Ch. 12 - Alkanes (sat’d HCs)

2. Alkanes Acyclic Saturated Hydrocarbons (chains)
General Formula: CnH2n+2
Structural: (ex.: C4H10)
Complete
Condensed
Skeletal
Line Angle
Decomposition of plant and animal matter in marshes is a good source of methane gas.

3. Alkane Nomenclature Methane Ethane Propane Butane Pentane Hexane
Heptane
Octane
Nonane
Decane

4. Alkane Isomerism
Isomers: compounds that share the same molecular formula but have different structural formulas
With an increased number of C atoms, there is an exponentially increased number of isomers
Constitutional - same molecular formula, different structural formula; differ in connectivity of atoms
Ex. C4H10 butane ; isobutane
Ex. C8H18 octane; 3-methyl heptane

5. Alkyl Groups & IUPAC names
Use the following rules to properly name hydrocarbon molecules:
1. Identify the longest, continuous chain of C atoms and name it (parent C chain and suffix.
2. # the C atoms in the chain from the end nearest an alkyl group.
3. # and name the attached alkyl group(s).
4. If more than one alkyl group:
1st substituent must have lower number.
Alkyl groups are listed in alphabetical order.
If two or more identical substituents are bonded, use prefixes to indicate how many
5. Separate #s from each other with commas; separate names from numbers with hyphens; do not use a hyphen/space after the last substituent, before the parent alkane name.
Carbons are classified 4 ways in a chain:
Primary, secondary, tertiary, quaternary
Based on the # of C atoms to which the carbon atom is bonded.

6. Branched-chain Alkyl Groups
“Simple”: 4 important ones to know!
Complex: “select the longest chain as the “base” alkyl, add “substituents.”
Ex.

7. Cycloalkanes

8. Isomerism of Cycloalkanes
Constitutional (ex.: C5H10) 5 isomers
Stereoisomers: possible with substituted cycloalkanes (ex.: 1,2-Dimethylcyclohexane)
Cis- (SAME side)
Trans- (ACROSS from)

9. Sources of Saturated Hydrocarbons
Natural Gas:
Methane (50-90%)
Ethane (1-10%)
Propane & Butane (up to 8%)
Petroleum (crude oil): this is a complex mixture of both cyclic and acyclic hydrocarbons which can be separated by a process known as fractional distillation.

10. Physical Properties of Hydrocarbons
All are insoluble in water
Consider the polarity of the compounds
Therefore they can make good protective coatings
All are less dense than water ( g/mL)
Oil & water
Boiling Points & States of Matter
Generally, BP increases with increasing # C atoms
Reason: increasing LDF
1-4 C atoms = gas; 5-17 C atoms = liquid; >17 C atoms = solid
Isomers: Branched BP < Unbranched BP
Cyclic Compounds have higher BP than Acyclic.

11. Chemical Properties of Hydrocarbons
Alkanes are the least reactive organic compounds (they have no fcn’l groups). However, two major reactions are common:
Combustion
R (some hydrocarbon) + O2 → CO2 + H2O + energy
very exothermic reaction.
If the quantity of O2 is insufficient, it will form a poison called carbon monoxide (CO).
Here is an example with methane:
CH4 + 2 O2 → CO2 + 2 H2O
with less O2:
2 CH4 + 3 O2 → 2 CO + 4 H2O (poison!)
with even less O2:
CH4 + O2 → C + 2 H2O (black soot forms)
Halogenation
R-H + X2 --> R-X + H-X

12. Hydrocarbon fuels
Fossil fuels (solid, liquid, or gas) form from organic material being covered by successive layers of sediment over millions of years
Oil & natural gas: slow decomposition & burying of marine phytoplankton & zooplankton that sank to the sea floor. 
Coal: ancient swamps and bogs - slow decomposition of land plants in anaerobic conditions:
e.g. peat bogs of Ireland
Fossil fuels supply over 80% of the world’s energy needs .All fossil fuels, whether solid, liquid, or gas, are the result of organic material being covered by successive layers of sediment over the course of millions of years. Oil and natural gas were formed from the slow decomposition and burying of planktonic marine plants and animals that sank to the muds of the sea floor. 
World crude oil reserves are estimated at more than one trillion barrels, of which the 11 OPEC Member Countries hold more than 75 per cent.
According to the reference case of OPEC's World Energy Model (OWEM), total world oil demand in 2000 is put at 76 million barrels per day, As world economic growth continues, crude oil demand will also rise to 90.6m b/d in 2010 and 103.2m b/d by 2020.
Oil provides about 40 percent of the energy Americans consume and 97 percent of U.S. transportation fuels.

13. Petroleum, Naphtha, or crude oil
From Greek petra = rock and oleum = oil
Thick, dark brown or greenish liquid
Complex mixture of various hydrocarbons,
largely of the alkane series
May vary much in appearance, composition, and
purity
Petroleum is also the raw material for many chemical products: fuels & solvents
Can be altered into: fertilizers, pesticides, and plastics
Think of the impact of a substantial oil crisis on our economy & society!
Crude oil is pumped from the ground in the Middle East (e.g., Saudi Arabian Arab Light), West Africa (e.g., Nigerian Bonny Light), the Americas, and Asia (Russia)
Crude oils and most of their distillation products are extremely complex mixtures of organic chemicals with hydrocarbons being the most numerous and abundant (comprising more than 75 percent of most crude and fuel oils). Over 200 hydrocar­bons, 90 sulfur‑containing organic compounds, and 33 nitrogen‑contain­ing organic compounds are present in crude oils. In addition, there are porphyrins, sulfur, trace metals, and residues called asphaltenes in many crude oils. Crude oils and most crude oil products contain a series of n‑alkanes with chain lengths of carbon atoms numbering between 1 and 60. The ratio of abundance of odd chain lengths to even chain lengths is approximately 1.0. A series of branched alkanes are also present including isoprenoid alkanes such as pristane, farnesane, and phytane, naphthenes (cyclic alkanes with or without side chains), aromatic hydrocarbons (ranging from alkyl substituted benzenes and naphthalenes to poly­nuclear aromatic structures), and naphthenoaromatics (naphthenes joined with aromatic ring systems). Alkenes (olefins) are not usually present in crude oils but they are formed in some refining processes and are present in some refined products.
A widely believed myth is that the oil itself is flammable, however it is actually the gas that evaporates from the oil that is flammable. Petroleum exists in the upper strata of some areas of the Earth's crust. Another name is naphtha, from Persian naft or nafátá (to flow).

14. A rock formation such as this is necessary for the accumulation of petroleum and natural gas.

15. Crude Oil History 1st oil wells drilled in China in 4th century depth
up to 800 ft.
Drilled using bits attached to bamboo poles
Burned oil to evaporate brine & produce salt.
10th century, bamboo pipelines connected oil
wells with salt springs.
The first oil wells were drilled in China in the 4th century or earlier. They had depth of up to 800 feet and were drilled using bits attached to bamboo poles. The oil was burned to evaporate brine and produce salt. By the 10th century, extensive bamboo pipelines connected oil wells with salt springs. Ancient Persian tablets indicate the medicinal and lighting uses of petroleum in the upper echelons of their society.
In the 8th century, the streets of the newly-constructed Baghdad were paved with tar, derived from easily-accessible petroleum from natural fields in the region. In the 9th century, oil fields were exploited in Baku, Azerbaijan, to produce naphtha. These fields were described by the geographer Masudi in the 10th century, and by Marco Polo in the 13th century, who described the output of those wells as hundreds of shiploads. (See also: Timeline of Islamic science and technology.)
The modern history of oil began in 1853, with the discovery of the process of oil distillation. Crude oil was distilled into kerosene by Ignacy Lukasiewicz, a Polish scientist. The first "rock oil" mine was created in Bobrka, near Krosno in southern Poland in the following year and the first refinery (actually a distillery) was built in Ulaszowice, also by Lukasiewicz. These discoveries rapidly spread around the world, and Meerzoeff built the first Russian refinery in the mature oil fields at Baku in 1861.
Oil field in California, 1938
The first modern oil well was drilled in 1848 by Russian engineer F.N. Semyenov, on the Aspheron Peninsula north-east of Baku.
The first commercial oil well drilled in North America was in Oil Springs, Ontario, Canada in 1858, dug by James Miller Williams. The American petroleum industry began with Edwin Drake's discovery of oil in 1859, near Titusville, Pennsylvania. The industry grew slowly in the 1800s, driven by the demand for kerosene and oil lamps. It became a major national concern in the early part of the 20th century; the introduction of the internal combustion engine provided a demand that has largely sustained the industry to this day. Early "local" finds like those in Pennsylvania and Ontario were quickly exhausted, leading to "oil booms" in Texas, Oklahoma, and California.

16. Ancient Persian tablets indicate the medicinal and lighting uses
of petroleum in the upper society.
8th century: streets of Baghdad paved with tar.
In the 9th century, oil fields were exploited in Baku, Azerbaijan, to produce naphtha.

17. Discovery of oil in 1859, near Titusville, Pennsylvania.
Great demand for kerosene and oil lamps.
Medicinal purposes, lighting, and lubricants for new steam engines.
Introduction of internal combustion engine lead to
major "oil booms" in Texas,
Oklahoma, and California.
The modern history of oil began in 1853, with the discovery of the process of oil distillation. Crude oil was distilled into kerosene by Ignacy Lukasiewicz, a Polish scientist. The first "rock oil" mine was created in Bobrka, near Krosno in southern Poland in the following year and the first refinery (actually a distillery) was built in Ulaszowice, also by Lukasiewicz. These discoveries rapidly spread around the world, and Meerzoeff built the first Russian refinery in the mature oil fields at Baku in 1861.
Oil field in California, 1938
The first modern oil well was drilled in 1848 by Russian engineer F.N. Semyenov, on the Aspheron Peninsula north-east of Baku.
The first commercial oil well drilled in North America was in Oil Springs, Ontario, Canada in 1858, dug by James Miller Williams. The American petroleum industry began with Edwin Drake's discovery of oil in 1859, near Titusville, Pennsylvania. The industry grew slowly in the 1800s, driven by the demand for kerosene and oil lamps. It became a major national concern in the early part of the 20th century; the introduction of the internal combustion engine provided a demand that has largely sustained the industry to this day. Early "local" finds like those in Pennsylvania and Ontario were quickly exhausted, leading to "oil booms" in Texas, Oklahoma, and California.

18. Fractional Distillation
The complex hydrocarbon mixture present in petroleum is separated into simpler mixtures by means of a fractionating column.
Differences in BPs of
hydrocarbon chains
can separate out
sections of
the crude oil:
Fractional Distillation
Crude oil is measured in barrels. When crude oil first came into large-scale commercial use in the United States in the 19th century, it was stored in wooden barrels. One barrel equals 42 US gallons, or 159 litres.
Cracking reactions
"Cracking" breaks larger molecules into smaller ones. This can be done with a thermic or catalytic method. The thermal cracking process follows a homolytic mechanism, that is, bonds break symmetrically and thus pairs of free radicals are formed. The catalytic cracking process involves the presence of acid catalysts (usually solid acids such as silica-alumina and zeolites) which promote a heterolytic (asymmetric) breakage of bonds yielding pairs of ions of opposite charges, usually a carbocation and the very unstable hydride anion. Carbon-localized free radicals and cations are both highly unstable and undergo processes of chain rearrangement, C-C scission in position beta (i.e., cracking) and intra- and intermolecular hydrogen transfer or hydride transfer. In both types of processes, the corresponding reactive intermediates (radicals, ions) are permanently regenerated, and thus they proceed by a self-propagating chain mechanism. The chain of reactions is eventually terminated by radical or ion recombination.
Here is an example of cracking with butane CH3-CH2-CH2-CH3
1st possibility (48%): breaking is done on the CH3-CH2 bond.
CH3* / *CH2-CH2-CH3
after a certain number of steps, we will obtain an alkane and an alkene: CH4 + CH2=CH-CH3
2nd possibility (38%): breaking is done on the CH2-CH2 bond.
CH3-CH2* / *CH2-CH3
after a certain number of steps, we will obtain an alkane and an alkene from different types: CH3-CH3 + CH2=CH2
3rd possibility (14%): breaking of a C-H bond
after a certain number of steps, we will obtain an alkene and hydrogen gas: CH2=CH-CH2-CH3 + H2

19. Residential heating oil 34.74 149,690 Gasahol 28.06 120,900 93 to 94
Fuel type    
Mega Joules / Liter 
BTU / US gal   
Research octane #
Gasoline
29.0
125,000
91 to 98
Diesel fuel oil
32.19
138,690
N/A
Residential heating oil
34.74
149,690
Gasahol
10% ethanol
90% gasoline
28.06
120,900
93 to 94
fuel type    MJ/L    BTU/imp gal    BTU/US gal    Research octane number (RON)
LPG , ,
Ethanol , ,
Methanol , ,

20. Octane: major component of gasoline
Octane is an alkane hydrocarbon:CH3(CH2)6CH3.
octane isomer: 2,2,4-Trimethylpentane = 100 pts
on the octane rating scale
n-heptane is the zero point (greatest engine knocking
or “pinging”)
Octane ratings are used to represent antiknock
performance (less premature combustion)
Octane is an alkane hydrocarbon with the chemical formula CH3(CH2)6CH3. It has many isomers.
One of the isomers, iso-octane or 2,2,4-Trimethylpentane, is of major importance, as it has been selected as the 100 point on the octane rating scale, with n-heptane as the zero point. Octane ratings are ratings used to represent the anti-knock performance of petroleum-based fuels (Octane is less likely to prematurely combust under pressure than heptane), given as the percentage of 2,2,4-trimethylpentane in an 2,2,4-trimethylpentane / n-heptane mixture that would have the same performance. It is an important constituent of gasoline.

21. Natural gas
Natural gas mainly methane (does contain other “small” HC cpds).
Highly flammable
No ash and very little air pollution.
From light portion of petroleum
Rises thru fissures in earth’s crust
Man-made wells can tap it
Discovered thousands of years ago could be burned for heat and light.
Colorless, odorless, & lighter than air.
Mercaptan, chemical odorant, is added for gas leaks.
natural gas combustion  CO2 + H2O
Natural gas found in different underground formations: shale, sandstone beds, coal seams, & deep, salt water aquifers
Gas is a collective term for one of three types of matter. The other two are solid and liquid. Gas has no set shape or volume. Solids have well defined shapes and are difficult to compress. Liquids are free flowing and bounded by self-formed surfaces. Gases expand to fill their containers and have a lower density than liquids or solids.
Natural gas is clean burning, easy to transport, convenient to use, and in abundant supply. It can be used:
in the home for heating, hot water and cooking,
commercially for catering, drying and heating purposes,
industrially for manufacturing and processing,
for power generation in power station turbines and cogeneration plants, and
in transportation as a fuel for vehicles such as buses.
Natural gas is found in porous rock formations beneath the surface of the earth. Natural gas should not be confused with, liquified natural gas (LNG), liquified petroleum gas (LPG), or town gas.
Liquified natural gas (LNG), is made by chilling natural gas to minus 160 C. It is then stored in special cylinders which makes shipping LNG to other countries an easier task.
Liquified petroleum gas (LPG) is a by-product of oil and gas production. LPG is made of propane or butane or a mixture of these gases. These turn into liquid under pressure and are then stored in cylinders or tanks. When the pressure is released, the liquid becomes a gas. Each year Australia exports one million tonnes of LPG.
Town gas
In the olden days, town gas, often called manufactured or coal gas, was often made by baking coal in large airtight ovens (gas retorts). The gas bubbles from the hot coals were piped off and used as a household fuel. Natural gas has replaced town gas.
Properties and characteristics
Natural gas is non-toxic before combustion, and the exhaust product from approved appliances is also non-toxic, provided equipment is properly maintained.
Natural gas is comprised of mostly methane (approx. 85%-90%) and lesser amounts of ethane (5%-15%), carbon dioxide (2%), nitrogen (1%-2%) and propane (0.2%).
The natural gas flammability range - air/gas volume ratio - varies between 5:1 and 15:1. For stoichiometric combustion the air/gas volume is 9.91:1.
Natural gas has an approximate auto-ignition temperature in air of 537°C - 680°C (dependent on air /gas composition and atmospheric pressure) and a flame speed of 0.4 metres per second. Natural gas has a relative density to air of 0.62.
Natural gas was formed millions of years ago when most of the earth was covered by water. Plant and tiny animal remains were mixed and layered with sand and mud. When the Earth underwent natural but drastic changes to form today’s landscape, the intense heat and pressure transformed these fossils into hydrocarbons—chemical compounds of hydrogen and carbon atoms. Natural gas is made up mainly of a chemical called methane, a simple, compound that has a carbon atom surrounded by four hydrogen atoms. Methane is highly flammable and burns almost completely. There is no ash and very little air pollution. Depending on the arrangement of the atoms, what were once sea plants and animals are now natural gas or crude oil deposits contained in the earth’s crust. Natural gas (a combustible, gaseous mixture of simple hydrocarbons) is a very light portion of petroleum, which includes both natural gas and crude oil. Natural gas may rise to the surface through natural openings in the earth’s crust or can be brought to the surface through man-made wells. Humans discovered thousands of years ago that this naturally occurring resource could be burned and used for heat and light.
In its natural state you can’t see or smell natural gas. It is colorless, odorless and lighter than air. Mercaptan, a chemical odorant, is added to natural gas so it can be smelled if it leaks. Natural gas is made up mostly of methane, which has a simple hydrocarbon structure of one carbon atom and four hydrogen atoms (CH4). This means it burns easily and emits less pollution. When natural gas is burned, it produces mostly carbon dioxide and water vapor.
Natural gas can be found in a variety of different underground formations, including: shale formations, sandstone beds, coal seams, and deep, salt water aquifers (underground ponds of water).

22. New sources of methane gas: Decomposition of organic
matter in landfills
CH4 gas can be tapped
instead of vented

23. Kivu Lake 3 lakes contain large concentrations of dissolved CO2 gas.
Lake Nyos & Lake Monoun sites of gas
explosions: 40 dead at Monoun & 1800 at Nyos
3rd lake is Kivu,
which contains
a 1,000x more
gas than Lake Nyos.
3 lakes in the world containlarge concentrationsof dissolved gas.
Lake Nyos & Lake Monoun in Cameroon sites of gas explosions 40 deaths at Monoun and 1800 at Nyos.
3rd lake is Kivu, which contains a 1,000x more gas than Lake Nyos.

24. Coal formation Vegetable matter accrues Prevented from decay
Forms peat beds.
Over time: buried &
compressed, forms lignite.
Increased P & T makes bituminous coal (higher C content).
At great depths, high temps
reduce CH4 & forms
anthracite (very high in C)
Coal is derived from the accumulation of partially decayed land plants. As the sediment solidifies into rock, the organic material decomposes under the influence of great pressure and high temperature. The burning of fossil fuels for energy is a major source of air pollution, contributing in particular to acid rain and the greenhouse effect.

25. What about as China and India modernize?
Current
Consumption?
What about as China and India
modernize?
These countries have 33% of world population!
Fossil Fuel “Facts”
                                         
Source: Shell Oil
The U.S. has 4% of the World's population.
The U.S. uses 34% of Earth's natural resources.

26. U.S. Sources of Energy Production Fossil Fuels 86% Geothermal 0.5%
Nuclear 8%
Wind Farms 0.1%
Hydroelectric 2%
Solar 0.1%
Biofuels 3.3%
source:
US Dept of Energy
Remember that, while hydrocarbons serve as a transportation fuel, they are also used to produce plastics, etc.
Enormous dependence on a limited resource.
Other alternatives?
-Wave energy
-Tidal energy
-New technology for solar panels, turbines, etc.
-Conservation!!
-Efficiency!!!

27. Problems associated with alkane hydrocarbons
Hydrocarbon pollution: (oil spills) of aquatic environments (e.g. BP in the Gulf of Mexico)
Global warming: CO2 and H2O
Acid rain due to sulfur impurities in oil and coal: damage crops, lakes, buildings, etc.
Smog and soot: increase respiratory problems
Land fill: non-decomposing plastics
Ozone depletion / increased UV radiation
The greenhouse gases
Water vapor (H2O) causes about 60% of Earth's naturally-occurring greenhouse effect. Other gases influencing the effect include carbon dioxide (CO2) (about 26%), methane (CH4), nitrous oxide (N2O) and ozone (O3) (about 8%). Collectively, these gases are known as greenhouse gases.
the residence time for water vapor in the atmosphere is short (about a week) so perturbations to water vapor rapidly re-equilibriate. In contrast, the lifetimes of CO2, methane, etc, are long (hundreds of years) and hence perturbations remain. Thus, in response to a temperature perturbation caused by enhanced CO2, water vapor would increase, resulting in a (limited) positive feedback and higher temperatures. In response to a perturbation from enhanced water vapor, the atmosphere would re-equilibriate due to clouds causing reflective cooling and water-removing rain

28. Accidental & Purposeful Oil Spills
Clean-up takes into account density and non-polar nature

29. Global warming: The Greenhouse effect:
Short wavelength
solar radiation
releases energy
as it hits molecules.
Turns into long
wavelength energy.
Gases in atmosphere
trap it and warm the atmosphere.
Many of the hottest years on record are recent ones.
Sea levels are slowly increasing, threatening cities such as Venice, Italy
Sea level as measured at San Francisco, California, USA.
     
Coastal ocean temperatures are so high that sea corals are being killed globally.
Glaciers are in retreat all over the world.
In Canada, polar bears are starving because Hudson's Bay is ice-free too long each year so they cannot catch enough seals to survive.
Also in Canada, river temperatures are so high now that salmon are being killed on their way to their spawning grounds - thus killing off the salmon FOREVER. (* NEW *)
Frogs are dying all over the world - not just a few frogs here and there but WHOLE SPECIES are dying off FAST.
Plants are germinating earlier and earlier and moving farther and farther North.
Louisiana (USA) is losing land at a rate of about 25 square miles per year.
This effect has now been shown to be primarily due to subsidence of
the land.  A new NOAA report  says that the northern part of the Gulf
of Mexico is sinking at a rate of 60 inches per century or about 0.6 inches
per year (whereas sealevel is only rising by 8 inches per century).   (* NEW *)
The Arctic and Antarctic are warming.
Increases in droughts and forest fires.
Animal ranges are changing due to changes in the local climates.
Temperature hit 100 in London (August 10, 2003) for the first time in recorded history.
Over 90% of the ice shelf north of Ellesmere Island (Canada) is gone.
Alaska data
Average temperature has risen 7 degrees in the last 30 years.
The sea level around Alaska has risen a foot in the last century.
The permafrost is melting - which is causing buildings to sink into the mud.
98% of glaciers & sea ice are melting.
Scary pictures of the northern polar regions in 1979 & 2000 
Polar ice has been decreasing by 1% per year since 1979.

30. Arctic ice sheet 1979 and 2000
CO2 increase correlates to average global temperature increase
Can cause: changes in sea level,
reduction of reflective ice caps,
increased storm ferocity,
plant & animal re-distribution,
shift ocean currents, create
droughts & forest fires, increased
short-term temperature fluctuations.

31. Alkane substitution reaction: Incoming atom or group of atoms (orange sphere) replaces a hydrogen atom in the alkane model.
Naming:
Treat halogen atoms like alkyl groups.
F = fluoro; Cl = chloro; Br = bromo; I = iodo
Ex.: CH3-CHBr-CHBr-CHI-CH2-CH3

32. Halogenation Reactions
General equation: RH + X2 → RX + HX
Hydrocarbon + Halogen  Halogenated + acid (diatomic) hydrocarbon
Ex. CH4 + Cl2 --> CH3Cl + HCl
Highly exothermic reaction: can lead to an explosion
Halogenation reaction
RH + X2 → RX + HX
These are the steps when methane is chlorinated. This is a highly exothermic reaction that can lead to an explosion.
1. Initiation step: splitting of a chlorine molecule to form two chlorine atoms. A chlorine atom has an unpaired electron and acts as a free radical.
Cl2 → Cl* / *Cl energy provided by UV.
2. Propagation (two steps): a hydrogen atom is pulled off from methane then the methyl pulls a Cl from Cl2
CH4 + Cl* → CH3* + HCl
CH3* + Cl2 → CH3Cl + Cl*
This results in the desired product plus another Chlorine radical. This radical will then go on to take part in another propagation reaction causing a chain reaction. If there is an excess of Chlorine, other products like CH2Cl2 may be formed.
3. Termination step: recombination of two free radicals
Cl* + Cl* → Cl2, or
CH3* + Cl* → CH3Cl, or
CH3* + CH3* → C2H6.
The last possibilty in the termination step will result in an impurity in the final mixture; notably this results in an organic molecule with a longer carbon chain than the reactants.

33. The process can continue to alter the resulting products as long as the halogen remains in sufficient quantities to drive further reactions. (The halogen would be the __________ reactant.)

34. Space-filling models of the four ethyl halides.
Do these molecules act as polar or non-polar?

35. Chlorofluorocarbons (CFCs)
Developed in the 1930's
Very stable compounds composed of C, F, Cl, & H
Freon is the tradename:
Trichlorofluoromethane
Dichlorodifluoromethane
Chlorofluorocarbons (CFCs) are a family of chemical compounds developed back in the 1930's as safe, non-toxic, non-flammable alternative to dangerous substances like ammonia for purposes of refrigeration and spray can propellants. Their usage grew enormously over the years. One of the elements that make up CFCs is chlorine. Very little chlorine exists naturally in the atmosphere. But it turns out that CFCs are an excellent way of introducing chlorine into the ozone layer. The ultraviolet radiation at this altitude breaks down CFCs, freeing the chlorine. Under the proper conditions, this chlorine has the potential to destroy large amounts of ozone. This has indeed been observed, especially over Antarctica. As a consequence, levels of genetically harmful ultraviolet radiation have increased.
Chlorofluorocarbons (CFCs) are highly stable compounds that are used as propellents in spray cans and in refrigeration units. They are several organic compounds composed of carbon, fluorine, chlorine, and hydrogen. CFCs are manufactured under the trade name Freon (q.v.). 
Developed during the 1930s, CFCs found wide application after World War II. These halogenated hydrocarbons, notably trichlorofluoromethane (CFC-11, or F-11) and dichlorodifluoromethane (CFC-12, or F-12), have been used extensively as aerosol-spray propellants, refrigerants, solvents, and foam-blowing agents. They are well-suited for these and other applications because they are nontoxic and nonflammable and can be readily converted from a liquid to a gas and vice versa.
Chlorofluorocarbons or CFCs (also known as Freon) are non-toxic, non-flammable and non-carcinogenic. They contain fluorine atoms, carbon atoms and chlorine atoms. The 5 main CFCs include CFC-11 (trichlorofluoromethane - CFCl3), CFC-12 (dichloro-difluoromethane - CF2Cl2), CFC-113 (trichloro-trifluoroethane - C2F3Cl3), CFC-114 (dichloro-tetrfluoroethane - C2F4Cl2), and CFC-115 (chloropentafluoroethane - C2F5Cl).
CFCs have been found to pose a serious environmental threat. Studies undertaken by various scientists during the 1970s revealed that CFCs released into the atmosphere accumulate in the stratosphere, where they had a deleterious effect on the ozone layer. Stratospheric ozone shields living organisms on Earth from the harmful effects of the Sun's ultraviolet radiation; even a relatively small decrease in the stratospheric ozone concentration can result in an increased incidence of skin cancer in humans and in genetic damage in many organisms. In the stratosphere the CFC molecules break down by the action of solar ultraviolet radiation and release their constituent chlorine atoms. These then react with the ozone molecules, resulting in their removal.
CFCs have a lifetime in the atmosphere of about 20 to 100 years, and consequently one free chlorine atom from a CFC molecule can do a lot of damage, destroying ozone molecules for a long time. Although emissions of CFCs around the developed world have largely ceased due to international control agreements, the damage to the stratospheric ozone layer will continue well into the 21st century.
Trichloro-trifluoroethane
Dichloro-tetrfluoroethane
Chloropentafluoroethane

36. Safe, non-toxic,
non-flammable
alternative to
dangerous
substances
(e.g. ammonia)
for aerosol-spray
propellants,
refrigerants,
solvents, and
foam-blowing agents

37. CFCs and refrigeration
propellants

38. UV radiation in
the stratosphere

39. The Ozone Layer Chemistry
CFCl3 + UV Light ==> CFCl2 + Cl
Cl + O3 ==> ClO + O2
ClO + O ==> Cl + O2
The chlorine free radical atom
is then able to attack another
ozone molecule
and again ...
and again... thousands of times!
A catalyst!
One billion years ago, early aquatic organisms called blue-green algae began using energy from the Sun to split molecules of H2O and CO2 and recombine them into organic compounds and molecular oxygen (O2). This solar energy conversion process is known as photosynthesis. Some of the photosynthetically created oxygen combined with organic carbon to recreate CO2 molecules. The remaining oxygen accumulated in the atmosphere, touching off a massive ecological disaster with respect to early existing anaerobic organisms. As oxygen in the atmosphere increased, CO2 decreased.
 High in the atmosphere, some oxygen (O2) molecules absorbed energy from the Sun's ultraviolet (UV) rays and split to form single oxygen atoms. These atoms combined with remaining oxygen (O2) to form ozone (O3) molecules, which are very effective at absorbing UV rays. The thin layer of ozone that surrounds Earth acts as a shield, protecting the planet from irradiation by UV light. 
The amount of ozone required to shield Earth from biologically lethal UV radiation, wavelengths from 200 to 300 nanometers (nm), is believed to have been in existence 600 million years ago. At this time, the oxygen level was approximately 10% of its present atmospheric concentration. Prior to this period, life was restricted to the ocean. The presence of ozone enabled organisms to develop and live on the land. Ozone played a significant role in the evolution of life on Earth, and allows life as we presently know it to exist.Ozone is produced naturally in the stratosphere when highly energetic solar radiation strikes molecules of oxygen, O2, and cause the two oxygen atoms to split apart in a process called photolysis.

40. The ozone destruction process requires conditions cold enough (-80oC) for stratospheric clouds to form. Once these stratospheric clouds form the process can take place, even in warmer conditions
As temperatures in the lower stratosphere cools below -80'C, Polar Stratospheric Clouds (PSC's) start to form.
In the area over Antarctica, there are stratospheric cloud ice particles that are not present at warmer latitudes. Reactions occur on the surface of the ice particles that accelerate the ozone destruction caused by stratospheric chlorine. Polar regions get a much larger variation in sunlight than anywhere else, and during the 3 months of winter spend most of time in the dark without solar radiation. Temperatures hover around or below -80'C for much of the winter and the extremely low antarctic temperatures cause cloud formation in the relatively ''dry''stratosphere. These Polar Stratospheric Clouds (PSC's) are composed of ice crystals that provide the surface for a multitude of reactions, many of which speed the degredation of ozone molecules.  This phenomenon has caused documented decreases in ozone concentrations over Antarctica.
In fact, ozone levels drop so low in spring in the Southern Hemisphere that scientists have observed what they call a "hole" in the ozone layer. The ozone destruction process requires conditions cold enough for stratospheric clouds to form. Once these stratospheric clouds form the process can take place, even in warmer conditions.
It was first noticed by a research group from The British Antarctic Survey in the 1970's. Joseph Farman, Brian Gardiner and Jonathan Shanklin, are the BAS scientists who discovered the Antarctic ozone hole. In the 1980's the first measurements of this loss were actually documented. In 1984, when the British first reported their findings, October ozone levels were about 35 percent lower than the average for the 1960s. When the first measurements were taken the drop in ozone levels in the stratosphere was so dramatic that at first the scientists thought their instruments were faulty.
The U.S. satellite Nimbus-7 quickly confirmed the results, and the term Antarctic ozone hole entered popular language. More recently an ozone hole has appeared over the North Pole. The ozone hole appeared first over the colder Antarctic because the ozone-destroying chemical process works best in cold conditions. The Antarctic continent has colder conditions than the Arctic, which has no land-mass. As the years have gone by the Ozone Hole has increased rapidly and is as large as the Antarctica continent. The hole lasts for only two months, but its timing could not be worse. Just as sunlight awakens activity in dormant plants and animals, it also delivers a dose of harmful ultraviolet radiation. After eight weeks, the hole leaves Antarctica, only to pass over more populated areas, including The Falkland Islands, South Georgia and the tip of South America. This biologically damaging, high-energy radiation can cause skin cancer, injure eyes, harm the immune system, and upset the fragile balance of an entire ecosystem.  News about the ozone hole that forms over Antarctica each October has spread around the world. The ozone hole can be as big as 1.5 times larger than the United States.
However, less-well-known is that ozone depletion has been measured everywhere outside the tropics, and that it is, in fact, getting worse. in the middle latitudes (most of the populated world), ozone levels have fallen about 10% during the winter and 5% in the summer. Since 1979, they have fallen about 5% per decade when averaged over the entire year. Depletion is generally worse at higher latitudes, i.e. further from the Equator.

41. Ozone consumption has been greatly reduced,
however CFCs may linger for another
150 years in the atmosphere
1997
ozone
hole
2003
ozone
hole
Ozone layer thickness

42. What do you need to know (about saturated hydrocarbons)?
Structural characteristics (know the functional group)
Substituents
Nomenclature (the rules for naming the molecules)
Physical and Chemical properties (basic/simple)
Occurrence and uses (common)
Preparation (what basic reactions produce the molecules)
Characteristic reactions of the molecules