The Alkanes

Uses of Alkanes, Cis/Trans Isomerism, Saturated and

Unsaturated Bonds

The Alkanes• Methane – of all fossil fuels methane is

the cleanest and most efficient. With Greenhouse gases such as CO2 becoming environmentally dangerous, the fact that methane when burned produces 30% fewer Greenhouse emissions than petroleum and 45% less than coal makes it very desirable as a fuel to provide us with electrical energy and transportation.

Alkanes as Fuels• Methane is also called natural gas. It

is odorless and colorless, and an artificial odor must be added to it so it can be smelled in the case of a leak.

Alkanes as Fuels• Methane is also a clean alternative to

other fuels such as octane. Compressed natural gas or CNG is becoming more common for transportation energy.

Methane as Natural GasMethane is produced from oil fields and natural gas

fields. At current usage rates, it is estimated that the earth has over a 1000 year supply of Methane.

The countries in brown are the largest producers of natural gas.

Methane as a Greenhouse GasMethane is considered to

be a greenhouse gas because of its ability to retain heat in the atmosphere. One of the major sources of natural methane is from cattle belching. The organisms in cow stomachs that breakdown the grass eaten release methane, which the cows burp up at an amazing rate of 600 liters per cow per day. This is becoming such a problem worldwide, that a pill has been developed to reduce the belching problem in herbivores.

Propane

• Propane is a byproduct of oil refining. It is most commonly used on outdoor grills, but it is also the third most commonly used vehicle fuel in the united states.

Butane• Butane is most commonly associated

with lighters. However, butanes greatest use is now for refrigerants and aerosol propellants, replacing chlorine based compounds because of their damage to atmospheric ozone.

Octane• Octane which is also known as gasoline or

petroleum because of its energy density, transportability, and relative abundance has been the world’s most important source of energy since the 1950’s. However, because of the rapidly depleting reservoirs of oil, the world will soon have to switch to other forms of energy for heat, transportation and electricity

Saturated and Unsaturated Bonds

Saturated Defined as a single bond in which all of the energy is utilized to hold the atoms together.

UnsaturatedDefined as a double or triple bond which does not use all of the bond energy to hold the atoms together.

Hydrocarbon Compounds and single, double, triple bonds

• Single saturated bonds are much more stable than unsaturated double and triple bonds. Chemists use the double and triple bonds as break points and attachment points to create the many different types of hydrocarbon compounds that we use today

Another situation in which saturated and unsaturated bonds play an important part in our lives is with the fats we eat in our food. Fats come in two varieties, saturated and unsaturated.

Saturated Fats are produced by animals and contain only single bonds along the polymer chain.

Unsaturated Fat is produced by plants and contain multiple double bonds along the polymer chain

Saturated fat is used to fry food with and is solid at room temperature.

Unsaturated fat is also used to cook food with and it is liquid at room temperature.

Fats and the bodyThe human body has a very difficult time breaking down the saturated fats because there is not a point along the polymer chain for the digestive chemicals to interact and break down the polymer. Unsaturated fats on the other hand have multiple double bonds that digestive enzymes react with to break down the polymer chain. If the fat polymer cannot be broken down, it becomes cholesterol and collects on the walls of our arteries creating problems with circulation and heart disease.

Another situation that occurs with food products is cis/trans isomerism. Single bonds allow the branches to rotate around the polymer chain. However double and triple bonds lock the branches in a fixed position and keep them from rotating. With cis isomers, the double bond is unprotected and easily broken by enzymes. The trans isomer protects the double bond and makes it virtually impossible for a chemical interaction to occur with enzymes and for the polymer to be broken down.

Margarine first came out in the 1940’s as a replacement for butter, and later became popular because it supposedly contained no saturated fat since it was made from corn. However, the process that was used to make margarine produced a transfat polymer that was just as difficult to digest as saturated fat. This discovery in the 1990’s changed the process of margarine production so it contained no transfat, and margarine became much easier to digest and much more healthy to eat. This is why virtually all margarine packages have the statement on the box, “contains no trans fatty acids”.