Section C: Petroleum as a Building Source

• In this section we study:– Common hydrocarbon “builder molecules” and– Some materials made from them

Section C.1: Creating New Options: Petrochemicals

• Petrochemicals – compounds produced from oil and natural gas

• Some petrochemicals are used directly: detergents, pesticides, pharmaceuticals & cosmetics

• Most are raw materials - mostly in plastics: paints, fabrics, rubber, insulation, foams, adhesives, etc.

• Only a few builder molecules are used to make 1000’s of new substances.

Section C.1: Creating New Options: Petrochemicals (continued)

• 1 key builder molecule is ethene, or ethylene

H H H H| | | |C==C + H–OH H–C–C–H | | | |H H H OHEthene Water Ethanol (addition reaction)

• Easily reacts due to double bond

Section C.1: Creating New Options: Petrochemicals (continued)

• Ethene can react with itself (500-20,000 times): H H H H H H H H H H | | | | | | | | | | n C=C -C-C-C-C-C-C- -(-C-C-)-n | | | | | | | | | | H H H H H H H H H HEthene (a monomer) Growing polymer chain Polyethene (a polymer)

• This reaction is an addition polymer

Section C.1: Creating New Options: Petrochemicals (continued)

• Many polymers can be created monomers that resemble ethene:

H H H H H H H H H H H H H H H H| | | | | | | | | | | | | | | |C=C(-C-C-C-C-C-C-)n C=C(-C-C-C-C-C-C)n| | | | | | | | | | | | | | | |H Cl H ClH ClH Cl H CN H CNH CNH CNVinyl chloride Polyvinyl chloride Acrylonitrile Polyacrylonitrile (a monomer) (a polymer) (a monomer) (a polymer)

• Also, styrene and polystyrene (benzene atom)

Section C.2 –Beyond Alkanes

• Carbon atoms bond with 4 other atoms (alkanes/saturated), they can also bond with 3 other atoms (alkenes/unsaturated)

• Carbon to carbon bonding like in Ethene is a double covalent bond and better building blocks – unsaturated prefer a 4th atom

• Different atoms(1) and arrangements of like atoms(2) dramatically changes the substance:

1. Oxygen, nitrogen, chlorine or sulfer

2. C2H6O (grain alcohol) & C2H6O2 (antifreeze)

Section C.3 (lab) – The Builders

• Alkene names are like alkane names: ethene, propene, butene, etc.

• No methene as must have 2 Carbon atoms.

• 1-butene, double bond is between 1st & 2nd, 2-butene, double bond is between 2nd & 3rd.

Section C.4 –More Builder Molecules

• Two new classes of compounds (rings): – Cyclohexane for nylon: a cycloalkane, saturated– Aromatic compounds: unsaturated, benzene is

simplest. No surprise – has a pleasing smell.

Cyclohexane Benzene

or

CH2

CH2 CH2

CH2

CH2

CH2

CH

CH CH

CH

CH

CH

Section C.4 –More Builder Molecules (continued)

• Oddly, the double bonds in benzene are not reactive. Evidence is that bonds are =, not alternating. Electrons are shared equally with all 6 carbon atoms!

• So… we draw benzene:

• Petroleum has few aromatic compounds, but many are made by cracking and fractionating.

• Dye and drug industries are based on aromatics

Section C.5 – Builder Molecules Containing Oxygen

Section C… More to come

• More to come…

• For more on diamonds, buckey balls, etc see: http://users.omskreg.ru/~kolosov/atlas/3D-crystals/bonding.html