1) Hydrocarbon Rings

2) Hydrocarbons From Earth’s Crust

*Chapter 22.4-22.5

*1) Hydrocarbon Rings

*Beta-carotene is an important nutrient in carrots that also gives carrots their orange color. The hydrocarbon skeleton of beta-carotene contains hydrocarbon rings. You will learn about hydrocarbon rings and the properties of compounds formed from these rings.

*Hydrocarbon Rings

*Within some hydrocarbons… they contain a chain of carbons that have formed a ring.

*Cyclic Hydrocarbons: hydrocarbons that contain a hydrocarbon ring.

*Predict how a hydrocarbon could form a ring…. Say butane or pentane….

*Three Ways to Represent Cyclic Hydrocarbons

*Cyclic Hydrocarbons

*The simplest is a 3 ring hydrocarbon.

*Rings containing up to 20 carbon atoms are found in nature.

*The most abundant are rings that contain 5 or 6 carbons.

*Aromatic Compounds

*These compounds are responsible for the aromas of spices such as vanilla, clove, cinnamon, and ginger.

*They are named this because of the pleasant aromas they give off

*NOT ALL aromatic compounds have an aroma. Though.

*Aromatic Compound

*Any compound that contains a benzene ring is an aromatic compound.

*Benzene Basic Structure: In a benzene molecule, the bonding electrons between carbon atoms are shared evenly around the ring.

*What is different about these two benzenes?

*Benzene can be shown as switching, or resonating, between two arrangements of alternating double and single bonds.

*Resonance

*If there are two (or more) equally valid structures for a molecule, resonance occurs.

*Benzene and other molecules that have resonance are VERY stable. More stable than molecules that do not have resonance.

*Show the resonance of Benzene…

*Substituted Aromatic

Compounds

*Compounds with a substituent on a benzene ring are named as a derivative of benzene. When benzene is a substituent, it is called a phenyl group.

*Aromatic Compounds

The molecules of many dyes include benzene rings.

*2) Hydrocarbons from Earth’s

Crust

*1) Natural Gas

*2) Petroleum

*3) Coal

*1) Natural Gas

*Natural gas is an important source of alkanes and aliphatic carbons of low molar mass.

*Aliphatic Carbons contain no benzene rings.

*The most important component of natural gas, methane, burns with a clean, hot flame.

*Other common: propane and butane (grills and lighters)

*2)Petroleum

*More complex hydrocarbons found in petroleum than in natural gas.

*It contains MANY types that need to be separated for it to be useful.

*We can refine it by distilling it into fractions according to the boiling points of the hydrocarbons. (See next slide)

*Next, we use cracking where hydrocarbons are broken down…. https://www.youtube.com/watch?v=Xsqlv4rWnEg

*2) Petroleum

*3) Coal*Coal is classified by its carbon content and

hardness.

* Hardness of coal tends to increase with higher carbon content.

*Lignite ~50% carbon

*Bituminous 70–80% carbon

*Anthracite >80% carbon

*3) Coal

*Coal consists largely of condensed aromatic compounds of extremely high molar mass.

*The rest of class…

*Use this time to complete your Chapter 22 Section Assessments.

*Completed Labs are due today. Turn those in by the end of class.