Transcript Aromatics and Earth`s Crust

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Hydrocarbon Rings
Hydrocarbons From Earth’s Crust
* Beta-carotene is an important nutrient in
carrots that also gives carrots their orange
color. The hydrocarbon skeleton of betacarotene contains hydrocarbon rings. You will
learn about hydrocarbon rings and the
properties of compounds formed from these
rings.
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* 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….
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* Three Ways to Represent 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.
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* 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.
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* 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.
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* What is different about these two benzenes?
*Benzene can be shown as switching, or
resonating, between two arrangements of
alternating double and single bonds.
* 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…
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* 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.
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The molecules of many dyes include
benzene rings.
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*1) Natural Gas
*2) Petroleum
*3) Coal
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* 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)
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* 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
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* 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
*Coal consists largely of condensed
aromatic compounds of extremely
high molar mass.
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* Use this time to complete your Chapter 22
Section Assessments.
* Completed Labs are due today. Turn those in by
the end of class.
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