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Hydrocarbon Rings. Chemistry 122/121. Cyclic Hydrocarbons. Both saturated and unsaturated hydrocarbons may be found in the form of a ring The resulting structure has two less hydrogen than its straight chain counterpart Butane = C 4 H 10 Cyclobutane = C 4 H 8. Aromatic Hydrocarbons.
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Hydrocarbon Rings Chemistry 122/121
Cyclic Hydrocarbons • Both saturated and unsaturated hydrocarbons may be found in the form of a ring • The resulting structure has two less hydrogen than its straight chain counterpart • Butane = C4H10 • Cyclobutane = C4H8
Aromatic Hydrocarbons • Historically, these compounds all had an odor associated with them • They may contain a single ring or group of rings • Benzene is the simplest aromatic • all examples of aromatics have a structure comparable to benzene • Another name for them are arenes
The Structure of Benzene • Benzene is a six carbon ring with a hydrogen atom attached to each carbon • This leaves each carbon available to make a double bond • A maximum of three double bonds can form within the ring • As a result, two diagrams can be written to represent all the places a double bond can exist within benzene • Page 710
Resonance • As a result of double bonds being found in more than one place, the bonding e- between carbon atoms are shared evenly around the ring • Resonance allows the structure to be more stable • Benzene is less reactive than its alkene counterpart
Substituted Aromatic Hydrocarbons • Compounds that contain substituents attached to a benzene ring are called derivatives of benzene • When the benzene ring is the substituent, it is called a phenyl group • Benzene rings that have two substituents are called disubstituted benzenes • The positions of the substituents can be in the 1, 2 (ortho), 1,3 (meta), or 1,4 (para) position
For the remainder of class… • Complete Guided Reading 22.4 • Practice Problems – use to review • Interpreting Graphics – 22.4