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22 Cards in this Set
- Front
- Back
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Aliphatic Compound
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An organic compound that is NOT aromatic.
(690) |
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Annulenes
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Cyclic hydrocarbons with alternating single and double bonds.
(694) |
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Aromatic Compound
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A cyclic compound containing some number of conjugated dboule bonds, characterized by an unsually large resonance energy.
1. All its ring atoms must have unhybridized p orbitals that overlap to form a continous ring. 2. must be planar and have (4N+2) pi electrons. 3. Delocalization of the pi electrons over the ring results in a lowering of the electronic energy. |
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Antiaromatic Compound
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Has a continuous ring of p orbitals, but delocalization of the pi electrons over the ring increases the electronic energy.
Must be planar and have 4N pi electrons. (700) |
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Arenes
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Aromatic hydrocarbons, usually based on the benzene ring as a structural unit.
(718) |
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Aryl Group
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The aromatic group tha tremains after taking a hydrogen atom off an aromatic ring; the aromatic equivalent of the generic alkyl group (R).
(718) |
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Benzyl Group
(PhCH2-) |
The seven-carbon unit consisting of a benzene ring and a methylene group.
(718) |
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Degenerate orbitals
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orbitals having the same energy.
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Fused Rings
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Rings that share a common carbon-carbon bond and its two carbon atoms.
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Heterocyclic Compound
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A cyclic compound in which one or more of the ring atoms is not carbon.
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Aromatic heterocycle
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A heterocyclic compound that fulfills the criteria for aromaticity and has a substantail resonance energy.
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Huckle's Rule
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A cyclic molecule or ion that has a continous ring of overlapping p orbitals will be
1. aromatic if the number of pi electrons is (4N+2) 2. antiaromatic if 4N |
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Kekule Structure
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a classical structural formula for an aromatic compound, showing localized double bonds.
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Nonaromatic Compound
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Lacking the continouos ring of overlapping p orbitals
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ortho
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Having a 1,2 relationship on a benzene ring.
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meta
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Having a 1,3 relationship on a benzene ring.
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para
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Having a 1,4 relationship on a benzene ring.
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Phenyl Group (Ph)
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The benzene ring, minus one hydrogen atom, when named as a substituent on another molecule.
(717) |
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Polygon Rule
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The energy diagram of the MOs of a regular, completely conjugated cyclic system has the same polygonal shape as the compound, with one vertex (the all-bonding MO) at the bottom. The nonbonding line cuts horizontally through the center of the polygon.
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Polynuclear aromatic compounds
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Aromatic compounds with 2 or more fused aromatic rings. Naphthalene is an example of a polynuclear aromatic hydrocarbon. And indole is an example of a polynuclear aromatic heterocycle.
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Resonance Energy
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The extra stabilization provided by delocalization, compared with a localized structure. For aromatic compounds, the resonance energy is the extra stabilization provided by teh delocalization of the electrons in the aromatic ring.
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Tropylium ion
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the cycloheptatrienyl cation
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