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18 Cards in this Set
- Front
- Back
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How would you describe the pie bonds in benzene?
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Delocalized - no longer localized in specific double bonds between two particular carbon atoms. They are spread out over all six atoms.
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What is it called when two cdouble bonds are separated by just one single bond?
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The two bonds are said to be ocnjugated.
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In order to have a conjugated system, do the double bonds have to be with carbons?
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No; the C=C and the C=O are conjugated in propenal, for example.
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In propane, which carbon(s) would a nucleophile most likely attack?
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The end carbons, because most electron density is on the central carbon, which means the end carbons are more positively charged.
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If a single electron is left from a bond breaking homolytically, what type of orbital can it be found in?
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The single electron would be in a p-orbital, because the carbon atom becomes trigonal, (sp^2), hybridized. The single electron in the p-orbital could overlap and combine with the pie bond.
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Show the delocalization of the carboxylate anion.
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B-13
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Show the delocalizaton of the amide group.
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B-14
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As compounds become more conjugated, does the energy transition between HOMO and LUMO become greater or smaller?
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Smaller
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As compounds become more conjugated, the energy transition between HOMO and LUMO becomes greater. Therefore, can it absorb light with a longer or shorter wavelength?
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Longer wavelength, which carries less energy
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If the conjugation of a compound is extended far enough, why does it become colored?
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The gap between HOMO and LUMO becomes sufficiently decreased to allow the comound to absorb visible light and, hence, be colored.
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What is process called by which a double bond is converted to a single bond due to the addition of H?
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Reduction
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What is the stabilization called that allows aromatics to adopt planar structure, despite the strain of being planar?
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The extra stabilization is called aromaticity.
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What is hydrogenation?
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The process by which unsaturated C=C double bonds are reduced using hydrogen gas and a catalyst, (usually nickel or palladium), to produce fully saturated alkanes.
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What are molecular orbitals considered degenerate?
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When different molecular orbitasl have exactly the same energy.
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What are annulenes?
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Compounds with alternating doulbe and single bonds.
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What is Huckel's Rule?
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PLanar, fully-conjugated, monocyclic systems with (4n+2)pie electrons have a closed shell of electrons all in bonding orbitals and are exceptionally stable. Such systems are said to be aromatic.
Analogous systems with 4npie electrons are described as anti-aromatic. |
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In terms of trans and cis, what conformation do annulenes take on?
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Trans-trans-cis
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Most aromatic systems are heterocyclic. What does this mean?
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Heterocyclic means they involve atoms other than carbon and hydrogen.
(A carbon is replaced by a heteroatom within the ring, as in pyridine.) |
