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17 Cards in this Set
- Front
- Back
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What is a radical?
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An atom missing an octet
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How is radical stability measured?
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bond dissociation energies of cleaved C-H bonds
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What is the substitution rule for stability of radicals?
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primary < secondary < tertiary
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How are radicals formed?
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From covalent bonds by adding energy in the form of heat or light
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Describe the selectivity and reactivity of bromination
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selective, not very reactive
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Describe the selectivity and reactivity of chlorination
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non-selective, quite reactive
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What is the rate determining step in a radical halogenation?
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There IS no determining step.
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Which step determines the product in a radical halogenation?
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The first step.
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Bromination: endothermic or exothermic?
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Endothermic
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Bromination: early or late transition state? Is the product stability important to Ea?
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late; yes
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Chlorination: endothermic or exothermic?
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exothermic
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Chlorination: early or late transition state? Is the product stability important to Ea?
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early; no
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Which is better for a controlled synthesis, chlorination or bromination?
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Bromination. It is more selective and you can get specific products. (unless there is only one possible product of chlorination, in which case it doesn't matter what is used)
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What is special about the reactant N-bromo-succinamide (NBS)?
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It is best to use for allylic bromination, because it only happens once instead of continuing to fill all spots on the molecule.
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What do orbitals have to do with resonance?
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Orbitals overlap, creating delocalized pi bonding which allows electrons to be shared over this pi bond cloud.
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Define the following types of dienes: cumulated, conjugated, and isolated.
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cumulated: both double bonds are to the same carbon
conjugated: double bonds separated only by a single bond, not by a carbon isolated: double bonds separated by a carbon (and therefore also two single bonds) |
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What are the 4 rules for judging stability of resonance structures?
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1.) More bonds and less formal charge = better resonance structure
2.)complete octets = better 3.) negative charge is best on most electronegative atom. positive charge is best on least electronegative atom. 4.)Use other concepts as needed |
