This phenomenon can explain why acetolysis rates for exo-substituted 2-norbornanes are 350 times greater than those for endo-substituted isomers. For 10 points each:
[10h] Name this phenomenon where a reaction center interacts with a non-conjugated lone pair or bonding electrons in the same molecule. A classic example of this phenomenon is the elevated SN2 rates for nitrogen mustards.
ANSWER: neighboring group participation [or NGP; accept anchimeric assistance]
[10m] In another example of NGP, pi electrons stabilize the 2-norbornyl one of these species, which George Olah isolated using magic acids. These species migrate to achieve more stable configurations in hydride or methyl shifts.
ANSWER: carbocations [accept carbenium ions; accept carbonium ions; prompt on cations or ions]
[10e] The 2-norbornyl cation can be described non-classically using bonds consisting of two electrons distributed over this many centers. Banana bonds are used to model cyclopropane, which has this many carbon atoms.
ANSWER: three [accept three-center two-electron bonds]
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