CHEM 3A Study Guide - Midterm Guide: Racemic Mixture, Stereocenter, Hyperconjugation
Document Summary
Stability of radicals: tertiary > secondary > primary, because of hyperconjugation (def: unfilled/partially-filled orbitals interact with filled orbitals) more potential for mixing causes a lowering of the energy. H = bonds broken bonds formed (negative = exothermic, positive = endothermic) Hammond"s postulate: if ts looks like reactants, exothermic. Bromine/chlorine: highly favor tertiary site of attack, fluorine: whichever. Resonance stabilization stabilized bases/radicals and is more powerful than hyperconjugation. This is why allylic carbons are favored for sites of attack, even with less substitution! Radical a and b are constitutional isomers of each other (bond connectivity is different) Stereoisomer: same connectivity, different orientation in space: geometric: isomers (cis/trans, diasteromers: stereoisomers that are not mirror images different. At least one but not all sc"s are flipped: enantiomer: nonsuperimposable mirror images of each other same. Can tell apart with plane polarized light enantiomers rotate light in equal magnitude and opposite direction. B (top) and b (bottom) are stereoisomers.
