InfoCoBuild

CHEM 125B - Freshman Organic Chemistry II

Lecture 08 - Solvent, Leaving Group, Bridgehead Substitution, and Pentavalent Carbon. The nature of nucleophiles and leaving groups has strong influence on the rate of S_N2 reactions. Generally a good nucleophile or strong base is a poor leaving group, but hydrogen-bonding solvents can alter nucleophile reactivity. Although amino and hydroxyl groups are poor leaving groups, they may be converted to groups that leave easily, even from bridgehead positions. Designing the preparation of a sugar analogue containing radioactive fluorine shows how understanding the S_N2 mechanism enables PET scanning for medical imaging. Quantum mechanics suggests that the pentavalent carbon species on the S_N2 reaction pathway is a transition state, not a stable structure. (from oyc.yale.edu)

Go to the Course Home or watch other lectures: