Carbanions and Base-catalyzed Formation of Caron.ppt

文档介绍：Carbanions and Base-catalyzed Formation of Carbon-Carbon Bonds
Formation of carbon-carbon bond
Free radical carbon
Charged or polar carbon
1.
2.
I. Formation and related principle of carbanion ( concepts and mechanisms)
Review
conjugated with other
double bond
shape of the carbanion
Formation of carbanion
pound and H
pound and halides
of halides with metal
of activating H with base
Activating group for the neighboring H
NO2 > COR > CN > CO2R
Strength order of monly used bases:
Factors influencing the stability of carbanions
1. Conjugation
2. Induction
3. Hybridization style
4. Aromaticity
The reactions of carbanions
1. With carbonyl-pounds
2. With alkyl halides
II. Condensations of Carbanions with Aldehydes and Ketones
a) The Aldol Condensation
Mechanism
Ketone
Rate-determining step
Some applications of aldol condensation
Formaldehyde is the most reactive among the aldehydes
One aldehyde containing no active hydrogen:
b) The Claisen Reaction