Book Cover Organic Chemistry 4e Carey
Online Learning Center

Chapter 17: Aldehydes and Ketones. Nucleophilic Addition to C=O



Nucleophilic Addition Reactions - Overview | Relative Reactivity | Reduction of Aldehydes and Ketones | Using Carbon Nucleophiles | Using Nitrogen Nucleophiles | Oxygen Nucleophiles | Oxidation Reactions |


Nucleophilic Addition

Chapter 17: Aldehydes and Ketones. Nucleophilic Addition to C=O

 

Nucleophilic addition of aldehydes and ketones
Nucleophilic addition reactions are an important class of reactions that allow the interconversion of C=O into a range of important functional groups.

What does the term "nucleophilic addition" imply ?

A nucleophile, Nu-, is an electron rich species that will react with an electron poor species (here the C=O)
An addition implies that two systems combine to a single entity.
There are three fundamental events in a nucleophilic addition reaction:
  1. formation of the new s bond between the nucleophile, Nu, to the electrophilic C of the C=O group
  2. breaking of the p bond to the O resulting in the formation of an intermediate alkoxide
  3. protonation of the intermediate alkoxide to give an alcohol derivative
Depending on the reactivity of the nucleophile, there are two possible general scenarios:
Addition of strong nucleophiles to aldehydes and ketones

            Examples of such nucleophilic systems are :  RMgX, RLi, RCºCM, LiAlH4, NaBH4
 

Addition of weaker nucelophiles under acidic conditions to aldehydes and ketones
            Examples of such nucleophilic systems are :  H2O, ROH, R-NH2
 
The protonation of a carbonyl gives a structure that can be redrawn in another resonance form that reveals the electrophilic character of the C since it is a carbocation. resonance in a protonated ketone

 

The reactions on the following pages are catalogued based on the nature of the nucleophilic atom involved.
In most cases it is useful to identify the mechanism in each case in terms of the two general schemes presented above.



HOME UP NEXT


Begin a search: Catalog | Site | Campus Rep

MHHE Home | About MHHE | Help Desk | Legal Policies and Info | Order Info | What's New | Get Involved


Copyright ©2000 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use and Privacy Policy.
McGraw-Hill Higher Education is one of the many fine businesses of The McGraw-Hill Companies.
For further information about this site contact mhhe_webmaster@mcgraw-hill.com.


Corporate Link