Organic Chemistry: Reactivity levels

[thatgirlyouknow]

This is a general Organic Chemistry question. How do the reactivities of the following compare?

Acyl Chlorides, Esters, Anhydrides, Amides, Ketones, Aldehydes

The Attempt at a Solution

I know the following "ladder:"

MOST REACTIVE

acyl chloride
anhydride
ester
amide

LEAST REACTIVE


I know also that aldehydes are more reactive than ketones. However, where do those two fit in according to the ladder layout?

Thank you!

 

[chemisttree]

Well acetone is certainly less reactive than an amide.

 

[naele]

It really depends what type of reaction you're considering. Simple nucleophilic addition to the carbonyl vs acyl substitution.

 

[thatgirlyouknow]

Well the reactions we've been doing have concerned creating amides, reducing them, and reactions with carboxylic acids. Mostly substitution/elimination stuff, I suppose. This also falls in line with Gabriel synthesis, Mannich reactions, etc.

Is there not just a general rule here?

 

[naele]

Well, if you're considering a substitution at a carbonyl, or more specifically, a beta elimination driven by carbonyl reformation. It's a good idea to look at the Pka of the leaving groups.
R^- ~ 50
NH₂ ~ 35
RO^- ~ 16
RCO₂^- ~ 5
Cl^- ~ -7

On the other hand, if you're just considering nucleophilic addition to the carbonyl, then electronic and steric effects are what you compare.