Question

Which is a better electrophile: aldehydes, ketones, or carboxylic acids?

Answer 1

The best electrophile here is the aldehyde.

Explanation:

Both aldehydes and ketones feature the electrophilic carbonyl group. The aldehyde `RC(=O)H` is much less sterically encumbered than the ketone, `RC(=O)R'`. On the other hand, a carboxyl group can be converted into a more potent electrophile by reaction with thionyl chloride to give the acid halide:

`RC(=O)OH + SO_2Cl rarr RC(=O)Cl + SO_2 + HCl`