Introduction to Substitution

We can use reactions we’ve learned in the past (particularly acid-base reactions) to understand substitution. In fact, substitution is just a category of Lewis acid-base reactions! 

Remember: Nucleophiles always attack electrophiles!

Let’s take a stroll through the reactions we’ve already learned so we can make this connection. 

Bronsted-Lowry Reactions:

Reactions where a nucleophile attacks an electrophile with an acidic hydrogen, and removes it. 

Lewis Reactions:

Reactions where a nucleophile attacks an electrophile without an acidic hydrogen, but with an empty orbital, to yield a covalent bond. 

Substitution Reactions:

Concept: Nucleophiles and Electrophiles can react in Substitution Reactions. 

2m

Reactions where a nucleophile attacks an electrophile without an acidic hydrogen, or an empty orbital, so a covalent bond MUST be broken to preserve the octet of the electrophile.

  • The bond that is broken to allow this reaction to take place makes a leaving group

Example: Predict the product. Identify all of the chemical species in the following reaction. 

6m