Chapter 21: Ester Enolates

• In some molecules there are H atoms that are adjacent to 2 carbonyl groups (which are electron withdrawing).
• Extra resonance stabilisation of the enolate anion makes these H more acidic (i.e lower pKa) than hydrogens adjacent to a single carbonyl group.
• These type of compounds are sometimes called "active methylenes"  (recall a methylene group is a CH₂)

Some common active methylene compounds are shown below as JMOL images... make sure you can see the acidic active methylene hydrogen atoms...

		Highlight most acidic H
		Highlight most acidic H
		Highlight most acidic H

• As we will see later is this Chapter, these compounds are useful synthetic intermediates.
• Their enolates can be formed readily and can be alkylated, then further manipulated.

© Dr. Ian Hunt, Department of Chemistry