a Halogenation Base-promoted halogenation of ketone. ·Base is consumed. Other products are water and chloride ion. OH H Chapter 22 11
Chapter 22 11 Halogenation • Base-promoted halogenation of ketone. • Base is consumed. • Other products are water and chloride ion. OH _ O H H O H _ O H Cl Cl Cl =>
Multiple Halogenations The a-halo ketone produced is more reactive than ketone. Enolate ion stabilized by e-withdrawing halogen. OH,H2O Chapter 22 12
Chapter 22 12 Multiple Halogenations • The -halo ketone produced is more reactive than ketone. • Enolate ion stabilized by e- -withdrawing halogen. O H Cl Cl2 OH , H2O _ O Cl Cl O Cl C Cl l O Cl C Cl l Cl =>
Haloform Reaction Methyl ketones replace all three H's with halogen. The trihalo ketone then reacts with hydroxide ion to give carboxylic acid. -OH O &-o HCI3 lodoform, yellow ppt. => Chapter 22 13
Chapter 22 13 Haloform Reaction • Methyl ketones replace all three H’s with halogen. • The trihalo ketone then reacts with hydroxide ion to give carboxylic acid. Iodoform, yellow ppt. => C O CH3 excess I2 OH - C O CI3 OH - C O OH CI3 - C O O - HCI3