Chapter 12 Aldehydes and Ketones Irene Lee Case Western Reserve University Cleveland, OH 2004, Prentice Hall Nomenclature of Aldehydes Nomenclature of Ketones An aldehyde has a greater partial positive charge on its carbonyl carbon than does a ketone The carbonyl carbon of an aldehyde is more accessible to the nucleophile Ketones have greater steric crowding in their transition states, so they have less stable transition states Steric factors contribute to the reactivity of an aldehyde Formation of a New CarbonCarbon Bond Using Grignard Reagents Grignard reagents react with aldehydes, ketones, and carboxylic acid derivatives Aldehydes and ketones react with nucleophiles to form addition products: nucleophile addition reactions Nu - Reaction with Acetylide Ions Synthesis Using Cyanohydrin Hydride addition Functional group transformation :H Utilization of DIBAL to Control the Reduction Reaction Imine formation a Schiff base The keto group is protected as a ketal in this synthesis Enolates lithium diisopropylamide LDA LDA is a bulky molecule and this prevents it attacking the carbonyl group in a nucleophilic substitution reaction. Alkylations