Second Trimester
Lesson 23: Aldehydes, Ketones, Alpha Carbon Chemistry, and Final Exam Review
Aldehydes and Ketones: Aldehydes (R-CHO) and ketones (R-CO-R') are characterized by the presence of a carbonyl group (C=O). They participate in various reactions due to the electrophilicity of the carbonyl carbon, making it susceptible to nucleophilic attack. Key reactions include nucleophilic addition (forming alcohols and other derivatives), oxidation (aldehydes to carboxylic acids), and reduction (to form alcohols). Aldehydes, with at least one hydrogen attached to the carbonyl carbon, are generally more reactive than ketones, which have two alkyl or aryl groups.
Alpha Carbon Chemistry: The alpha carbon is the carbon atom adjacent to the carbonyl group. Its significance lies in the acidity of the alpha hydrogens, which can be deprotonated to form enolate ions. These enolates are versatile nucleophiles in various reactions, including:
Aldol Reaction: An enolate ion attacks another carbonyl compound to form a β-hydroxy carbonyl, which can dehydrate to form α,β-unsaturated carbonyl compounds.
Claisen Condensation: An enolate reacts with an ester to form a β-keto ester.
Michael Addition: The enolate ion adds to an α,β-unsaturated carbonyl compound, forming a 1,5-dicarbonyl compound.
Final Exam Review: The final exam review consolidates the topics covered throughout the course. It includes detailed examinations of the reactivity and mechanisms of aldehydes, ketones, and alpha carbon chemistry. Students are expected to understand the principles behind nucleophilic addition, oxidation, reduction, and condensation reactions, as well as the formation and reactivity of enolates. Key concepts include:
The mechanisms and outcomes of the aldol and Claisen condensations.
The stereochemistry and regioselectivity of nucleophilic additions.
The practical applications of these reactions in organic synthesis.