TAILIEUCHUNG - Lecture Organic chemistry - Chapter 23: Ester enolates and the claisen condensation

After attending lectures, reading the text and working assigned problems related to this chapter, students will have acquired the following knowledge and abilities: Know the origin of the unusual acidity of H α atoms located between two carbonyl groups, know the relative acidity of H α in aldehydes, ketones, esters, and 1,3-dicarbonyls; given starting material and reaction conditions, predict the major product that will form;. | Chapter 23: Ester Enolates and the Claisen Condensation Recall the aldol addition: Can we do this with ester enolates? The Claisen Condensation Driven by deprotonation of 3-oxoalkanoate (“β–ketoester”). Endothermic as written “Ketoester” versus two esters Mechanism: Addition-Elimination Has to be the same or transesterification will occur Acidic Claisen Products of Claisen condensation are alkyl 3-oxoalkanoates (IUPAC), common name β-keto-esters and, generally, β-dicarbonyl compounds The hydrogens between the two carbonyls are unusually acidic: Due to inductive effect of two carbonyls and resonance in the anion. Low pKas mean that alkoxide or hydroxide can make the enolates stoichiometrically! Acidity of Claisen product is essential to drive the reaction. Without the acidic H, reaction goes in the reverse! No go, starting on the left. Goes from right to left, when starting with the product (made by a different route, as will be seen later). Mechanism of reverse Claisen .

• Hoá học
• Organic chemistry
• Lecture Organic chemistry
• Hóa học hữu cơ
• Bài giảng Hóa học hữu cơ
• Ester enolates
• Caisen condensation
• In this workbook
• experiments are elaborated using small scale glassware and equipments from a Small Lab Kit
• developed at the Department of Chemistry
• Faculty of Science
• Chulalongkorn University in Thailand
• This Small Lab Kit was created as a result of the research project entitled “Chemistry Laboratory Based on Chemical Safety and Pollution Minimization” sponsored by Thai Research Fund (RDG 3 07 2543)
• One of the outcomes of this project is the organic laboratory book entitled “Organic Chemistry Laboratory Based on Chemical Safety and Pollution Minimization” written in Thai by professors from 7 universities in this project
• They compiled
• adjusted and tested the experiments taken from several traditional organic chemistry laboratory books using the prototype of Small Lab Kit
• Currently
• some selected experiments from this Thai organic chemistry laboratory text have further been modified
• rewritten and edited in English as appeared in this workbook
• Some experiments ar
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