Aldol Condensation In some cases, the adducts obtained from the Aldol Addition can easily be converted (in situ) to α,β- unsaturated carbonyl compounds, either thermally or under acidic or basic catalysis. The formation of the conjugated system is the driving force for this spontaneous dehydration. Under a variety of protocols, the condensation product can be obtained directly without isolation of the aldol. The ...
Carbonyl Condensation Reactions The Aldol Reaction • Recall that the characteristic reaction of aldehydes and ketones is nucleophilic addition. An aldol reaction is a nucleophilic addition in which an enolate is the nucleophile. Figure 24.1 The aldol reaction—An example of nucleophilic addition 2 Carbonyl Condensation Reactions The Aldol Reaction • A second example of an aldol reaction is shown with propanal as the ...
Carbonyl Condensation Reactions The Aldol Reaction • In the aldol reaction, two molecules of an aldehyde or ketone react with each other in the presence of a base to form a -hydroxy carbonyl compound. 3 Carbonyl Condensation Reactions The Aldol Reaction • In the aldol reaction, two molecules of an aldehyde or ketone react with each other in the presence of a base to form ...
The Zimmerman Traxler Model Overview: The Zimmerman-Traxler model is invoked to rationalize the unexpected stereochemical outcomes of certain aldol reactions, such as the Reformatsky and Ivanov reactions. It models the stereochemistry of the products, based on the steric hindrance in the possible six-membered transition states in the aldol condensation reactions. Enolate Formation Wiki Page: Aldol Reaction- Traxler Model 1. Zimmerman and Traxler, JACS, 1957 79 ...
Introduction Functional group pK • The acidity of organic compounds is often determined a by neighboring groups because they can help stabilizing Alkane ~50 the resulting anion (i.e., halogen, nitro, etc.) because of Ester ~25 their electronegative character or due to resonance Aldehyde/ketone ~18-20 (i.e., enolate in carbonyl compounds) Alcohol ~15-19 Nitro ~8-10 • For instance, the presence of a carbonyl group ...
Schedule of day: PPE check – at the door Pre-lab check – at the door Quiz Recitation – Synthesis of Dibenzalacetone Safety – Put bags away – Goggles – Gloves – Lab Coat LAB! Due Dates Today – Synthesis of Banana Oil Report due – End of lab – notebook copy pages (Synthesis of dibenzalacetone) Next Week – At the beginning of lab – Synthesis ...
Course Overview I • Why do students take chemistry labs? • Most lecture courses provide a theoretical background in general and in organic chemistry but usually do not consider much many of the practical aspects of an experiment. • Conducting an experiment in lab is often times much more complicated than chemistry conducted on paper because many details have a significant impact on the overall ...
. Carbanion I Acidity of α-Hydrogens; the Enolate Anion The α-hydrogen in a carbonyl compound is more acidic than a normal hydrogen bonded to a carbon atom. There are two reasons. First, the carbonyl carbon carries a partial positive charge. Bonding electrons are displaced toward the carbonyl carbon and away from the α-hydrogen (shown by the red arrows below), making it easy ...
Carbonyl Condensation Reactions The Aldol Reaction • In the aldol reaction, two molecules of an aldehyde or ketone react with each other in the presence of a base to form a -hydroxy carbonyl compound. 2 Carbonyl Condensation Reactions The Aldol Reaction • The mechanism of the aldol reaction occurs in three steps. 3 Carbonyl Condensation Reactions The Aldol Reaction • The aldol reaction is a ...
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