What is the knoevenagel condensation catalyzed by?

Conclusion. The Knoevenagel condensation reaction of acetylacetone with benzaldehyde catalyzed by piperidine in methanol solvent takes place via carbinolamine, iminium, and enolate intermediates.

What catalyst is used in Knoevenagel reaction?

Sakaiused Indium (III) Chloride as a catalyst in reaction of acetic anhydride and aldehyde which is followed by Knoevenagel reaction.

What is the role of piperidine?

Used to make rubber and as a solvent. Piperidine is an azacycloalkane that is cyclohexane in which one of the carbons is replaced by a nitrogen. It has a role as a reagent, a protic solvent, a base, a catalyst, a plant metabolite, a human metabolite and a non-polar solvent.

Which intermediate is formed in Knoevenagel reaction?

Knoevenagel condensation is nucleophilic addition of an active hydrogen compound to a carbonyl group followed by a dehydration reaction in which a molecule of water is eliminated (hence Condensation). The product is often an alpha, beta conjugated enone. 6.  Step:1: An enol intermediate is formed initially.

Why is it called aldol condensation?

However, the aldol reaction is not formally a condensation reaction because it does not involve the loss of a small molecule. This reaction is named after two of its pioneering investigators Rainer Ludwig Claisen and J. G. Schmidt, who independently published on this topic in 1880 and 1881.

Which gas is used in Knoevenagel reaction?

The Hantzsch pyridine synthesis, the Gewald reaction and the Feist–Benary furan synthesis all contain a Knoevenagel reaction step. The reaction also led to the discovery of CS gas.

Which base is use in Knoevenagel reaction?

Knoevenagel condensation (Scheme 1) is a widely used reaction in research and industry and has been of importance for several pharmaceutical products. Generally this reaction is catalyzed by organo-bases, such as pyridine or piperidine.

Which drug contain piperidine ring?

Use in pharmaceutical drugs Many pharmaceutical drugs contain a piperidine ring because the group tends to impart pharmacokinetics such as water solubility and bioavailability. Examples of drugs that contain piperidines include mesoridazine, thioridazine, haloperidol, droperidol, PCP, benperidol, and risperidone.

Which is used in Knoevenagel reaction?

The Knoevenagel reaction is a modified Aldol Condensation with a nucleophilic addition between an aldehyde or ketone, and an active hydrogen compound in the presence of a basic catalyst, resulting in C–C bond formation. The active hydrogen compound contains a C–H bond which can be deprotonated by the basic catalyst.

What is the difference between aldol condensation and Claisen condensation?

The key difference between aldol condensation and Claisen condensation is that aldol condensation describes the addition of enolates to aldehydes or ketones, whereas Claisen condensation describes the addition of enolates to esters. Claisen condensation progresses with an aldol condensation as a part of it.

What is the difference between aldol condensation and Cannizzaro reaction?

The difference between aldol condensation and Cannizzaro reaction is that aldol condensation is the coupling reaction while Cannizzaro reaction is redox reaction.

What is the mechanism of the Knoevenagel condensation?

Mechanism of the Knoevenagel Condensation. An enol intermediate is formed initially: This enol reacts with the aldehyde, and the resulting aldol undergoes subsequent base-induced elimination: A reasonable variation of the mechanism, in which piperidine acts as organocatalyst, involves the corresponding iminium intermediate as…

What is the name of the aldol condensation?

It is important to distinguish the aldol condensation from other addition reactions of carbonyl compounds. When the base is an amine and the active hydrogen compound is sufficiently activated the reaction is called a Knoevenagel condensation. In a Perkin reaction the aldehyde is aromatic and the enolate generated from an anhydride.

What kind of reaction is a Claisen condensation?

A Claisen condensation involves two ester compounds. A Dieckmann condensation involves two ester groups in the same molecule and yields a cyclic molecule A Henry reaction involves an aldehyde and an aliphatic nitro compound.

What happens in the condensation of aldehydes?

The condensation of carbon acid compounds with aldehydes to afford α,β-unsaturated compounds. The Doebner Modification, which is possible in the presence of carboxylic acid groups, includes a pyridine-induced decarboxylation.