What is the mechanism of the Claisen condensation reaction?

The mechanism of the Claisen condensation reaction proceeds with the removal of an alpha proton through the action of a strong base to result in the formation of an enolate ion.

What is the difference between Claisen and Dieckmann condensation?

What is the Difference Between Claisen and Dieckmann Condensation? Claisen condensation is a type of coupling reaction in which a carbon-carbon bond forms between two esters or an ester and a carbonyl compound. Dieckmann condensation is a type of ring-forming reaction in which diesters react to give beta-keto esters.

What is Dieckmann condensation reaction for the preparation of Cycloalkanes?

The Dieckmann condensation is the intramolecular chemical reaction of diesters with base to give β-keto esters. It is named after the German chemist Walter Dieckmann (1869–1925). The equivalent intermolecular reaction is the Claisen condensation.

What drives Dieckmann condensation?

The mechanism of the Dieckmann condensation is the same as a Claisen condensation. An alkoxide base removes an alpha-hydrogen from one of the esters to form an ester enolate. The enolate then adds to the carbonyl carbon of the other ester to form a tetrahedral alkoxide intermediate.

What is aldol and Claisen condensation explain the mechanism of it?

Explain the mechanism of Aldol condensation. Aldol condensation is an organic reaction in which an enolate ion reacts with carboxyl compound in order to form a β– hydroxy aldehyde or β– hydroxy ketone. Hydroxide functions as a base and therefore moves the acidic a-hydrogen producing the reactive enolate ion.

What is the thermodynamic driving force for Claisen condensation?

The Claisen Condensation between esters containing α-hydrogens, promoted by a base such as sodium ethoxide, affords β-ketoesters. The driving force is the formation of the stabilized anion of the β-keto ester.

What is Dieckmann ring closure?

The Dieckmann condensation is a base-promoted intramolecular condensation of α,ω-diesters to form cyclic β-ketoesters that can be further transformed into cyclic ketone upon hydrolysis and decarboxylation. Occasionally, this reaction is also known as Dieckmann ring closure.

What is the primary difference between aldol condensation and Claisen condensation?

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.

What is the product formed in Dieckmann reaction?

The Dieckmann condensation is the intramolecular chemical reaction of diesters with base to give β-ketoesters. It is named after the German chemist Walter Dieckmann (1869–1925). The equivalent intermolecular reaction is the Claisen condensation.

Is Dieckmann condensation reversible?

[Note that this reaction is reversible. There is an equilibrium between the tetrahedral intermediate and the starting materials (i.e. the ester enolate + ester).]

What is the driving force of Claisen condensation?

Which is the first step in the mechanism of an aldol condensation reaction?

Aldol reaction: its chemistry and mechanism. Typically, aldehydes and ketones undergo an aldol reaction. This reaction involves 3 basic steps: Step 1: Electrophilic attack of a base at the alpha-carbon (C α​start subscript, α, end subscript) of the aldehyde or ketone to generate an “enolate” carbanion.

What is Stobbe reaction give the mechanism and application?

Stobbe condensation involves reaction of aldehyde or ketone with succinic ester in the presence of basic catalyst like sodium hydroxide or potassium tertiary butoxide to form alkylidene succinic acid. This reaction limited to α – ω diester ester group at 1st carbon and last carbon.

Why is a full equivalent of base necessary for the success of the Claisen condensation of an ester?

(ii) In contrast to the catalytic base used for aldol reactions, a full equivalent of base (or more) must be used for the Claisen condensation. The extra base is needed because beta-ketoesters having acidic hydrogens at the alpha-carbon are stronger acids (by about 5 powers of ten) than the alcohol co-product.

What is Stobbe condensation?

Stobbe Condensation The condensation reaction of aldehyde or ketone with succinic ester in the presence. of basic catalyst like sodium hydroxide or potassium tertiary butoxide to form alkylidene. succinic acid is known as Stobbe condensation.

What determines whether a reaction is an aldol or Claisen reaction?

Whereas the Aldol reaction is the addition of enolates to aldehydes or ketones, this reaction is the addition of enolates to esters. It’s called the Claisen condensation. It follows the same 2 first steps that the Aldol reaction does. First, we use a strong base – in this case, EtO(-) , to form the enolate.

What is benzoin condensation reaction?

Definition– Benzoin condensation reaction can be defined as the reaction between two kinds of aromatic aldehydes especially benzaldehyde, in the presence of some catalyst (either nucleophile or heterocyclic) to form an aromatic parent compound.

Why is Claisen condensation important?

Claisen Condensation of Thioesters: A Biochemical Process A variation on the Claisen condensation is an important biochemical reaction responsible for carbon–carbon bond formation in the biosynthesis of fatty acids. Also, a reverse Claisen condensation occurs in the catabolism of fatty acids.

What is the rate determining step in aldol condensation?

Previous works indicated that enamine formation and/or carbon-carbon bond formation is the rate-determining step [19] [20] [21][22].

What type of reaction is Dieckmann condensation?

Dieckmann condensation. The Dieckmann condensation is an organic reaction used to form a carbon-carbon bond between two tethered ester groups using an alkoxide base in alcohol to make a cyclic β-keto ester. This reaction is essentially an intramolecular form of the Claisen condensation.

How does a Dieckmann reaction form a six-membered ring?

Here is the mechanism for a Dieckmann reaction forming a six-membered ring: The product is a cyclic β-keto ester which has a very acidic alpha hydrogen.

Can cationic Dieckmann-type be used for β-lactams?

Cationic Dieckmann-type was performed on β-lactams such as 247 to give synthetically useful fused bicycles 248 ( Scheme 68 ). 180 Under these conditions, a silyl enol ether of the β-lactam may be formed, which in turn, upon activation with TBAF, leads to a Dieckmann condensation. Scheme 68.

Who discovered Diekmann’s reaction?

The reaction was discovered by German chemistry Walter Diekmann in 1894. The reaction has a same intermolecular mechanism as Claisen Condensation.