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 type of reaction is a Claisen reaction?
The Claisen condensation reaction is an organic coupling reaction that results in the formation of a C-C bond between either a single ester and one carbonyl compound or between two esters. The reaction proceeds when a strong base is present and the product of the reaction is a beta-keto ester or a beta-diketone.
What is Claisen condensation with example?
The Claisen condensation is the ester analogue of the Aldol condensation. The reaction involves an ester enolate reacting with another molecule of the ester. … A simple example of a Claisen condensation is the reaction of ethyl ethanoate which is shown below in two representations.
What is the product of a Claisen condensation?
The product of a Claisen condensation is a beta-keto ester, which is a significantly stronger acid (pKa = 11) than either alcohols (pKa = 16-17) or esters (pKa = 25).
How do you do Claisen rearrangement?
An example for the Claisen rearrangement reaction of an allyl vinyl ether is given below. The reaction can also be performed with allyl phenyl ethers. In this rearrangement, the regio selectivity is affected by the meta-substitution. The [3,3]-sigmatropic rearrangement of the allyl phenyl ether gives an intermediate.
How do you stop aldol condensation?
Therefore, chemists have adopted many ways to prevent this from occurring when performing a crossed aldol reaction.
- The use of a more reactive electrophile, and a non-enolizable partner.
- Making enolate ion quantitatively.
- Silyl enol ether formation.
Which is an example of claisen Schmidt reaction?
Claisen Schmidt condensation: When a base-catalyzed cross aldol condensation between an aromatic aldehyde and an aliphatic aldehyde or a ketone is called Claisen Schmidt condensation or simply Claisen reaction. For example, Benzaldehyde reacts with Acetaldehyde to form 3-Phenylprop-2-en-1-al.
Which is the starting material used in claisen Schmidt reaction?
The most widely used base catalyst is NaOH because of the greater yield [4]. Some base catalysts that have been used in the Claisen-Schmidt reaction are KOH (yield 88-94%) [5], Ba(OH)2 (yield 88-98%) [6], NaOH (yield 90-96%) [7].
Which intermediate is involved in Claisen and condensation?
In the ‘main’ part of the Claisen condensation mechanism, the α-carbon of a second acetyl CoA is deprotonated (step 1), forming a nucleophilic enolate. The enolate carbon attacks the electrophilic thioester carbon, forming a tetrahedral intermediate (step 2) which collapses to expel the cysteine thiol (step 3).
What is Claisen Smith reaction?
The Claisen-Schmidt reaction (crossed-aldol reaction) is a condensation reaction of aldehydes and carbonyl compounds leading to β-hydroxycarbonyl compounds and it has played an important role in synthetic organic chemistry [1,2,3,4,5,6].
What is the name given to the Claisen reaction between two different esters?
A Claisen condensation between two different esters is called a crossed Claisen condensation.
Is Claisen condensation in JEE mains?
Claisen condensation is one of the most important reactions of esters included in JEE syllabus. It is generally described as an ester analogy of aldol condensation.
Why strong base is added in Claisen condensation?
The base used must not interfere with the reaction by undergoing nucleophilic substitution or addition with a carbonyl carbon. For this reason, the conjugate sodium alkoxide base of the alcohol formed (e.g. sodium ethoxide if ethanol is formed) is often used, since the alkoxide is regenerated.
What is the driving force of the 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 catalyst is used in Claisen condensation?
Although many Claisen condensations are carried out with a full equivalent of the alkoxide base, an effective alternative procedure, used in reaction #5, uses sodium hydride (NaH) together with a catalytic amount of alcohol.
Is claisen exothermic?
The Claisen rearrangement is an exothermic, concerted (bond cleavage and recombination) pericyclic reaction.
Is Claisen condensation and Claisen rearrangement same?
Claisen condensation, not to be confused with Claisen rearrangement, is the reaction of an enolizable ester with a strong base to give a β-ketoester.
What is meant by Beckmann rearrangement?
An acid-induced rearrangement of oximes to give amides. This reaction is related to the Hofmann and Schmidt Reactions and the Curtius Rearrangement, in that an electropositive nitrogen is formed that initiates an alkyl migration.
Who discovered the aldol condensation?
evich Borodin The aldol reaction was discovered by Aleksandr Porfir’evich Borodin in 1872 where he first observed the formation of aldol, 3-hydroxybutanal, from acetaldehyde under the influence of catalysts such as hydrochloric acid or zinc chloride.
Is heat required for aldol condensation?
Careful control of reaction temperature is critical because high temperatures promote aldol condensation. The optimum temperature depends on the nature of the aldehyde or ketone. Typically, heating the reaction mixture results in aldol condensation.
Is heat necessary for aldol condensation?
In most cases two sets of α hydrogens need to be considered. As with most ring forming reaction five and six membered rings are preferred. As with other aldol reaction the addition of heat causes an aldol condensation to occur.
What is the use of Claisen condensation?
The Claisen condensation of ethyl acetate yields ethyl acetoacetate. This readily available compound and other β-keto esters formed by Claisen condensations are used as intermediates in the synthesis of alkyl derivatives of ketones.
What functional groups are involved in a Claisen condensation?
The Claisen condensation is a carbon–carbon bond forming reaction that occurs between two esters or one ester and another carbonyl compound in the presence of a strong base, resulting in a β-keto ester or a β-diketone. It is named after Rainer Ludwig Claisen, who first published his work on the reaction in 1887.
What is the other name for the intramolecular Claisen condensation?
What is the other name for the intramolecular Claisen condensation? Explanation: Diester compounds can be used to give an intramolecular Claisen condensation which is known as the Dieckmann condensation.
Graduated from ENSAT (national agronomic school of Toulouse) in plant sciences in 2018, I pursued a CIFRE doctorate under contract with Sun’Agri and INRAE in Avignon between 2019 and 2022. My thesis aimed to study dynamic agrivoltaic systems, in my case in arboriculture. I love to write and share science related Stuff Here on my Website. I am currently continuing at Sun’Agri as an R&D engineer.