What can Enolates attack?
The enolate attacks the electrophilic carbonyl carbon of oxaloacetate ion.
Can an enolate attack a double bond?
A most important property of enolate anions, at least as far as synthesis is concerned, is their excellent nucleophilicity, which enables them to add to double bonds and to participate in nucleophilic substitution.
Why is an enolate a good nucleophile?
Because the enolate is a delocalized anion, it can be protonated in two different places to get two different conjugates. Enols typically are not seen because of a rapid equilibrium with that related carbonyl compound. Enamine, enolates and enols are all turbo-charged nucleophiles.
Which of the following carbonyl compound undergoes aldol condensation?
All carbonyl compounds containing α−H or α−D undergo aldol condensation. In given example, benzaldehyde does not contain α−H to -CHO, hence does not undergo aldol condensation.
Can benzaldehyde undergo aldol condensation?
Benzaldehyde does not undergoes aldol condensation.
What does an Enolate act as?
An enolate ion is the anion that forms when a proton is removed next to a carbonyl. Other oxygen anions are also able to act as strong bases, unless there is some resonance factor that delocalises the anion and makes it less reactive. Methoxide ion and butoxide ion are also common strong bases.
How does the Enolate react with bromine?
The enolate anion attacks the bromine molecule yielding a mono-substituted bromoketone. The reaction continues until the tribromoketone is formed. The hydroxide then attacks directly at the carbonyl and a tribromomethyl anion is lost.
Which carbon on the enolate is nucleophilic?
alpha carbon
The nucleophilic atom is the alpha carbon. Although that carbon can be thought of as a double bonded carbon, with no lone pair, that position is motivated to donate electrons because of pi donation from the oxygen (or nitrogen).
Which carbonyl compound Cannot form an enolate ion in an aldol condensation reaction?
q Since carbonyl compounds which do not have alpha hydrogens can not form an enolate, they cannot undergo the aldol reaction. Therefore the simplest aldehyde, methanal (formaldehyde) cannot undergo the aldol reaction.
Which compound does not give aldol condensation?
The correct option as per the compound will not give aldol is Formaldehyde and Pivaldehydethey do not undergo aldol condensation reaction because both formaldehyde and pivaldehyde does not contain alpha hydrogen atom. Formaldehyde does not undergo aldol condensation, but acetaldehyde does.
How do you catalyze condensation of aldol?
An acidic or basic solution can catalyze the condensation of aldol. By bases such as hydroxide ions and alcoxide ions, an aldehyde is partially converted to its enolate anion. The enolate is subjected to nucleophilic addition to the carbonyl group in a solution that contains both an aldehyde and its enolate ion.
What is the general reaction between aldol and carbonyl?
Overall the general reaction involves a dehydration of an aldol product to form an alkene: Molecules which contain two carbonyl functionalities have the possibility of forming a ring through an intramolecular aldol reaction. This is where the “head” of the molecule “bites its own tail”. In most cases two sets of α α hydrogens need to be considered.
Who discovered aldol condensation reaction?
In organic synthesis, aldol condensations are a very important class of reactions. Charles – Adolph Wurtz and Alexander Porfyrevich Borodin discovered the reaction independently in 1872. The name aldol was chosen because there is often an aldehyde and an alcohol group in the product of an aldol condensation.
Why are ketone aldol reactions thermodynamically favorable?
The additional stability provided by the product’s conjugated carbonyl system makes some thermodynamically favorable ketone aldol reactions (# 4 & 5) and stereoisomer (E & Z) mixtures are obtained from reaction #4. Reaction #5 is an interesting example of a reaction of intramolecular aldol; these reactions create a new ring.