Irreversible Enolate
Irreversible Enolate - Related Videos
01:19
Types of Enols and Enolates
0 Views •
2025
Aldehydes and ketones form enols, although only about 1% of the enol is present at the equilibrium for simple monocarbonyl compounds. The enol form is undetectable for acetaldehyde, present as only 1.5 × 10−4 % of acetone, and present as only 1.2% of cyclohexanone. Two kinds of regioisomeric enols are possible for unsymmetrical ketones, and their net composition is 1% at equilibrium. This instability is due to the lower bond energy of C=C than the C=O group. The additional instability of enols...
01:18
Reactivity of Enols
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2023
Enols are a class of compounds where a hydroxyl group is attached to a carbon–carbon double bond, which implies that it is a vinyl alcohol. A carbonyl compound with an α hydrogen undergoes keto–enol tautomerism and remains in equilibrium with its tautomer, the enol form. Usually, the keto tautomer is present in a higher concentration than the enol tautomer due to the higher bond energy of C=O compared to C=C. Moreover, the direction of the keto–enol equilibrium is governed by factors like...
03:50
Irreversible Electroporation: A Technique for Ablating Pancreatic Tumor in Mouse
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2023
This video describes the procedure for performing irreversible electroporation (IRE) for non-thermal ablation of pancreatic tumors in mice. Both subcutaneous (SQ) and orthotopic tumors can be successfully treated with IRE in a highly controlled setting, facilitating various studies post-procedure.
14:05
A Murine Model of Irreversible and Reversible Unilateral Ureteric Obstruction
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Cited by 47 •
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The murine model of irreversible unilateral ureteric obstruction (UUO) is presented together with the model of reversible UUO in which the ureteric obstruction is relieved by anastomosis of the severed ureter into the bladder. These models enable the study of renal inflammation and scarring as well as tissue remodeling.
01:14
Reversible and Irreversible Processes
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2023
The thermodynamic processes can be classified into reversible and irreversible processes. The processes that can be restored to their initial state are called reversible processes. It is only possible if the process is in quasi-static equilibrium, i.e., it takes place in infinitesimally small steps, and the system remains at equilibrium However, these are ideal processes and do not occur naturally. An ideal system undergoing a reversible process is always in thermodynamic equilibrium within...
FAQs
Kinetic control favors the α-position that reacts most readily under the selected conditions. At low temperature, a strong base removes the α-hydrogen from the less hindered site, while limited reprotonation preserves the initially formed lithium enolate. Rapid capture by an electrophile then converts this positional preference into a predictable regioisomer.
LDA serves as a strong, non-nucleophilic base, so it promotes α-deprotonation without being intended to add to the carbonyl compound. Using it at low temperature supports selective removal of the less hindered α-hydrogen. The resulting lithium enolate can then be rapidly exposed to an electrophile before reprotonation becomes effective.
Preventing effective reprotonation preserves the deprotonation choice made during the initial base treatment. This matters because the reaction can retain the regioselectivity established under kinetic conditions instead of losing that preference through repeated proton transfer. The preserved enolate is therefore positioned for selective carbon–carbon bond formation with an added electrophile.
A carbonyl compound is treated with a strong, non-nucleophilic base such as LDA at low temperature. The base removes an α-hydrogen, producing a lithium enolate under conditions that limit reprotonation. An electrophile is then introduced rapidly to trap that intermediate, allowing the selected carbonyl substrate to undergo alkylation, acylation, or aldol addition.
Steric hindrance helps determine which α-hydrogen is removed during kinetic enolate formation. Under the stated low-temperature, strong-base conditions, deprotonation typically favors the less hindered α-position. This preference is especially useful when a carbonyl compound has more than one possible site, because it supports formation of a selected enolate before electrophile trapping.
They are useful when a synthesis requires controlled carbon–carbon bond formation from an aldehyde, ketone, or related carbonyl compound. After selective enolate generation, electrophiles can support alkylation, acylation, or aldol addition. These reactions help assemble more complex molecules while using kinetic control to improve the predictability of regioselective bond construction.