Enols and Enolates
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Chemistry involving enols and enolates happens where?
On the carbon next to the double bond
What does tautomerism mean?
Intramolecular proton transfer Moved from one part of a molecule to another
What is an enol?
A molecule with C=C bond with an OH group joined directly to it
What is enolization?
The conversion of a carbonyl compound into its enol
Why is the enol less stable than the ketone?
Enols bond swaps are unfavourable C=O and C-H which is 1160 to C=C and O-H which is 1120
What can enol formation be catalysed by?
Both base and acid
Is it faster to form an enol by base or acid?
Base
Do enols and enolated act as electrophiles or nucleophiles?
Nucleophiles as they are electron rich
What can the enol-type species enamine (Draw it) be formed by?
an electophilic imine
What can the enol-type species nitronate (draw it) be formed by?
Nitro alkane Et3N (base)
What are some examples of stable enols?
1,3-dicarbonyl compounds as there is increased conjugation Ph-enol - enol form is aromatic and therefore much more stable
Why do reactions occur through the carbon and not the C=O?
In order to keep the stable C=O
What condition is needed for enolate alkylation?
Strong base with a pKaH value higher than the pKa of the carbonyl compound
What base is usually used for enolate alkylation and why?
LDA (Lithium diisopropylamide) Has large isopropyl groups added as it needs to act as a base but not the nucleophile so it wont attack the C=O
What is the aldol reaction?
Enolates reacting with aldehydes and ketones to form an adol product
What reagents are needed to replace C=O with C=C?
Ph3P-CH2 Et2O