Active methylene compound
Active methylene compounds are compounds that have a methylene group between two strong electron withdrawing groups. The groups generally present are nitro,aldehyde,ketone,nitrile.Treatment of these compounds with strong base form enolates which are often used in organic synthesis. The methylene group is called an active methylene group.
Some examples of active methylene compounds are :
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Active methylene compounds show reactions characteristic of the functional groups attached to the methylene group. They also show reactions because of the considerably acidic hydrogens in the active methylene group.
Knoevenagel condensation is a reaction between an active methylene compound and a carbonyl compound in which there is nucleophilic addition of the active methylene compound to the carbonyl group followed by dehydration.
Malonic ester synthesis
The malonic ester synthesis is a chemical reaction where an ester of malonic acid is alkylated at the carbon alpha (directly adjacent) to both carbonyl groups, and then converted to a substituted acetic acid.