Knoevenagel condensation between benzaldehyde and malononitrile yields which product?

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Knoevenagel condensation between benzaldehyde and malononitrile yields which product?

Knoevenagel condensation forms a carbon–carbon double bond by linking an aldehyde’s carbonyl carbon to the activated methylene carbon of malononitrile. Deprotonation of malononitrile gives a stabilized carbanion that attacks benzaldehyde, forming a β-hydroxynitrile intermediate that dehydrates to give an α,β-unsaturated nitrile. The product is benzylidene malononitrile, with the structure Ph–CH=C(CN)2. This explains why the other described adducts or esters don’t arise in this reaction—the process directly yields the conjugated alkene, not a saturated addition product or an ester.

Knoevenagel condensation forms a carbon–carbon double bond by linking an aldehyde’s carbonyl carbon to the activated methylene carbon of malononitrile. Deprotonation of malononitrile gives a stabilized carbanion that attacks benzaldehyde, forming a β-hydroxynitrile intermediate that dehydrates to give an α,β-unsaturated nitrile. The product is benzylidene malononitrile, with the structure Ph–CH=C(CN)2. This explains why the other described adducts or esters don’t arise in this reaction—the process directly yields the conjugated alkene, not a saturated addition product or an ester.

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