The carbonyl carbon of an aldehyde or ketone is attacked by nucleophiles because

  • A. it carries a partial positive charge, oxygen being more electronegative
  • B. it carries a partial negative charge
  • C. it has a lone pair of electrons
  • D. it is bonded to hydrogen

Explanation

The carbon to oxygen double bond is strongly polarised towards oxygen, leaving the carbon electron deficient and open to attack by a species with a lone pair. This is why the characteristic reaction of the carbonyl group is nucleophilic addition, in contrast with the electrophilic addition of alkenes, whose double bond is non polar. The oxygen carries the lone pairs and the partial negative charge.

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