Figure 6.9. Imine Formation
Ammonia is added to the carbonyl, resulting in the elimination of water, and generating an imine.Imines and related compounds can undergo tautomerization to form enamines, which contain
both a double bond and a nitrogen-containing group. This is analogous to the keto–enol
tautomerization of carbonyl compounds and will be explored in Chapter 7 of MCAT Organic
Chemistry Review.
CYANOHYDRINS
Hydrogen cyanide (HCN) is a classic nucleophile on the MCAT. HCN has both triple bonds and an
electronegative nitrogen atom, rendering it relatively acidic with a pKa of 9.2. After the hydrogen
dissociates, the nucleophilic cyanide anion can attack the carbonyl carbon atom, as shown in Figure
6.10. Reactions with aldehydes and ketones produce stable compounds called cyanohydrins once
the oxygen has been reprotonated. The cyanohydrin gains its stability from the newly formed C–C
bond.
Figure 6.10. Cyanohydrin Formation
Cyanide functions as a nucleophile, attacking the carbonyl carbon and generating a cyanohydrin.