CHEM 212 Chapter Notes - Chapter 19: Wittig Reaction, Ylide, Hemiacetal
Document Summary
19. 8: nucleophilic addition of amines: imine and enamine formation: primary amines (rnh2) added to aldehydes and ketones give imines (r2c=nr) Imines common as intermediates in biological pathways: called schiff bases, formed in a reversible, acid-catalyzed process, secondary amines (r2nh) added to aldehydes and ketones give enamines (r2n- Cr=cr2: reactions are similar, nucleophilic addition reaction, water eliminated from the initially formed tetrahedral intermediate, new c=nu double bond formed, slow at high and low ph, maximum rate at weakly acidic ph around 4-5. 19. 11: nucleophilic addition of phosphorus ylides: the wittig reaction: wittig reaction, aldehydes and ketones converted into alkenes by means of nucleophilic addition, ylide (r2. C-pph3) when added to an aldehyde or ketone gives a 4-membered cyclic intermediate: yields a pure alkene of predicable structure. 19. 13: conjugate nucleophilic addition to , -unsaturated aldehydes and ketones: 1,2-addition, addition of a nucleophile directly to the carbonyl group, conjugate addition/ 1,4-addition, nucleophile to the c=c bond of an , -unsaturated aldehyde or ketone.
