Wolff–Kishner reduction (N2H4, KOH, ethylene glycol, heat) converts the aldehyde group to amethyl group in step 4. The synthesis is completed in step 5 by hydrolysis (H3O1) of the acetal-protecting group.17.42We need to assess the extent of resonance donation to the carbonyl group by the pelectrons of thearomatic rings. Such resonance for benzaldehyde may be written asElectron-releasing groups such as methoxy at positions ortho and para to the aldehyde functionincrease the“single-bond character”of the aldehyde by stabilizing the dipolar resonance formsand increasing their contribution to the overall electron distribution in the molecule. Electron-withdrawing groups such as nitro decrease this single-bond character. The aldehyde with the low-est carbonyl stretching frequency is 2,4,6-trimethoxybenzaldehyde; the one with the highest is
This is the end of the preview. Sign up
access the rest of the document.
This note was uploaded on 09/28/2011 for the course CHM 2210 taught by Professor Reynolds during the Fall '01 term at University of Florida.