三、羧酸衍生物的结构比较 …酰胺 CH3-NH2 C-N键长： 137.6pm 147.4pm ·酯 H-OCH: CH3-OH C-0键长： 133.4pm 143.0pm 酰氯 Hac-4-cl CH3-CI C-CI键长： 178.9pm 178.4pm
% /012/313 %4 /003/305 %% /167/163
Three Keys to Understanding the Chemistry of Carboxylic Acids Derivatives The key to managing the information in this chapter is the same as always: structure determines properties. The key structural feature is how well the carbonyl group is stabilized. The key property is reactivity in nucleophilic acyl substitution
# ( )) *+ # ( * * ) , # ( - , # . / ) % % 0 - -
Electron Delocalization and the Carbonyl Group .The main structural feature that distinguishes acyl chlorides,anhydrides,thioesters,esters,and amides is the interaction of the substituent with the carbonyl group.It can be represented in resonance terms as:
!"# ! $ 0 % 1
Electron Delocalization and the Carbonyl Group .The extent to which the lone pair on X can be delocalized into C=O depends on: 。 1)the electronegativity of X 。 2)how well the lone pair orbital of X interacts with the zorbital of C=O 变离…览
8 9 :%;4& /# . 9 # 9 %;4 0 % 1
Most Least reactive CHgC-CI stabilized 。9 CH3C-OCCH3 CH2C-SCH2CH3 Least Most reactive CH2C-NH2 stabilized
% &$ ' ' ( $ ' ' ( $ $ ! $ ! &$ $ ! $ !