least stabilized C=O RCCI most stabilized C=O
$$ ! $$ ! $$ ! $$ !
Orbital Overlap in Acid Anhydrides lone pair donation from oxygen stabilizes the carbonyl group of an acid anhydride *the other carbonyl group is stabilized in an analogous manner by the lone pair
: : 1 2 -
least stabilized C=O O RCCI 9 RCOCR' most stabilized C=O
%4 %4 %4 %4
Orbital Overlap in Thioesters R *Sulfur (like chlorine)is a third-row element. Electron donation to C=O from third-row elements is not very effective. Resonance stabilization of C=O in thioesters is not significant
< # , %;4 . . ! :%;4 1 2 % % - #
least stabilized C=O O RCCI 99 RCOCR 。 CSR' most stabilized C=O
$$ ! $$ ! $$ ! $$ ! %