Organic Chemistry

To answer this question, Myron Bender investigated the hydroxide-ion-promoted

hydrolysis of ethyl benzoate, with the carbonyl oxygen of ethyl benzoate labeled

with When he isolated ethyl benzoate from an incomplete reaction mixture, he

found that some of the ester was no longer labeled. If the reaction had taken place by

a one-step direct-displacement mechanism, all the isolated ester would have

remained labeled because the carbonyl group would not have participated in the

reaction. On the other hand, if the mechanism involved a tetrahedral intermediate,

some of the isolated ester would no longer be labeled because some of the label

would have been transferred to the hydroxide ion. By this experiment, Bender pro-

vided evidence for the reversible formation of a tetrahedral intermediate.

PROBLEM 23

If butanoic acid and labeled methanol are allowed to react under acidic conditions,

what compounds will be labeled when the reaction has reached equilibrium?

PROBLEM 24

D. N. Kursanov, a Russian chemist, proved that the bond that is broken in the hydroxide-

ion-promoted hydrolysis of an ester is the acyl bond, rather than the alkyl

bond, by studying the reaction of the following ester with HO->H 2 O:

C¬O C¬O

(^18) O
(^18) O.
698 CHAPTER 17 Carbonyl Compounds I
Myron L. Bender (1924–1988)was
born in St. Louis. He was a professor
of chemistry at the Illinois Institute of
Technology and at Northwestern
University.
HO− H 2 O
H 2 OHO−
18

• −
  −
  −
  OCH 2 CH 3 OH
  O
  18
  OH
  OH


• 
  

  C OCH 2 CH 3
  CH 3 CH 2 O
  18
  OH
  C OCH 2 CH 3
  OH
  18
  O
  C OCH 2 CH 3
  −^18
  OCH 2 CH 3 OH
  18
  −

  
  


• CH 3 CH 2 OH


• 
  


• 
  

  CH 3 CH 2 O
  18
  −
  O
  δ−
  δ−
  C
  18
  OH
  C
  O
  OH
  C
  O
  C
  O
  C
  O
  O
  unlabeled ester