Organic Chemistry

1030 CHAPTER 24 Catalysis

Problems

26. Which of the following two compounds would eliminate HBr more rapidly in basic solutions?


27. Which compound would form a lactone more rapidly?

a. b.

28. Which compound would form an anhydride more rapidly?


29. Which compound has the greatest rate of hydrolysis: benzamide,o-carboxybenzamide,o-formylbenzamide, or
    o-hydroxybenzamide?


30. Indicate the type of catalysis that is occurring in the slow step in each of the following reaction sequences:

a.

b.

31. The deuterium kinetic isotope effect for the hydrolysis of aspirin is 2.2. What does this tell you about the kind of
    catalysis exerted by the ortho-carboxyl substituent? (Hint:It is easier to break an bond than an bond.)


32. Draw the pH–activity profile for an enzyme with one catalytic group at the active site. The catalytic group is a general-acid catalyst
    with a of 5.6.


33. A complex catalyzes the following hydrolysis of the lactam shown:

Propose a mechanism for the metal-ion catalyzed reaction.

Co^2 +

O

+ H 2 O

CH 2

N

NH

R 2 NCH 2 N

O

CH 2

−OCCH

2 CH 2 NCH 2 NH 2

R 2 NCH 2 N

Co^2 +

pKa

O¬H O¬D

1 kH 2 O>kD 2 O 2

slow

C COH HO

OH O−

HO OH

O

+OH

COH

OH

O

+

CH 3 CH 2 SCH 2 CH 2 Cl CH 2 CH 2 CH 3 CH 2 SCH 2 CH 2 OH

CH 2 CH 3

S+

Cl−

slow HO−

+

H CH 2 C

H

O Br

or

O

CH 2 CO−

O

H C

H

O Br

O

CO−

O

or

COOH COOH

OH OH

CH 3

H H

or

OH OH

H COOH H 3 C COOH

−O CH 2 Br

H

or CH 2 Br

O− H