Organic Chemistry

Section 4.5 Addition of Water and Addition of Alcohols 153

a. How many transition states are there?

b. How many intermediates are there?

c. Which is more stable, the protonated alcohol or the neutral alcohol?

d. Of the six steps in the forward and reverse directions, which are the two fastest?

PROBLEM 9

Give the major product obtained from the acid-catalyzed hydration of each of the follow-

ing alkenes:

a. c.

b. d.

Addition of Alcohols
Alcohols react with alkenes in the same way that water does. Like the addition of
water, the addition of an alcohol requires an acid catalyst. The product of the reaction
is an ether.

The mechanism for the acid-catalyzed addition of an alcohol is essentially the same
as the mechanism for the acid-catalyzed addition of water.

PROBLEM 10

a. Give the major product of each of the following reactions:

b. What do all the reactions have in common?

c. How do all the reactions differ?

H+

CH 3 CCH 2 + CH 3 OH

CH 3

CH 3 CCH 2 + HBr

CH 3

H+

CH 3 CCH 2 + H 2 O

CH 3

CH 3 CCH 2 + HCl

CH 3

CH 3 CH CH 2 + CH 3 OH CH 3 CH CH 2

OCH 3 H

2-methoxypropane

H+

CH 2

CH 3 CH 2 CH 2 CH“CH 2 CH 3 CH 2 CH 2 CH“CHCH 3

CH 3 CH CH 2 + H OCH 3 CH 3 CHCH 3 + CH 3 OH CH 3 CHCH 3

OCH 3

H

H

slow fast

fast

CH 3 OH

CH 3 CHCH 3 + CH 3 OH

OCH 3 H

+

+

+ +

an ether