559 / 912
Chapter 16 551
Copyright © 2017 Pearson Education, Inc.
94.
_
OH
CH
2
CH
3
Br
OH
O
Br
2
h
O
1. CH
2. HCl
3
CH
1. CH
2. HCl, H
2
O
3
CO
2
MgBr
NaOCl
CH
3
COOH
0
°
C
95.
a.
This carboxyl group is more acidic, because its conjugate base is more stable since it is closest to the
electron-withdrawing keto group. (Recall that the more stable the base, the stronger its conjugate acid.)
HO
OH
O O
O
b.
The data show that the amount of hydrate decreases with increasing pH until about
pH
=
6
and that
increasing the pH beyond 6 has no effect on the amount of hydrate.
A hydrate is stabilized by electron-withdrawing groups. A COOH group is electron withdrawing, but
a
COO
-
group is less so. In acidic solutions, where both carboxylic acid groups are in their acidic
(COOH) forms, the compound is essentially all hydrate. As the pH of the solution increases and the
COOH groups become
COO
-
groups, the amount of hydrate decreases. Above
pH
=
6,
where both
carboxyl groups are fully in their basic
(COO
-
)
forms, there is no change in the amount of hydrate.
HO
OH
O O
O
HO
OH
O
O
+
H
2
O
oxaloacetic acid
hydrate
HO OH
96.
R'
R
OH O
+
H R'
O
O
R
N N
R
N N
O
−
+
O
−
O
R'
R
H
N N
+
N N
R'
R
O
−
O
+
N N
N
H N
+